CA1289295C - Optical article containing a linear polymer exhibiting a high level of second order polarization susceptibility - Google Patents

Abstract

AN OPTICAL ARTICLE CONTAINING A LINEAR POLYMER
EXHIBITING A HIGH LEVEL OF
SECOND ORDER POLARIZATION SUSCEPTIBILITY
Abstract of the Disclosure An optical article is disclosed containing, for the transmission of electromagnetic radiation, a medium exhibiting a second order polarization susceptibility greater than 10-9 electrostatic units comprised of a linear polymer containing as pendant groups polar aligned noncentrosymmetric molecular dipoles having an electron donor moiety linked through a conjugated .pi. bonding system to an electron acceptor moiety to permit oscillation of the molecular dipole between a ground state exhibiting a first dipole moment and an excited state exhibiting a differing dipole moment. The linear polymer contains repeating units derived from vinyl addition polymerization, at least 5 percent of the repeating units incorporate the molecular dipoles as pendant groups, and the molecular dipoles include a sulfonyl electron acceptor moiety.

Description

~2~g~95 AN OPTICAL ARTICLE CONTAINING A LINEAR POLYMER
EXHIBITING A HIGH LEVEL OF

Field of the Invention The invention relstes to opticsl srticles, psrticulsrly srticles which exhibit effects sttrlbut~ble to the polsrlzstion of electromsgnetic - r~diatlon. The invention relstea specificslly to opticsl srticle~ which exhibit effect~ attributable to the nonlinesr polsriz~tion of electromsgnetic radistion.
Hsck~round of the Invention The ~ignlficsnt polarizstion component~ of a medium produced by contact with sn electric field sre first order polsrizstion (linear polarizstion), second order polsrizstion (first nonline~r polarization), snd third order polsrization (second nonlinesr pol~rizstion). On a moleculsr level thi~ cQn be expres~ed by Equation 1:
(1) P = aE + BE2 + ~E3...
where P is the totsl induced polsrization, E is the locsl electric field crested by electromsgnetic rsdistion, snd a, B, snd y sre the first, second, and third order polsrizsbilities, esch of which is Q function of moleculsr properties.
B snd y are also referred to a8 first snd second hyperpolsrizabllltles, respectlvely. The molecular level terms of Equstlon 1 ~re first order or llnesr polarlzatlon aE, ~econd order or first nonllnear polarizatlon BE2, ~nd thlrd order or second nonlinear polsrizstion yE3.
On a mscromolecular level corresponding relstionahlps csn be expressed by Equstion 2:

t39~95 (2) P ~1)E ., X(2)E2 + X(3)E3 where P i8 the totsl induced polarization, E is the local electric field created by electromagnetic radiation, and x(l), x(2), 8nd x(3) 8re the first, - second, snd third order polsrizstion susceptibilities of the electromagnetic wsve trsnsmission medium.
x(2) and x(3) are al80 referred to 8s the first snd second nonlinesr polarizstion su~ceptibilities, respectively, of the trsnsmission medium. The m~cromoleculAr level terms of Equation 2 are first order or line~r polsrization xE, second order or first nonlinear polarization x(2)E2, and third order or second nonlinear polarizstion x(3)E3 Second order pol~rization (x( )E ) has been suggested to be useful for a vsriety of purposes, including optical rectification (converting electromagnetic radiation input into a DC output), generatin2 an electro-optical (Pockels) effect (using combined electromagnetic rAdiation and DC inputs to slter during their Qpplication the refractive index of the medium), phase alteration of electromagnetic rsdistion, snd parametric effects, most notsbly frequency doubling, also referred to as second hsrmonic generation (SHG).
To achieve on a mscromolecular level second order polsrizstion (x(2)E2) of sny significant msgnltude, lt i8 es~entlal that the transmission medium exhibit second order (first nonlinear) polarization susceptibilities, x(2), greater than 10 9 electro~tatic units (esu). To realize such value~ of x(2) it i~ nece~aary that the first hyperpolarizability B be greater thsn 10 30 esu.
For 8 molecule to exhibit values of ~ greater than zero, it i9 nece~ssry that the molecule be ssymmetrlcsl about it~ center - thst is, noncentrosymmetrlc. Further, the molecule must be cspsble of oscill~ting (l.e., resonsting) between sn excited ~tste snd 8 ground stste dlffering ln polsrity. It h~ been ob~erved experimentslly snd expl~ined by theory thst lsrge ~ vslues sre the result - of large differences between ground and excited 3tste dipole moments 8~ well 8~ lsrge o~cillstor strength~
(i.e., lsrge chsrge trsnsfer resonsnce efficiencies).
For x~2) to exhibit 8 usefully lsrge vslue it is not only necesssry thst ~ be lsrge, but, ln sddition, the moleculsr dlpole~ must be sligned so 88 to lack lnverslon symmetry. The lsrgest vslues of x(2) 8re regllzed when the molecular dlpole~ sre - srrsnged ln polsr sIlgnment- e.g., the slignment obtsined when moleculsr dipoles sre sllowed to slign them~elves in sn electric field.
D. J. Willisms, ~Orgsnic Polymerlc snd Non-Polymerlc Msterlsls with Lsrge Opticsl Nonllnesrities", Angew. Chem. Int. Ed. Engl. 23 (1984) 690-703, postulstes msthemstlcslly snd experimentslly ~- corroborstes schievement of second order polsrizstion susceptlbllltles x(2) uslng orgsnlc moleculsr dlpoles equslllng snd exceedlng tho~e of conventionsl lnorg~nlc noncentrosymmetric dlpole crystsls, such 8 llthlum niobste snd potssslum dlhydrogen phosphste.
To obtsin the polsr slignment of the orgsnic moleculsr dipoles necesssry to lsrge vslues of x(2) Willisms dispersed smsll smounts of the orgsnic moleculsr dipoles 8s guest molecules ln host llquld crystslllne polymers. Upon hestlng the host polymers above their glsss trsn~ition temperstures, pollng ln sn externslly spplled electrlc fleld to produce the deslred polsr slignment of the moleculsr dipoles, snd then cooling with the fleld spplied, orgQnic fllms wlth the messured levels of x(2) were obtslned.
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i`l` ' ~ '''' ' ,. , . . . , . - .

