GB2258465A - Derivatized alkylpolysilane npreceramic polymers - Google Patents

Description

)115; n 1 1) 5 --- t- i DERIVATIZED ALKYLPOLYSILANE PRECERAMIC POLYMERS

The United States Government has rights in this invention pursuant to Contract Number F33615-83-C-5006 awarded by the United States Air Force.

This invention relates to derivatized alkylpolysilanes, and especially derivatized methylpolysilanes, which are useful as preceramic polymers in the preparation of ceramic materials and articles. This invention further relates to the methods of preparing such derivatized alkylpolysilanes and derivatized methylpolysilanes as well as the ceramics prepared from such preceramic polymers.

Baney et al. in U.S. Patent 4,310,651 (issued January 12, 1982) disclosed a polysilane of general formula (CH,Si)((CH,),Si) where there was present 0 to 60 mole percent ((CH3)2Si) units and 40 to 100 mole percent (CH3Si) units and where the remaining bonds on silicon were attached to other silicon atoms and chlorine atoms or bromine atoms. The polysilane was converted to a beta-silicon carbide containing ceramic material at elevated temperatures (about 1400'C). The polysilanes of U.S. Patent 4, 310,651 generally are difficult to handle due to their high reactivity in air.

Baney et al. in U.S. Patent 4,298,559 (issued November 3, 1981) prepared polysilanes of general formula (CH3Si)((CH3)2Si) where there was present 0 to 60 mole percent ((CH3)2S') units and 40 to 100 mole percent (CH.Si) units and where the remaining bonds on silicon were attached to other silicon atoms and additional alkyl radicals of 1 to 4 carbon atoms or phenyl radicals. Upon heating, these polysilanes are converted into silicon carbide-containing ceramics in high yields.

2- Baney in U.S. Patent 4,310,481 (issued January 12, 1982) disclosed polysilanes of the general formula (CH3SM(CH3)2Si) where there was present 0 to 60 mole percent ((CHA2S') units and 40 to 100 mole percent (CH.Si) units and where the remaining bonds on silicon were attached to silicon and (CHA3SiO- radicals. A silicon carbide containing ceramic was obtained by firing this polysilane to an elevated temperature under an inert atmosphere or vacuum.

Baney in U.S. Patent 4,310,482 (issued January 12, 1982) disclosed polysilanes of the general formula (CH3SiMCH3)2Si) where there was present 0 to 60 mole percent ((CHA2Si) units and 40 to 100 mole percent (CH3Si) units and where the remaining bonds on silicon were attached to silicon and hydrogen. A silicon carbide containing ceramic was obtained by firing this polysilane to an elevated temperature under an inert atmosphere or vacuum.

Baney et al. in U.S. Patent 4,314,956 (issued February 9, 1982) disclosed polysilanes of the general formula (CH,S')((C1.13)2S') where there was present 0 to 60 mole percent ((CHA.S') units and 40 to 100 mole percent (CH3S') units and where the remaining bonds on silicon were attached to silicon and amine radicals of the general formula -NHR- where R- is a hydrogen atom, an alkyl radical of 1 to 4 carbon atoms or a phenyl radical. A silicon carbide containing ceramic was obtained by firing this polysilane to an elevated temperature under an inert atmosphere or under an ammonia atmosphere.

Baney et al. in U.S. Reissue Patent Re. 31,447 (reissued November 22, 1983) disclosed polysilanes of the general formula (CH3SiMCH.)2Si) where there was present 0 to 60 mole percent RCHAISi) units and 40 to 100 mole percent (CH3Si) units and where the remaining bonds on silicon were attached to other silicon atoms and alkoxy radicals containing 1 to 4 carbon atoms or phenoxy radicals. Silicon carbide containing ceramics were obtained by firing these polysilanes to elevated temperatures.

These polysilanes are further discussed in Baney et al., Organometallics, 2, 859 (1983).

What has been newly discovered are derivatized alkylpolysilanes of general formula (R2SiMRSi)(R'Si) wherein each R is independently selected from alkyl radicals containing 1 to 4 carbon atoms, where each R' is independently selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X (3-Y) Si(CH2) Z_ wherein each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1, where there are from 0 to 40 mole percent (R2S') units, 1 to 99 mole percent (RSi), and 1 to 99 mole percent (R'Si) units, and where there are also bonded to the silicon atoms other silicon atoms and radicals selected from the group consisting of hydrogen atoms, additional alkyl radicals containing 1 to 4 carbon atoms, vinyl radicals, allyl radicals, phenyl radicals, (CHA3SiOradicals, -OR... radicals, and -N(RV)2 radicals where R... is an alkyl radical of 1 to 4 carbon atoms or a phenyl radical and R v is hydrogen, an alkyl radical of 1 to 4 carbon atoms, a phenyl radical, or a SiA'3 radical where each A' is independently selected from alkyl radicals containing 1 to 4 carbon atoms, hydrogen or vinyl. These derivatized alkylpolysilane preceramic polymers can be pyrolyzed at elevated temperatures under an inert atmosphere to yield ceramic materials or articles. These derivatized alkylpolysilanes represent a significant advance in the art of preparing ceramic materials 4- or articles, especially in the art of preparing ceramic fibers.

This invention relates to derivatized alkylpoly silanes of the average formula (R2S'MRSi)(R'Si) wherein each R is independently selected from alkyl radicals containing 1 to 4 carbon atoms, wherein each R' is independently selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X (3-Y) Si(CH) Z_ where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1, where there are from 0 to 40 mole percent (R2Si) units, 1 to 99 mole percent (RSi), and 1 to 99 mole percent (R'Si) units, and where there are also bonded to the silicon atoms other silicon atoms and radicals selected from the group consisting of hydrogen atoms, additional alkyl radicals containing 1 to 4 carbon atoms, vinyl radicals, allyl radicals, phenyl radicals, (CH3)3SiO-radicals, -OR- radicals, and N(Rv)2 radicals where each R... is independently selected from alkyl radicals of 1 to 4 carbon atoms or a phenyl radical and Rv is hydrogen, an alkyl radical of 1 to 4 carbon atoms, a phenyl radical, or a -SiA', radical where each A' is independently selected from alkyl radicals containing 1 to 4 carbon atoms, hydrogen or vinyl.

The non-derivatized alkylpolysilanes useful in this invention to prepare the inventive derivatized alkylpolysilanes are described by the average formula (R2Si)(RSi)(R'Si) where each R is independently selected from alkyl radicals containing 1 to 4 carbon atoms and each R' is independently selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X (3-Y) Si(CH2) Z_ where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1, and there are from 0 to 40 mole percent (R2Si) units, 1 to 99 mole percent (RSi) units, and 1 to 99 mole percent (R'Si) units and wherein the remaining bonds on silicon are attached to either other silicon atoms, chlorine atoms or bromine atoms. These are chlorine or brominecontaining polysilanes where the remaining bonds on silicon are attached to other silicon atoms and chlorine atoms or bromine atoms. Preferably, these polysilanes contain from 0 to 40 mole percent (R2S') units, 40 to 99 mole percent (RSi) units, and 1 to 30 mole percent (R'Si) units. Most preferably, these polysilanes contain from 0 to 10 mole percent (R.Si) units, 80 to 99 mole percent (RSi) units, and 1 to 20 mole percent (R'Si) units. The chlorine- containing polysilanes are preferred in the practice of this invention.

The non-derivatized polysilanes may be prepared by the method described in U.S. Patent Application Serial No. 945,126 entitled "Polysilane Preceramic Polymers", in the names of Duane Ray Bujalski, Gary Edward LeGrow and Thomas Fay-oy Lim, which was filed on the same date as this application. In general, these polysilanes may be prepared by reacting a mixture of about 40-99 weight percent of one or more chlorine-containing or bromine-containing disilanes and 1 to 60 weight percent of one or more monoorganosilanes of the formula R'SiX, where R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A Y X (3-Y) Si(CI-I2) Z_ where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1, w-.,, .

0.001 to 10 weight percent of a rearrangement catalyst at a temperature of 1000C to 3400C while distilling by-produced volatile materials. More preferably, these polysilanes are prepared by reacting a mixture of about 70-99 weight percent of one or more chlorinecontaining or brominecontaining disilanes and 1 to 30 weight percent of one or more monoorganosilanes of formula R'S'X3 where R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X G-Y) Si(CH2)z_ where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1, with 0.001 to 10 weight percent of a rearrangement catalyst at a temperature of 1000C to 3400C while distilling by-produced volatile materials.

