CA1281475C - Organopolysilazane precursors to silicon nitride-rich mixed sic/se3n4 - Google Patents

Abstract

ABSTRACT

A method for preparing preceramic polymers is disclosed.
This method includes the steps of reacting in solution anhydrous ammonia with a mixture of R1SiHX2 (where R1 is a lower alkyl group having from 1 to about 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to about 6 carbon atoms, a substituted or unsubstituted lower alkenyl group having from 2 to about 6 carbon atoms, or a substituted or unsubtituted lower aryl group having from 6 to about 10 carbon atoms, and X is a halogen) and RSiX3 (where R is H, a lower alkyl group having from 1 to about 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to about 6 carbon atoms, a substituted or unsubstituted lower alkenyl group having from 2 to about 6 carbon atoms, or a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms), thereby forming a mixture of precursor polymers; and reacting the precursor polymers in the presence of a basic catalyst capable of deprotonating the NH functions in the precursor polymers to form the preceramic polymer. Preferably, this preceramic polymer is treated with an electrophile compound. Pyrolyzing the polymer in an inert gas stream or ammonia atmosphere to form a ceramic material is also disclosed.

Description

7~
This application is a division oE co-pending Canadian Patent Application, serial no. 545,027 filed August 21, 1987 and entitled M~THOD FOR USING
ORGANOPOLYSILAZANE PRECURSORS T() FORM NEW PRECERAMIC
POLYMERS AND SILICON NITRIDE-RICH CERAMIC MA~ERIALS.
The present invention relates to a process for preparing silicon-containing preceramic polymers that is particularly useful for making silicon nitride and silicon nitride/silicon carhide and silicon oxynitride ceramics and for their pyrolysis to such ceramic materials~
There is a great deal of interest in preceramic polymer materials, which,can be pyrolyzed to yield silicon carbide, silicon nitride, silicon oxynitride and other silicon-based ceramic materials. R.W. Rice, Amer, Ceram.
SOG . BU11 ., 62 ; 889-B92 (1983). Applications for such polymers include, among others.
1. formation into complex shapes and subsequent pyrolysis to give a ceramic material of the same shape;
2. spinning into continuous fibers whose subsequent pyrolysis yields ceramic fibers;
3. as a matrix material for carbon or ceramic fibers, or as a binder for ceramic powders (with subsequent pyrolysis to form a ceramic body);
4. oxidation-resistant coatings on otherwise oxidizable materials (such as carbon/carbon composites) -after the polymer coating is made, it can be pyrolyzed to give the resistant ceramic coating;
5. infiltration of porous ceramic bodies such as ones obtained from reaction-sintered silicon nitride by the polymer itself (if ~ ,, ~JS~";

4~5 liquid) or by a solutlon of ehe polymer, with ~ubsaqu~nt pyrolysi~ to for~ a cera~ic, resulting in b0tt~r str~ngth, oxldation rasistance, etc., of the body; and 6. ~ormation of thin films of thc ceraMlc Msterial for elactronics appllcatlon~.
For lnstance, Penn ~t al., ~ es,~ 3751-61 (19S2) describe thc preparation of silicon carbide~sllicon nltride fibers irom a polycarbosilaYane precursor. Tr~s(N-methylamino) methylsilane monomer was formed by reaction of monomethylamine and methyltrichloros$1ane in dry p~troleum ether and a polycarbo~ilazane resln was formed by passing the monomer over glass Raschig rings at 520C. The brlttle polymer was soluble in methylene chloride and chloroform, etc. This product was spun into fibers, crosslinked in air and then pyrolyzed to give ceramic fibers.
Other polymer precursors for forming silicon carbide and silicon nitride ceramics hava been described in U.S. Pat. Nos. 3,108,985;
3,353,S67; 3,892,583; 4,310,651 and 4,312,970. Ihesa linear or crosslinked polymers and processes for producing ceram~c materials have generally been found to be deficient in one or ~ore ways.
S. Ya~ima, ~ C~ c ~L , 6?: 893-898; 903 (1983) discloses using (CH3)2SiCl2 as a qtarting materisl for a preceramic poly~er for tha preparation of S~C-containin~ caramics.
The polymer of Ya~im~ is prepared by ~odium metal condensation of (CH3)2SiCl2 to re~ult in a poly~ilanc, -[(C~3)2Si]n- ~n i9 approximately 30). Thic polysilan0 can then for~ either a "Mark I" poly~er or a ~ark III" polym~r dependin~ upon tha treatmeat used. Heating in an autoclave under argon at 100 kPa at 450V-470C for 14 hours results In a Mark I polymer while adding a few pcrcent of a polyborodiphenylsiloxane and h~ating under nitrogan at ambient pressure at 350C for 10 hours results in the Mark III poly~er. In either case, the polysilicon backbone is L~ 7~

convarte~ to a poly~arlc chain in which the main repeat unit is:

I-li-CH~

Ths Mark I polymer also contains ~ome -[(CH3~2SiCH2]- unlts. Th~
Mark III polymer contain~ so~c Si-Si bondq in the form -[(C~3~2Si-Si(CH3)2ln((n 2-8) units and a low p~rcen~age oi [(C6H5)2SiO] units~ These preceramic polymers can be processsd to glve ceramic flbers contalning SiC, soms free carbon and some SiO2. Howevsr, there are problems assoclated with these polycarbosilane-deri~ed ceramlcs. They have a tendency to crystallize below 1200C, they have a SiO2 content as a result of an oxidativa cure step, and free carbon and a relatively low cer~mic yield is obtained upon the$r pyrolys~s for a com~ercial product. ~hile the ceram~c yield for the Mark III polymer i 68%, the yield for the Mark I
polymer is only 54~.
Silicon oxyni~rides are another i~portant group of ceramic~. This ceramic material has most of the same advantages as sllicon nitride, but is exper-ted to have a better oxidation stability. These are h~gh re~ractory matarials able to withstand t~mperatureq up to about 1500C before decomposing. Although K. Okamura at al, Çhe~. Let~.
(1984): 2059-2060 (See also K. Oka~ura et ~l, Fi~th Int. Con~. on L ~9 ~ L~ , July 29 - Augu~t 1, 1985, ProcQedings: 53S-542), reported obt~ining silicon oxynitrid~ fibers after pyrolysis under ammonia, of SiQ2-containing polycarbosilan2s (having [CH35i(H~CH2J as the ma~or rspeat unit3, this WRs an expensive and inefficient process.
U.S. Pstent 4,482,669 issued Novembar 13, 1984, describes organopolysilazane preceramic poly~ers whose pyrolysis gives a mixture of silicon carbide and ~ilicon nitrlde wherein, generally, neither component is in large excass over the other. Th~se polymers were obtained by the reaction of a base (such as an alkali metal hydride, amide, etc.) with the = onolysis product of a dihalosilane, for 14 7~;

~xflmplo, CH3SlHC12 which r~sults in a poly~arlz~tion procas3bcliQved to lnclude the ~çhY~rocY~lodim~riz~ion (DHCD) reAction ~hown in cq. A.

base / N
2 -~i.7~ 2 H~ ~ /si Si ~ (A) H H \ N

The action of a caealytic ~mount of the bsse on thssa cyclic oligomers l$nks them togeth0r via such cyclodi~ilazan~ units into 8 sheet-llke array. Treatment of, for example, the CH3SiHC12 ammonolysis product by th~ base, usually KH (9.5-4 mol perc~nt based on CH3SiHNH units), pro~idP~ a polysilazane lntermediate of type [~CH3SiHN~)a(CH3SiN)b~CH3SiHNK)C~n, l.e. a "living~
polymer which still contains reactlve silylamide functions. This "living" poly~llazane intermedlate c~n bc tr~sted with a suitabla slectrophil~, such a~ C~3I or a chloro~ n~, to "n~tralizs" the reactive ~ilylamide functions. Ultimat~ly, on pyrolysis in an inert gas s~ream ~N2 or Ar) to 1000C, the yield of ceramic r2sidu~ is high (80-85~. A typical composition of such ~ cer~mic material is 0.9 Si3N4 ~ 1.3 SiC + 0.75 C or, on a weight ~ basls, 67%
Si3N4, 28~ SiC and 5~ C.
U.S. Patent Applicaelon Serial ~o~. 756,353, fil0d July lR, 198~, and 781,934, filed Septemb~r 30, 1985 describe methods for converting organosillcon polymers contatning SL-H repeat units to ne~ and u~eful preceramic poly~ers and ceramic materials. The prec~ramic poly~ers, which are prepared by reactine elth~r an organopolysilan~ or a polycarbosilane with a silylamide result in preceramic polymers whose pyrolysis gives a ~ixture of silicon carbide and silicon nitride ceramic materisls, which ara ~enerally r~ch in silicon carbide.
It would ba useful to have a polymer precursor that is form~d from readily available and relatlvely inexpensiv~ startin~ materials, ~hat is stab1e at room temperaturc, ls fusible and/or solublc in ;

organic solvents and whose pyrulysis can provido a high yield of cer~ic produc~s. It would also be usaful to b~ abla to have such a poly~er precursor which forms a cora~ic materi~l upon pyrolysls that iq rich ln the silicon nitride compon~nt.

Sum~ar~ of Invention W~ have discovered a method for preparin~ pr~ceramic organosillcon polymers, where the resultant ceramic materlal i9 generally richer in silicon ni~ride than obtained with the corresponding dihalosilane alone as initial start~ng ma~erial. The process comprises the following steps:
(a3 reacting in solution anhydrous ammonia with a mixture of RlSiHX2 (wher~in Rl ls B lower alkyl group having from 1 to about 6 ca~bon atoms, a ~ubstituted or unsubstltuted cycloalkyl group having fro~ 3 to about 6 carbon atoms, a substitutcd or unsubstituted lower alkenyl group havin~ fro~ ~ to about 6 carbon atoms, or a substituted or uQsubstituted low~r aryl group having from 6 to about 10 carbo~ atomc, and X is a halogen) and RSiX3 (~h~reln R is H, a lower alkyl group having from 1 to about 6 carbon atom~, a substituted or unsubstituted cycloalkyl group ha~ing from 3 to about 6 carbon atoms, os a substituted or unsubstituted lower alkenyl group ha~ing from 2 to about 6 carbon atoms, or a substituted or unsubstitut~d lDwar 3ryl ~roup havlng from 6 to about 10 carbon atoms~ ther~by forming a mixture of precur~or poly~6rs; ant (b) reacting ~sid pracursor polymer~ in the pr~senc~ of a basic catalyst capable of daprotonatlng the NH functlons ~n ~aid precursorq to for~ said preceramic polymer, thereby carrying out the DHCD
reaction. Preferably, the resultant preceramic polymer is treated wlth an electrophilc compound. In a preferred embodime~t X is Cl, Rl is a lswer alkyl group and R i H or a lower alkyl group.
The polymer formed by this method can be pyrolyzed in an inert gas stream to fo~m a black ceramic material. Pyrolysis of a prsc~ramic poly~er formed wher~ ~1 is a lower alkyl group and R is lX~ 75 ~ or a lower alkyl group under a stream of ammonia results in a white ceramic material.

Detailed Descript_on of_the Invention The following description of the inven-tion includes not only the method for preparing preceramic polymers summarized above, but also a method comprising reacting a polymeric silylamide with an organosilicon polymer, which is claimed in co-pending Canadian Patent Application Serial No. 545,027, of which the present application is a division.
We have now discovered that by using the coammonolysis product of a mixture of a dihalosilane and a trihalosilane, one can obtain a preceramic polymer whose pyrolysis results in a ceramic material richer in silicon nitride than the polymer obtained by using the ammonolysis product of the corresponding dihalosilane alone.

4~

Additionally, the co&mmonoly3is product i3 oft0n ~ora soluble than the ammonolysis produce of the correqpondlng trlh~losil~na, and because an lwportant rQquire~ent for ~ u~ l precera~ic polymsr is that it ba proces~ablc, ~. 9 ., fusible, and/or sol~ble in organic solvent-~, the coam~onoly3is produce i~ preferable.
Preferably, the dihslosilane i~ of th~ formula RlSiNX2, wherein Rl ls a low~r alkyl group having from 1 to about 6 carbon ato~s, a substituted or un~ubstituted cycloalkyl group h~ving from 3 to about 6 carbon atom~, a sub~tituted or unsub~tituted lower alkenyl group having from 2 to about 6 carbon a~oms, .or a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, while X is a halogen, preferably, fluorine, chlorine, bromine or iodine. More preferably, Rl is a lo~er alkyl group. Host preferably, Rl is CH3. X is preferably chlorin2.
Prefsrably, the trihalosilane has the formula RSiX3, wherein R is hydrogen, a lower alkyl group having from 1 to about 6 carbon atoms, a substituted or un~ubstituead cycloalkyl group having from 3 to aboue 6 carbon atoms, a substituted or unsubstituted lower alkenyl group having from 2 to about 6 carbon atom~, or a substituted or unsubstituted lower aryl group havlng from 6 to about 10 carbon atoms and X i~ a halogen, preferably, fluorine, chlorine, bromine or iodine. More preferably, R ii 8 hydrogen or ~ lower alkyl group.
Still more preferably R is hydro~en or CH3. ~ost pref~rably, R ls hydrogsn. X ls preferably chlorine.
The coa~monolysis reaction is carried out in any or~anic sol~ent ln which the two reactants are soluble. Solvent~ wh$ch may be used include ethers such as dialkyl ethers, partlcularly dlethyl ether ~Et20); cyclic ethers s~ch a~ tetrahydropyrsn, 1,4-dioxane, preferably tetrahydrofuran (THF); glycol ather~; aliphatic hydrocarbons such as pentane, hexane; and aromatic hydrDcarbon~ such a~ benzene, toluene, xylenes. Oth~r useful solventq ara well known eo the person of ordinary skill in the art, based upon this disclosure. The RlSi~X2~RSiX3 ~ixture is then reacted with ammonia in such a solvent to effece the co~monolysis reaction.

14~

In a prsferred embodimene ~f eh~ prosent i~v~ntion, ehe coammonolysis product is treatad ~ith catalytic quantltia~ of a base capable of deprotonating th~ NH function3 in the re~ultant coam~onoly~ls product, for sxa~Rl0, ~H, in an organie solvont. A
dahydrocycl~dimerl~ation resction (DHCD) tak~s pl~co, whlch re~ults in a preceramic polym~r that givas high c~ramic yield~ upon pyrolysis. Preferably, th~ bas~ 19 an alkali metal, an alkali metal hydr{~e, an alkalin~ earth m~tal hydride, an ~lkali m~tal amids, an alkaline earth metal amlde, a complex alkali metal hydridc, e.g. XB
(sec-Bu)3H, LlAlH4, etc., alkali and alkaline earth metal silylamides, an alkall metal organic compound and the like. More preferably, the base is KH. Only small amounts of the base are necessary (0.1-10 mole percent based upon the NH containing repaat unit) because the reaction is catalytic.
The coammonolysis product is reacted with the base in any organic solvent, in wh$ch the coammonolysi~ produc~ is Qoluble without raaction. Such organic solvent~ includa sthers, such as dialkyl ~thers, pr~ferably dl~hyl 3ther; cycl$c ~th~r~, for example, p~eferably, THF; glycol ethers, aliphatic hydrocarbonq such as alkan~s, ar2nes, and combinations thereof.
The temperature at which this reaction takes plac generally rang~s ~rom about -10C to about ~30C. Aftes the reaction i9 complete, the mixture may be quenched wieh an electroph$1e, EX, capabla of reaction w~th residual ~llyla~ide functlons. E is any organ$c group, praferably, a lower alkyl group or 3ilyl group; ~ is pref8rably 8 halide, sulfate or sulfonate. The alectrophile can be an alkyl halide, sulfate or sulfonae~; a hslosilane; or the like.
Typically, CH3I or a chlorosilane is used although other equi~alent elactrophiles well-known to those skilled in the art csn also be us~d. This qu~nching limlta ehe reactiYity of th~ "living~ polymer int~rmediate.