1;~89'~95 Zyss "Nonlinesr Organic Materi~l~ for Integrated Optics", Journal of Moleculsr Electronic~, Vol. 1, pp. 25-45, 1985, though generally cumulstive with Williams, provides a review of passive llnear light guide construction techniques snd elsborates on LB film con~truction techniques including radiation patterning, showing in Figure 8 ~n LB film - construction converted into B linear polymer.
Recently ~ttempt~ have been reported to prepare linear polymers contsining pendant groups capable of acting as molecular dipole~ for enhancing second order polarizstion effects These attempts are illu~trated by the following papers, all published in SPIE, Vol. 682, Moleculsr and Polymeric Optoelectronic Materials: Fuda~ental~ snd Applications (1986):
Le Barny, Ravaux, Dubois, Parneix, N~eumo, Legarnd, and Levelut, "Some New Side-Chain Liquid Crystalline Polymers for Non-Linear Optics", pp.
56-64, discloses un~ucces~ful attempts to obtain liquid crystal properties in vinyl addition copolymers containing aminostilbene pendant groups in concentrations of 2.6 percent.
Griffin, Bhatti, and Hung, "Synthesis of Sidechain Liquid Crystal Polymers for Nonlinear Optics", pp. 65-69, reports polyester copolymers containing stilbene molecular dipoles linked to the polymer backbone through an oxy electron donating moiety.
DeMartino et al U.S. Patent 4,694,066 disclo~es a thermotropic liquid crystalline polymer which is characterized by a recurring monomeric unit of the formula:

_(_p_) -M
where ~ , , , , ~L~89~95 P 19 8 polymer main chain unit, S ~g a flexible spacer, snd M i~ a pendant mesogen which exhibits a second order nonlinear optical ~usceptibility B of st lesst about 20 X 10 30 eau under ststed conditions of measurement. In one form the me~ogen satisfies the formuls:
--X--Y--Z
where X i~ -NR- or -S-;
Y csn tske various stilbenoid forms; snd Z is sn electron donsting or withdrswing group, the latter including nitro, hsloslkyl, scyl, alkanoyloxy, slkoxysulfonyl, snd the like.
S. Matsumoto, K. Kuboders, T. Kurihars, and T. Kalno, "Nonlinesr Optical Properties of an Azo Dye Attached Polymer", App. Phys. Lett., Vol. 51, No. 6, July 1987, pp. 1 snd ~, discloses the synthesis of copolymers of azo dye disubstituted acrylic monomer snd methyl meth~crylste.
SummsrY of the Invention In one aspect, this invention is directed to sn opticsl srticle contsining, for the transmission of electromagnetic rsdistion, 8 medium exhibiting a second order polsrization susceptibility greater than 10 9 electroststic units comprised of a linesr polymer containing ss pendant groups polsr sligned noncentrosymmetric moleculsr dipoles hsving sn electron donor moiety linked through 8 con~ugsted bonding system to sn electron scceptor moiety to permit osclllstion of the moleculsr dipole between 8 ground stste exhibiting 8 first dipole moment snd sn excited stste exhibiting 8 differing dipole moment.
The opticsl srticle is charscterized in thst the linear polymer contsins repesting units derived from vinyl sddition polymerizstion, st lesst 5 percent of the repeating units incorporste the moleculsr : ., .
,; - .

, .
:~, 9'~95 dipoles ~ pendant groups, snd the moleculsr dipoles include ~ sulfonyl electron scceptor moiety.
Opticsl srticles comprised of linesr polymer~
h~vlng pendant moleculsr dipoles sstisfying the sbove requirements offer distinct sdvsntsges over the prior stste of the srt. First, the formation of linesr polymers with moleculsr dipoles 8S pendsnt groups - svoids a vsrlety of problems (e.g., limited solubilltles And ph~se sepsratlon) that srlse from lo sttempts to dlsperse or dissolve moleculsr dipoles in sepsrste polymerlc binders.
Second, substltution of sulfonyl a8 sn electron scceptor moiety for electron acceptor moieties previously known to the srt offers 8 vsriety of sdvsntsges. For exsmple, none of the e~ficient electron scceptor moieties, such 88 cysno or nitro moieties, csn be chemicslly ~ubstituted without de~troying their essentisl electronic properties. On the other hsnd, the sulfonyl moiety of the invention requires by definltion 8 hydrocsrbon substituent, which csn be further substituted, if desired. Thus, the sulfonyl electron scceptor moiety offers much 8rester synthetic freedom for controlling the phy~icsl properties of the moleculsr dlpole for optimum utlllzstlon. The substltutlon of ~ulfonyl electron sccep~or moieties for conventlonsl electron scceptor moleties csn extend opticsl utllity to different wsvelength regions of the spectrum by belng more trsnspsrent to input electromsgnetic rsdistlon, output rsdlstion e.g., second hsrmonlc rsdistion, or 8 combinstion of both. The sulfonyl contsining dipoles offer 8 brosder rsnge of solvent snd binder compstlbllities for schievin8 the required polsr slignments for useful effects produced by second order polsrizstion in opticsl srticle~. Sulfonyl ~ub~titution to schieve optimized physicsl compstibility with other msterlsls encountered in :~;

., ' ` '---7--optlcsl artlcle fsbricAtion i~ resdily Qchleved. By emplying 8 sulfonyl electron scceptor group in combinstion with 8 hydrocsrbon substituted electron donor group it is spp~rent thst both ends of the dipol~r molecule csn be optlmized for the constructlon of pol~r sligned moleculsr dipoles.
Brief DescriPtion of the Drswings Flgure 1 ls s second hsrmonic genersting optic~l srtlcle.
l Figure 2 i8 a DC signsl providing opticsl article.
Figure 3 i~ sn electromRgnetic be~m dlsplscement opticsl srticle.
Fi8ure 4 iB sn slternstive form o~ 8 second hsrmonic genersting opticsl srticsl.
Figure 5 is sn optical srticle for schievlng psrsmetric effects.
Figure 6 is 8 section tsken slong ssction line 6-6 in Figure 5.
Figure 7 ls sn opticsl ~rtlcle for schieving psrsmetric effects snd phsse shifting.
DescriPtion of Preferred Embodiments The following sre illustrstive of opticsl srticle~ sstisfying the invention exhibitlng effects sttributQble to second order polsrizstion:
Referrlng to Figure 1, the opticsl srticle 00 iB cspsble of genersting 8 second hsrmonic of electromsgnetic rsdistion 101 supplied to lt.
Incoming electromsgnetlc rsdistion is introduced through input mesns 103, shown ss 8 first pri~m, into sn opticslly sctlve trsnsmlssion medium 105 whlch exhlbits 8 hlgh level (> 10 9 esu) second order or flrst nonllnesr polsrlzstion susceptiblllty, hereinsfter referred to slmply Q~ the opticslly ~ctlve - 35 trsnsmission medium sccording to the invention or, more succinctly, 8s the opticslly sctive trsnsmls~ion ~ medium. Electromsgnetic rsdistion ls trsnsmltted ,; ' .