The chlorine-containing or brominecontaining disilanes used to prepare the non-derivatized polysilanes are of the general formula (R b X c Si)2 wherein each R is independently selected from alkyl radicals containing from 1 to 4 carbon atoms, b has a value of 0 to 2.5, c has a value of 0.5 to 3, the sum (b+c) equals three, and X is chlorine or bromine. R in the above disilane may be^phenyl, methyl, ethyl, propyl or butyl. Examples of such disilanes include CH3C12S'S'Cl(CHA21 CH3C1.S'S'Cl2CH3, CH3Br2SiSiBr(CH.)2, CH2Br2SiSiBr2CH3, and the like. Preferably in the above disilane, R is a methyl radical and X is chlorine. The disilane can be prepared from the appropriate silanes or the disilane can be utilized as it is found as a component of the process residue from the direct synthesis of organochlorosilanes. The direct synthesis of organochlorosilanes involves passing the vapor of an organic chloride over heated silicon and a catalyst. See Eaborn, "Organosilicon Compounds," Butterworths Scientific Publications, 1960, page 1. The disilanes CH.Cl2SiSiCl2CH3 and (CHA2C'S'S'Cl2CH3 are found in large quantities in the residue from the reaction and, therefore, this Direct Process residue is a good starting material for obtaining the non- derivatized polysilane polymers used in this invention.

The monoorganosilanes used to prepare the non- derivatized polysilanes are of formula R'S'X3 where R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X (3-Y) Si(CH2) Z_ where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1. The A radicals in the formula A y X GY) S'(CH2) Z_ may be the same or different. Generally, the monoorganosilane should have a boiling point of about 180'C or greater at one atmosphere. Examples of suitable monoorganosilanes include phenyltrichlorosilane, n-hexyltrichlorosilane, n-octyltrichlorosilane, phenyltribromosilane, n-octyltribromosilane, C13SiCH2qH2SiC131 CH3C12SiCH2CH2S'Cl31 (CHA2C'S'CH2CH2SiC131 H(CHA2SiCH2CH2S'C13, and the like. Phenyltrichlorosilane and n- octyltrichlorosilane are the preferred monoorganosilanes.

Mixtures of such monoorganosilanes may also be used. Indeed, mixtures of monoorganosilanes are generally preferred in the practice of this invention. One especially preferred mixture of monoorganosilanes contains n-octyltrichlorosilane and phenyltrichlorosilane. The use of such monoorganosilanes, either singly or in mixtures, appears to allow for control of both the softening or glass transition temperatures of the derivatized polysilanes and the relative silicon and carbon content of the ceramic materials produced -a- from the derivatized alkylpolysilanes by a variation of the (R'Si) content in the non-derivatized alkylpolysilanes. In general, it appears that increasing the (R'Si) content of the non-derivatized, and thus the derivatized, alkylpolysilanes results in a reduction in the glass transition temperature. Incorporation of (n-octyl-Si) units allows for a significant reduction of the glass transition temperature with the amount of the reduction being dependent on the level of (n-octylSi) units in the alkylpolysilane. Incorporation of (phenylSi) units also results in a decrease in the glass transition temperature but the observed effect is generally less than for incorporation of (n-octyl-Si) units. Upon pyrolysis of the derivatized alkylpolysilanes containing (n-octyl-Si) units, it appears that the n-octyl group is lost from the ceramic material as an olefin thereby leaving the ceramic material carbon deficient relative to ceramic materials prepared from similar polymers without (n-octyl-Si) units. It is expected that other alkyl groups containing at least six carbon atoms will behave in a similar manner. Phenyl groups are generally not lost upon pyrolysis. Therefore, pyrolysis of the derivatized alkylpolysilanes containing (phenyl-Si) units allows more carbon to be incorporated into the final ceramic material and therefore produces ceramic materials that are carbon rich relative to ceramic materials prepared from similar polymers without (phenyl-Si) units. Thus, by incorporation of (R'Si) units where R' is n-octyl and phenyl, the relative silicon and ca rbon content of the resulting ceramic materials can be controlled to a large extent. It is possible by the practice of this invention to prepare ceramic materials containing SiC with either excess carbon or excess silicon as well as stoichiometric amounts of silicon and carbon. Methyl radicals in the form of (CH.Si) or ((CH.)2S') units are generally not lost on pyrolysis. Therefore, the -g- relative amounts of silicon and carbon will also depend in part on the presence of the other units in the derivatized alkylpolysilane but the incorporation of (n-octyl-Si) and (phenyl-Si) units can be used to "fine tune" the relative silicon and carbon content of the ceramics.

The disilane and monoorganosilane mixtures are reacted in the presence of a rearrangement catalyst. Suitable rearrangement catalysts include ammonium halides, tertiary organic amines, quaternary ammonium halides, quaternary phosphonium halides, hexamethylphosphoramide, and silver cyanide. Preferred catalyst includes quaternary ammonium halides having the formula W4W', quaternary phosphonium halides having the formula W4PX', and hexamethylphosphoramide where W is an alkyl or aryl radical and X' is halogen. Preferably, W is an alkyl radical containing 1 to 6 carbon atoms or a phenyl radical and X' is chlorine or bromine. One especially preferred catalyst is tetra-nbutylphosphonium bromide.

The amount of catalyst utilized can range from 0.001 to 10 weight percent and preferably from 0.1 to 2.0 weight percent based on the weight of the starting disilane/monoorganosilane mixture. The catalysts and starting materials require anhydrous conditions and therefore one must take care to insure that moisture is excluded from the reaction system when the reactants are mixed. Generally, this can be done by using a stream of dry nitrogen or argon as a cover over the reaction mixture.

The mixture of about 40 to 99 weight percent disilane or disilanes and 1 to 60 weight percent monoorganosilane or monoorganosilanes is reacted in the presence of 0.001 to 10 weight percent of a rearrangement catalyst at a temperature of 100'C to 340'C while distilling by-produced volatile materials until there is produced the chlorine- containing or bromine-containing polysilane. Preferably the reaction mixture contains 70 to 99 weight percent disilane or disilanes and 1 to 30 weight percent monoorganosilane or monoorganosilanes. Most preferably, the reaction mixture contains 80 to 98 weight percent disilane or disilanes and 2 to 20 weight percent monoorganosilane or monoorganosilanes. The order of mixing the reactants is not critical. Preferably, the reaction temperature is from 1500C to 3000C. When the final reaction temperature is higher than the boiling point of the monoorganosilane, it is preferred that the reaction temperature be raised slowly to the final temperature so that the monoorganosilane will have a greater tendancy to incorporate into the polymer as opposed to simply distilling out of the reaction mixture. Increasing the incorporation of the monoorganosilane may also be accomplished by removing the volatile by- products only in the later stages of the reaction. Typically the reaction is carried out for about 1 to 48 hours although other time durations may be employed.

The chlorine or bromine atoms in the chlorine- or bromine-containing nonderivatized alkylpolysilanes are very reactive. This reactivity makes the handling of these alkylpolysilanes difficult. These alkylpolysilanes are especially difficult to handle when a low oxygen containing ceramic material is desired. Therefore, it is preferred that the chlorine or bromine atoms be replaced with less reactive groups. By the practice of this invention, the highly reactive chlorine or bromine atoms of the chlorine or bromine-containing alkylpolysilanes may be replaced by the generally less reactive radicals selected from the group consisting of hydrogen atoms, additional alkyl radicals containing 1 to 4 carbon atoms, vinyl radicals, allyl radicals, phenyl radicals, (CH.),SiO-radicals, -OR.. .

11 radicals, and -N(R v)2 radicals where R... is an alkyl radical of 1 to 4 carbon atoms or a phenyl radical and R v is hydrogen, an alkyl radical of 1 to 4 carbon atoms, a phenyl radical, or a -SiA', radical where each A' is independently selected from alkyl radicals containing 1 to 4 carbon atoms hydrogen or vinyl thereby forming the derivatized alkylpolysilane preceramic polymers of this invention.