~i4>7S

The precer~ic polymer produced by th~ DHCD re~ctlon typicAlly ls a wh~te solid, which 1~ produc~d ln virtually qu~ntitatIv~ yleld.
Whsn Rl was CH3, X ~as Cl ~nd R w~s H, the proton MMR spectra of the products showed ~n incr~a~ Ln the SICH3/SlH ~ NH proton ratio, while the r21ative SiH/NH ratlo was unchanged. Thls indlc~te~ that a hydrogen loss had taken plac~.
In the D~CD raaction~, the molecular wei~he of the solid product was greater th~n that of the starting cosm~onolysis produce, thus a polymerization rsaction had occurred. The convarsion of the olls which typically are formed in ehe coa~monolysis reactions to the solids of the present invention results in a material that is more easily handled.
Pyrolysis ~f the whit2 solid obtained in these base-cataly~ed, DHCD reactions under argon fro~ 50 to 950C, typically producPs black cer~mic residues. The cera~ic yields were generally excelle~t. These caramic ~atarials have a rich ilicon nitride coneent.
Relatively pure slllcon nitride material can be for~ed when the precera~ic poly~er is pyrolyzed in a s~ream of a~onia rather than of an inert gas such as nltrogen or argon. The ammonia reacts wlth ths polymer at higher te~peratures to cleave methyl groups from silicon, so that essentially all carbon ls lost. For exa~ple, where Rl is CH3 ~nd R ~s H, the pyrolysis of the preceramic polymer derived f~om the DHCD product of the 1:1 coam~onolysis (in THF~ product to 1000C in a stre&~ of ~mmoni~ produced a ~hit¢ cer~mic resldue in high yield containing only 0.29~ by weight C, with the remainder being sillcon nitride. When both Rl and R were CH3, the pyrolysis of the preceramic polymer derived from the DHCD product of the 6:1 coammonolysis (in Et20) pro~uct to 1000C in A stream of 2mmonla produced a white ceramic residue containin~ only 0.36~ by weight of carbon. Si~ilarly, pyrolysis of a 3:1 CH3SiHC12:C2H5SiC13 ~coa~monoly~is product in Et20) KH-cataly~ed DHCD (in THF) product ~o 1000C in ~ stream of ammonia produced an essentially pure white residue with a very faint brown ~2~3~4'7~
tinge. How~var, ~lk~nyl groups ~ppeAr ~o b~ ~ore lneim~t~ly involved wlth eh~ pyrolysi~ ch~mlQtry. Pyroly~1~ of a control n~monolysis product of CH2-CHSiC13 to 1000C in a 3tr~m of ~monia produced a brown cer~mic re~idue, while pyrolysl3 of a 3:1 CH3SiHC12:e~2~C~SiC13 (coammonolysis in THF) KH-catalyz~d DHCD (in THF) product in 8 s~r0am of s~monia produced 8 ceramic that was bl~ck with touches of white nnd brown.
A wide range of RlSiHX2:RSLX3 raelos can be used in preparing the coam~onolysis product, the mole ratio can be Eor ex~mple from about 20:1 to 1:20, it preferably ranges from about 8:1 to 1:7. Generally, the higher the mole ~ of dihalosilane used, the more soluble is the co~mmonolysis product. However, this product ~enerally forms a ceramlc material in lower yields. In addition, at a hlgh mole ~ of trihalosil~ne, the DHCD reaction has less effect.
The DHCD reaction at hlgh mole ~ of trihalosilane should be limlted to the qoluble reaction product. For certain halosilanes, however, the coammonolysis product obta~ned wlth high levels of trihalosilanP
has properties that are quite use~ul without ~ subsequent DHCD
re&ction. When ~ DHCD reactlon is contemplated, the mole ratio of RlSiHX2:RSi~3 is preferably from about 8:1 ts about 1:6, more preferably fr~m about 8:1 to about 1:2, e~en more preferably About 6:1 to about 1:1. A higher mole ratio of dihalosilane to trihalosilane, such ~s about 6:1 to 3:1, provides ~ coammonolysis product that 5s typically soluble, which, when subjected to a DHCD
r~ction, ~esults in a preceramic poly~er that provides ex~ellent yiel.ds o~ ceramic material. No~ever, a ratio ~f about 2:1 to ~:2, preferably aboue 1:1, produces a preceramic poly~er whose pyrolysis in an inert atmosphere, typically, resules in a greater percent of silicon nitride in the ceramlc material than obtained on using the higher mole ratio of dihalosilane. Thus, depending upon the desired end product and reaction sequences, the molP ratio of dihalosilane:trihalosilane will vary. The particular ratio to use in a given situation can readily be determined empirically by the dçsired end use based upon the present disclosure.

For example, = onolysi~ of HSiC13 ~lon~ giVY~ ~o~tly lnsolublc, highly croYs-link~d product~. The hi8h~t ylold of soluble products (47%) was obt~ined wh~n the HSiC13 ~m~onolysis was carried out at -20C (at 0C eh~ yleld of solublQ product wa5 17~, ae -78C it wa9 20~). However, thes~ initially ~oluble silazanes become insolubl~ ~fter th~ solvent 13 removed. Since th~
main requ~re~ent of a precera~ic poly~er is that lt must be processabl~, i.e., fusible and/or soluble in organic qolvents, = onolysis of HSiC13 alone is not satisfactory.
When R is H, and Rl is CH3 nd X is Cl, the pr~ferred ratio of RlSiHX2:RSiX3 ranges from about 8:1 to about 1:4; more preferably, the ratio is about ~:1 to about 1:2 when a DHCD reaction is used; ~ore preferably about 6:1 to about 3:1 when one is concerned with the solubiliry of the starting materials; and about 3:1 to about 1:2, mor~ preferably about 1:1 when one is Intere~ted ln the result~nt w~ight percent of the ceramlc residus obtained after pyrolysis in an inert atmosphere; and 1:1 to about 1:4, most preferably about i:3 when the coam~onolysi~ product wlthout a DHCD
reaction is desired.
In either Et2O or THF, the 6:1 and 3:1 ratios used in the coammonolysis produced polysilazane oll~ wieh ~olecular weights in the ranBe 390-401 g/mol and 480 g/mol, respectively. When Q 1: 1 reactant ratio was used, waxes of so~ewhat higher (764-778 g/~ol) molecular weights were obtained in both solvents. In the 1:1 react$on carried oue in Et20 the yield of soluble product was only 40~, but in THF it was nearly q~antitative.
The oils produced in the 6:1 and 3: l reactions in Et2O are stable on long-term storage at room te~perature ln the absence of moisture (e.g., in an inert atmosphere box). However, the waxy product of 1:1 reactions in (Et20) and all the co = onolysis products prepared in THF formed gels (i.e., became insol~ble) after 3-4 weeks at room temperature, even when stored in a nitrogen-filled dry box. (See Tables 1 and 2).

1~ 8~ 5 ~L~L

RQ~
12EI~l)RQ~YÇl,OI)I~

~2 Ccramic HSlC13 _ Yield by Re a c t i oT~ ~i e 1 d ( 9~ ~ MU TÇA . %

6 oil 74 390 33 Coammonolys 1~
in Et20 3 oil 79 484 41 wax 40 778 72 . . ~ .
6 so1id 100 1300 85 DHCD Reactl~n, 1~ KH in THF 3 ~lid 99 1250 B8 so1id 53 1630 87 -12~

~2 ~__~C~$~

~2 Cer~nic ~SS~C13 Yield ~-'GL tbl~R,qt~o ~rPduct ~ield(~GA~
6 oll 91 401 28 Coa~nmonolysis ln THF 3 oi l 85 482 67 6 sol~d 96 10~4 82 : DHCD Reactlon, 1% XH in THF 8 solid 97 942 82 solid 93 1620 B6 The in~gr~t~d proton N~R ~p~ctra of ~h~ various co~mmonolysl products ~stablish thsir ~25Q$~ QS~ con~tleu~lons:

ÇH~ Ç~ iÇ~3_~1Q~ o~- _ 6:1 [CH3Si~NH]1 o[~Si~NH)1.5]0.17 3:1 [CH3SiHNH]l.olNsi(NH)l.5lo.33 1:1 [CH3SiHNH]l.~[HSi~NH)1.530.37 These formul~s carry no ~truc~ural impllcat~ons, they meraly are average formulstions. The HSiC13 component probably introduces both SiNHSi brid~ing and SLNH2 ter~inal groups into the structur~. From these approximate formulas one can calculate expec~ed ~ C, H, N and Si compositions a~d, in g~ner~l, the agreement of obs~r~ed ~ C, H and ~ for the 6 :1 ~nd 3:1 products with these values i good (+ 0.55~). (Analyses were not obtained of the w~x~s prepared in the 1:1 reactions).
The pyrolysis of th~se coammonolysis products was studied.
The 5 CH3Si~C12:1 HSiC13 am~onolysis product gives low ceramic yields on pyrolysis. Pyrolysis of the 3:1 products gives increased ceramic yields, whil~ pyrolysls of the ~ost highly cross - linked 1:1 am~onolysis products glves quite good cers~lc yields*, 72~ for the product prepared i~ Et20, 78% for that prepared in THF.

*Ceramic yield ls defined as weig t of residue _~ 100 weight of sample pyrolyzed 7~

Sub~cting ~ha3s coam~onoly~is produces to Ch~ DHCD
reaction, using XH as n bAse rc~llt~d in white ~olLd~ in ~lrtually quantitative yield. Th~ solids Ar3 ea~i~r to handle and store ehsn th~ oil~. Pyroly3i3 of the whiee 9011ds obtained ln these RH-catalyzed DHCD r~actions (under srgon from 50-950C) produced black cera~ic r~sid~3~, ~ith the exception of the 1:1 THF ammonolysis-d~rlved sol~ d which left a brown residue. The ceramic ylelds ~sre excellent (all gre~ter than or equal to 82~, with the highest being 88%).
Analysis of bulk samples of the c8ra~ic materialq produced in the pyrolysis of the various XH-catalyzed DHCD products shows that a higher Si3N4/SiC ratio has been achieved ~Table 3~:
for the 1:1 coam~onolysis products-deriYed polymers, 86 Si3N4, 8~ SiC and 5~ C ~THF coa~onolysis) and 83~
Si3N~ SiC and 6~ C (E~20 ~o~mmonoly~is); for the 3:1 and 6 :1 coammonolysis products-dsriYed poly~ers: 779~ Si3N4, 18-199d SiC and 4-5~ C (Et20 cosmD~onolysis) and 743 Si3N4, 20~ SiC and 5-69~ C (THF cosmmonolysis).
~ owev~r, th~ KH-cata~yzed DHCD re~ctions w~th the 1:3 coammonolysis-derived polyner were 810w, producing soluble products in poor yields. Pyrolysis ~f this material produced a black ceramic.
ere are s~ tuations where one desir0s a cer2mic material and/or preceramic polymer tbat co~tains differin~ amount~ of silicon carbide ant silicon nitride. The present process can be ~sed to result in ~ preceramic polymer that will typically produce a ceramic material that is enriched in silicon nitride when compared to reactions in which the precursor dihalosilane i~ ussd alone as the initial starting ~atesial.
For exa~ple, when Rl wzs CH3, X W8S Cl, and R was CH3, CH2 CH or C2~5, the following results w~re obtaln~d.
As control experiments, ehe ~mono~ysis of CH3SiC13 alone was studied. Ammonolysis of this precursor in Et20 ga~e -lS-~:8~

46~ yiold of soluble ~olid jproduct, ~olecul~ lght 702 g/~ol, c~ra~lc yield (by TGA to 950C) 56~. A ~imilar CH3SiC13/NH3 r~action ~n ~HF g~v~ ~olublQ ~olld product ln 824 yi~ld, mol~cul~r wslght 672 g/mol, c~ramic yi~ld (by TGA) 69~. By proton N~R (C~3Si/N~ int~graelon), the ~t20 product ~ay be fo D l~t~d 2~ [CH3Si(NH)1 3]x~ ~he T~F product ~3 [ 3 tNH)1,6]X. (This ls only n rou~h approxi~ation because in~egrseion of the bro~d ~ si~n~ls is rath~r inaccurate). The results of the coam~onolyses of CH3Si~C12 s .TA~ 3 CH3SiHC12~
HSIC13 Molar Ra5~o ~ Qduçt ~ ~ ELlL~ Si~
of a~monolysi~ 17.75 7.53 25.80 in Et20 6 of DHCD 20.05 6.73 25.82 ceramica 10.36 30.94 58.92 of ammonolysis in Et20 16.19 7.31 27.04 3 of DHCD 17.61 6.46 25.85 ceramicb 9.35 30.79 59.99 . . . ~
1 of D~CD 14. la 6.12 27.60 c~r~icC 9.10 0.70 32.56 56.52 of ammonolysis in THF 18.22 7.89 25.21 6 of DHCD 19.89 6.85 25.08 ; cera~icd 11.72 29.71 59.03 of am~onolysis ~n THF 16.10 7.45 25.Sl 3 of DHCD 18.00 6.71 27.32 ceramice 11.21 29.77 59.09 1 of DHCD 1~.42 5.97 ceramicf 7.74 0.54 34.29 57.17 aCalc. 77% ~by weight~ Si3N4, 18~ S~C, 5~ C
bCalc. 77~ Si3N4, 19% SiC, 4% C
CCalc. 83~ Si3N4, 1;~ SlC, 5.7j C
dCalc. 74% Si3N4, 20~ SiC, 6~ C
eCalc. 74~ Si3N4, 20~ SiC, 5~ C
fCalc. 87~ Si3N4, 8~ SiC, 5.4~ C

?L~8'1~7S

and CH3SiC13 are giv~n in Tnbl~s 4 ~nd 5. In all CRS~g, whethar the solvent wa-q Et20 ~r THF, oil3 w0r~ obtained ln high yi~ld. rhesc w~re of low (300-500) ~olecular ~iBht ~nd th~ir pyrolysis gsvs only low ceramic yi~ld~. The KH-cataly~ed DHCD reaction of these coammonolysis products gAve whlte ~olid products of higher (c~. two-to-threefold) ~olecular weight.
Based upon the lH NMR analycis~ the followlng formulatlons of the products were generated:
cN3siHcl2/
CH3SiC13 Reaction Molsr Ratio Solvent Formula 6 Et20 1CH3SiHNH]l.o[CH3Si(NH)1.5]0.26 IHF [CH3S~HNH]1 o[CH3Si(NH)2.1]0.27 3 Et20 [cH3si~NH]l.o[c~3si~NH)l~l]~29 THF [~3siHNH]l.o~cH3si(NH)l.l]~29 Et20 [c~3s~NH]l.olcH3si(~3H)l.s]o~63 THF [CH3S~HNH]l.olc~3si(NH)l~8]o.8o Thes~ are only approxlmate con~qtitutions, but agreement ~f co~bustion analysPs ~C, H, N) was fairly good for the formulaeions given. The ceramic yields obtained on pyrolysis of these polymers were high:
78-82~ for the products generated by initial coam~onolysiq in THF. In all cases, A black ceramic residue resulted when the pyrolys$s to 950G w~s carried out in a stream of argon. As expected, the carbon content (in the for~ of SiC ~nd free C) was higher than that of the CH3SiHC12/HSlC13-derlved ceramics (Table 6): 12-18% SiC, up to 9.~ carbon. Nonetheles~, hlgher Si3~4 contents than those obtained when CH3SiHC12 is used alone ( 67%) were obtained.
DHCD products of polysilazanes ~ro~ ammonolysis in Et20:
75-76% Si3N4; 15-18~ SiC; 7 9~ C.