"

.: .
,,~ - .'' ~ ' `.

1;~8~95 through the medium 105 to output means 107, shown 88 8 second prism. In the simplest form of the opticsl ~rticle neither the input nor output prisms sre required. Escspe of electromsgnetic rsdistion from the transmission medium csn be minlmized by locsting option~l guiding elements 109 snd 111 sbove snd below the tr~nsmis~ion medium. The guiding elements csn - minimize rsdistion 1088 by being chosen to exhibit 8 lower refrsctive index thsn the trsnsmis-~ion medium.
Additionslly or slternstively, the guiding elements can be chosen to be reflective to the electromsgnetic rsdistion.
When the trsnsmission medium is constructed sccording to the requirements of the invention, specificslly described below, st lesst 8 portion of - the electromsgnetic rsdistion entering the trsnsmission medium will be slterred in frequency during its trsvel through the medium. More specificslly, 8 second hsrmonic of the frequency will be genersted. The electromsgnetic rsdistion lesving the output mesns, indicsted by srrow 113, exhibits both the originsl frequency of the input rsdistion snd 8 second hsrmonic of this frequency. The electromsgnetic rsdistion retsining the originsl frequency csn, if desired, be removed by pss~ing the electromsgnetic rsdistion lesving the srticle through 8 filter 115 cspsble of sbsorbing rsdistion of the originsl frequency while trsnsmitting higher frequency (~horter wsvelength) portions of the electromsgnetic rsdi~tion. By employing one or 8 combinstion of filters sny brosd or nsrrow frequency bsnd of electromsgnetic rsdistion csn be retsined in the trsnsmitted output electromsgnetic rsd$stion 117.
Referrlng to Figure 2, sn opticsl srticle 200 is shown cspsble of producing 8 DC potentisl when electromsgnetic rsdistion 201 is supplied through input mesns 203, shown 88 8 prlsm, to opticslly sctive ' ~ .

~i~8~95 _g _ trsnqml~slon medium 205, which csn be identicsl to medium 105, described sbove. When electromsgnetic radiation i8 belng trsn~mltted through the medlum a potenti~l difference i8 produced between upper electrode 207 snd lower electrode 209 in electricsl contsct with the upper snd lower surfsces of the trsn~mi~qion medium. Electricsl conductor~ 211 snd ~ 213 csn be u~ed to relsy the potenti~l of the upper ~nd lower electrodes to sn electronic re~pon~e unit 215. The electronic re~ponse unit csn in it~ ~imple~t form be 8 unit thst provides 8 digitsl re~ponse indicstive of the the pre~ence or absence of electromsgnetic radiation in the trsn~mi~ion medium.
Alternstively, the electronic response unit csn provide an snslog respon~e indicative not only of the presence, but al80 the inten~ity or wsvelength of electromsgnetic rsdistion in the trsnsmis~ion medium.
Referring to Figure 3, the optic~l article 300 i~ cspsble of physicslly displscing 8 beam 301 of electromsgnetic rsdistion bein8 trsn~mitted through it ag a function of the concurrent receipt of a DC bis~.
Opticslly sctive tran~mission medium 305, which csn be identicsl to opticslly sctive medium 105 or 205, i8 provided with trsnspsrent upper snd lower electrodes 307 and 309. The electrode-q csn, for exsmple, be thin layer~ of a vscuum vapor depo~ited metsl or metsl oxide -e.g., indium tin oxide. An electromsgnetic rsdistion input mesns, shown a8 pri~m 311, i~ locsted on the upper trsnspsrent electrode. The electromsgnetic rsdiation ps~ses through the prism a5 indicsted by srrow 313. When the electromsgnetic rsdistion enters the tran~mi~sion medium, it follows either psth 315a or path 315b. Depending upon which of the two slternstive psths sre followed, the first electromsgnetic rsd~stion either trsvels slong psth 317a or 317b upon emerging from the lower tr~nspsrent electrode. The psths 3158 snd 317a together 12E~

con~titute an A psth through the optlcsl artlcle while the psth~ 315b snd 317b together con~titute ~ B p~th through the opticsl srticle. Sensing units 3198 snd 319b sre located to receive electrom~gnetic rAdistion trflveling Qlong the A ~nd B psths, respectively. It i8 sppsrent that only one of the two sensing units 18 e~sentisl, ~ince fsilure to sense electromagnetic radiation csn be employed to indicste that the electromsgnetic rsdiation hss shifted to the alternste path.
Shifting of electromagnetic r~di~tion between the A snd B psth~ i9 schieved by supplying 8 DC bis~
to the upper snd lower electrodes while transmi~sion of the electromagnetic rsdistion through the opticslly sctive trsnsmission medium is occurring. To sccomplish the required DC biQs 8 DC potentisl source i8 ~hown connected to the upper and lower electrodes by electricsl conductors 327 and 329.
Applicstion of the DC bis~ slters the refrsctive index of the trsn~mi~sion medium when it is formed of 8 msterisl exhibiting ~ signific~nt ~econd order suAceptibility. This csuses the fir~t electromsgnetic radistion besm to be refracted st 8 different sngle when the transmission medium i~
electrically bissed, snd this chsnges the first electromsgnetic rsdiation psth through the transmi~sion medium. In ~ome in~tances the refractive index of the trsnsml~ion medium is incres~ed by the electrical bias and in other instances lowered by the electricsl biss, depending upon whether the molecular dipole contsined within the trsn~mission medium exhibits a positive or negstive first hyperpolarizsbility ~.
In Figure 4 sn opticsl srticle 400 is ~hown ~5 compri~ed of 8 reflective ~ubstrste 401 snd sn opticslly sctive trsn~mis~ion medium 403 sccording to the invention shown in the form of a layer.
. .