The derivatized alkylpolysilanes containing additional alkyl, vinyl, allyl, or phenyl groups can be prepared using the general techniques of U.S. Patent No. 4,298,559. Such derivatized alkylpolysilanes can be prepared by reacting the non-derivatized alkylpolysilanes of this invention with an alkyl, vinyl, allyl, or phenyl Grignard reagent of general formula R'v MgX or with an organolithium compound of general formula R iv Li where R iv is an alkyl radical containing 1 to 4 carbon atoms, a vinyl radical, an allyl radical, or a phenyl radical and X is chlorine or bromine. The Grignard reagents useful herein are those reagents commonly known in the art for Grignard type reactions. Such materials are, for example, alkyl magnesium halides and aryl magnesium halides. For purposes of this invention, it is preferred to use Grignard reagents having the general formula R'V MgX wherein R'v is an alkyl radical of 1 to 4 carbon atoms, a vinyl radical, an allyl radical, or a phenyl radical and X is either chlorine or bromine. Most preferred Grignard reagents are CH.MgC1, CH3MgBr, (CH,=CH)MgC1, (CH, =CH)MgBr, (C.H.)MgC1, and (C.H.)MgBr. Typical Grignard reaction solvents can be used with alkyl ethers and tetrahydrofuran being preferred. The organolithium compounds useful herein are of the general formula R iv Li wherein R iv is an alkyl radical of 1 to 4 carbon atoms, a vinyl radical, an allyl radical, or a phenyl radical. Methyllithium is the preferred organolithium compound.

Suitable solvents for the organolithium compounds include toluene, xylene, benzene and ethers. Combinations of Grignard reagents and/or organolithium compounds may also be used. For best results, dry reaction conditions should be observed. Solvents for the starting non-derivatized alkylpolysilanes can be any organic solvent in which the material is soluble and which does not react with the material except in the desired manner. Examples of useful solvents include toluene, xylene, benzene, tetrahydrofuran and ethers. Specifically, toluene is preferred. Generally, it has been found preferable to add the non-derivatized alkylpolysilane to an excess of Grignard reagent or organolithium compound, both in a solvent solution. This addition and reaction is carried out while the materials are stirred or otherwise agitated. The reaction is carried out in a dry inert atmosphere such as in the presence of nitrogen or argon gas to prevent the introduction of water into the reaction vessel. The reaction can be run at temperatures of 0 to 1500C but preferably the reaction is run at room temperature or slightly below room temperature to prevent or decrease undesirable side reactions. After the addition of the reagent is complete, the reaction mixture is stirred for a time, with or without heating, to ensure the completion of the reaction. Typically, the reaction is carried out for a time period of about 1 to 48 hours. Excess Grignard reagent or organolithium compound is then destroyed using water, HCl, an alcohol, or an aqueous NH4C1 solution. The reaction mixture is cooled to room temperature and then filtered by conventional means and the solvents and other volatile materials are then removed by stripping under vacuum with the addition of heat. The general procedures for such replacement reactions are described in more detail in U.S. Patent 4,298, 559. The resulting derivatized alkylpolysilanes containing additional alkyl, vinyl, allyl, or phenyl groups are solids. The resulting alkylpolysilanes are of the general formula (R2SMRSi)(R'Si) where each R is independently selected from alkyl radicals containing 1 to 4 carbon atoms, where R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X (3-Y) S'(CH2) z- where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1, where there are from 0 to 40 mole percent (R2S') units, 1 to 99 mole percent (RSi), and 1 to 99 mole percent (R'Si) units, and where there are also bonded to the silicon atoms other silicon atoms and radicals selected from the group consisting of additional alkyl radicals containing 1 to 4 carbon atoms, vinyl radicals, allyl radicals, and phenyl radicals. Preferably, the resulting alkylpolysilanes contain 0 to 40 mole percent (R2Si) units, 40 to 99 mole percent (RSi), and 1 to 30 mole percent (R'Si) units.

The derivati ' zed alkylpolysilanes containing (CHA3SiO-radicals can be prepared using the general techniques of U.S. Patent 4,310,481. Such derivatized alkylpolysilanes can be prepared by reacting the nonderivatized alkylpolysilanes of this invention with hexamethyldisiloxane. Generally, the reaction is carried out adding (CH.), Si0Si(CH.)3 and a strong acid such as F3CS03H or sulfuric acid to the nonderivatized alkylpolysilane in an organic solvent and then adding water with agitation. The reaction may be carried out at room temperature to 125'C but it is generally preferred that the reaction temperature be about room temperature or slightly above room temperature to prevent or decrease undesirable side reactions. After the addition of the disiloxane, acid, and water is complete, the reaction mixture is stirred for a time, with or without heating, to ensure the completion of the reaction. The reaction mixture is then cooled to room temperature and filtered by conventional means. The solvent and other volatile materials are removed by vacuum stripping. The general procedures for such siloxylating reactions are described in more detail in U.S. Patent 4,310,481. The resulting (CHA3SiO-containing alkylpolysilanes are solid at room temperature. These (CHA3SiO-containing alkylpolysilanes are of the general formula (R2SiMRSi)(R'Si) where each R is independently selected from alkyl radicals containing 1 to 4 carbon atoms, where R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X (3-Y) Si(CH2) Z_ where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1, where there are from 0 to 40 mole percent (R2Si) units, 1 to 99 mole percent (RSi), and 1 to 99 mole percent (R'Si) units, and where there are also bonded to the silicon atoms other silicon atoms and (CHA3SiO- radicals. Preferably, the (CHA3SiO-containing alkylpolysilanes contain 0 to 40 mole percent (R2Si) units, 40 to 99 mole percent (RSi), and 1 to 30 mole percent (R'Si) units.

The derivatized alkylpolysilanes containing hydrogen attached to silico n can be prepared using the general techniques of U.S. Patent 4,310,482. Such derivatized alkylpolysilanes can be prepared by reacting the nonderivatized alkylpolysilanes of this invention with a reducing reagent such as lithium aluminum hydride under anhydrous conditions. Generally, the process consists of t 15- placing the reducing agent (as a slurry in a dry solvent) in a reaction vessel which is purged with an inert gas. The non-derivatized alkylpolysilane is then added to the slurried reducing agent over a period of time to control any exotherm. After the addition, the mixture can be refluxed to ensure complete reaction or can be stirred at room temperature for several hours. Excess reducing agent can be destroyed by the addition of aqueous sodium hydroxide. The reaction may be filtered if desired. It is preferred that the reaction mixture be dried, using, for example, M9S04, and then filtered. The reaction mixture may then be vacuum stripped to obtain the desired solid, hydrogen-containing alkylpolysilanes. The general procedures for such reduction reactions are described in more detail in U.S. Patent 4,310,482. These hydrogencontaining alkylpolysilanes may be described by the general formula (R2S'MRSi)(R'Si) where each R is independently selected from alkyl radicals containing 1 to 4 carbon atoms, where R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X (3-Y) Si(CH2) Z_ where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1, where there are from 0 to 40 mole percent (R2Si) units, 1 to 99 mole percent (RSi), and 1 to 99 mole percent (R'Si) units, and where there are also bonded to the silicon atoms other silicon atoms and hydrogen atoms. Preferably, the hydrogen-containing alkylpolysilanes contain 0 to 40 mole percent (R2Si) units, 40 to 99 mole percent (RSi), and 1 to 30 mole percent (R'Si) units.