Ceramic CH3S~HC12/CH3siC13 Yield Co~monolys is in Et20 6 oil 75 376 21 3 o~l ~0 ~73 40 oil ~1 526 44 1/3 w~x 89 627 --- l/6whitc solid 65 642 --DHCD R~action, 1% KHin l~F 6 ^qolid 97 12S0 82 ~' 3 solid 100 795 78 solid 98 786 78 1/3 white solid95 850 58 1/6 white solid90 1012 56 . .

~L~

Ceramic CH3SiHCl~/CH3SiC13 Yleld : Reaction ~ ~ Molar Ratio ~_ ~Product y~QLd~%) MW _ bv TGA.

6 oil 81 311 26 Coammonolysis ln THF 3 oil 91 363 31 1 oil R9 434 44 ; lJ3white solid 88 l/6white solid 98 -~

6solld 72 1171 86 DHCD R2action, 1% KH in THF 3solld 84 1173 83 1solid 100 838 82 1/3whlte solid 92 1180 76 1/6whits solld 9S 925 71 4~7S
~L~

C~3Si~C12/
CH3SiC13 An~ly.
Molar R~ti~ L~duct _ ~_ C.~ $i~
of am~onolysis in Et20 20.248.02 6 of DHCD 21.857.09 ceramica 12.160.5l 30.44 57.23 ~ . .
of ammonolysis in Et20 20.017.90 3 of DHCD 21.677.26 ceramicb 13.040.72 31.05 55.30 . __ . ~ _ ._ .
of ammonolysis ln ~t~O 19.66 7.49 l of DHCD 21.04 7.29 22.20 c~ramicC 11.36 0.61 31.90 56.35 . .. _ . . __ . ~
of ammonolysis ~ THF 20.26 8.06 23.79 6 of DHCD 21.85 7.02 c~ra~icd 12.37 0.60 29.35 53.94 of ammonolysis in THF 20.13 7.93 3 of DHCD 22.05 7.03 cera~ice 12.36 0.63 29.57 56.77 4~75 of a~onolysi~
ir~ TllF 19 . 53 7 . 42 of DHCl) 22 . 35 7 . 24 cQr&micf 11.19 0 . 63 31. 01 56 . 36 aC~lcd. 76~ (by weight) Si3Nb" 16~ SiC, 7~ C
bCalcd. 78~ S13N4, 12~ SiC, g9~ C
CCalcd. 809~ Si3N4, 129~ SiC, 89~ C
dCalcd. 769~ S13N4, 15~ SiC, 99s C
eCalcd. 75~ Si3N4, 18~ SiC, 7'~ C
fCalcd. 79% Si3274, 14~ SiC, 7~ C

t~ 5 Chnnging the ~monomer~ r~tlo fro~ 6 ~o 3 to 1 do~ not v~ry the compositions of the final cer~mic materlals very ~uch: th~ Si3N4 content vari~s by only 54, whila the SiC contene ~how~ a 6~ range ~nd the carbon c~ntent i8 within 28 for ~11 the ~steriAls.
To produce a c~ra~ic m~erial containfng only S13N~, the white sol~d polysila~ane derived from ~h~ DHCD of the oil obtalned by ammonolys1s of 6:1 CH3SlHC12~CH3SiC13 in Et20 medlum wa~
pyrolyzed in a stre&m of ~mmonia ~to lOOOnC). ~ ~h~S~ ceramic residue containing only 0.36% by weight C resulted.
Essentially the same reartions were carried out using vinyltrichlorosilane in pl~ce of methyltrichlorosilane ~CH3SiHC12/CH2-CHSiC13 molar ratios of 6, 3 and 1; ammonolysis in Et20 and THF medium; subsequent KH-catalyzed DHCD in THF: se8 Tables 7, 8, and 9). Control experiments lnvol~ing the amMonolysis of CH2-CHSiC13 Alone, in Et20 and in THF medium, w~re also performed. In both solvents, glassy white solids were obtained. The yield of soluble products in Et20 was low (61~); in THF it was quantitati~e. The molecular weights w~re relatively high (1165 and 1185, respectively) and the ceramic y~ elds obtained on pyrolysis to 950C wsre high (76% and 82~, respectively). This is a result, at least in part, of a greater incorpor~tion of carbon. Analysis of the ceramic obtained in the pyrolysis of the CH2-CHS~C13 ammonolysis (in THF) product sho~ed a composition 71~ Si3N4, 29~ C.
The coammonolys~s of CH3S~HC12 and CH2-CHSiC13 in ~t20 " ~28~7S

CH3siHcl2/ Ceramic C~2 CHSiC13 _ Yield Co=onolys is in Et20 6 oil 86 305 43 3 oil 87 333 53 oil 90 ~05 74 ~ . . . _ _ __ . . _ ... -- . __ .... . _ DHCD React~ on, 1% XH in llHF 6 solid 99 880 83 3 solid 98 999 34 ~olid 98 970 78 .

-2~-~L2~1~75 ~L~

~,~,~

C~i3SlHC12/ Ceramic CH2oC}lSiC13 Yield eact~o~_ ~loLar Ratio ~oduct~ ~d(~) ~ by TÇA~%
Coammonolysis in l~lF 6 oil 89 350 47 3 oil 92 361 57 oil 94 536 74 DHCD Reaction, 1~ KH in l~lF 6 solid88 773 84 3 solid 100 716 78 solid 99 777 85 12~ 7 ~L~

CH3siHcl2/
CH2-C~SiCl3 An~ly~is ~olar ~a~iQ Produc~ C~ ~L ~ % --of = onoly~ls in Et~0 22.80 7.86 23.91 6 of DHCD reaction 24.48 6.86 23.51 ceramica 17.06 28.33 54.62 .. . .... .. . ..
of smmonolysis in Ee20 24.39 7.65 24.59 3 of DHCD reaction 26.21 6.89 23.31 ceramicb 17.21 28.43 54.91 of ammonolysi~
in Et20 26.83 7.08 24.73 1 of DNCD re~ction 27.66 6.48 25.14 ; ceramicC 20.87 29.09 49.85 ~Calcd. 71~ (by weight) S13N4, 17% SiC, 12~ C
Calcd. 71% Si3N4, 17% SiC, 12~ C
CCalcd. 73% Si3N4, 9~ SiC, 18~ C
dCalcd. 69~ Si3N4, 19~ SiC, 12~ C
eCalcd. 70~ Si3N4, 16~ SlC, 13~ C
~Calcd. 71% Si3N4, 11~ SiC, 18~ C

s and in THF ~odiu~ ~av9 polysilaznn~ oil~ in hlgh yicld, nol~cular weight3 300-600 g/mol. Pyrolysl~ of ths co~mmonoly~is product3 gave hi8her cer~mlc yields, the higher the CH2~CHSlC13 oontent in the chloro3ilane mixture. Appl~cation of the KH-cat~lyz~d DHCD raaction to the ~mmonolysis products i~ all c~saq gave whlte solids of higher molecul~r weight whose pyroly~l~ to 950C gava high (78-85~) cerRmic yields. However, their S13N4 cont~nt wa~ lower and their carbon content (as SiC + free C) w~s higher than observed in the ceramics from the CH3SiHC12/HSiC13 and CH~SiHC12/
CH3S~C13 systems: For the CH3SiHC12/CH2 CHSiC13 ratio -6 and 3 products: 69-71% Si3~4; 16-19~ SiC; 12-13~ C. For the 1:1 products: 71-73~ Si3N4; 9-11~ SiC; 18~ C.
A mixture of CH3SiHC12 and C2H5SiC13 (3:1 molar ratio) was treated wieh ammonia in Et20 and in THF at 0C. In both cases, sllazane oils, ~W 350-370, were obtained in hi~h yield.
Their cera~ic yields on pyrolysis to 950C were low (15~ ~nd 234, respectively). Application of the DHCD reaction (1~ KH in THF) to these oils ln both cases gave white sol-ds with increased ~ (972 and 860, respectively) and increased ceramic yield on pyrolysis to 950C (Bl~ and 78~, respectively). The pyrolysis product in each case was a black foam when the pyrolysis gas stream was ar~on.
Analysis of the ceramic products ~a~e ~ C, N ~nd Si values from which compositions of about 71-73~ Si3N4, 14-17~ SiC and 11-12~ C rould be calculated. Th~, there i9 essentially no difference between these results and the calculated composit~on of the ceramic product of the corresponding 3:1 CH3SiHC12/CH2-CHSiC13 system (70-71%
Si3~4, 16-17~ Si~, 12-13~ C).
I~ the case of the present polymers, as is seen in Table 10, some WerQ self-curing and on pyrolysis gave cera~ic ~ibers (those noted lyesn). Others melted ~hen heated, so that the fibers ~ere destroyed (those noted "non). Conversion of the meltable fiber to an infusible ilber by a cure step prior to pyrolysis will enable one to melt spin these materials into fibers.

~81~7S

~Q

CE~A~IC FI~R~ Q~m~l5_~ B_Ç~?Q~LI~L
Molar Am~onoly~ls FLbor on CH3siHcl2/
CH2-SiCl3 6/1 Et20 xb Yes n 3/l Et20 x No 1/l Et2 ~ No n ~/1 THF x Yes n 3/1 THF x No n 1/1 THF x Yes . _ . . . _ . .. . _ CH3SiHC12/
HSiCl3 6/1 Et20 x Yes n 3/1 E~20 ~ Yes 1/1 Et20 x Yes n 6/1 l~lF x ~0 3/1 THF x ~g n 1/1 THF x Yes .. _ , _ . .... _ .
CH3S iHG12/
CH3SiCl3 6~1 Et2~ x Yas 3/1 Æt2~ ~ No 1/1 Et~0 x No . . ~
n ~/1 THF x Yes 3/1 - THF x ~o n 1/1 THF x Yes a Yes - Fibers re~alned after heating to 1000C under Ar.
No - Fibers did not remain after pyrolysis eo 1000OG.
b x means a bar was made and pyrolyzed to obtain a cera~ic bar.

-2~-s She ~curs~ step prior to pyroly~l~ cnn be ~ccompll~h~d when ~ith~r R or Rl i~ alkenyl by curing the flbcr through hydrosilylstion. Thls roaction can ba ~nduced by ultr~viol~t snd other high on~rgy radiation, ~s well as by ch~mical frcc radical ources and transitlon metsl c~talyst~. $hasc compounds can resdily be ~el~cted by the per~on of ordinary skill in the art and include H2PtC166}~20, p~roxlde and a~o compounds, prefer~bly organic peroxides, such a-~ benzoyl p~roxide, more preferably azo co~pounds such as azobisisobutyronitrile and the like. Preferably, a rsdiatlon source is used.
W irradiaeion, irradiation with an slectron be~m or an X-ray source, eec. will cure the alkenyl containing polymer~ Sub~ecting the precera~ic fiber to W irradiation tRayonet Reactor) for 2 hours results ln an infusible fiber that does not melt upon subsequent pyrolysis under argon, producing ceramic fibers. By incorporating C-C
into the coa~monolysis product, this strategy can be broadly applied to the present $nvention. The addition of a third co~pound containing an unsaturated functionality to the ammonolysis ~ixture rasults ln a mixture of oligomers. The particulRr amount to be ~dded to the co~mmonolysis mixture will depend upon the desired use and compounds being used.
~Fibers w~re prepared ln th~ following manner: In the dry box, a ;few drops of toluene was added to a poly~er sample and the resulting ~ix~ure ~tirred with a glass rod unt$1 a seicky residue resulted from which fibers could be drawn. mes~ fibers (1/4" to 2" ln length) were placed in a boat, taken out of the dry box and placed in a tube furnace 1ushed with Argon. The fibers were heated to 1000C ae 10C/~inute. The polymers listed in Table 10 were used ln preparing f~bers.
~ he present polymers can be used as binders for SiC powder processing.
Ceramic composite bars were prepared in the following manner:
In the dry box, a 100 ml, one-necked, round-bottomed flask was charged with 0.6 g polymer and 2.4 g of commercial Fujima SiC powder.