,. :

~2~39'~95 Electromagnetic rsdistion i8 supplied from 8 source 405 ss indicated by srrow 407. The electromsgnetlc rsdistion traver~es the optic~lly sctive trsnsmission medium, iB reflected by the sub~trste, snd trsverses the opticslly sctive tr~nsmis~ion medium 8 second time. Electromagnetic rsdiation lesving the optically sctive trsnsmis~ion medium is indicsted by srrow 409.
A sensor 411 which is re~pon~ive to the second hsrmonic of the input electromsgnetic radistion, but not r~di~tion at the wavelength of the input rndistion, is shown provided to receive electromsgnetic rsdistion from the lsyer 403. Instesd of employing 8 sensor that is selectively r~sponsive to the second hsrmonic wsvelength, a sensor with 8 brosder frequency bsnd of response csn be employed in combinstion with one or more filter elements, ~8 described sbove in connection with Figure 1. The thinner the lsyer of the optically sctive trsnsmission medium, the higher the intensity of the input electromsgnetic rsdistion must be in order to schieve 8 given output of second harmonic rsdistion. In the limiting csse the opticslly sctive trsnsmission medium csn be a monomoleculsr oriented moleculsr dipole lsyer.
In Figures 5 snd 6 sn opticsl srticle 500 sccording to the invention i8 shown cspable of inducing psrsmetric effect~, such 88 second hsrmon~c generstion, by scting on lnput electromagnetic rsdistion, indicsted by srrow 501. To achieve slterstion of the input radistion a trsn~psrent opticsl wsveguide 503 of sny convention~l type i8 provided hsving on its externsl surfsce 8 layer of sn opticslly sctive trsnsmission medium 505 according to the invention, which csn hsve the ssme properties a8 the medium 105, described sbove. The opticsl wsveguide 503 is normslly opticslly psssivc thst is, exhibits no significant levels of nonline~r (second or third order) polsrizstion.
, ~9~ 9 5 Mesn~ 507, shown 88 8 prl~m, is provided to lntroduce the input electroma~netic rsdlstion into the wavegulde. Means 509, shown 8~ a prlsm, is provided to retrieve electromsgnetic r~di~lton from the wsveguide. Although the opticslly sctive trsn~mlsslon medium is shown interpo~ed between the input snd output prism~, it 18 apprecisted thst ~n interpo~ed layer i8 not required in the~e locations.
As the input electromagnetic radiation traverses the wsveguide, a portion of the radiation will impinge on the surrounding layer of the optically sctive trsnsmission medium and be refracted back into the wsveguide. To svoid esc~pe of electromsgnetlc rsdistion 8 reflective lsyer, not shown, csn be costed over the opticslly sctive trsnsmission medium.
Successive lmpingements of trsnsmitted rsdistion on the opticslly sctive medium result in mes~uresble parflmetric effects, such as ~econd hsrmonic generstion.
In Flgure 7 an optical artlcle 600 ig shown cap~ble of producing useful parsmetric effects ~lmilsrly 88 optical article S00, but exhibiting a greater cspsbility for better phase matching, such ss thst desired for improved efflclency second hsrmonlc gener~tion. A ~ubstrate 601 18 shown supportlng ~uperlmposed wsveguide lsyers 603, 605, 607, snd 609.
Whlle four superlmposed lsyers are shown, ln practice any odd or even number of superlmposed lsyers csn be provlded. The odd lQyers (603 and 607) ln the ~equence csn be formed of sn optlcslly sctive trsnsmisslon medium sccording to the invention (~lmilsrly a8 medlum lOS) whlle the even lsyers (605 snd 609) csn be formed of 8 passlve or linear optical medium, as described above. Alternstively, the optlcslly sctlve and psssive tr~nsmlsslon medls lsyers csn be reversed ln order.
To achleve useful psrametrlc effects, ~, .
electromagnetlc rsdlation, lndlcsted by srrow 611 is ,~ .

39;~:95 supplied to the wsvegulding lsyer~ through input me~n~
613, shown Q8 8 prlsm. In psssing through the wsveguidlng lsyers to output mesns 615, shown 8~ a prism, the optically sctive snd psssive medis lsyers together slter the form of the electromsgnetic rsdistion, indicsted by output srrow 617, 80 thst psrQmetric (e.g., second hsrmonic) effects sre more efficiently genersted.
The opticsl srticle con~truction~ de~cribed lo above ~re exemplsry of ~ lsrge vsriety of possible differing opticsl srticle con~truction~. The present invention is compstible with ~ny conventionsl construction of sn opticsl srticle relying on ~
significsnt ~econd order pol~riz~tion susceptibility to produce 8 useful effect. For exsmple, wheress in connectlon with Figure 5 sn opticsl article is disclosed in which the opticslly sctive tr~nsmission medium surrounds 8 substrate, which csn h~ve line~r optic~l propertie~, Zy~s, cited sbove, in Figure 2(d) - 20 discloses ~ust the converse srrsngement, ln which the optic~lly sctive trsnsmission medium forms 8 core clsd with 8 shell of 8 linesr opticsl trsnsmis~ion medium.
Zyss 8180 discloses sn srrsngement in which the optically sctive tr~nsmission medium is locsted in 8 groove on the surfsce of 8 linesr opticsl trsnsmis~ion substrste. All of the opticsl srticle constructions of Zyss exhibiting second order nonpolsriz~iton effects csn be spplied to the prsctice of this invention.
An essentlsl component of esch of the opticsl srticles of this invention is sn opticslly sctive tr~nsmission medium comprised of 8 linesr vinyl sddition polymer which exhibits 8 second order polsrizstion susceptibility ~(2) grester thsn 10 9 ~prefersbly 8rester thsn 10 8) electroststic unlts. This hi8h level of ~(2) is schieved by choosing st lesst 5 percent of the repesting units of ' ~:

, -~ ~ ~g~ 9 5 the polymer to cont~in ~ 8 pendant group 8 molecul~r dipole exhibiting ~ high level of flrst hyperpol~rizflbility ~. For succinc~ne~s, the~e moleculsr dipoles sre hereinafter referred to 8~ hlgh B molecular dipoles and the repesting units in whlch they sre incorporsted sre referred to 8 high B
repe~ting unit~. When the high B repesting units constitute At lesst 5 percent of the totsl repesting units of the linear polymer, they usu~lly constitute about 20 percent, on ~ weight b~sis, of the linesr polymer, ~ince they gener~lly exhibit a relstively higher moleculsr weight thsn the remsining repe~ting units, lf ~ny, of the linear polymer.
The moleculsr dipole pendsnt group~ of the repeating unit include ~ sulfonyl electron acceptor moiety In 8 preferred form the repesting units cont~ining pend~nt moleculsr dipole~ csn be represented by Formuls 3:
~3) Rl H
~C C~
H
C = o o L
MD
where L is a divslent flexible spscer moiety;
MD is 8 high ~ moleculsr dipole containing a ~ulfonyl electron scceptor; snd R is hydrogen, hslogen, or slkyl of from 1 to 6 csrbon stoms.
It i8 sppsrent thst when Rl is hydrogen or methyl the repesting unit is derived from sn acrylste or methscrylste ester, respectively. These ~re the most common alkenoic scid esters employed in vinyl ~ddltlon ~olymerlz~tlon, but ~ v~rlety o~ varl~nt~ ~re .