The derivatized alkylpolysilanes containing amine and substituted amine groups attached to silicon can be -16 prepared using the general techniques of U.S. Patent No. 4,314,956. The amine and substituted amine groups can be described by the general formula -N(Rv)2 where RV is hydrogen, an alkyl radical containing 1 to 4 carbon atoms, a phenyl radical, or a -SiA', radical where each A' is independently selected from hydrogen, alkyl radicals containing 1 to 4 carbon atoms and vinyl. The aminolysis reagents useful in this invention are ammonia or substituted or unsubstituted organic amines having the general formula N(Rv)22 where RV is a hydrogen atom, an alkyl radical of 1 to 4 carbon atoms, a phenylradical, or a SiA'3 radical where each A' is independently selected from hydrogen, alkyl radicals of 1 to 4 carbon atoms and vinyl. Examples of suitable aminolysis reagents include NH3, CH3NH2, (CH3)2NH, C4H 9 NH2, (CH3),SiNH., and aniline. Combinations of these aminolysis reagents may also be employed. By treatment with such aminolysis reagents, the chlorine or bromine atoms are replaced by radicals of formula -N(R:V)2' Generally, the aminolysis reagent is used in a stoichiometric excess based on the amount of halogen present in the non-derivatized alkylpolysilane to ensure that the aminolysis reaction is enhanced. Excess reagent as well as any solvents and byproducts can be stripped or strip distilled at the end of the reaction. For best results, dry reaction conditions should be observed. Solvents for the starting non- derivatized alkylpolysilane can be any organic solvent in which the material is soluble and which does not react with the material except in the desired manner. Examples of useful solvents include toluene, xylene, benzene, tetrahydrofuran and ethers. Specifically, toluene is preferred. Generally, the order of addition of the components is not critical, but it has been found preferable to add the neat aminolysis reagent to the non-derivatized alkylpolysilane in a solvent solution, such as toluene. This addition and reaction is carried out while the materials are stirred or otherwise agitated. The reaction is carried out in a dry inert atmosphere such as in the presence of nitrogen or argon gas to prevent the introduction of water into the reaction vessel. After the addition of the aminolysis reagent is complete, the reaction mixture is stirred for a time, with or without heating, to ensure the completion of the reaction. Typically the reaction time is about 3 to 96 hours. The reaction can be run at temperatures of 25'C to 100'C but preferably the reaction is run at reflux temperature. The reaction mixture is cooled to room temperature and then filtered by conventional means and the solvents and other volatile materials are then removed by stripping under vacuum with or without the addition of heat. The resulting alkylpolysilanes are solids at room temperature. The general procedures for such reactions are described in more detail in U.S. Patent 4,546,163. These amino-substituted alkylpolysilanes may be described by the general formula (R2SMRSi)(R-Si) where each R is independently selected from alkyl radicals containing 1 to 4 carbon atoms, where R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X (3-Y) Si(CH2) Z_ where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1, where there are from 0 to 40 mole percent (R1Si) units, 1 to 99 mole percent (RSi), and 1 to 99 mole percent (R'Si) units, and where there are also bonded to the silicon atoms other silicon atoms and radicals of the formula -N(RV)2 where R v is hydrogen, an alkyl radical containing 1 to 4 carbon atoms, a phenyl radical, or a -SiA', radical where -Is- each A' is independently selected from hydrogen, alkyl radicals containing 1 to 4 carbon atoms and vinyl. Preferably, the amine- substituted alkylpolysilanes contain 0 to 40 mole percent (R2S') units, 40 to 99 mole percent (RSi), and 1 to 30 mole percent (R'Si) units.

The derivatized alkylpolysilanes containing alkoxy or phenoxy groups attached to silicon can be prepared using the general techniques of U.S. Reissue Patent Re. 31,447. These alkoxy- or phenoxy-containing alkylpolysilanes may be prepared by reacting the non-derivatized alkylpolysilanes, under anhydrous conditions, with a reagent selected from the group consisting of (i) alkyl orthoformates having the general formula (RO).CH, (ii) carbinols having the general formula R... OH, and (iii) alcoholates having the general formula R... OM, where R is an alkyl radical containing 1 to 4 carbon atoms, R... is an alkyl radical containing 1 to 4 carbon atoms or a phenyl radical, and M is sodium, potassium, or lithium. By treatment with such reagents, the chlorine or bromine atoms are replaced by radicals of formulae RO- and R... 0. The treating reagents are of three different types; namely, alkyl orthoformates having the general formula (RO).CH, carbinols having the general formula R... OH, and alcoholates having the general formula R... OM and in which R is an alkyl group of 1-4 carbon atoms, R... is an alkyl group of 1 to 4 carbon atoms and phenyl, and M is sodium, potassium or lithium. Specific examples of materials useful in this invention are CH. 0H, CH3CH20H, CH3(CH2)30H, Na0CH., KOCH., LiOCH2CH3, (CH30)3CH, (CH3CH. 0)3CH and phenol. Preferred for this invention are the alkyl orthoformates and alcoholates. Most preferred is NaOCH.. Combinations of these reagents may also be employed. Generally, the reagent is used in a stoichiometric excess based on the amount of halogen present in the nonderivatized alkylpolysilane to ensure that the alcoholysis reaction is enhanced. Excess reagent as well as any solvents and by-products can be stripped or strip distilled at the end of the reaction. For best results, dry reaction conditions should be observed. Solvents for the starting non-derivatized alkylpolysilanes can be any organic solvent in which the material is soluble and which does not react with the material except in the desired manner. Examples of useful solvents include toluene, xylene, benzene, tetrahydrofuran and ethers. Specifically, toluene is preferred. Generally, the order of addition of the components is not critical, but it has been found preferable to add the neat reagent to the non-derivatized alkylpolysilane polysilane in a solvent solution, such as toluene. This addition and reaction is carried out while the material are stirred or otherwise agitated. The reaction is carried out in a dry inert atmosphere such as in the presence of nitrogen or argon gas to prevent the introduction of water and air into the reaction vessel. After the addition of the reagent is complete, the reaction mixture is stirred for a time, with or without heating, to ensure the completion of the reaction. Typical,ly the reaction time is about 1.5 to 65 hours. The reaction can be run at temperatures of 250C to 1100C but preferably the reaction is run at reflux temperature. The reaction mixture is cooled to room temperature and then filtered by conventional means and the solvents and other volatile materials are then removed by stripping under vacuum with or without the addition of heat. The resulting derivatized alkylpolysilanes are solids at room temperature. The general procedures for such alkoxylating or phenoxylating reactions are described in more detail in U.S. Reissue Patent Re. 31,447. The resulting alkoxy- or phenoxycontaining alkylpolysilanes are of the general formula (R2SiMRSi)(R-Si) where each R is independently selected from alkyl radicals containing 1 to 4 carbon atoms, where R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X G-Y) Si(CH2) Z where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1, where there are from 0 to 40 mole percent (R.Si) units, 1 to 99 mole percent (RSi), and 1 to 99 mole percent (R'Si) units, and where there are also bonded to the silicon atoms other silicon atoms and radicals of formula R... 0where R... is an alkyl radical containing 1 to 4 carbon atoms or a phenyl radical. Preferably, the resulting alkylpoly silanes contain 0 to 40 mole percent (R2Si) units, 40 to 99 mole percent (RSi), and 1 to 30 mole percent (R'Si) units.

The resulting derivatized alkylpolysilanes are solids at 25'C and have the general formula (R.Si)(RSi)(R'Si) where each R is independently selected from alkyl radicals containing 1 to 4 carbon atoms, where R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X G-Y) S'(CH2)z_ where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1, and where there are from 0 to 40 mole percent (R2Si) units, 1 to 99 mole percent (RSi), and 1 to 99 mole percent (R'Si) units, where there are also bonded to the silicon atoms other silicon atoms and radicals selected from the group consisting of hydrogen, additional alkyl radicals containing 1 to 4 carbon atoms, vinyl radicals, allyl radicals, phenyl radicals, (CH3)3SiOradicals, -OR... radicals, and -N(RV), radicals where R... is an alkyl radical of 1 to 4 carbon atoms or a phenyl radical and R v is hydrogen, an alkyl radical of 1 to 4 carbon atoms, a phenyl radical, or a -SiA', radical where each A' is independently selected from hydrogen, alkyl radicals containing 1 to 4 carbon atoms and vinyl. Preferably, the derivatized alkylpolysilanes contain 0 to 40 mole percent (R2S') units, 40 to 99 mole percent (RSi) units, and 1 to 30 mole percent (R'Si) units. It is most preferred that the derivatized alkylpolysilanes contain from 0 to 10 mole percent (R,Si) units, 80 to 99 mole percent (RSi) units, and 1 to 20 mole percent (R'Si) units.

Especially preferred derivatized alkylpolysilanes are the derivatized methylpolysilanes of general formula HCH3)2S'MCH3S'MR'Si) where R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X (3-Y) S'(CH2)z_ where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1 and where there are from 0 to 40 mole percent ((CH.),Si) units, 1 to 99 mole percent (CH3Si) units, and 1 to 99 mole percent (R'Si) units, where there are also bonded to the silicon atoms other silicon atoms and radicals selected from the group consisting of hydrogen, additional alkyl radicals containing 1 to 4 carbon atoms, vinyl radicals, phenyl radicals, (CH,),SiO-radicals, -OR... radicals, and -NHR v radicals where R... is an alkyl radical of 1 to 4 carbon atoms or a phenyl radical and R v is hydrogen, an alkyl radical of 1 to 4 carbon atoms, a phenyl radical, or an -SiA'3 radical where each A' is independently selected from alkyl radicals containing 1 to 4 carbon atoms. Preferably, the derivatized methylpolysilanes contain 0 to 40 mole percent (R.Si) units, 40 to 99 mole percent (RSi) units, and 1 to 30 mole percent (R'Si) units. It is most preferred that the derivatized methylpolysilanes contain from 0 to 10 mole percent ((CH. )2Si) units, 80 to 99 mole percent (CH3Si) units, and 1 to 20 mole percent (R'Si) units.