She fla~k W~9 r~mov~d ~ro~ the dry box nnd ch~rgod wl~h 25 ml of tnlu~n~. Th~ fln-~k wa~ piaced ln ~n ultrn~onic bneh for at least 15 minute~. The toluon~ was thcn re~ov~d on a rotary ~vaporator and the re~idue thcn driad und~r vacuuu ~t 0.03 ~m Hg for ~t lcast 1/2 hour.
~he SiCJpolymer residue wa~ ground wlth & mortar snd pestle to produce a fine powder. This powder was pres~d $n a 1.5" x 0.5" x 0.1~ die at 6000 lb~. for 5 ~inutes. The b~r was then iso~tatically pressed at 40,000 lbs. Finally, the bar ~as pyrolyzed under Ar in n tube furnace to lO~O~C.
The polymers shown in Table 10 were used to form composite bars.
All bars r~tained eheir rectangulsr shape upon pyrolysis.
In a different embodiment, the polymeric silylamide which ~s the intermediat~ formed from the DHCD reaction of [RlSiHX2] and [R2SiX31 (wherein Rl, R2 and X are as defined above) can be used to form another preceramic polymer. This polymeric silylamide is the intermediate formed after the DHCD react5on and prior to treatment with an electrophila, such ~s Ch3I. This inter~ediate species (sometimes al~o referred to as a rreactlve 'living' polymer~, silylnmide, poly(silylamide) or alkali mstal silylamide)~) can raact with electrophiles other than CH3I. ~e have discovered that the raaction of this silyamide with an organos~licon polymer containlng Si-H repeat units ~referred to as an Si-H containing or~anosilicon polymer) results in noval preceramic polymers.
The Si-~ containing or~anosilicon polymer ~s pref~rably a polysilans compound of the for~ula [(RSiH)X(RSi)y~n~ ~where x + y - 1, n is an Lnteger greater than 1, R is a lower alkyl group having from 1 to about 6 carbon stoms, a substituted or unsubstltuted lower nlkenyl group having from 2 to abou~ 6 ~arbon atoms, a substituted or unsubstituted lower aryl group hnving from 6 to about 10 carbon atoms, or a ~ri(lower)alkyl- or di(lowar)alkylsilyl group) (See U.S. Patent Application Serial No. 756,353 filed July 18, 1985), a polycarbosilane polymer containing repeat unit~ of the formula [Rasi(~)-(c~2)q~,~-e-~
Ra ~~i~(CH2)q~ (II) (where q is an integer 1 or greater, Ra is ~, a lower alkyl group ~,8 3L~75 havlng fro~ 1 to about 6 carbon atom~, n cyclo~lkyl group having from 3 to about 6 carbon Atoms, A substitutad or unsub~titut~d low~r alkanyl group haviD~ fro~ 2 to about S carbon atoms or a qubstituted or unsubstitut~d lowar aryl group h~ving fr~ 6 t4 abou~ 10 carbon atoms) (Sec U.S. Pat~nt Application Sarial No. 781,934 filed S~ptember 30, 1985), or an organohydrogansiloxane polyw~r containlng r~peat units of the for~ula [RbSi(H)O]n,i.~., ~b -~i-O- (III) (where n is an lnteger 1 or greater, Rb is a lower alkyl ~roup havin~
from 1 to about 6 carbon atoms, a cycloalkyl group having from 3 to about 6 carbon atoms, a substituted or unsubstituted lower slkenyl group having from 2 to about 6 carbon atoms or a aubstltuted or unsubstituted lower aryl group having from 6 to sbout 10 carbon atoms) (Se~ U.S. Patent Application Serlal No. S49,390 filed April 8, 1986).
In accord with the present lnvention, treat~ent of, for example, organopolysilanss ~ith the silyl~ide will provide higher moleculsr weight preceramic materials and improve the ceramic yield.
~ e have now found that organopolysilanes ~uch as methylpolysilanes ([(CH3Si~)x(CH3Si)y]n) obtainsd in the above reactions, upon treatment wieh catalytic quantlt~es of silyla~ides in accord ~ith the present invention, yield preceramic poly~ers of hlghar molecular ~eight which upon pyrolysis give slgniflcantly higher ceramic yi~lds. Such polymers, when prepared as described herein, sr~ soluble in organi solvents.
Polycarbosilane polymers that are used in the presant invention preferably contain a multiplicity of repeat units of the fDrmula [R~Sl(H)-(CH2)q~ (where q and Ra are as define~
abovR)(hereinafter polymers containing such repeat units are referred to as "polycarbosilanesn). The reaction of thasc polycarbosilan~s ~ith an alkali m~tal silylamide results in novcl preceramlc poly~rs.
Typically, the pyrDlysis of this na~ polymer gi~es a black cera~ic 47~j ~olid in a yiald thAt i~ gr~8tor ehRn th~t obtained on pyrolysi3 of the parent polyc~rbosilan~.
The polyc~rbosllana poly~er ~hould contaL~ at l~ast 25 ~ola ~ of rcpcat unit~ of th~ for~ula II, i.e. [RaSl~H~-~CH2)q], in additlon to other repeat units, ~uch as [R82Si(CH2~q~ ~o.g. the Ya~ima poly~ers). Prefersbly th~ polycarbosil~n~ polyuer contains nt least 35 mol~ ~ of repcat unlt~ of formul~ II. More praf~rably, the polymer contains at least 50 mole 2 rop~at units of for~ula II.
The polymer may ~lso contain a mixture of repeat unies of ths above described formula, e.g., both [RaSi(H)-(CH~)q] and ~R~Si(H)~(CH2)q~ (Ra' and q' sr~ d~fin~d the sa~e as Ra and q, respectively, but Ra' may be different than Ra and q'may be ~ifferent than q). R~ is preferably a lower al~yl ~roup, ~ore preferably Ra is CH3. Preferably q is ~ual to 1 - 3, ~ore preferably it is equal to one.
The polycarbosilane.and silylamide ~r~ typically added in a ~eight ratio of polycarbosilane: silyla~lde of about 10:1 or less. ~referably this ratio is about S:l or le~s. More pr~f~rably the ra~io i~ ~bou~
3:1 or le~s. ~ost preferably the r~tio i~ about 1:1.
Additionally, the reaction of organohydrogensiloxane polymers containing ~ plurality of repeat units of the for~ula [RbSi(H)O~n (where n and Rb are as defined above) (herainafter poly~ers containing such repeat units are refsrr~d to as ~polyslloxanesn), with a poly(silylamide) also results in a no~el precera~lc polymer.
The pyrolysis of this new precera~ic poly~er under ~ strea~ of ammonia typicslly results ln a high yield of a Yhite cer~mic material.
By choosing the correct stoichiometry one is readily able to obtaln a ceramic material that is v~rtually only silicon oxynitride. This process provides silicon oxynitrides at high yield and at low costs.
The pyrolysis of the preceramic polymer of the present invention under an inert atmosphere such ~s nitrogen or argon typically r~sults in a bl~ck ceramic solid in high yi~ld. This black ceramic mater~al generally contalns SiC, S13~4 and SiO2 and can be used as a binder or coating.

14'7~rj The polysiloxane poly~r u~ad In the pr~nt inv~nti~n can be r~dily obtainod by the hydrolysis o~ th~ appropri~t~ RbSlHC12 (wh~re Rb is as defin~d ~bove). Th~ hydroly31s ~ay be stcer~d to givo a high yleld of cyclLc [RbSi~H)O]n oll,gomer or to produc~
hi8h~r molecular w~i8he l$near [RbSi(~)Ol polymers. They yield of cyclic oligomers (n 4, 5, 6,...) ~ay be maxl~iz~d by using the m~thod eaught by Seyferth, D., Prud'homme, C; and Wl~em~n, G.H-, Inor~. Che~h, ~: 2163-2167 (1983). Additionally, one can u3e com~erclally ~vailable RbSi(H)O]n polymers.
The polysiloxane polymers useful in th~ present invention encompass polymers having a wide rnn~e of ~RbSl(H)0] repeat units. The number of repest units contained in the polymer will ~ary depending upon the desired end product.
Preferably, the polysiloxane polymer shoul~ contain at least 25 mole % of repeat unlts of the for~ula III, i.e. IRbSi(H)O]n, in addition to other repe~t units, for example, [R~R~ SiO], ~Rb Rb SiO], Rb ~nd Rb are dcflned the s~e ~s Rb;
and Rb, Rb , and Rb ay be the same A8 or d~fferent fro~ each other. ~ore prefer~bly the polysiloxane polymer contain~ at least 35 mole ~ of rep~at units of for~ula III. Even more preferably, the polymer contains at least 50 mole ~ repeat units of formula III. Most preferably, the polymer contains at least 75~ mole repeat units of formula III.
~ ith respect to the silylamid~ used, Rl is preferably a lower alkyl group, ~ore preferably CH3, while R2 is preferably H or a lower alkyl group, more preferably H or CH3. 2 is prsferably chlorine, fluorine, bromine or lodine. The dihalosilane can be added to the trihalosilane over a ~ide range, but preferably the mole ratio of RlSiHX2:RSiX3 is about 20:1 to 1:20, more preferably it is from about 8:1 to about 1:6, still more preferably about 8:1 to aboue 1:2, and even more preferably from about 6:1 to about 1:1.
This silylamide when pyrolyzed will eypically produce a cera~$c material ~hat is richer in sillcon nitride than that obtained on pyrolysis of the polysilazane DHCD pro~uct obtained from the 7~j corre~pondine, dih~lo~lane ~lon~.
Th~ usc of the ~bo~s polyM~ri~ ~1lyl~mide in on~ embodim~nt of ths presen~ inventlon up~radcs thc Si-H containing or~ano~llicon polymer, for exampl~, the organopoly~ilan~s, the polycarbo~llanQs ~nd the polysiloxanes to n~w polymers which giv~ a high ceramic ylsld on pyrolysis. When this silyl~ide i~ react~d with an Si-H contnining organosilicon polymer, tha reaction product after tr~atment with a suitable electrophile such as an organic or a 5ilyl halide, incorporates ~oth starting ~at~rials. When this reaction prod~ct is pyrolyz~d, the csramic yield is signif~cantly greatcr than thst of the "parent" organosilicon polymer. Additi3nally, the silicon nitride/silicon carbide ratio of the resulting ~aterial can be varied dependin~, upon the particular dihalosllane and trihalosilane, ratio of dlhalosilane to trihslosilane and Si-H organosilicon poly~er used. The ratios to use to obtaln a particular result can be determined empiricAlly by the ~kllled artisan based upon the present disclosur~.
The w~ight ratio of Si-H containing polymer to poly~eric silylamide can vary ~id~ly. For exa~ple, mole ratios of or~,anopolys~lsne:
polymeric sllylamide from about 4:1 to aboue 1:4, and pr2fsrably from 2.5:1 to 1:2 typically provlde useful r~sults. Ueight ratios of polycarbosllane: polymeric silylam~de from about 10 to about 1; and preferably fro~ 5 :1 to 1:1 typically provide useful results. ~eight ratios of polysiloxane: polymeric silylamide of 1~ d 1:5 typioally provided useful results. ~eight ratios of polysiloxane: poly~sric silylamide from about 15 to abo~t 1 to about 1 to about 15, hould also provide useful results. Preferably the weight ratio of polys~loxane:
polymeric silyla~ide ranges from about 5.1 to 1:5, and more pref~rably, from 5:1 to 1:1. However, in all three cases other ratlos can be used depend~ng on the particular starting materials and their pyrolysis characteristics.
The organosilicon polymers thus formed by reaction of the organosilicon polymer containing Si-H repeat units with the prsformed silylamide ~ iDg intermediate" followed by treatment with sn elactrophile, heneeforth ~ill be referred to as ~graft" polymers.

Poly~ n~s of typ~ (R3~H)n (iØ, ~h~ g~n~ral 08~ whora y - O, x - 1) al~o r~act with th~ polymeri~ ~llylamido~ th~t ar~ tbe DHCD
resctlon product of ehe coa~onolysl~ of a dih~lo~llan~ ~nd trihalo~ n~. Thus, a r~action of (C6H5SiH)~ ~lth the ~ilyla~id~ ~livlng intermediate" (1:1 ~olar r~tlo) ln THF at roo~
t~mperat~re ~iV~9 a new organo3ilicon polymer which 1~ an effective ceramic precursor, giving ~ Si3N4/SlC/C cer~mic product ln hiBh yi~ld upon pyrolysis eo lOOO-C.
Additionally, USQ of the resction product of or~anopolysil~nes or polycarbosilanes with t~e polymeric ~llylamlde re3ults ~n a prod~ct that is self-curing as the temperatuxe is raised in the production of cer~Lc mseerial. Consequently, with these poly~ers lt is poss~ble to avoid the formation of S102 which results when an oxidative cure step i~ used. This again is an improvement over pyrolysis of the precursor silane compound alone.
In ~his syste~, R or Ra is preferably a lower ~lkyl, ~ore preferably, R or Ra i8 CH3. However, R or R~ need not b~ the same and, as aforesaid, ~ixtures of Si-N containlng or~nosilicon compounds and/or repeat unit~, e.g., [(RSiH)X(RSi)y~n and [(~ Si~)x,~R Si)y,]n,> [RaSi~H)-(CH2)qJ and [Ra Si(H~-(CH2)q~ and [(RSiH)X(RS~)y]n and [RaSi(H)-(CH2)q] can be u3ed to obtain further flexibility in tailorin~ the properties of the aforesaid product. Si~ilarly, m~xed polymers of the type [(RS~H)a(RSi)b(RR Si)c]~ (~h~ e ~ nd R are a~ defined aboYe, and R ls defined a3 is R above snd R may be the same or different than R) c~n be used as well.
Preferably, at least one of ehe grouping R, R', ~a, and Ra for each mixture is CH3.
The polysiloxane polymer may also contain a ~ixture of repeat units of the above described formula, ~ . g., both [RbSi(H)O] and [Rb Si(H)O] ~Rb is defined th~ same as Rb but Rb' m~y be different than Rb). Rb is preferably a lower alXyl group, ~ore preferably Rb is CH3.
Further, these aforesaid ~ixtures of oo~pounds can b0 used to obtain addltional fl~xibllity in tailoring the proporti~q of th~ sforesQid produc t .
Mlxtur~s of polysllazanc~, for ~x~l~ whcr~ R2 19 H and R2 i3 CH3 also nu~y bc used.
A~ indicated abov~ hls inv~ntion also in/~luda4 th~ ca~e of [ (RSiH)X(RSi)y]n~ wh~re x~ 0, with R ns defined sbov~. Thus, [(RSiH)]n may be 2 linear or a m~xture of cyclic species, or a hybrid of both types. For example, lPhSiHln (Ph i~ a phenyl group), cf, Aitken, C. at al., ~ Qrganome~_h~ 2:Cll-C13 (1985), reacts in the same way ~s ths above - described organopolysilanes ~o proYide ne~
organopolysilane/organopolysilazane hybrid poly~ers. These mixtures will be particularly useful in ~tte~pts to avoid excess free silicon or carbon. Similarly, aryl-substituted repeat units of zither [RaSi~H)~(CH2)q] or [RbSi(H30], for example, where Ra or Rb is a phenyl or substituted phenyl group, ~nd Ra and Rb can be a lower aryl group is also lncluded.
The precera~ic product on~ obtains by using the~e silyl~mide~, aven in only catalytic amounts, differ3 fro~ the starting organo~ilicon compound. This difference in products apparently arises because both Si-H and Si-Si bonds sre reactive towards nucleophilic rea~ents.
The "graft~ poly~er is for~ed by combining the already formed polymeric silylamid~ with the Si-H containing organosilicon polymer, for example, the or~anopoly~ilane in varylng proportions in an organic solvant. Thereaftar, the mixture is seirred at room temperature for ~fficient ti~e for the two compound3 ~o react. In one e~botiment, the polysiloxane, for oxample, [CH3Si(H30]n ol~gomers with a high cyclic content, is added slowly to an organic solution such as THF
containing the prefor~ed silylamide. An im~etiate reaction with some gas evoluei~n occurs. Thereafter, the ~ixture i~ stirred at room te~perature for sufficient time for the two compounds to more complctely reac~.
Any or~anic solvent in which both poly~er syseems are soluble without reaceion can be used. Such organic solvents include, for example, THF, diethyl e~her, glycol ethers, alkanes, arenes and 7~
combln~ions ther~of. Th~ tur~ may b~ h~at~d ~bov~ room t~mper~tur~, and cnn b~ r~nu~d to ~peed up th~ compl~tion o~ the r~actlon. A~tar rcfluxing, the ~ixtura 19 quenched with an al~ctrophll~, E-Xl, to for~ the org~nosillcon ~graft~ poly~sr. The el~ctrophile can b~ an alkyl b~lid~, sulfate, or sulfonate; a halosilane; or the llke. Typic~lly, CH3I or a chlorosilane ls u3ed, ~lthough other ~qulvalent electrophlles well-~nown to those sk~ d ln the art can also be used. ~ is preferably a lower Alkyl group or 8ilyl group; Xl is preferably a halide, sulfate or sulfonate.
The organosilicon poly~er formed by tha present (~graft") process with the organopolysilane is typically obtained ln yields greater than 85~ based on weight of the starting materials with a ~ariabls molecular weight, typical values being in the 1600-2200 g/mol range. Thi5 preceramic orgsnosilicon poly~er can then by pyrolyzed ~nder ~nert ~tmosphere condltions (As used herein, nitrogen will be considered ~n inert gas, argon is anoeher example~ to result in ~ cer~mic materi~l in hlgh yield. Pyrolysis under nitrogen ~ave cer~mic prsducts in a yield of 75-85~.
The orgaDosilicon preceramic polymers formed by the present (ngraftn) process when polycarbosilane is uqed were produced in hlgh yields (as hlgh as ss%). Pyrolysis of this precerAmic polymer gave caramic products in a yield of 75-85~ (based on weight of the starting materlals).
The resultant preceramic polymer when polysiloxane was u3ed were produced in ~ood yialds, ~ypically better than 70%. The polysiloxane-derived preceraQic organosil~con polymers can then by pyrolyz~d under nitrogen or other inert atmosphere to result ~n ceramic ~aterials in high yield. Typically, pyrolysls under nitrogen gav~ black cer~ic products in a high y~eld (as h~gh as 88~). More significantly, pyrolysis under ammonia will give a whi~e ceramic solid in high yield. The white c~ra~ics contain little, if any, carbon.
What i9 referred to herein as sn "1~ ~iE~" polymer can be obtained by carrying oue the DHCD reaction of the dihalosilane and trihalosilana co~mmolysis product in solution in the presence of the Si-H containing 14t7~