~`' , ' .

12l!~9295 known ~nd csn be employed slternstlvely, if deslred.
The scrylste snd methscrylste esters sre ~dvsntsgeou~
in offering the least moleculsr bulk.
To sllow the molecul~r dipole freedom of spatlsl orientation with respect to the polymer bQckbone, a8 is required for efficient poling, a divslent flexible spscer L is interposed between the polymer backbone snd the moleculsr dipole. A
generslly preferred flexible spacer is sn slkylene group contsining from 1 to 12 carbon stoms. In a vsrisnt form one or seversl nonsd~scent carbon stoms can be replsced by oxygen, ~o thst the llnksge become~
sn slkylene oxide llnksge - e.g. sn ethylene oxide linksge. Such a flexlble ~pacer moiety c~n be resdily provited by esterifying with the slkenoic scid 8 moleculsr dipole which contains 8 terminslly hydroxy substituted slkyl or slkylene oxide substituent.
The high 8 molecul~r dipole MD slong with the flexible spscer moiety L csn be generally repre~ented by Formula Psir 4:
(4) A
E - - L
D
; 25 t ¦ Ae ~ L-11~
D
I where A 18 a sulfonyl electron acceptor moiety;
D is en electron donor moiety;
E is 8 linking moiety, specificslly a con~ugated ~ bonding system consisting of two terminsl csrbocyclic aromatic rings linked through 1 to 3 vinyl 8rouPs; ~nd ~' ~, `
. , "~ .

: . ~ ' ' ' 8 ~ 95 L is a flexible spacer molety.
The molecular dipoles are represented by the oscillation (resonsnce) ground stste and excited stste extremes, since these lend themselves to representstion by chemicsl formulse. Formula pair~
sre useful in bracketing the range of structural variance, even though it is recognized that in practice neither of the oscill~tion extremes may be sctuslly fully re~lized. As is customary becsuse of the simpler chemicsl nomenclsture, the moleculsr dipoles snd their moieties sre nsmed by their ground ~tate structures.
The electron scceptor moiety A i~ 8 sulfonyl - moiety. It csn be represented by Formuls Psir 5:
15 (5) R

O=S=O

I e o--s~
where R is L or sn optlonslly substituted hydrocsrbon moiety.
The electron donor moieties csn tske sny convenient conventionsl form. The electron donor moiety csn be sn smino moiety. Primsry, secondsry, snd tertisry smino moietles sre contemplsted for use, with the lstter being most preferred snd the former belng lesst preferred. Only the secondsry and tertisry smlno moieties sllow for substituent modificstion of properties through optionsl substitution of a hydrocsrbon moiety similsrly ss the sulfonyl moiety, snd only the tertisry smino moiety produces the most highly polar excited ~tste. When ~. , :, .

:

~9~:95 the electron donor moiety, lt csn be represented by Formul~ P~ir 6.
(6) ~ 1 3 R -N--R

K - ~ R3 where R2 and R3 sre independently L, hydrogen, or optionslly ~ubatituted hydrocsrbon moieties.
In~tesd of employing sn smino group as sn electron donor moiety, it ia ~pecifically contemplated to employ sn oxy or thio electron donor moiety. When ~uch oxy ~nd thio electron donor moietiea csn be represented by Formuls Psir 7.
(7) X

I

X~

where R4 i~ sn optionally ~ubstituted hydrocarbon moiety and X i~ oxygen or ~ulfur.
The moiety E linking the electron acceptor snd donor moieties i8 ~elected to sati~fy three fundsmentsl c~sracteristic~. Firat, it is chosen ~o thst the molecule will be noncentrosymmetric, thereby exhibiting ~ dipole moment even in it8 ground state.
Second, it i8 cho~en to provide ~ufficient ~patisl sepsration of the electron donor snd scceptor moietie~
to provide a lsrge dipole moment in the polsr excited ~tste of the electron donor snd scceptor moietie~.
Third, the linking moiety 1~ chosen to permit efficient o~cillstion or chsrge trsnsfer resonance between the ground and exclted ~tate~. This re~ults in lsrge difference~ between the excited stste and ground state dipole moments.
A con~ugated ~ bonding system csn ~atisfy all three requirements. On its mo~t elementsl level ~uch a bonding sy~tem can be provided by chains of methine (a.k.a., methenyl snd methylidyne) group~, which sre (except a~ ~pecificslly noted) to be understood a~ including ~ubstituted form~. Such chslns csn optionally include one or more azs (-N=) moietie-~.
To satisfy the requirement for oscillation or charge trsnsfer resonance, it 18 e~ential thst the re~on~nce path be defined by an even number of atoms.
The number of atoms ln the resonance path between the electron donor and acceptor i8 preferably at lea~t 4 and optimally at least 8.
While incressing the number of atom~ in the re~on~nce path should increa~e the excited stste dipole moment, it also tend~ towsrd nonplsnar moleculsr conformstions which lead to lo~es in hyperpolsrizability den~ity, defined above, as well a~
thermsl and other energy losses (e.g., lo~e~ in trsnsparency), ~o that at first diminishing gains and then overall losses result from increasing the number of atoms in the resonance path. It is generally preferred that the number of stoms in the resonance psth between the electron donor and acceptor be 20 or le~s and optimslly 14 or les~.

' ~3~'~95 In a preferred form the linking moieties csn be represented by Formula Psir 8.
(8) G
I I Im I
Il I
G
G

11_Im where G is independently in each occurrence methine or Qzs snd m i~ 4 to 20, preferably 8 to 14.
For ~ynthetic convenience it i~ generslly preferred thst no more thsn two sd~scent G group~ be sza groups Thus, both ind$vidual sza (-N=) snd diazo (-N=N-) groups sre contemplated to be pre~ent in the linking moiety.
While the BZ8 groups permit no ~ubstitution, the methine group~ csn be subst~tuted, if deaired.
Preferred linking moieties sre tho~e which hsve been at les~t psrtislly rigidized by aubstituent~ bridging methine groups in the resonsnce psth. Rigidizstion of the linking moiety reduce~ energy di~sipstion. In a ~pecifically preferred form of bridging ~ubstitution of the methine groups in the resonsnce path, the linking moiety i8 wholly or, prefersbly, psrtislly ~romstized. Both csrbocyclic snd heterocyclic sromstizstion i~ ~pecificslly contemplsted.
The ~ulfonyl electron acceptor moiety A snd the sd~scent terminal portion of the linXing moiety E