The most preferred derivatized alkylpolysilanes are the derivatized methylpolysilanes of the general formula ((CH,), Si)(CH3Si)(R'Si) where R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X 6-Y) Si(CH2) Z_ where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1 and where there are from 0 to 40 mole percent ((CH3),Si).units, 1 to 99 mole percent (CH3Si), and 1 to 99 mole percent (R'Si) units, where there are also bonded to the silicon atoms other silicon atoms and additional methyl radicals. Preferably, these additional methyl radicals attached to silicon are introduced via a methylation reaction using methyllithium. Preferably the derivatized methylpolysilanes contain 0 to 40 mole percent (R2Si) units, 40 to 99 mole percent (RSi) units, and 1 to 30 mole percent (R'Si) units. It is most preferred' that this derivatized methylpolysilane contain from 0 to 10 mole percent ((CH.)2Si) units, 80 to 99 mole percent (CH.Si) units, and 1 to 20 mole percent (R'Si) units.

These derivatized alkylpolysilanes may contain residual chlorine or bromine atoms and still be useful in this invention. The chlorine or bromine content of these derivatized alkylpolysilanes is, however, less than the chlorine or bromine content of the starting non-derivatized alkylpolysilanes. Preferably, the derivatized alkylpolysilanes contain less than 5 weight percent chlorine or bromine; more preferably, they contain less than 2 weight percent chlorine or bromine; and most preferably, they contain less than 1 weight percent chlorine or bromine. The reduced levels of chlorine or bromine in these derivatized alkylpolysilanes result in easier and safer handling of the derivatized alkylpolysilanes relative to the nonderivatized alkylpolysilanes which contain significant amounts of chlorine of bromine.

The derivatized alkylpolysilanes of this invention may be converted to ceramic materials by pyrolysis to an elevated temperature of at least 7SO'C in an inert atmosphere, vacuum or ammonia-containing atmosphere for a time sufficient to convert them to a ceramic material. Preferably, the pyrolysis temperature is from about 1000'C to about 1600'C. If the preceramic polymers are of sufficient viscosity or if they possess a sufficiently low melt temperature, they can be shaped and then pyrolyzed to give a ceramic shaped article such as a fiber. Preferably, the preceramic polymer of this invention have a softening or glass transition temperature of about 50 to 3000C and most preferably in the range of 70 to 200'C. Such a softening temperature allows for the formation of preceramic fibers by known spinning techniques. As noted earlier, the softening or glass transition temperatures of the derivatized alkylpolysilanes can be controlled by varying the content of the (R'Si) units in the non-derivatized alkylpolysilanes.

So that those skilled in the art can better appreciate and understand the invention, the following examples are given. Unless otherwise indicated, all percentages are by weight. The examples are intended to illustrate the invention and are not intended to limit the invention.

In the following examples, the analytical methods used were as follows:

24- The glass transition temperature, T 9. was determined on a Thermomechanical Analyzer, Model 1090, from Dupont Instruments. The glass transition temperature is related to the softening point.

Carbon, hydrogen, and nitrogen were determined on a C, H, N Elemental Analyzer, Model 1106, manufactured by Carlo Erba Strumentazione of Italy. The sample was combusted at 1030'C and then passed over a chromium oxide bed at 6500C and a copper bed at 6500C. The NI, C02, and H20 produced were then separated and detected using a thermal conductivity detector.

Percent silicon was determined by a fusion technique which consisted of converting the silicon material to soluble forms of silicon and then analyzing the soluble material quantitatively for total silicon by atomic absorption spectrometry. Percent chlorine was determined by fusion of the sample with sodium peroxide and potentiometric titration with silver nitrate. Oxygen was determined using a Leco Oxygen Analyzer equipped with an Oxygen Determinater 316 (Model 783700) and an Electrode Furnace EF100 (Model 77600) manufactured by Leco Corporation, St. Joseph, Michigan. The oxygen method involves the high temperature carbothermic reduction to CO with CO analysis by IR.

Thermogravimetric analyses (TGA) were carried out on a Netzsch STA 429 (2400'C) TGA instrument manufactured by Netzsch Instruments, Selb, West Germany.

The preceramic polymers were fired to elevated temperature using an Astro Industries Furnace 1000A (water cooled graphite heated model 1000.3060-FP12), a Lindberg furnace (Heavy Duty SB Type S4877A), or the TGA instrument.

Chlorine-containing methylpolysilanes of the general formula ((CH3)2Si)(CH3Si)(R'Si) were prepared by the general procedures outlined in U.S. Patent Application Serial 25-.

No. 945,126 in the names of Duane Ray Bujalski, Gary Edward LeGrow, and Thomas Fay-oy Lim, entitled "Polysilane Preceramic Polymers" which was filed on the same date as this present application. Unless otherwise indicated, all procedures, including polymer preparation and derivatization, were carried out under an inert atmosphere of nitrogen or argon.

Examples 1 through 6 demonstrate the preparation of derivatized polysilanes by alkylation using organolithium compounds and/or Grignard reagents. Example 1 Four different chlorine-containing polysilanes containing (CH,(CH2)7S') units were prepared using the procedures of the above described U.S. Patent Application Serial No. 945,126 entitled "Polysilane Preceramic Polymers" by reacting 436.0 g (2 moles) of a mixture of disilanes and 24. 85 g (0.1 moles) n-octyltrichlorosilane in the presence of 4.4 g tetra-n- butylphosphonium bromide under an inert atmosphere. The disilane mixture was a Direct Process residue which contained about 9.0 percent ((CH3)2C'S')2, 32.9 percent (CH,)2C1SiSiCI2CH3, 57.3 percent (CH3C12S')., and 0.8 percent low boiling chlorosilanes. For sample A, the reaction temperature was raised from room temperature to 1SO'C at a rate of 2. O'C/min, held at 1SO'C for 16 minutes, and from 150 to 2700C at a rate of 3.OOC/min; for sample B, from room temperature to 1100C at a rate of 6. O'C/min, from 110 to 1500C at 2.OOC/min, and 150 to 2800C at 5.OOC/min; for sample C, from room temperature to 110'C at a rate of 7.5'C/min and from 110 to 280'C at 5.OOC/min; and for sample D, from room temperature to 1080C at a rate of 2.OOC/min and 108 to 2500C at 1.5'C/min. By- produced volatile products were removed by distillation during the course of the reactions. The chlorine-containing polysilanes were -26 estimated to contain about 20 percent chlorine. After cooling the chlorine-containing polysilanes to room temperature, various alkylating reagents were slowly added to the polysilanes dissolved in toluene (about a 20 percent solution) in the same reaction setup used to prepare the polysilanes. For sample A, the alkylating agent was 9.7 g (0.44 moles) methyllithium in diethylether. For B, the alkylating agent was 45.9 g (0. 35 moles) vinyl magnesium bromide in tetrahydrofuran. For sample C, the alkylating agent was 6.6 g (0.30 moles) methyllithium and 13.1 g (0.10 moles) vinyl magnesium bromide in tetrahydrofuran. For sample D, the alkylating agent was 34.1 g (0.26 moles) vinyl magnesium bromide and 19.4 g (0.26 moles) methyl magnesium chloride in tetrahydrofuran. Upon addition of the alkylating agent an exotherm was generally observed. The reaction mixtures were then heated to about 100'C for up to 40 minutes. Generally, a large amount of salt precipitated from solution. After cooling to room temperature, a saturated aqueous solution of NH4C1 was added until the precipitated salt turned into a gray mass. The reaction mixture was filtered and the resulting filtrate was stripped to obtained the desired derivatized methylpolysilanes. The derivatized samples A, C, and D were soluble in toluene; derivatized sample B was partly soluble in toluene. The following results were obtained on the methylated methylpolysilanes.