organo~illcon poly~9r. In this mathod, the or~anopolysil~nt or polycarhosilane ls added to ~n organic solv~9nt. Afterw4rd~, the ~ixture (generated by reacting in ~olut~on anhydrous a~onia with the dihalosilan~ and trihalosilane) i9 add~d. The poly~iloxane i9 added to tha coammonoly~is ~ixture which is in an organic solve9nt.
One then add~ to th~ solution a b~3ic cataly~t capable of deprotonating tha hydrogen fro~ a nitrogan atom ad~acant to a silicon &tom. See U.S. Patent No. 4,482,669. Th~9 re~ction ~ixture gradually change~ color and hydrogen is svolv~d. The rasulting solution is then stirred at roo~ ~emperatur~ for ~ufficient time for the silylamide inte~mediates and the Si-H containing organosilicon poly~er to react.
It can b~ heated above room temperat~re, and can b~ heated at reflux to speed the completion of the reaction. Afterwards, the reaction mixture i~ allow~d to cool to room te~perature, if required, and quenched ~ith an electrophile such as CH3I or a halosilane, such as a chloro3ilane, to produce the organosilicon "~n situ" polymer. ~h~9 molecular weight of the "i~ u9n polymer i9 variable. On pyrolysi~ this material provide~ a high yield of a black ceramic material.
On pyrolysis the polycarbosilane-deri~ed material provides a yield of a black c~ramic ~aterial, that ls typically greatar than that obtained on pyrolysi3 of the polycsrbosilane ~lone.
On pyrolysls under nitrogen or ar~on the polysiloxane-derlved material provide~9 a yiald of a black ceramic mat~rial9 thst is typically greater than that obtained on pyrolysis o~ the p901ysiloxane alone9. Pyroly~is under a~onia typically results ln qilicon oxynierides in high yields.
The or~anosillcon poly~er formed by either of the abova ngraft" or ~ ethods usually is separated ~rom solution. The solvent i~
removed by using t~chniqu~s well known to a person of ordinary skill in the art. One standard method i~ distillation, pr~ferably trap-to-trap distillation. The polym~r, typically a whito powder that is solubla in an organic solvent, is ther~by obtaI~ed. On~ ~ay also combin~
trap-to-trap distillation with centrlfuging, followed by trap-to-trap dl~tillstion to separate the polymer from solution.

4~

The ~ln ~ prscar~lc polym~r difQr~ phy~icAlly ~ro~ the ~graft~ precsramlc polymer. Pla~or difference~ will be ob~erved in thsir proton NMR spectra snd in the form of their thermogravimetrlc analysis ~TGA) curves. Both types of polym~r8 Are useful ag preceramic materials.
The u.4e of coammonolysl~-derivad, DHCD-catalyz~d ~ilylamide described herein not only lmproves ths c~ramic yield of tha organ4polysil~nes, but, more significantly, when thls silyla~ide is reacted wieh organopolysilane of the formula [(~SiH)X(RSi)y]n in the approprlats stoichiometry, the reaction product of [(RSiH~x(RSi~y]n and the "livlng intermedi~te" cilyl~mide after treatment with a suitable electrophile such as an organic or a sllyl halide, incorporates both starting mAeerials. When this reaction product is pyrolyzed, the excess silicon nor~ally obtained in the pyrolysis of the or~anopolys~lane alone and the exc0ss carbon normally obtained in the pyrolysls of the quenched poly~eric ~ilyla~ide alone combine so that there i-~ no substantial excess of ~ieh~r element in the ceramic product. Consequently, one can obta$n a cerA~ic material preferably with less than about 1~ fre¢ sillco~ or free csrbon, more preferably 18~s ehan about 0.5~ free carbon and le~s than 0.5~ free sIlicon, and mo~t preferably with less than about 0.1% of free ~llicon and less than ~bout 0.1% of free carbon, i.~ ceramic material containing substantially no free carbon and nc free ~ilicon. The exact combination of the two compounds necessary to r~sult in the d~sired stoichiometry can readily be calculated by a pcr~4n of ordinary skill in $he art on the basis of the re~ults of the ~nalyses of the ceramic products obtained in the pyrolysis of ehe sepRrate polymers. Mols ratios of organopolysilane: metal silyls~lde from about 4:1 to abou~
1:4, and preferably from 2.5:1 to 1:2 should provide useful results.
However, other ratios can be used depending on the part~cul~r star~ing mater1al~ and ~heir pyrolysis characteristics.
The excess of fres carbon, which can be a proble~ with the starting polycarbosilanes, can be dealt with by using a ternary system of: (1) the polycarbosll3ne; (2) the polysilazane (as the polymeric silyla~ide, 4'7~

elth~r prcfor~d or K~n~ratud L~ ) and ~3) ~ poly~ no whos-pyrolyqis alona givos a c~ra~ic produce which contalns 3n exces~ of ~ilicon. Ex~mpl~s of ~uch poly3ilsn~s ar~ org~nopoly~ n~ as d~crlbed above, for ~xampl~, ehos~ which ~r~ produced by tha 30diu~
condans~tion of ~thyld~chloro~ilano. In th~s~ re~ctlon~ tho organopoly~ nc i9 pra~erably a3 d3fin~d abova, i.c [(RSiH)X(RSi)y]n~ More pr~f~rAbly R ls ~ lowcr ~llqrl group, mo~t proferably ~ i9 CH3. U~lng ~n ~ppropriate ~l~tur~ of th~ thro~
poly~rs (which can be c21culated fro~ th~ resul~ of ~h~ analyse~ of the csrn~lc product~ of the pyroly~l~ of ~ach individual polymer, ~.g., the CH3I- quench~d polymex in tha case of ths poly~erlc sllyla~id~), one c~n obtain ~ ceramic product ~hlch contains a ~inf~al exces~ o~
~ither element, carbon or silicon. Such hybrid tern~ry precaramic poly~ars are ~oluble in organlc solvents and, depanding on component ratios usct, are of v~rlable ~olecular w~lghe. Their pyroly~i3 give~
black c~ra~ic product~ in high (generally > 80~) yiold.
I~ tho pr~c~r~lc poly~r which ro~ults fro~ a combinati~n of 8 poly-~ilo%~n~ poly~r (A) and ~ alk~ t~l (poly)~llyl~lda (B), th~
ratio of Si/0/~ of th~ r~ule~nl c~ramic ~etari~l can bc broadly varlsd by ad~u~tlne the ~toichio~etry of th~ pr~c~ra~lc poly~r, i.~. the A:B
ratio. For ex~mplo, at on~ ~xere~o, th~ pyrolysl3 o ~
CH3I-quench~d ~ilyla~ld~ dcr~vo~ fro~ tho coam~onolys$~ of CH3SlHC12 nnd HSiC13 and sub~u~nt DHCD rs~c~ion undor a NB3 at~o~ph~ro producod whit~ ~licon n~e~id~. By appropriate ~lact~on of r~actsnt s~oichio~try it ~hould b~ po3~iblo eo obtain a coraDi~
prcduct that 1~ virt~ally puro ~llicon oxynltrid0.
For exa~pl~, it 3hould bo po~iblo to o~eain dlstinct cry~tall~ne pha~ Si20~2 aft~r pyroly~i~ und~r a ~tr~a~ o~ oni~ fro~ a prcceraDic p31ymQr one obtain3 by ~h~ proc~s~. In thi~
lnstanc~ th~ w~i~ht raelo o~ poly~lloxan~:alk~li Motal poly~sllyl~3ida) i~ ~bout 1:1 and R and Rl aro CB3 and a2 1~ H or CH3. In th~
abov0-d~scrib~d sy~te~, dovlating from a 1:1 r~tio r~sults in a c~ra~ic poly~er hæving 90~ Si3~4 wh~n you u~o mor~ poly(~llyamid0) or so~
SiO2 when you u~a ~oro poly~iloxano. It is ~i~pl~ to e~pirically dotor~ th~ appropri~ta w~lght ratio for ~ da~lr~d c0ra~ic product with the w o of any of ~hs clai~d ~tartlng ~atorlal~.
Tho polysiloxane and qilyla~id~ ar~ typ~cally ~dded ln ~ weight ra~io of polysilox~n~: sllyla~lds fro~ 15:1 to 1:15. Pr~ornb~y ehis ratio i~ abo~t 5:1 to 1:5. Moro pra~orably tha ratlo 1~ about 3:1 ~o 1:3. Most pr~forably th~ rstio is about l:l.
Phy~ical bl~nd~ of Si-H containing organo~ilicon polymers, for oxa~pl~ tha or~2nopoly~ilano, ehe polycarbo311~no poly~ oonta~ning repe~ unit~ of [R~SS(H)-(CH2)q]~ for example, th~ Ya31~a polycarbosilan~ or ths polysiloxane containing r~peat units of ~RbSl(H)O]n, with the ~quenched~ organo.~ilazane poly~er of U.S.
Patant Application Serial No. 899,471 can bo used sinc~ these will rsact when thay ar~ heated togeth~r. When approximataly equal molar qusnti~ies of the polymor~ wher2 R, Ra or R~ r CH3 ~ Rl -CH3, ~ ~ H or C~3, are mixed and finQly ground tsg~thar and then ~ub~ectnd to pyrolysls to 1000C, cara~ic yialds ar~ obtaln~d which aro ~pproxi~ataly th~ av~r~ga of tha cera~ic yloldJ when th-organopolysilan~ ~nd tho organo~ zan~ poly~r~ ar- pysolyzad ~aparatsly, ~re significantly high~r than ehat wh~ch r~ult~ ~h~n tho polycarbosllans 18 pyrolyzed 3~p~rat~1y and i~ ~till high~r than that ~hich resule~ wh~n tho polysiloxano i~ pyrolyzad ~oparately.
~ h~n polycarbo~ilano/or~ano~ilazan~ mix~re~ Aro h~at~d, l~ th~
3bs~nco of a solv~nt at 200C under nierog~n, whlt~ ~c~y ~ol~db ~r~
o~ta~n~d whlch sre insol~blo i~ nonpolar or~nic ~olYe~ hQn or~anosilana/or~anosil~zano mixeur~ ara ho~o~, o~th~r ~ tho abs~nco of a sol~nt at 100-C undor nitrog~n or ln ~ toluen~ ~olution ae roflux, whita powd~r~ ars obtain~d which ar~ in~olublo in nonpolsr organic solv~nc3.
TQrnarY bl~nd3 o~ the polyosrbosilan~, thc polysilaz~no and tho (CH3S~U)~(C~3S~)yln polysilana b~havo si~ilasly.
Tho co~binot polymor~ obtalned by ~h~ ~gra~t,~ and phy~ical blond ~othod3 can b~ convoreed to black c~ra~ic fib~r~.
Pyrolysis of pre~sad bar~ of the co~blnat polymar3 to lOOO~C provides bl~c~ solld product. In oth~r 0xpcrl~nt~, o~llcon carbid~ powd4r is ~l~p~r~-d in ~ tolu~n~ ~olutlon cont~lnln6 25~ by ~lghe ~f eh~
o~blned orgsno~ilano/organo~ilaz~nQ poly~0r~. Th~ solvont 18 ovaporated ~nd ~he r0~idu-, ~ fins powd~r of ~illcon carbide ~ith ~ombined polym~r binder i~ pr~ss~d Into bar~ and pyrolyz~d At 1000-C.
A ceraslc bar is obt~lned showin~ ~ low w~lght loss And sll~htly ~hrunken 3iZ~.
Similarly, ~hen ~llicon c~sbide powder ~ dlsp~rsed In tolu~ne ~olu~lon~ of the co~b~ne~ polyc~r~osilane/organosilazane polymers, the solvene evaporated and the residue, ~ fine pGwder of ~ilicon carbide with co~bined polymer binder, is pr~ssed in~o bars and pyrolyzed at 1000C, a ceramic bar is obtAined ~howing a low weight 103s and 61ightly ~hrunken ~ize.
Pyrolysis of bsrs of the oomblned polysilox~ne-org~nosllaz~ne polymers under ~mmonia results in a wh~te rectangular ~ody. Pyrolysis ~nder eithes pyrolysis condition r0~ults in oeramlc bar~ showlng low to od2rat~ we~ght lo~s ar~d sl$ghtly ~hrunken D~Zel.
The l~vention will b~ furth~r lllustrat~d by the ~ples th~t follow:

I . . ~Ç~
All r~ac~ions ~nd ~nlpulations were carri~d out under a dry nitrogen ~no~phere u¢ing ~tand~rd Schlenk ~echniquen or ~ Vacuu~
At~o~pheres try 'box. All ~ol~rent~ ~ere distilled under n~trog~n:
di~thyl ~thor and tet~a~ydrofuran froDI sodiu~ b~nzoph~non~ l~etyl, ~nd h~xane froJD lithiw12 aluminu~ hydrlde. Chloro~ ere obt~ined rcm Petr~rch Syste~Ds, In~. or Sil~r Lsbs., Irlc. ~nd ~rQ distill~d from ~agnesium fillngs prior to u~e. Anhydrou~ ammonia (Matheson) was dried by p~ssing through a KOH-f$11ed drying tub~. Hethyl iodide W85 di~tilled under nitrogen from P295. Potassiu~ hydrid~ ~Alf~ ~a~
obta~ned as ~ 40~ ~lurry in mineral oil which wa~ filtered, wash~d with hexane and d~ied pr~or to use.
Proton NMR spectra were obtained on ~ithzr ~ Jeol ~X-9OQ ~90 MHz) or a Bruker ~N-250 (250 ~Hz) using a CDC13 r~f~rsn~ (7.24 ppm -~2-... . . .
. . .