--2~
can be repre~ented by Formuls Psir 9.
(9) A

I

e R

where A ls an electron scceptor molety snd R8 repre~ent hydrogen, ~ub~tituents which together with the electron scceptor moiety collectively enh~nce the electron scceptsnce of the phenyl ring to which they ~re attached, or, optionally in one occurrence, L.
When the electron acceptor moiety ia 8 ~ulfonyl moiety S02R and the sd~acent atom of the linklng moiety is an aza (-N=) group, the ~ulfonyl snd aza groupa ln combinatlon form 8 sulfonimino group =N-S02R. In 8 ~pecific preferred form of the invention the terminal ~ulfonlmino group snd an ad~acent sromatlzed portion of the llnking group can ~2~9~95 be represented by Formula Pair 10.
(10) R
O=S=O
N
Ra i~ ~I RRa R
e o=s~
N
~5 ~ 0- ~

where Ra and Rl are a~ previously defined.
The electron donor moiety D and the ad~acent terminal portion of the linking moiety E csn be repre~ented by Formula Pair 11.
~11) 1 Rd~ --Rd Rdd= I il - Rd D +
where D is an electron donor moiety snd Rd represent hydrogen, substituents which together with the electron donor D collectively enhsnce the electron donstion of the phenyl ring to 1289~95 which they ~re utt~ched, option~lly including sub~tltuent~, such ~8 hydroc~rbon substituent~, or ln one occurrence L.
When electron donation is from ~ nitrogen atom, a terminal sromatic rigidizing ring system formed by 8 4-pyr$dinium and 4-pyrido t~utomer is possible, as illustrated by the preferred dipolar compounds of Formula Pair 12.
(12) ll Rd~ Rd l2 Rdd 1~ li_Rd +

l2 where Rd snd ~2 are as previously defined.
In specifically prefe~red forms of the moleculsr dipoles the linking moiety is aromatized ~d~scent both the electron ~cceptor moiety, as indicsted by Formulse 9 ~nd 10, and the electron donor moiety, a8 lndicated by Formul~e 11 and 12.
A specifically preferred cl~ss of molecular dipoles s~tisfying the requirements of the invention sre 4-A-4'-D-stilbenes, where A and D are as previously defined. In these stilbenes the electron acceptor and donor moieties are each bonded to one terminal aromstized portion of the con~ugated ~
bond$ng linking moiety, with the aromatized portions of the linking moiety being ~oined by an ethylene (vinylene) group. When the single ethylene linking group of the stilbene is replaced by two or more ethylene groups, within the resonance psth ch~in length limits noted above, highly advantageous - 12~9~95 snslogue~ are resllzed. Substitution of lndlvidusl methlne group~ with ~zs groups, psrtlcul~rly ln the ethylenic portlon of the llnksge, sre compstlble with schlevlng hlgh B vslue~. The ethylenlcslly expsnded ~nd 8Z8 ~ub~ltuted stilbene vsrlsnts sre hereln~fter referred to 88 ~tilbenoid compound~, since they sre compounds which ~hsre ~igniflcsnt property ~lmilsritie~ with ~tilbene~.
In a preferred form of the lnvention, the lo ~tilbenold compounds c~n be pre~ented by Formul~ Psir 13:
(13) - A
15 1 ~,,i~i I
I G I
G L-Ae I G
G L
~ I! In Rd=~ Rd _ where ,~
.,,: ' ' ` . .
~ :
: ' ' ' .~ ` .

9s A, D, L, R8, and Rd are ~ previously defined;
G is independently in each occurrence 8 methine or szs group with the proviso thst no more than two aza moietie3 sre next sd~scent; ~nd n is sn integer of from 1 to 3.
A sulfonimino group is incompstible with the atilbenoid structure~ of Formula Pair 13. One preferred clsss of dipolsr compounds exhibiting high levels of hyperpol~riz~billty incorporating a terminal 9s sulfonimino group Are represented by Formuls Psir 14.
~14) _ _ O=S=O
N
R~ / ~ =R~

il G _L

d ' d I i1 G

N

R~ i il-RRa I G I L -G

~ d G
D
where D, L, R, Ra, and Rd are a~ previously defined;
G is independently in esch occurrence 8 methine or szs moiety, with the proviso thst no more th~n two azs moieties are next ad~scent;
snd p i8 0 or 1.
In Formuls Psir 14 neither of the two terminal resonsnce psth stoms of the linking moiety are included in a rigidizing aromatic ring, but the r$gidizing aromatic ring or ring~ -are locsted next ad~acent to each re~onance psth terminal stom of the linking moiety. Note that either 6 or 12 atom~ are preaent in the resonance path provided by the linking moiety.
When electron donation i8 from 8 nitrogen atom, a terminQl aromstic rigidizing ring system formed by a 4-pyridinium snd 4-pyrido tsutomer i~
posaible, as illustrsted by the preferred dipolsr :

, -: . ~ . , '9 5 compounds of Formul~ Psir 15.
~15) R
0=~=0 R
. I G
L
' I! ' q o_s_oe N

RR~ I Il-l l l ~ L--where L, Rl, R2, Ra, and Rd ~re as previously defined;
: G is independently in e~ch occurrence a methine or ~za moiety, wlth the proviso that no more th~n two Rza 9s moieties sre next sd~scent; snd q i8 sn integer of fro~ 0 to 3.
When the linking moiety contsins two or more sromstic rings, it is specificslly preferred thst they be copl~nar, since coplansrity achieves the highest hyperpolarizability den~ities To preserve the coplsnarity of the rings it i8 preferred thst sny intermediate methine groups which are not psrt of sn aromatic ring remain un~ub~tituted. However, ~terically compact methine sub~tituent~ compatible with copolsnsrity, such 8~ fluorine snd lower slkyl groups of from sbout 1 to 3 csrbon atoms, sre contemplated.
Where the electron donor and/or electron scceptor moieties sre relied upon for linking of the moleculsr dipoles to the polymer bsckbone, the aromatic rings of the linking moiety csn be left unsub~tituted while schieving high levels of performance. In other in~tsnces it may be ~yntheticslly convenient to employ the sromstic rings of the linking moiety a~ site~ for linking the moleculsr dipoles to the polymer bsckbone. In either instsnce, it iB spprecisted thst the dipole moment of 8 moleculsr dipole csn be incressed by employing in svsllsble phenylene ring positions substituents which ~upplement the electronic ssymmetry induced by the electron scceptor A moiety snd the electron donor moiety D. Electron donating snd accepting properties of phenyl rings imparted by substitution have been extensively studied and quantified by the as~ignment of Hsmmett ~igma vslues. Substituents which render phenyl rin8s electron accepting are sssigned positive Hsmmett sigms values while negstive Hsmmett sigma vslues are sssigned to substituents which render phenyl rings electron donsting. Hydrogen atoms sttsched to phenyl rings sre ss~igned a Hammett sigms vslue of zero. By slgebrsicslly summing the Hsmmett , ' .