1 -27 A B c 61.0 T c 38.0 Sil % 47.1 32.8 45.5 C, H, % 0, cl, % 39.4 18.7 38.4 9.5 5.7 9.3 0.5 5.2 8.1 1. 1 8.1 D 49.8 38.5 36.1 8.3 1.3 6.7 7.1 Polymer Yield (g) 60.5 57.2 56.4 54.8 Molecular Weight (g/mole):

Num. Av. 675 1020 1044 865 Wt. Av. 922 2928 1771 2106 The derivatized methylpolysilane A was fired to 12000C under argon at a rate of about 5.OOC/min. The ceramic yield was 31.5 percent. The ceramic. contained 70.0 percent silicon, 28.7 percent carbon, non-detectable levels of hydrogen and nitrogen, and 1.10 percent oxygen. Samples C and D were converted to ceramics in yields of 61.0 and 67.2 percent, respectively, by firing to 1200'C under an argon atmosphere. Example 2 Several different chlorine-containing polysilanes containing (C.H.Si) units were prepared using the general procedures outlined in Example 1. For sample A, 437.6 g (2 moles) disilanes were reacted with 10.8 g (0.05 moles) phenyltrichlorosilane in the presence of 4.8 g tetran- butylphosphonium bromide by heating the mixture from room temperature to 2SO'C at a rate of 1.500C/min. For sample B, 436.0 g (2 moles) disilanes were reacted with 63.45 g (0.3 moles) phenyltrichlorosilane in the presence of 4.4 g tetranbutylphosphonium bromide by heating the mixture from room temperature to 270'C at a rate of 3.6'C/min and holding the reaction temperature at 270'C for 30 minutes. The disilanes were the same as used in Example 1. The resulting chlorinecontaining polysilanes were then reacted with methyllithium using the same procedure as in Example 1. Polysilane A, dissolved in a toluene and diethylether mixture, was reacted with 10.8 g (0.49 moles) CH.Li in diethylether. Polysilane B, dissolved in toluene, was reacted with 6.8 g (0.31 moles) CH.Li in diethylether. The derivatized polysilanes were soluble in toluene. The following results were obtained on the methylated methylpolysilanes.

A c T.9 c 136.4 122.0 si, % 54.7 43.9 C, % 34.3 44.3 H, % 7.3 6.5 0, % 0.8 0.8 cl, % 0.3 0.1 Polymer Yield (g) 53.1 67.5 Molecular Weight (g/mole):

Num. Av. 642 744 Wt. Av. 1018 1208 The derivatized methylpolysilanes were converted to ceramic materials by pyrolysis at 12000C under argon as in Example 1. The following results were obtained.

A c Ceramic Yield, % 32.5 53.8 Sis % 68.4 61.9 c ' % 29.8 38.1 0, % 0.68 0.55 cl, % 0.08 - Example 3

Several chlorine-containing polysilanes containing both (CH3(CH,)7S') and (C.H,Si) units were prepared using the general procedures outlined in Example 1. For sample A, disilanes (437.6 g, 2 moles) were reacted with 20.9 g (0.08 moles) n-octyltrichlorosilane and 25.1 g (0.12 moles) phenyltrichlorosilane in the presence of 4.9 g tetra-n-butylphosphonium bromide by heating the mixture from room temperature to 250'C at 2. O'C/min. For sample B, disilanes (436.0 g, 2 moles) were reacted with 24. 85 g (0.1 moles) n-octyltrichlorosilane and 63.45 g (0.3 moles) phenyltrichlorosilane in the presence of 4.4 g tetra-nbutylphosphonium bromide by heating the mixture from room temperature to 1100C at a rate of 10.OOC/min, held at 1100C for 8 minutes, from 110 to 1500C at 2. OOC/min, and from 150 to 3000C at 5.00C/min. The disilanes employed were the same as in Example 1. The resulting chlorine-containing polysilane A in toluene and diethylether was reacted with 13.6 g (0.62 moles) of methyllithium in diethylether as in Example 1. The resulting chlorine- containing polysilane B in toluene was reacted with 10.1 g (0.46 moles) of methyllithium in diethylether as in Example 1. The derivatized polysilane were soluble in toluene. The following results were obtained on the methylated methylpolysilanes.

30- A c T 11 c 30.0 52.6 si, % 45.7 39.0 c, % 43.4 46.9 I-I, % 8.3 7.8 0, % 0.5 3.3 cl, % 0.1 0.5 Polymer Yield (g) 72.5 75.3 Molecular Weight (g/mole):

Num. Av. 548 774 Wt. Av. 844 1069 The derivatized methylpolysilanes were converted to ceramic materials by pyrolysis at 1200'C under argon as in Example 1. The following results were obtained.

A Ceramic Yield, % 19.5 33.4 si, % 66.3 60.8 cl % 31.8 37.9 0, % 0.86 1.82 cl, % 0.17 - Example 4 Two chlorine-containing polysilanes containing ((CH3) Y Cl (3-Y) Si(CH.)2S') units where y is 2 or 3 were prepared using the same procedures and disilanes as in Example 1. For sample A, 436 g (2 moles) disilanes was reacted with 128 g (0.5 moles) (CHA2C'S'CH2CH2SiCl. in the presence of 4.4 g tetra-n-butylphosphonium bromide by heating the reaction mixture from room temperature to 2840C at a rate of 2.OOC/min. For sample B, 436 g (2 moles) disilanes was reacted with 23.6 g (0.1 moles) (CH.),SiCH2CH.SiCl. in the presence of 4.4 g tetra-n-butylphosphonium bromide by heating the reaction mixture from room temperature to 300'C at a rate of 3.OOC/min. Both derivatized polysilanes were soluble in toluene. The following results were obtained on the methylated methylpolysilanes.

A B T 9 9 c 58.0 97.0 si, % 41.5 54.6 C, % 34.2 32.4 H, % 8.5 8.3 0, % 0.5 0.4 cl, % 3.2 1.9 Polymer Yield (g) 46.5 54.6 Molecular Weight (g/mole):

Num. Av. 806 713 Wt. Av. 1348 1122 The derivatized methylpolysilanes were converted to ceramic materials by pyrolysis at 12000C under argon as in Example 1. The following results were obtained. Chlorine was not determined.

A B Ceramic Yield, % 25.7 62.3 si, % 67.4 66.2 C, % 28.6 30.4 H, % 0.05 0.16 0, % 1.75 0.43 Example 5

A chlorine-containing polysilane containing both (CH3(CH2)7S') and (C13SiCH.CH2S') units was prepared using the general procedures outlined in Example 1. Disilanes (436 g, 2 moles) were reacted with 24.85 g (0.1 moles) n-octyltrichlorosilane and 29.7 g (0.1 moles) Cl,SiCH.CH.SiCl. in the presence of 4.4 g tetra-n-butylphosphonium bromide by heating the mixture from room temperature to 1100C at a rate of 20.O'C/min and from 110 to 2500C at 2.O'C/min. The disilanes employed were the same as in Example 1. The resulting chlorine-containing polysilane in toluene was reacted with a mixture of 7.7 g (0.35 moles) of methyllithium. in diethyl ether and 28.2 g (0.1 moles) phenyl magnesium bromide in tetrahydrofuran as in Example 1. The derivatized polysilane yield was 58.5 g. The derivatized polysilane was soluble in toluene with a glass transition temperature of 124.OOC. The number average and weight average molecular weights were 1343 and 3951, respectively. This derivatized polysilane contained 39.4 percent silicon, 38.3 percent carbon, 8.8 percent hydrogen, and 0.5 percent chlorine. oxygen was not determined.