4~5 ehlft). Infr~rad ~p~cer~ ~r~ o~t~ln~d o~ P-r~in~ or ~odel 1439 l~fr~r~t ~p~ctrophoto~-tor, ~olocul~r ~clghe~ ~r~ d~ton~in~d by cryo~copy in bsnzone.
Thor~ogr~vi~ctric sn~lysi~ ~TGA) yi~ld~ ~or~ ~bt~ln~d u~lng ~
P~rkin-ElDler TGS~2 syse~m. S~plos ver~ ho~d fro~ 50C tD 950C
under ~n argon tmosph~r~ ~t 10C~ ln. Large-~c~l~ tubo furnace pyrolyE~eh to produce gr~ qu~nt~ti~ of coraloics ~r~ p~rformed in a Lindberg Mod~l 59344 tube furnace ~ith controllor. Sa~plos wero heuted fro~ 200C to 1000C at 10C/~inue2 in an argon ~tmosphere.
~nalyses of all oils and poly~ers ~ere performed lby Scandinavian ~icsoan~lyticRl Lsbs, Herlev, DenE~rk. Cer~mic ~n~lyses were performed by Galbraith L~bs, Xnoxville, Tennessee.

s~ 5len-A typlcal r~action is describ~d. All other ~mmonolyses of the ~SiC13 ~lone or of mixtures of CH3S$HC12 ~ith RSlC13 (R ~ H, CH3, CH2-CH) were carried out u~lng th~ ~ame gen~rsl proc~dure.
For ~ach ~H3S~HC12/RSiC13 ~olar r~tlo u3ad, ~psrat~ r~act~ons w~re c~rrled o~t ~n ~t20 ~nd i~ THF ~diu~. Th~ yi~lds of ~olublo protuct~ (solubl~ ~n the rosctio~ ~edium), th~ ~olecular ~ei~ht3, the ~rs~ic yl~lds (by TGA u~der ar~on3 obtain~d on ehelr pyroly~i~ and their ~nalyses ~r~ given in the ~ppropri~ee T~bl~ 9~.
A 1000 ~1 three-necked, round-~ottomed ~las~ ~quipped w~th a Dry Ice condens~r, an overhe~d ~echanical ~tirrer and a rubber septum ~s 1~-drl~d while a ~trcnm of dry D~trogen ~a~ passQd ehrou~h. Dry di~thyl ~ther (600 ~ll V~8 ~ddsd and eh~n 33.6 8 (0.292 ~ol) of CH3SiHC12 and 6.8 g ~0.05 ~ol) of HSiC13. Th~ solution was cooled to 0C (~ce bath). ~he orlginal septum wa3 replaced with another septum through ~hich a o~-foot gas inlet eube passed.
aa~aous ammoDia then wa~ bubbled into ehe ~olueion at B mod~rate rate for 4.5 hours until ammonia ~as observcd condenslng on ehe -78C
condenser. Th~ a~monia inlet ~ube ~as replaced with a rubber septu~
~fter the addleion of ~m~onla had been stopped.

Tho r~ctlon ~lx~ur~ ~a~ l~llo~cd to ~ar~ to rooD t~p~tur~ and stirr~d und~r nitrogon ov~rnlght. F~ltrseion ~in th~ dry box) r~movot NM4Cl ~nd ~ny othar ln~olublo productD of tho r0-ction.
The ~olld3 ~ro w~shed with throa 50 ol portions o~ ~th~r.
~rap-to-trap distillatlon of th~ ~olY~nt (25C, 0.1 ~m ~8) fro~ th~
co~binffd ~th~r ph~s~ ft a cl~r, ~obllo oil ~l5.0 ~, 74% bssad on th~ (CH3SiHNH) and [HSl(NH)l 33 component3). Th~ oll wa~
ch~racterl~ed by ~nnlysl~ (T~bl~ 3), by IR und H ~R
spectro~copy. Th~ ~ol~cular wel~ht wa~ ~ca3ur~d ~cryoscopy ~n benzene) and a thermogravimetric tra~e wa3 obtained (50-950C, 10C pcr minu~
H NMR (250 ~Hz, in CDC13): ~ 0.17 (broad m, 2.6 H, CH3S~), 0.85 (broad m, 1.3, ~), 4.37 (broad 6, 0.25 H, SiN), 4.63 (bro~d s, 0.41 H, SiH) and 4.81 (broad s, 0.33 H, SiH).
IR (thln ~ilm, cm 1): 3380 (s), 2960~3), 2900(w), 2140-2120 (bro~d,~), 1545(w), 1405(m), 1255(s), 1200-1150 (bro~d, v~3, 980-750 (broad, vs).
~W: 390 ~m~l TGA: 33~ by wsight c~r~ic r~Ridu~, black s~lid . (Based on ~MR-derived for~ul~ 1~H3SIH~H]lHSl(NH)l 4]~ 17) C~1cd f~r CHs.41N1.24Sil.17~ C~ 17- ;
Found: C, 17.75; H, 7.53; ~, 25.80.

III. ~
One such ~xperiment i~ de3cribed in ord~r to provide dbtai1s of the prorodure u~ed. A11 reaction~ w~re c~rri~d out 1n IHF using 1 mol ~ of the KH catalyst. In all cases, the wh~ta solid poly~er obtained after the CH3I quench ~as char~cterized by ~nalysis and IR
a~d lH NMR spectroscopy. The ~ol~cul~r w~ght wa3 m~asured by cryoscopy in benzene and ~ thermal ana1ysis trace (TGA, 50-950 at 10C/minute, under argon) was ob~alned. The results of these experiments are given in the Tables.
A 250 ml, three-necked, round-bottomed f1ask was equipped with a -~4-m~netlc ~tis-bar, a g~s inlot eubo and t~ rub~r septa ~nd ch~rg~d wie~ KH (0.04 g, 1.0 m~ol). Th~ fla~k thon was connact~d to tha nitroga~ lln~. Dry T~F (100 ~1) W~J addad by syrlng~ snd thon 6.355 8 (0-1 mol, b~d on CH3Si~N~ + [HSl(NH)l 5] unlt~) o tho polysilazane oil (ob~ained by am~onDly~i~ of Y 1:1 ~olar ratio ~ixturu of CH3SiHC12 and HSiCl3 in dlathyl 4th~r~ ti~solvad ln 20 ~1 of T~F. Th~ latter solution wa~ add~d dropw~so ov~r a perlod of 20 minutes. Gas cvolution (H2) wa~ ob~rv~d. Th~ r~sulting clear solution wa~ ~tirred at roo~ t~psratur~ undar nitrogon for 1 hour. Sub~equently, m~thyl iodido (0.46 8, 3.2 ~ol) wa~ addod by ~yringe. An l~sdiate whlt~ preoipi~at~ of XI for~d. Th~ mixturo waq qtirr~d for 30 minute~ at roo~ ta~perstur~ snd the~ the solY~nt wa-c r~moved by trap-to-trap d~tlllation. To th~ r~idue was added 70 ml of benzen~ snd tha ~ixtur~ ~a~ centrifugcd to r~ovo insolublo~. Ih~ 301ution phaso ~ rap-to-tr~p di~till~d (25C, 0.03 ~m Hg) to remova tho b~nzen~, loaving a ~h~eo organlc-solublo ~olid (',.41 8. 93~ yi~ld). (Ge,n~rally, in ~11 oth~r 3uch r~ctiona, the raa~tion ~lxturo wa~ seirr~d for 1-18 ho~r3 ,se roo~ t~,~p~raturc aft,3r th~ ~itial gas evolutlon was ob~,orvod. In th~ presene cas~, ~uch longar r~Action ti~,~s l~d eo ~or~atlo~ of ln~olubl~
lH ~MR (250 HHæ, in CDC133: ~ 0.17 (bro~d ~, 2.~ H, CH3Si), 0.94 (broad, 1.2 H, NH~, 4.82 (brosd ~" 1.0 H, S~

IR(CC14, c3-l): 348,0 Sw), 3400(s), 2960(s), 2900(~ 120(s3, 1540(w), 1410(~), 1250(s), 1180-1130~bro~d,R), 1030~s), 970-8SO(broad,v~).

~: 1630 g~ ol TGA (50-950Q, 10C p~r ~lnut~, und~r ar,g,on): 87~ c~ra~ic yie,ld (black sol~d).
Q~l- Found: C, 14.10; N, 6.12; N, 27.60.

A 3 g sa~pls of this product wa3 pyrolyz~d ln a tubo urnac~ undcr _~95_ 4~
argon, l~Avi~g a r~id~e of 2.4 g (80~) ln th~ fon~ of ~ ohunk of black solid.
~ l- Found: C, 9.10; H, 0.70; N, 32.56; Si, 56.52.
A~suming that all nltrogen is pre~ene a~ Si3N4, th~t ~h~ r~st of the silicon ls pr~sent as SiC and tha~ thc rQ~aining carbon ls presen~ ~3 free carbon, one can calcul~te fro~ ~hi~ ~nalysis ~he composltion 1.0 Si3N4 ~ 0.46 SiC ~ 0.81 C or, by Yelght, 83 Si3N4, ll~ SiC snd 6~ C.
Pyrolysis of ehe whlte solid obtainQd from ~nother such preparatlon (1:1 CH3SlHC12/HSlC13 a~monolysls in THF
followed by KH-cataly~ed DHC~ and CH3I quench; a 3.53 g sample) ln ~ fus~d sil~ca bo~t in a tube furnace ~n a ~trea~ of ammonia (25~-1000C within 3 hours) gave a whit~ powder resldue in 84~ by weight yield (100~ yi~ld based on the ~ilicon content of the polysilaz~ne). Analysi~ indicated a carbon cont~nt of only 0.29~.

IV. Preparation o~ Organosilicon Compounds 1. p~,~,a~Qn o~,~(Ç~
tall operstions unde~ n~trog~n~ _ a. In ~F Mediw~.
A 500 ml, three-necked, round-botto~ed fl~sk equipped with a stir-bar, a dropp~n~ funnel and n reflux eondenser was charged with 50.5 g (2.20 g ato~) of Na m~tal. The flaqk ~a~ attach~d to ~ Schlenk ~anifold, evacuated and ref~lled ~ith nitrogen thr~e ti~es. THF (200 ~l~ was added snd the dropping funnel was charged with 65 ml (0.625 ~ol~ of CH3Si~C12. ThQ s~lane was added to th~ stirr~d ~a ~uspension during the coursa of 45 ~in., aft~r which time the reaction mixture was cloudy ~nd ~ligh~ly warm. The ~ixture was stlrred for 16 hours at room te~perature and 48 hours at reflux; i~ then was cooled to roo~ temperaeure.
Hexane ~60 ml~ was added. Th~ ~ixture was transferred by cannula to a heavy-walled centrifuge bottle and cantri~uged.

~ 2~3~L47.~

The ~uporn~tant layar ~ tr~nsf~rr~d to ~ 1 lit~
round-bottomod flask (under nitrog~n). THF (50 ~ nd hexans ~30 ml) wera addod to tha rasidu~l ~ol.Ld and ~h~ ~sultln~
suspens~on wa~ centrifuged. The 3up~rnatan~ lAy~rs war~ combined ~nd 801vents wers r~ov2d by trsp-to-trap distillatLon ln vacuum until ths residual liquid volum~ wa~ about 100 ~ 19 liquid ~a~ csnnulsted into a 250 nl ~ingle-necked flask and the r~maining solvent WAS ramov~d in ~acuo t~ lenv~ 13.2 e (0.30 ~ol, 48% yield) of a white, glassy 8011~. OD b~ing h~ated ln a ~ealed capillary (in YacUo) this solid soft~ned around 40-C and amsltsd"
between 130-140-C with gas evolution, leaving a ~hick gu~. There was no further change up to 300~C excep~ fDr n gradual increase in visc03ity. The product was poorly soluble ln hexane, only somewhat soluble in benzene (precluding measurement of it~
cryoscopic molecular weight in thi~ solvent) and qulte soluble in THF.
~NR (90 MHz, in CDC13): ~ 0.10-0.61 (~, SiCH3, 7.5H) and 3.55-3.90 (m, SiH, lH). Based on tho reasonable ~ssu~pti~n ehat ~very Si ~tom baaring a H substl~uent also bears a CH3 ~ubstituent, the integrated CH3Sl and SlH intensiti~s lead to a Constitution [~CH3siH)0.4(cH3si)o.6ln-Calcd for CSiH3 4: C, 27.60; H, 7.87.
Found: C, 27.1B; H, 7.17.
IR (KBr, Nu~ol): 2170(sh), 2100(s, Si-H), 140B(m), 1260~m, Si-CH3), 1249(s, Si-C~3), lG60(br), 1019(~), 931~s), 865(v~, Si-CH3), 770(vs), ~85(~s), c~
TGA(25-lOOO-C, 10-C/min.): 60~ yield of a gray-black cer~m~c ~olld. A tube furnace pyrolysis of 3.20 g of this mater~l to 1500C ~ava 1.52 g (48~) of a gray ceramic powder.
An~ ~ . Found: C, 22.56; S~, 78.42; H, 0.01; ~, 0.009~. (SiC requires C, 29.94; Si, 70.06~; ac~ual ~1 2~4'7 co~position: SiC ~ 0.49 Si). X-ray powd~r diffraction (do~
A): 1.315(s) ~p-sic), 1.542(s) (~-sic~, 1.91(n~) ~s~ 8~ -sic), 2.52(~9) (,~ -sic), 3.13 si) .
A ~ass ~pectral analysi~ o~ th~ pyrolysis gas in ~nother axperi~ent ~howed the following: no ~B5eoUa pr~duct3 wer~
obs~rved up ~n 385~C, then fragment ion~ corr2sponding w~ll with th~ repcsted fragm~nta~ion of ~H3Si~3. At 445-C, C~3SiH3 was still observed and a pea~ at m/z ~ 16 (CH4) began to grow in. By 580-C, when weigh~ loss - was about over, only the ~ethane peak W8-~ ohservable.

b. In Hexane/lHF ~ed~u~
In a dry box, a 1 liter three-necked, round-bottomed flask equipped with 8 stir-bar, a dropping iunnel and a reflux cond~n-~er ~as charged with 75.0 g (3.26 ~ol) of sodium ~tsl. The flask was attached to a Schlenk manifolt, ovacuat~d and flu3h~d ~ith nitro~en. THF ~70 ~1) and hsxane (420 ~1) wera added and the dropping funnel wa~ charged wieh 150 ~1 (1.44 ~ol) of ~thyldl~hlorosilane. ~ethyldichlorosilane was added slowly into the ilask over ~ 3 hour period. The reactlon solution turned purpl~ and by the end o~ the addition was at gentlc reflux. The rcactlon mlxture was 3tirred at room temperatur~ for 2 hous~ and then heated at r~lux for 16 hours. After it had been cooled to ro~m tempera~ure, th~ reaction ~ix~ure (~xcept or the lar~e NaCl crystals) ~as ~ransferred via oannula into a h~avy-walled glass bottle. The mixture was centr~fuged and the clesr, colorless supernatant layer transferred by cannula into a 1 liter round-botto~ed flask equippQd with a seir-bar. Hexane (200 ml~ and THF (20 ~1) were adtsd to the remaining solids, the ~ixtur~ agaln was csntrifu~ed, and the ~up~rnatant liquid combined with ehs supernatant solution previously separaeed. Solvent ~as re~oved by trap-~o-trap dis~illation until the voluMe of th residue was about 100 ml, and the remaining liquid was transf~rred by cannula into a weighed 250 ml round-bottomed flask.

:

4~t~

Ro~aining ~olven~ w~s romov~d by tr~p-to-tr~p di~till~t~on ~t approxlm~t~ly 0.05 ~m Hg at roo~ ta~perature to givo 51.2 g ~31~, l.lS
mol) of a cloudy whlt~ oil.
H NMR (90 ~Hz, C~D6):~ 0.37 (brosd, SlC~3, 3.74N) 3.92 (broad, SiH, l ~).
NMR in~gration ~f the product gav~ a constitution of [ (C~3s~)0.8(c~3si)o~2]n IR (thin fil~, cm 1): 2967(s), 2900~), 2800~w), 2099(vs), 1410(s), 1385(w), 1249(s), 1055(br), 933(s) t 865(vs), 770(~s), 685(br), 650~sh), 585(w).
Molecular weight (cryoscopic in benzene): 600 g~mol.
~nal. (mater1al from another similar preparation). Calcd. for CSiH3 76; C, 27.39; H, 8.55; Sl, 64.05. Found: C, 27.49; H, 8.98;
Si, 61.58%.
TGA (25-lOQ0C, 10C/min): 20~ yield of A gray-black ceramic solid.
Pyrolysis of ~ sample from another preparation in ~ tube furnace gavs a ~ray-black cera~ic solid in 36~ yield (by wei~ht).
~nal. ~of CÇ~ . Found: C, 22.93; ~1, 75.99~.
The pure liquid obtained by this procadure i3 ~ery alr-sensitive, particularly ~hen its effecti~c surface area is high, ~8 ~hen in contact wi~h a fritted funnel or & paper or cloth towel (in which c~ses spontaneous inflammatlon may occur).
Other, ~imilar reactions have given 62-75% yields of (CH3SiH)X(CH3Si)y~ Molecular weight det~rminaeions of several preparations ranged from 520-740 g~mol. All products had very similar lH NMR spectra, but with different SiCH3:SiH rat~os. Physical daea of these products are liseed ln Table 11.