., : -,~. .
, , ' 9~

sigma vslues of substituents to a phenyl rlng lt is possible to arrive at A net Hammett sigma vslue for the phenyl ring that is indicative of whether the substltuted phenyl rin8 i8 electron sccepting ~indicsted by ~ positive net Hsmmett sigms v~lue) or electron don~ting (indicsted by 8 negstive net Hammett sigms value). Further, the elgebrsic ~um of the sub~tituent Hsmmett sigms vslue~ qusntifie~ the degree to which the ~ubstituted phenyl ring i8 electron ~ccepting or donsting.
Lsnge'~ Handbook of Chemiatry, 12 Ed., McGrsw-Hill, 1979, Tsble 3-12, pp. 3-135 to 3-138, li~ts Hammett sigma values for a lsrge number of commmonly encountered substituents. Ortho and psra position substituents usu~lly exhibit identical Hsmmett sigms vslues, which differ to only a limited degree from met~ sigms vslue~ snd can, in any event, be determined from published li~ts. Exemplary simple substituents snd their publi~hed meta H~mmett sigma vslues sre primsry snd ~econd slkyl substituents, such 8S methyl a = -0.07, ethyl a = -0.07, n-propyl a = -0.05, _-propyl a = -0.07, n-butyl a = -0.07, snd sec-butyl a = -0.07. These slkyl substltuents sre synthetically convenient snd therefore contemplsted. Alkyl substituents containing tertisry csrbon stoms snd particularly tertisry slkyl groups tend to be even more highly electron donsting.
Aryl groups such as phenyl, a-nsphthyl, snd B-nsphthyl groups are contemplsted (e.g., phenyl a - +0.06). Other useful snd specificslly contemplsted hydrocsrbon sub~tituents include slksryl substituents (e.g., E-methylphenyl), sr~lkyl ;~l substituents (e.g., benzyl a = -0.05 and phenethyl), slkenyl substituent~ (e.g. vinyl a - +Q.02), srslkenyl substituents (e.g., 2-phenylvinyl a = +0.14), slkynyl substituents (e.g., ethynyl a = +0.21, propsrgyl, snd 2-butynyl), and aralkynyl 2 ~ 9 5 substituents ~e.g., phenethynyl a = +0.14).
Substituted hydrocsrbon substituents sre ~180 contemplated, such 8S hsloalkyl substituent~ (e.g., bromomethyl, chloromethyl a = -0.12, fluoromethyl, snd iodomethyl), hsloaryl sub~tituents (e.g., ~-bromophenyl, m-bromophenyl, snd ~-chlorophenyl, snd hydroxyslkyl substltuents (e.g., hydroxymethyl a = +0.08).
It i8 specificslly preferred to select R~
substltuent~ independently from smong known phenyl ring substituents h~ving ~ positive Hammett sigma value snd to select Rd substituent~ independently from among known phenyl ring substituents having 8 negstive Hsmmett sigms value. However, it is recognized that combinQtions of R8 substituent~ Qre possible, some of whlch sre electron donsting, some of which are es~entislly neutrsl, snd some o~ which sre electron sccepting. Combinstions of Ra substituents sre possible which, together with the electron scceptor moiety A, slgebrsically sum to 8 positive net Hsmmett sigms vslue. Prefersbly the combinstion of R8 ~ubst~tuents, without inclusion of the ~ulfonyl group, provide 8 positive net Hsmmett sigma vslue.
Similsrly, sny combinstion of Rd substituent~ is possible which, together with the electron donor, D, slgebrsicslly sum to 8 negstive net Hammett sigms vslue. Prefersbly the combinstion of Rd ~ubstituents, without inclusion of the substituent D, provide 8 negstive net Hsmmett sigms value.
To svoid perturbstion of the desired re~onsnce psttern no one R8 substituent should hsve 8 Hsmmett sigms vslue more positive thsn thst of the electron scceptor moiety, snd no one Rd substituent should hsve 8 Hsmmett sigms vslue more negstive thsn thst of the electron donor moiety D. It is 8180 importsnt to be~r in mind thst lsrge ~ values depend not only on schieving 8 lsrge dipole moment, but 8180 .~

~ ~ ~ 9~ ~5 on achieving a lsrge difference between the excited state snd ground stste dipole moments. Thu~
sub3tltuent~ must be cho~en from among tho~e which sre compstible wlth rever~lble charge tr~n~fer- i.e., chsrge trsn~fer resonsnce. Thu~ sub~tituents of the very highe~t and lowest Hsmmett sigma values sre preferably svoided It is recognized thst two ad~scent Ra or Rd substituent~ cQn, if de~ired, together form 8 lo ring fu~ed with the phenyl ring to which they are sttached. Fu~ed benzo rings are ~pecificslly contemplsted. Polycyclic sromstic rings, ~uch 8~
nsphthyl snd snthracyl aromstic ring~, in the linking moietie~ sre therefore pos~ible. Fu~ed benzo ring~
are compstible with the coplsnsrity of the aromatic nucle1 and, unless they sre themselves sub~tituted, hsve little effect on electronic s~ymmetry. It is further recognized thst R2, R3, and R4 can, if de~ired, form with sn Rd substituent ortho to D 8 fused ring, prefersbly of 5 or 6 member ring. For exsmple, the smino electron donor moiety in Formula Psir 11 csn form with the linking moiety 8 ~ulolidene ring. Numerou~ other fu~ed ring~ contsining the hetero~tom of the electron donor moiety sre po~ible.
However, while within the contemplstion of u~eful dipole moleculsr structures, fu~ed ring substituent psttern~ sre not generslly preferred, since they incres~e moleculsr bulk, thereby reducing the hyperpolsrizsbility den~ity, while lacXing in msny in~tsnces the synthetic convenience of monovslent sub~tituents.
The substituents R snd R4 sre optionslly substituted hydrocsrbon sub~tituent~ in 811 instsnce~, while the sub~titutents R2 snd R3 csn be hydrogen or optionslly substituted hydrocsrbon ~ub~tituents, with one or both mo~t prefersbly being optionslly substituted hydrocsrbon sub~tituent~. Specificslly ~ ~ 8~ 9 S