1 Example 6

A chlorine-containing polysilane containing (CH3(CH2) 7 Si), (C.H.Si), and (C13S'CH2CH2Si) units was prepared using the general procedures outlined in Example 1. Disilanes (436 g, 2 moles) were reacted with 24.85 g (0.1 moles) noctyltrichlorosilane, 21.1 g (0.1 moles) phenyltrichlorosilane, and 29.7 g (0.1 moles) CI.SiCH2CH2S'Cl. in the presence of 4.4 g tetra-n-butylphosphonium bromide by heating the mixture from room temperature to 1000C at a rate of 10.OOC/min and from 100 to 2500C at 2.00 C/min. The disilanes employed were the same as in Example 1. The resulting chlorine-containing polysilane in toluene was reacted with 17.4 g (0.79 moles) of methyllithium in diethylether as in Example 1. The derivatized polysilane was obtained in 72.5 g yield. The derivatized polysilane was soluble in toluene with a glass transition temperature of 118.O'C. The number average and weight average molecular weights were 1453 and 3016, respectively. This derivatized polysilane contained 37.4 percent silicon, 40.7 percent carbon, 9.1 percent hydrogen, and 1.3 percent chlorine. Oxygen was not determined. Example 7 This example demonstrates the preparation of a derivatized polysilane containing SiH bonds by reacting a chlorine-containing polysilane with lithium aluminium hydride. A chlorine-containing polysilane was prepared by reacting 436 g (2 moles) disilanes with 24.85 g (0.1 moles) n- octyltrichlorosilane in the presence of 4.4 g tetra-nbutylphosphonium bromide by heating the reaction mixture from room temperature to 110'C at a rate of 17.5'C/min, held at 1100C for 6 minutes, from 110 to 1SO'C at 2. OOC/Min, from 150 to 3000C at S.O'C/min, and holding at 3000C for 16 minutes using the same disilanes and procedures as in Example 1. Lithium aluminum hydride (5.4 g, 0.095 moles) was slowly added to the chlorine-containing polysilane in a solution of heptane (35 g) and diethylether (185 g) at OOC. After the addition the reaction mixture was heated to 350C in one hour. Residual lithium aluminum hydride was destroyed by addition of aqueous KOH. The derivatized polysilane was obtained in 50.1 g yield. The derivatized polysilane was soluble in toluene and had a glass transition temperature of 63.O'C. The number average and weight average molecular weights were 813 and 1642, respectively. This derivatized polysilane contained 49.7 percent silicon, 27.4 percent carbon, 6.7 percent hydrogen, 1.5 percentoxygen, and 7.4 percent chlorine. Both NMR and IR confirmed the presence of hydrogen bonded directly to silicon.

Examples 8 through 11 demonstrate the preparation of derivatized polysilanes using various aminolysis reagents. Exam-ple 8 A new chlorine-containing polysilane was prepared for each different derivatization reaction by reacting 436 g (2 moles) disilanes with 24.85 g (0.1 moles) n-octyltrichlorosilane in the presence of 4.4 g tetra-nbutylphosphonium bromide by heating the mixture from room temperature to 1100C at a rate of 5.80C/min and from 110 to 300'C at a rate of 2.00C/min. The disilanes employed were the same as in Example 1. In sample A, the chlorinecontaining polysilane (about 20 percent in toluene) was reacted with methylamine by bubbling methylamine through the reaction mixture. In sample B, the chlorine-containing polysilane (about 20 percent in toluene) was reacted with dimethylamine by bubbling dimethylamine through the reaction mixture. Samples A and B were treated with the organoamine until the organoamine began to condense in a water-cooled condenser attached to the reaction flask. The reaction time was normally about 2 to 3 hours. Excess organoamine was removed by an argon purge. The derivatized polysilanes were obtained after filtering and stripping. For sample C, a 20 percent solution of the chlorine-containing polysilane in toluene was loaded in a 2.4 liter autoclave which was pressurized to 90 psi with ammonia. The reaction continued for 16 hours at room temperature. Excess ammonia was removed by an argon purge. The derivatized polysilane C was filtered and stripped. It gelled during stripping. The derivatized polysilane C ignited upon exposure to air. Derivatized polysilanes A and B were soluble in toluene; C was insoluble. The following results were obtained on the derivatized methylpolysilanes.

A T 9 3 C S i 9 81.0 49.0 34.1 8.9 3.9 L. -1) Polymer Yield (g) 56.0 Molecular Weight (g/mole) Num. Av.

Wt. Av.

1134 2269 B 48.0 38.5 32.1 8.2 C 50.8 31.0 7.7 2.0 3.2 6.1 3.8 57.0 1004 1422 5.6 2.0 51.0 2431 8309 The derivatized methylpolysilanes were converted tceramic materials by pyrolysis at 1200'C under argon as in -36 1 Example 1. The following results were obtained. Hydrogen was nondetectable and chlorine was not determined.

A Ceramic Yield. % B si, % 67.7 65.0 C, % 26.0 26.2 N, % 4.8 2.2 0, % 4.4 80.0 Example 9

Two chlorine-containing polysilanes were prepared using the procedure of Example 1. Sample A was prepared by reacting 436 g (2 moles) disilanes with 21.15 g (0.1 moles) phenyltrichlorosilane in the presence of 4.4 g tetra-nbutylphosphonium bromide. Sample B was prepared by reacting 436 g (2 moles) disilanes with 63.45 g (0.3 moles) phenyltrichlorosilane in the presence of 4.4 g tetra-nbutylphosphonium bromide. Both samples were heated from room temperature to 110'C at a rate of 8.O'C/min and from 110 to 3000C at a rate of 2.O'C/min. The disilanes employed were the same as in Example 1. Both samples were then reacted with dimethylamine using the same procedure as in Example 8 except that the present sample B was further reacted with ammonia. A 20 percent solution of the dimethylamine treated polysilane B in toluene was loaded into a 2.4 liter autoclave which was pressurized to 90 psi with ammonia. The reaction continued for 16 hours at room temperature. Excess ammonia was removed by an argon purge. The dimethylamine/ammonia treated polysilane B was filtered and stripped. Both derivatized polysilanes A and B were soluble in toluene. The following results were obtained for the polysilanes.

A B T 3 c 168.0 141.0 si, % 49.2 37.8 C, % 18.1 39.6 H, % 5.6 7.1 N, % 2.5 3.8 0, % 5.2 - cl, % 3.5 - Polymer Yield (g) 57.0 31.0 Molecular Weight (g/mole):

Num. Av. 990 Wt. Av. 1643 The derivatized methylpolysilanes A and B were converted to ceramic materials in 74.2 and 67.8 percent yield, respectively, by pyrolysis at 1200'C under argon as in Example 1. The ceramic material A contained 65.0 percent silicon, 28.5 percent carbon, non-detectable levels of hydrogen, 2.0 percent nitrogen, and 0.93 percent oxygen. Chlorine was not determined. The composition of ceramic B was not determined. Example 10 Two chlorinecontaining polysilanes which contained (CH3(CH,) 7 Si) and (C. H,Si) units were prepared by reacting 436 g (2 moles) disilanes with 24.8 g (0.1 moles) n-octyltrichlorosilane and 21.1 g (0.1 moles) phenyltrichlorosilane in the presence of 4.4 g tetra-n-butylphosphonium bromide using the same procedures and disilanes as Example 1. Chlorine-containing polysilane A was reacted with methylamine as described in Example 8. Chlorine-containing polysilane B was reacted with dimethylamine as described in Example 8 except that after the dimethylamine flow was terminated, ammonia was bubbled through the reaction mixture for about 2 hours at room temperature. Both reaction mixtures were filtered and stripped to recover the desired derivatized polysilanes. Both derivatized polysilanes were soluble in toluene. The following results were obtained for the polysilanes.

A B T 9 3 c 94.0 80.0 H, si, % 53.2 C, % N, % 37.8 8.2 40.7 34.8 7.0 3.4 0, % - cl % 1.7 1.7 3.0 2.9 Polymer' Yield (g) 62.0 69.0 Molecular Weight (g/mole):

Num. Av. 934 1020 Wt. Av. 1020 1726 The derivatized methylpolysilanes were converted to ceramic materials by pyrolysis at 12000C under argon as in Example 1. The following results were obtained. Hydrogen was non-detectable.

1 A Ceramic Yield, % Si$ C, cl, Example 11

Chlorine-containing polysilanes with (CH,(CH2) 7 Si) units were prepared as in Example 8. Sample A was then treated with methylamine as in Example 8 except that a 20 percent solution of the derivatized polysilane in toluene was loaded in a 2.4 liter autoclave which was pressurized to 90 psi with ammonia. The ammonia reaction continued for 16 hours at room temperature. Excess ammonia was removed by an argon purge. Polysilane B was reacted with dimethylamine as described in Example 8 except that after the dimethylamine flow was terminated, ammonia was bubbled through the reaction mixture for about 2 hours at room temperature. Both reaction mixtures were filtered and stripped to recover the desired derivatized polysilanes. Both derivatized polysilanes were soluble in toluene. The following results were obtained for the polysilanes.