'75 ~L~

P~YSICAL I~A FQR~a~.~;~L~

Sa~nple # Polymer M. W. a SiCH3: SlHb CeramicC x y Y~,e~
YFY III-l 81 600 3.74:1 20 0.80 0.20 YFY II -40 74 740 3 . 56 :1 16 0 . 84 0 .16 YFY II-25 73 650 3.51:1 26 0.85 0.15 YFY II-12 66 520 3.27:1 16 0.91 0.09 YFY I-73 73 680 3.48:1 27 Q.86 0.14 aCryoscopic in benzene.

b lH NMR lntegration ratio.

CUnder nitrogen gas, 2S-1000C, lO-C~IDin (TGA) 4~

For tha pUrpO5e of ~impllfyin~ e~lcul~ion, ~ ~vora~ for~ula w~ight vslua 44 wa~ assign~d for th~ u~it (~3S~H)~(CH3Si)y~
Therefore, ~n each of th~ following axperi~enta, the nu~bcr of mole~ of th~ reaction unit (CH3~1H) wa~ calculae~d from the w~i~ht of th~
polymer us~d divided by 44.
The product formed in ehc T~F solution gi~es a 60% ceraMic yleld, but le iq of li~ited solubility in org~nlc ~olvent~ ~nd it conversion to ceramic fibers requires a curing step of photolysis/oxid~tion.
Preparatlon of the [~CH3SiH)X(CH3Si)y]n in ~ hexarle/THF
mixture of approximately 6 to 7:1 resulted in satisfactory yields of 8 soluble product. Howe~er, pyrolysis of this material resulted in vary-low ceramic ylelds, rangin8 from 16 to 27~.

2. Characterization ~f the PolYcarbosilane The polycarbosilane, a white solid, w8s purchased from Dow Corning Corporation. The following dAta w~re collacted on ie:
H NMR (90 ~H~, C6D6): ~ 4.52 ~broad, Si~, lH) 0.26 (broad, SiCH3 ~d SiCH2Si, 8.6H) IR (KBr, Nu~ol, cm~l): 2104(s), 1253(s)~ 1014( , broad), 845(s, broad~, 734(s).
Molecular U~lght (cryo~copic in benzene): 1210 g~mol TGA ~25-1000C, 10C/~in): 58~ yield of a black c~ramic solid.
Tlj2 - 510C

3. Pre ~rat$on of SiL~
a. ~reParation of lcH~siLH)ol~(Iv-3l~
A 500 ml three-necked, round-bottomed flssk equipped with a stir-bar, a reflux condanser, and a ~eruM cap was eharged with 90 ml ~0.87 mol) of CH3SiHC12 and 250 ml of CH2C12. To the solution was addPd slowly (syring~ pump) 20 ml (1.11 mol) of H2O over a two hour period. The reaction mixture was stirred at room temperature for 24 hours. Eight 100 ml portions of H2O were added to the reaction '7~

Dixtur~. Th~ ~H2C12 l~y~r wa!i washed wlth two 100 81 portions of H20 and drl~d ov~r H~S04. ~ solvent w~s r~moved by roenry evaporation to give 44.5 g (85~ yield based on (CH3Sl~H)0~ unit) of 8 cle~r oll.
H ~MB (90 MHz, C6D6):~ 4.71, 4.69 ~broad, Si~, 1 H) O.23, 0.21 (broad, SiÇ~3, 3 ~) (neat, on 1): 2976(s~, 2918~w), 2162(5), 1410(w), 1260(s), 1030-1140 (broad,s~, 830-920 (broad,s), 769(s), 715(w).
Thls ls the procedure described by D. Seyfertb, C. Prud'hom~e and G.H. Uise~an (Inor~. Che~ (1983) ~163) in ehe hydrolysis of CH3SiHC12. A good yield of cyclic [CH3Sl(H)O]n oligomers ~as reported, mostly n-4, 5 and 6, but some higher n (up to n-22) was also obtained in lower yield. The ceramic yield of these oligomers is low and will vary from 0 to 5 ~ dependin~ upon the pyrolysls conditions and the particular ollgo~er used.

b .
IIL~ 2~~s ~

A 500 ~1 three-necked, round-bottomed flask equipp~d with a stir-bar, a reflux condenser, and 8 serum cap ~as charged with 100 ml (O 96 mol) of CH3SiHC12, 50 ml (0.41 ~ol) of (C~3)2SiC12, and 250 ~1 of CH2C12. To th~ solution eher~ ~as added 60 ml (3.33 mol) of H20 (slo~ly by syringe pump~ over a 4 hour period. Reaotion occurred im~ediately. The reactio~ ~ixture w~s ~tirr~d ~t roo~
temperature for 24 hours and then was washed with fifteen 200 ~1 portlons of H20 until the H20 washin~s ~ere neutral pH. The ~H2C12 layer was dried over MgSO4 and the solvent was removed by rotary eYaporation ~o give 64.7 g (87~ yield by ~eight) of a clear oil.
H NM~ (90 MHz, C6D6):6 4.99 (broad, Si , 1 ~) 0.22, 0.16 (broad, SiCl3, 6H) R (neat, c~ 2972(s), 2168(s), 1410(w), 1260~s), 1030-1120 (broad,s), B80(s), 836(s), 804(s), 769(s), 708(w) , C ~b9~5s~5~iLu~ 9~_5b~ lCH3S~(H) P~-12~
(neat): 2982~), 2171~), 1413(w), 1262(s), 1030-1140 (~,brond), 860-905 (s,broad), 765(9), 718(w) CD~-1 H ~B (C6D6):~ 0.25 (bro~d s, SiCH3, 3.4H), 5.04 (broad s, SlH, lH) Average Molecular Weigh~: 4500-5000 (vendor d~ta) ceraT~R~ic Yield: (TGA, ~5-1000C., 10C./minute): 13~ (black solid) V. Graft Reactions A. Graft ~e~tion o~
Methyldichloro~ilane and viny~Lr~ 3~ ~o. ~H~ and Polynethylhydridosilo7~ane Lp~_122LW~h P~um ~ drl~de in ~1~.
A 100 ml, three-necked, round-bottomed fl8s~ was equipped ~ith a refl~x condenser with gas inlet tube on top, n ~tir-bar ~nd t~o septa snd o~en-drl~d for 1 hour. (This will b~ tcrmed ehe asenndard r~action ~pparatusR.) Th~ apparatus wa~ taken lnto the dry box and char~ed with potassium hydride (0.02 g, 0.50 mmol~ ~nd w~s then connected to a nitrogen line, and charged with 50 ml of THF. ~he oil (1.64 g, 26.0 mmol) from the coammonolysis of CH3SiHC12 ~nd CH~-CHSiC13 (3:1 rat:Lo) in THF was added dropwise by syring~ 0~2r 15 ~in~tes. Gas ~volution wa~ ob~erv~d. Th~ reaction ~ixture ~as ~tirred for an additional hour at room te~p~rat~re. By syringe, polymethylhydridosiloxane (Petrarch syse~ms, Inc. PS 122) (1.59 g, 26.5 mmol) was added to the reaction ~lxture. After stirring 35 minutes, methyl iodide ~0.46 g, 3.2 m~ol) ~as added nnd an im~ediate white precipitate for~ed. The sol~ent ~as removed by trap-to-trap distillatlon (25C, 0.03 m~ Hg) and the residue e~tracted with 40 ml of hexane. The reaction mixture was c~ntrifuged and the supernatant liquid cannulated into a 100 ml fl~sk. ~emoval of the hexane by trap-to-trap distillation left a white solld (2.44 g, 75~).

-53~

lH NMR (CDC13, 250 MHz): S 0.17 (bro~d, 9.7 ~, SlC~3), 0.99 (broad, 3.0 H, NM), 4.38 (broad, 0.07 ~, SlH), 4.74 (broad, 0.93 H, SiH), 5.91 (bro~d, 2.1 H, SiCH-CH2).
IR (CC14, cm l): 3400(9), 3050(~), 3010~h), 2960(9), 2900(~h), 2140-2120 (bro~d, s), 1595(m~, 1405(~), 1270-1250 (broad, ~s), 1200-1020 (broad, vs~, 990-840 (broad, ~9).
MW (cryoscopy in b~nz~ne): 1340 gJm~l.
TGA (10CJmln, Ar, 50-950C): 36~ c~r~mic yield, black residue.

B. C~a~t Reacei~n of the Coammonolysis Produot o~_ thy~d~chloro$11ane and Vinvltrichlorosilane (3:1 Ra~i~lHF) and_ PolvmethylhYdridosilane with Potassium Hydride in ~HF~

The standard r~action apparatus was charged with potasslum hydrlde (O.02 g, 0.50 ~mol) and 50 ml THF as previously described. The oil (1.70 ~, 27.1 m~ol) fr~m the co~mmonolysis of CH3SiHC12 and CH2-CHS$C13 (3:1 ratio) in THF ~as added dropwise over 15 minutes.
G~s evolution was observ~d. The reartion mixtuse w~s stirred an additional ho~r at room temperature. Polymethyl~ydridosilane (1.24 g, 28.2 mmol) from the reaction o~ CH3SiHC1~ snd excess sodium in a 6:1 hexane~THF solvent mixture ~a3 added by syri~ge. Tha re~ction ~ixture became or~ng~ and then after 10 minutes turned yellow. The reaction mixture was stlrred an additlonal 35 ~inutes at room te~perature and then ~ethyl iodlde (0.46 g, 3.2 E~ol) was ~dded by syringe. An i~mediate whlte precipitate formed ~nd the yellow color of the re3ctlon mixtur~ ~as disch~rgad. The solvent was removed by trap-to-~rap distillation and the residue extracted ~ith 40 ml hexane.
The r~action mlxture was centrifuged and th~ supernatant liquid c~nnulated into a 100 ~1 flask. Removal of the hexane by trap-to-trap distillation lef~ a whiee solid (2.74 g, 93~).
H N~ (CDC13, 250 MHz~: ~ 0.28 (broad, 3.1 H, SiCH3), 1.25 (broad, 0.55 ~, NH), 3.65 (broad, 0.21 H, SiH~, 4.38 (broad, 0.35 H, SiH), 4.76 (broad, 0.44 H, SiH), 5.95 ~broad, 0.53 H, SiCH-CH2).
IR (CC14, cm 1): 3390(w), 3150(~), 3050(m), 2960(s), 2900(m), ~2J8~7S

2160-2140 (bro~d, v~), 1410(s), 1260(~), 1190-1140 (bro~t, 8), 1040-840 (bro~d, v~), 710 (v~), 590(w).

M~ (cryoscopy in bsn~n~): 1612 g/~ol.
TGA (lOGC/Din., Ar, 50-950C~: 864 c~ra~ic yi~ld, blAck solid r~-cidue.
C. ~

Cornin~_~q~ 8) with Potassi~ Hydride in THF, The apparatus was charged with potassium hydride ~0.02 g, 0.50 mmol) and ~0 ml of THF. The oil (l.S5 g, 26.0 m~ol) from the coam~onolysis of CH3SiHC12 and CH2~CHSiC13 (3:1 ratio) in THF
was added dropwise by syringe over 15 minutes. Gas evolution was observed. The reaction mixture was stlrred for ~n addit~onal hour at roo~ temperature. Polycarbosilan~ (1.64 g, 28.0 m~ol, Do~ Corning ~9-6348) was ground to a fin~ powder with a mortar and pestle and placed in a 25 ml, one-necked flasX. The flask w~s degasse~ and then 10 ml of THF was added. The resulting solution w~s cannulated into ehe reaction mixture. After stirring for 35 minutes., methyl iodide ~0.46 g, 3 .2 mmol) was added and an immediate whlte precip~ate for~ed. The solvent wa~ removed by trap-to-trap dist~llatlon (25C, 0.03 m~ Hg) and the residue ~xtracted wlth 40 ml of hexans. The reaction mixture was centri~uged and the supernaean~ liquid cannul~tedinto a 100 ml i`lask. R~moval of the hexane by trap-to-trap distillation left a ~hlte solid (3.04 g, 92~).

H NMR (CDC13, 250 MH2): ~ 0.16 (broad, 5.6 H, SiC~3), 0.95 ~broad, 1.25 H, NH), 4.16 (bro~d, 0.3 H, SiH), 4.71 ~broad, 0.7 H, SiH), S.91 (broad, 0.8 H, SiCH~CH2).
IR (CC14, cm~l): 3400(s), 3050(m), 3010(sh),. 2960(s), 2900(m), 2120-2100 (bro~d, s), 1600(w), 1410(s), 1360(m), 1270-1250 (b~oad, vs), 1190-1130 (broad, vs), 1050-84a (broad, vs).
~W (cryoscopy in benzene): 862 g/mol.

~ ~L~3L4~7~
TGA (10C/~in., Ar, 50~g50C): 85~ c~r~mlc ~l~ld, black so11d residua .

D.

A three-neckad ro~nd-b~ttomed flask waq equipp~d with a ga~ inle~
tube, ~ stir-bar and two septa, o~en-dried for 1 hour and then w~
charged wieh pot~ssium hydride (0.02 g, 0.50 ~ol). The app~ratus was then connected to a nitrogen line and 50 ml of THF was ~dded. The oil (1.64 g, 0.029 mol) from the coammonolysis of CR3SiHCl? and RSiC13 ~3:1 ratio) ln THF, was ~dded over S minutes. Gas evolution was observed. The reactlon mixeure was stirred for an additional 45 minutes at room temperature. ~y syringe, polymethylhydridosiloxane (1.58 g, 0.026 mol., Petrarch Systems, Inc., PS 122) was added to the reaction ~ixture. After stirring 30 m~nutes, ~ethyl lod~de tO.46 g, 3.2 mmol) WBS added and an im~edlatP white precipitate for~ed. The ~olvent was removed by trap-to-trap distillation (25C, 0.1 ~m ~8) ~nd the ~esidue extracted with 40 ml ~f hexane. The reaction mlxture was centrifuged and the supernatan~ liquid cannulst~d lnto a 100 ml flask. Re~oval of the h2xane by trap-to-trAp dlstillation left ~ white solid (2.30 8, 71%).

H NMR (CDC13, 250 HHz): ~ 0.10 (broad, 4.5 H, SiCH3), 0.93 (broad, 2.0 H, NH), 4.84 (bro~d, 1.0 H, SiH).

IR (CCl4, cm~l): 3490(w), 3400(s), 2960(s), 2900(w?, 2870(3h), 2820(w), 2130(s), 1580(w), 1425(m), 1265 ~broad, 5), 1200-1020 (broad, vs), 980-850 (broad, V5).
MW (cryoscopy in ben~ene); 1855 g~mol TGA (10C/min, Ar, 50-950C): 88% cera~ic yield, black s~lid residue.

~2~1~75 E. ~ ~ L~ I--WL ~ _ ~.

The apparatus w~s chnrged wlth RH (0.02 8, 0.50 ~ol) and 50 ~1 of THF. Tha oil (1.77 g, 0.031 mol) from the co~Q~nolysis of C~3SiHC12 and HSiC13 (3:1 ratio) in THF wa3 added over 5 minutes. Gas evolution w~ observed. Th~ r~act~on m~xture was stirrQd ~n addition~l 45 minutes at room ~empersture. Polymethylhydridosilane ~1.30 g, 0.030 mol) from the reaction of C~3SiHC12 ~nd excess sodium in 6:1 hexane/THF was added. The reaction mixture bec~e orange and then after 10 minutes t~rnsd yellow. The rea~tion mixture was stirred an additional 30 minutes at room te~perature and then methyl iodide (0.46 g, 3.2 m~ol) was added. An 1~m2diate white precipitate for~ed and the yellow color of the m~xture was discharged. The solvent was removed by trsp-to-tr~p distill&tion and the residue extracted wtin 40 ml of hexane. The resction m~xture wa~ centri~uged an~ the supernatant liquid cannulated into ~ 100 ~1 flas~. Remov~l of the h~xane by ~rap-to-trap distillation lef~ a whit~ solid (2.70 g, 88%).

1~ NMR (CDC13, 250 MHz): ~ 0.30 ~broad, 2.6 H, SiCH3), 1.23 (broad, 0.58 H, NH), 3.65 (broad, 0.19 H, SiH3, 4.4 (broad, 0.28 H, SlH), 4.8 (broad, 0.53 H, SlH).

IR (CC14, cm~l: 3S70 (broad, w), 3490 (m), 3150 (s), 3060 ~s), 2960(s), 2900(w), 2280(s~, 2150 (broad, vs), 1815(s), 1570~w), 1415(s), 1265(s), 1190 (broad, w), 1050-1020 (broad, vs), 980-850 (broad, ~s), 700(w).
NW (cryoscopy in benzene): 2200 ~/mol TGA (10C~min., Ar, 50-950C): 75~ ceramic yield, black solid residue.

~%~ 7~rj F.

X~-6~48L ~ ,5~LL~ L ~IY~

The apparatu~ was char~d v$th KH ~0.02 g, 0.50 ~ol) ~nd 50 ~1 of THF. The oil (1.61 g, 0.028 ~ol) from tha coaDmonoly~is of CH3SiHC12 snd HSlCl3 (3:1 ratio) in ~HF was ~dded ov~r 5 minutes. Gas evolution was obs~rved. ~he re~ction mixture was stirr~d an additional 30 minutes at roo~ temperature. Polycarbosilane (1.45 g, 0.025 mol, Dow Corning X9-6348) w~s gro~nd to ~ fine powder and placed in 8 25 ml one-necked flask. The flask was degassed ~nd then 10 ml of THF was added. This solution was then cannulated into the re~ction m~xture. After stirring for 30 minutes, methyl iodide (0.46 g, 3.2 m~ol) was added and an im~edlate white pr~cipitate ~ormed. Th~ solvent W8S removed by trap-to-trap dlstillation (25C, 0.1 m~ Hg) and the residue e~tracted with 40 ml of h~xane. The reaction mixture ~a~
centrifuged ~nd the supernatant llquld cannulated into a 100 ml flask.
Removal of the hexane by trap-eo-trap di~t~llatlon lcft a white 301id (2.97 g, 95~).
H NMR (CDC13, 250 MH~ 0.16 (broad, 5.0 H, SlCH3), 0.95 (broad, 0.8 H, NH), 1.24 ~0.7 ~, NH), 4.4 (broad, 0.3 H, SiH), 4.8 (broad, 0.7 H, Si~).
IR (CC14, c~-l): 3490(w), 3400(s), 2960(s), 2900(~), 2875(sh), 2120 (broad, s), 1460(w), 1415(D)~ 1365(~), 1260(s), 1175 (broad, vs), 1030 (broad, ~), 1080-850 (broad, vs).
M~ (cryoscopy in benzen~): 845 g/mol TCA (10C/min., Ar, 50-950~C): 76~ cer~mic y~eld, black solid residue.
i:

~L~2 ~Q
C~rsmic Yield Rça~tlQn 3:1 CH3SiHG1 VlSiC13 (THF) with KH/PS 122 solid 75 1340 86 3:1 CH3SiHC12/
ViSiC13 ~THF) solid 92 862 85 with KH/D.C. Polycarbosilane 3:1 CH3SiHC12/
ViSLC13 (THF) solid 93 1612 86 wi~h RH/(CH3siH)0~78 (CH3SI)~.22 3:1 ~H3SlHC12/
HSiC13 (T~F) with KH/PS 122 301id 71 1855 88 3:1 CH3SiHC12/
HSiC13 (THF) solid 95 845 76 with KH/~.C. Polycarbosilane 3:1 C~3S~HCl2/
HSiC13 (THF) ~olid 88 2200 75 with KH/(CH3SLH)~), CH3Si)o 22 : Vi ~ vinyl ~ -59-'7~
VI. ~In-Situ Procedure~
A. ~ ~ ~ Ç13 Lf~2~f~y~

In ~ dry box, a 250 ml round-bottom~d flask equipp~d with a ~eir-bsr, reflux condenser and a ~erum csp i8 charged with 0.10 g of KH
(O.0025 ~ol). ~HF (50 ml) is added to suspend the KH. A separate 250 ml Schlenk flask is charged ~th 2.0 8 f a CH3SLHC12/HSiC13 co~mmonolysis mixture that is prepared as described in section II.
This mixture is prepared by = onolysis of CH3SiHC12 and HSiC13 in ether solution, and then combined with 2.2 g of [(CH3SlH)X(CH3Si)y]n (0.05 mol, x - 0.74, y - 0.26), and 100 ml of THF. The mixed polymer solution ls transferred by cannula into the KH suspension. The reaction mixture gradually changes color to light orange and hydrogen gas is slowly e~olved. The resulting solution is st~rred at room temperature for 14 hours and i5 then heated at reflux for 1 hour. The light orange color of the solution persists. The reaction mixture is allowed to cool to room te~perature and 0.5 ~1 (7.9 ~ol) of CH3I is added to for~ a whits precipitate.
Th~ solvent ls removed by trap-to-tr~p distill~tion. The product is extracted with 200 ml of hexane and the insoluble residue is removed by centrifugation.
The clear, colorless supern~tant layer is tr~nsferred ~la cannula into a weighed 250 ml round-bottomed flssk The hexane is removsd by trap-to-~rap d~stillatlon lea~ing 3.8 g (91~ by weight~ of ~ white powder. The latt~r is soluble in THF, benzene, and he~ane.

2. Vs~ a co ~m~n~lysis mixture of ~H3SiHCl~ SiCl3 ~repared in Acoording to the procedurP de~cribed above, the reaction between 0.1 g of R~ (0.0025 mol), 2.0 g of the coaGmonolysis product of CH3SiHC12/HSiC13 (prepar~d in THF solution), ~nd 2.2 g o~

t8~4'75 [(CH35iH)X~CH3$i)y]n (x ~ 0.74, y - 0.26) 1~ c~rrled out under nltrogen. The r~ulting rsaceiDn mixture al~o graduslly change~
color ~o llght orange wlth ~low ~volution of hydroge~ ga~. Th~
~olution is stirr~d ~e room t~mp~rature for 14 hours ~nd th~n 0.5 ~1 (7.9 mmol) of CH3I is added. ~ork-up &~ described in th~ pre~ious experiment leaves a ~hlt~, solubl~ ~olld.
B. 8~~ctiQna o A Ml~lr* ~ oa~D~ly~ æ~tur9 ~nd po~,ycar~Qsllane wlth-~ Catal~t~
1. Uslng a Coammonol~is Hixture o~ SiHCl~ 3_ Pre~E~d from ~iethvl Ether.
c. PolYcarbosilane/Coammonolysis ~i~ture_in l;l wei~ht ~i~ ' In a dry box, a 250 ml round-bottomed flask equipped with a stir-bar, reflux cond~nser and a serum cap is charged with O.lS g of ~H
(3.75 mmol). T~F (50 ml) is added to suspend the ~H. A separate 250 ml Schlenk flask is charged wtlh 5.0 g of the coa~onolysis product of CH3SiHC12 and HSiC13 prepared in ~ther solution, Qnd 5.0 g of polycarbosilane, and 150 ml of THF. The ~i~ed polymer solution 1s transferred by cannula into the KH s~spension i~ THF. Ihe reaction ~ixture grsdually turns clear and hydrogen gas slowly evol~es. The resulting solution is stirred at room temperature for ~ hours snd is then heat~d at refl~x ~or 24 hours. The reaction ~ixture is allowed to cool to room temperature and 0.5 ~l (7.9 ~ol) of CH3I i~ added and the -mixtu~e i5 heated for several hours. The sol~ent is remo~ed by trap-to-trap distillation. The product i3 extracted with 200 ~1 of hexane and the insoluble residue is re~oved by centrifugation. The clear, colorless supernstant layer is tran~ferred v~a a cannuls into a weighed 250 ml round-bottomed flask. The hexane is removed by trap-to-trap distillation leaving a white powder. The white powder is soluble in THF, benzene, and hexane.

C. ~eactions of a ~ixture of a Coammonolysis Mixtu~e and cyclic Ql~ withlgi_~QtalYg5 ~ 2~

In a dry box, a 250 ml round-botto~0d ~lask ~quipped with 3 stir-bar, reflux condens~r, ~d ~ saru~ c~p i~ char~od with 0.1 g of XH
(2.50 mmol). THF (100 ~ dded to susp~nd the KH. A separAte 250 ml flask is ch~rsed with 4.0 g of the product, prepared by co~mmonolysi3 of CH3SiHC12 and ~SiC13 in THF ~olution, and 3.6 g of [CH3Si(H)O~n, and 50 ml o THF. ~his soluelon is transferred by cannula into the KH suspens~on in THF. Th~ reaction mixture ~radually turns clear ~nd hydrogen gas is slowly evolved. Tbe resulting solution ~s stirred ~t room temperature for 4 hours and then 0.5 ml (7.9 mmol) of CH3I is added. The solvent is removed by trap-to-trap distillation. The residual solid is treated with 80 ml of hex~ne and the insoluble residue is removed by centrifugation. The clear, colorless supernatane layer i~ transferred via rannula into a weighed 100 ml round-bottomed flas~. The h~xane is removed by trap-to-trap distillat~on leaving of a white powder. The latter is soluble in THF, benzene, and hexane.

This invention has been de~cribed in detail with reference to the preferred embodiments thereof. However, it ~ill be appreciated that those skilled in the art, upon consideration of this disclosure, may make modificatlons and i~provements witbln the spirit and scope of the invention.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for preparing preceramic organosilicon polymers, wherein the method comprises:
(a) reacting in solution anhydrous ammonia with a mixture of R1SiHX2, wherein R1 is a lower alkyl group having from 1 to about 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to about 6 carbon atoms, a substituted or unsubstituted lower alkenyl group having from 2 to about 6 carbon atoms, or a substituted of unsubstituted lower aryl group having from 6 to about 10 carbon atoms, and X is a halogen, and RSiX3 wherein R is H, a lower alkyl group having from 1 to about 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to about 6 carbon atoms, or a substituted or unsubstituted lower alkenyl group having from 2 to about 6 carbon atoms, or a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, thereby forming a mixture of precursor polymers; and (b) reacting said precursor polymers in the presence of a basic catalyst capable of deprotonating the NH functions in said precursors to form said preceramic polymer.
2. The method of claim 1 further comprising the additional step of treating said preceramic polymer with an electrophile compound.
3. The method of claim 1 wherein X is Cl, R1 is a lower alkyl group and R is H or a lower alkyl group.
4. The method of claim 3 wherein R1 is CH3.
5. The method of claim 4 wherein R is H or CH3.
6. The preceramic polymer formed by the method of claim 2.
7. The preceramic polymer formed by the method of claim 4.

8. The preceramic polymer formed by the method of claim 5.
9. The method of claim 1 wherein the mole ratio of R1SiHX2:RSiX3 is from about 8:1 to about 1:6.
10. The method of claim 9 wherein the mole ratio is about 8:1 to about 1:2.
11. The method of claim 3 wherein the mole ratio of R1SiHX2:RSiX3 is from about 8:1 to about 1:6.
12. The method of claim 11 wherein the mole ratio is about 6:1 to about 1:2.
13. The method of claim 4 wherein the mole ratio of R1SiHX2:RSiX3 is from about 6:1 to about 1:6.
14. The method of claim 13 wherein the mole ratio is about 6:1 to about 1:2.
15. The method of claim 14 wherein the mole ratio is about 6:1 to about 3:1.
16. The method of claim 14 wherein the mole ratio is about 2:1 to about 1:2.
17. The method of claim 5 wherein the mole ratio of R1SiHX2:RSiX3 is from about 6:1 to about 1:2.
18. The method of claim 17 wherein the mole ratio is about 6:1 to about 3:1.
19. The method of claim 14 wherein the mole ratio is about 2:1 to about 1:2.

20. The method of claim 2 wherein the preceramic polymer is pyrolyzed under an inert gas stream at a sufficient temperature and for a sufficient time to form a ceramic material.
21. The method of claim 3 wherein the preceramic polymer is pyrolyzed under a stream of ammonia at a sufficient temperature and for a sufficient time to form a ceramic material.
22. The method of claim 4 wherein the preceramic polymer is pyrolyzed under a stream of ammonia at a sufficient temperature and for a sufficient time to form a ceramic material.
23. The method of claim 5 wherein the preceramic polymer is pyrolyzed under a stream of ammonia at a sufficient temperature and for a sufficient time to form a ceramic material.
24. The method of claim 1 wherein said basic catalyst is selected from the group consisting of alkali metals, alkali and alkaline earth metal hydrides, complex metal hydrides, alkali metal alkoxides, alkali metal and alkaline earth metal amides, alkali and alkaline earth metal silylamides and alkali metal organic compounds.
25. The method of claim 2 wherein the electrophile has the formula E-X1 where E is an organic or silyl group, and X1 is a halide, sulfate or sulfonate.
26. The method of claim 25 wherein E is a lower alkyl group or silyl group.
27. A method for preparing ceramic fibers from the preceramic polymer of claim 2 which further comprises introducing C-C functionalities into the coammonolysis product; forming preceramic fibers, curing said preceramic fibers by a hydrosilylation reaction, and thereafter pyrolyzing the cured preceramic fibers.

28. The method for preparing ceramic fibers of claim 27 wherein the C-C functionalities are introduced by having R or R1 be a substituted or unsubstituted lower alkenyl group having from 2 to about 6 carbon atoms.

29. The method for preparing ceramic fibers of claim 27 wherein the C-C functionalities are introduced by adding a third compound containing an unsaturated functionality to the mixture containing anhydrous ammonia, R1SiHX2 and RSiX3.

30. The method of claim 27 wherein the curing is initiated by irradiation with an electron beam, an X-ray source, or ultraviolet irradiation.

31. The method of claim 2 wherein R is a lower alkyl group or hydrogen, R1 is a lower alkyl group and the preceramic polymer is pyrolyzed under a stream of ammonia at a sufficient temperature and for a sufficient time to form a ceramic material.