69.0 63.6 30.6 4.5 B 59.0 64.2 30.8 3.6 0.63 -40 A B T 9 c 140.0 69.0 Si$ % 47.0 45.9 C, % 33.8 34.9 H, % 8.5 8.4 N, % 4.0 3.9 0, % 2.5 5.2 cl, % 0.3 0.9 Polymer Yield (g) 38.9 28.2 Molecular Weight (g/mole):

Num. Av. 2036 986 Wt. Av. 3550 1547 The derivatized methylpolysilanes A and B were converted to ceramic materials by pyrolysis at 12000C under argon as in Example 1 with ceramic yields of 70.0 and 59.0 percent, respectively. Example 12 This example demonstrates the preparation of a derivatized polysilane which contains -OR- radicals. Disilanes (1176.8 g, 5.4 moles) and n- octyltrichlorosilane (66.7 g, 0.27 moles) was reacted in the presence of tetra-n-butylphosphonium bromide (12.5 g) by heating the reaction mixture from room temperature to 90'C at S.O'C/min, from 90 to 1080C at 2.OOC/min, hold at 1080C for 17 minutes, and from 108 to 2500C at 1.50C/min. The chlorine-containing polysilane was obtained in a 245.6 g yield. CH(OCH3)3 (135 g, 1.3 moles) was slowly added over a 31 minute period to the chlorine-containing polysilane (75.2-g) in toluene. After the addition was completed, the reaction mixture was refluxed at 79 to 1000C for about 1.5 hours. The methoxy-containing polysilane (52.8 g) was obtained by stripping the reaction mixture at 2SO'C and 20 torr for 15 minutes. The product was soluble in toluene and contained 47.8 percent silicon, 25.8 percent carbon, 6.62 percent hydrogen, 2.83 percent oxygen, and < 1 percent chlorine. The methoxy- containing polysilane was converted to a ceramic material in 63.27 percent yield by pyrolysis to 12000C in argon. The ceramic material contained 66.2 percent silicon, 20.7 percent carbon, < 0.05 percent hydrogen, 3.09 percent oxygen, and < 1 percent chlorine.

Claims (9)

Claims:

1. A derivatized alkylpolysilane of the average (R.Si)(RSi)(R-Si) where each R is independently from alkyl radicals containing 1 to 4 carbon atoms, f ormula selected where R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A y X 6-Y) Si(CH2) Z where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1, where there are from 0 to 40 mole percent (R2Si) units, 1 to 99 mole percent (RSi) units, and 1 to 99 mole percent (R'Si) units, and where there are also bonded to the silicon atoms other silicon atoms and radicals selected from the group consisting of hydrogen atoms, additional alkyl radicals containing 1 to 4 carbon atoms, vinyl radicals, allyl radicals, phenyl radicals, (CHA3SiO-radicals, -OR... radicals, and N(RV)2 radicals where R- is an alkyl radical of 1 to 4 carbon atoms or a phenyl radical and R' is hydrogen, an alkyl radical of 1 to 4 carbon atoms, a phenyl radical, or an -SiA'3 radical where each A' is independently selected from hydrogen, alkyl radicals containing 1 to 4 carbon atoms and vinyl.

2. A derivatized alkylpolysilane as claimed in claim 1 wherein the derivatized alkylpolysilane contains 0 to 40 mole percent (R2S') units, 40 to 99 mole percent (RSi) units, and 1 to 30 mole percent (R'Si) units.

W

3. A derivatized alkylpolysilane as claimed in claim 2 wherein R' is a radical of the formula A y X (3-Y) Si(CH2) Z_ where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1.

4. A derivatized alkylpolysilane as claimed in claim 2 wherein there is also bonded to the silicon atoms other silicon atoms and radicals selected from the group consisting of additional alkyl radicals containing 1 to 4 carbon atoms, vinyl radicals, and phenyl radicals.

5. A derivatized alkylpolysilane as claimed in claim 2 wherein there is also bonded to the silicon atoms other silicon atoms and (CH.),SiOradicals.

6. A derivatized alkylpolysilane as claimed in claim 2 wherein there is also bonded to the silicon atoms other silicon atoms and -OR- radicals where R- is an alkyl radical of 1 to 4 carbon atoms or a phenyl radical.

7. A derivatized alkylpolysilane as claimed in claim 2 wherein there is also bonded to the silicon atoms other silicon atoms and -N(R v)2 radicals where Rv is hydrogen, an alkyl radical of 1 to 4 carbon atoms, a phenyl radical. or a -SiA', radical where each A' is independently selected from hydrogen, alkyl radicals containing 1 to 4 carbon atoms and vinyl.

8. A derivatized alkylpolysilane as claimed in claim 2 where the derivatized alkylpolysilane contains 0 to 10 mole percent (R2Si) units, 80 to 99 mole percent (RSi) units, and 1 to 20 mole percent (R'Si) units.

9. A method of preparing a ceramic material, said method comprising heating the derivatized alkylpolysilane of Claim 1 in an inert atmosphere or in a vacuum to a temperature of at least 7500C until said derivatized alkylpolysilane is converted to a ceramic material.

9. A method of preparing a ceramic material, said method comprising heating the derivatized alkylpolysilane of Claim 1 in an inert atmosphere or in a vacuum to a temperature of at least 7SO'C until said derivatized alkylpolysilane is converted to a ceramic material.

Anwndnients to the clakns have been filed as fokm 1. A derivatized alkylpolysilane of the average formula (R2SiMRSi)(R1Si) where each R is independently selected from alkyl radicals containing 1 to 4 carbon atoms, where R' is selected from the group consisting of alkyl radicals of at least six carbon atoms, phenyl radicals, and radicals of the formula A YX(3-y)Si(CH2)z- where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1, where there are from 0 to 40 mole percent (R2Si) units, 1 to 99 mole percent (RSi) units, and 1 to 99 mole percent (R'Si) units, and where there are also bonded to the silicon atoms silicon atoms of other (R2Si), (R'Si) or (RSi) units and radicals selected from the group consisting of hydrogen atoms, additional alkyl radicals containing 1 to 4 carbon atoms, vinyl radicals, allyl radicals, phenyl radicals, (CH3)3SiOradicals, -OR' 1 1 radicals, and -N (Rv) 2 radicals where R' 1 1 is an alkyl radical of 1 to 4 carbon atoms or a phenyl radical and Rv is hydrogen, an alkyl radical of 1 to 4 carbon atoms or phenyl radical.

2. A derivatized alkylpolysilane as claimed in claim 1 wherein the derivatized alkylpolysilane contains 0 to 40 mole percent (R2Si) units, 40 to 99 mole percent (RSi) units, and 1 to 30 mole percent (R'Si) units.

3. A derivatized alkylpolysilane as claimed in claim 2 wherein R' is a radical of the formula A YX(3-y)Si(CH2)z- where each A is independently selected from a hydrogen atom or alkyl radicals containing 1 to 4 carbon atoms, y is an integer equal -- 4- - - to 0 to 3, X is chlorine or bromine, and z is an integer greater than or equal to 1.

4. A derivatized alkylpolysilane as claimed in claim 2 wherein there is also bonded to the silicon atoms silicon atoms of other (R2Si), (R'Si) or (RSi) units and radicals selected from the group consisting of additional alkyl radicals containing 1 to 4 carbon atoms, vinyl radicals, and phenyl radicals.

5. A derivatized alkylpolysilane as claimed in claim 2 wherein there is also bonded to the silicon atoms silicon atoms of other (R2Si), (R' Si) or (RSi) units and (CH3)3Sioradicals.

6. A derivatized alkylpolysilane as claimed in claim 2 wherein there is also bonded to the silicon atoms silicon atoms of other (R2Si), (RISi) or (RSi) units and -OR''' radicals where R"' is an alkyl radical of 1 to 4 carbon atoms or a phenyl radical.

7. A derivatized alkylpolysilane as claimed in claim 2 wherein there is also bonded to the silicon atoms silicon atoms of other (R2Si), (R'Si) or (RSi) units and -N(Rv)2 radicals where Rv is hydrogen, an alkyl radical of 1 to 4 carbon atoms ora phenyl radical.

1 --4-7- 8. A derivatized alkylpolysilane as claimed in claim 2 where the derivatized alkylpolysilane contains 0 to 10 mole percent (R2S') units, 80 to 99 mole percent (RSi) units, and 1 to 20 mole percent (R'Si) units.