contemplated forms of hydrocsrbon substltuents sre aliph~tic hydrocsrbon substituent~ contsinlng from 1 to sbout 40 ~prefersbly 1 to 10 csrbon atom8 snd optim~lly 1 to 6) csrbon stoms e.g., slkyl, alkenyl, snd alkynyl, including all cyclic forms thereof;
~romstic hydrocsrbon ~ubstituents containlng from 6 to 20 csrbon ~tom~ (prefersbly 6 to 10 c~rbon - ~tom~ - i.e., phenyl ~nd nsphthyl); snd hydrocarbon ~ub~tituent~ which sre compo~ite~ of the~e sliphstic snd sromstic ~ubstituents e.g., slksryl, sralkyl, slksralkyl, srslksryl, etc. The aliphatic substituents and substituent moieties csn contsin unssturstion for steric or synthetic convenience. All of the hydrocsrbon substituents csn, optionslly, themselves be substituted to fscilitate polsr sllgnment in the trsnsmission medium.
The hydrocsrbon and substituted hydrocsrbon substituent~ of the electron scceptor snd donor moieties csn be chosen, if desired, to enhsnce the electron sccepting or donating functions of the electron scceptor snd donor moieties, respectively.
Hammett ~igms vslues of the electron donor snd electron scceptor moieties sre useful for this purpose, a8 explsined sbove in connection with the selection of Ra and Rd substituents. For exsmple, the Hammett ~igms values of a primary smino group (-NH2); second smino groups, such as alkylamino (e.g., -NHCH3, -NHCH2CH3, 8nd -NH-n-C4H9);
snd tertisry smino groups, such a8 dislkylamino (e.g., dimethylsmino) rsnge from -0.04 for the primsry amino group to -0.83, with the secondsry snd tertisry amino groups generslly hsving Hsmmett sigms vslues more negative than -0.20.
In one specific preferred $orm of the invention the repesting units contsining moleculsr dipole pendsnt groups of the llnear polymers exhlbiting high ~(2) vslues can be represented by .

lZ~ 9S

the Formul~ P~ir 16:
~16) R
H
~C C~
H
C = 0 o (CH2)r R - N

î
R
H
~C C~
H
C = O
O
(CIH2)r E
: Ae where A is ~ sulfonyl electron scceptor;
E is 8 4,4'-~tllbene linking moiety;
r 18 sn integer of from l to 12;
R2 is hydrogen or a hydrocsrbon contsinlng from 1 to 6 c~rbon stoms; snd Rl i~ hydrogen or methyl.
; The linesr polymers contsining repeating unit~ with pendsnt moleculsr dipole~ ~ de~cribed sbove cQn, lf de~lred, contsin only repesting units with pendsnt moleculsr dipole~. The ssme or dlfferent pendant molecul~r dipoles c~n be present in the repeetin~ unlt~. In the forcer in~tsnce, the llnesr ' ~

. . . .

9~

polymers are homopolymers. When 811 of the repeating units contaln a pendant molecular dipole, the hiBhest - attainable hyperpolsrizability densities ~hould be obtained.
One dissdvAntsge that ha~ been encountered in prepsring homopolymers sstisfying the requirements of the invention i8 limited solubility. This is believed to result from 8 smsll smount of unwsnted addition occurring st the sites of the vinyl moieties in the pendant groups. The homopolymers t despite their stiffness, can be shaped into u~eful optically active tran~mission media by hot pressing and poling.
To allow solubility of the linear polymers in common organic solvent~ te.g., benzene, chlorobenzene, toluene, dimethylformamide, dimethylsulfoxide, chloroform, dichloromethsne, acetonitrile, and acetone) snd thus to allow spin casting of the linear polymers, it i8 preferred to limit the proportion of the repeating units containing vinyl groups to 35 percent or less of the total repeating units. Thus, in one preferred linear polymers contempl~ted for use in the prsctice of this invention are tho~e containing from 5 to 35 percent (optimslly 20 to 35 percent) repeating units contsining molecular dipoles containing vinyl unsaturation (e.g., ~tilbene molecular dipoles) High ~(2) value~ can be achieved, even when the high B repeating units ; constltute only 5 percent of the tot~l repeating units of the linear polymers.
In another preferred form of the invention vinyl groups in the repeating units of the linear polymers are avoided entlrely, thereby entirely avoiding the problem of limited solubility. This can be sccomplished while still retaining high B repeating units by employing pendant molecular dipoles according to the invention which contain a pair of aza groups rather than one or more vinyl groups- e.g., azobenzene ~9 ~ 9 ~

~-C6H4-N2-C6H4-) moleculsr dlpoles.
The remsinlng repestlng units of the linesr polymer csn be provided by vinyl sdditlon monomers cho~en from smong 8 wide vsrlety of conventionsl forms. In one form the remslning repestlng unlts csn 8180 lnclude pendsnt moleculsr dlpoles. To svold unwsnted sddition resctions ln the pend~nt molecular dipoles durlng polymerizstlon the pendsnt groups of the remsining repesting units should be free of vlnyl moleties. For exsmple, the pendsnt molecular dipoles in the remsining repesting units csn be identical to the high B repesting units described sbove, except thst the 4,4'-stilbenoid linking i8 replsced by s 1,4-phenylene or 4,4'-biphenylene linking moiety.
Any remsinlng repestlng units other thsn those contsining moleculsr dipole pendsnt groups csn, but need not, contsin ~ pend~nt group. In one preferred form of the inventlon the remsining repesting units sre chosen from smong esters snd nitrile~ of 2-slkenoic ~cids. Preferred repesting units of this type c~n be represented by Formuls 17:
(17) R
H
H l5 R
where Rl is ~8 hss been previously defined, prefersbly hydrogen or methyl;
R5 is -CN or -C(O)OR6; ~nd R6 i~ sn option~lly substituted hydrocsrbon, prefersbly slkyl of from 1 to 6 csrbon stoms.
Methyl ~nd ethyl scrylstes snd methscrylstes, scrylonitrile, ~nd methscrylonitrile ~re specificslly preferred exsmples of these repesting units.
- 35 Another preferred clsss of repeating units !~ sre those derlved from styrenic monomers (monomers of :,:
-~ styrene snd its derivstlves formed by hydrogen ' :"

, . , . , -:, `' - ..
, - . : , ;.,~ ' ', . ~ , 9s di~placement- e.g., halo snd R6 substltuted 8tyrene.
Any one or combinstion of the repesting unlt~
described ~bove CAn, with the high B repesting units, sccount for all of the repeating unlts of the lineAr polymer~ employed in the opticsl srticle~ of this invention. However, no repesting unit~ other thsn the high B repesting unit~ sre required.
To form the polymer~ de~cribed sbove it i8 merely nece~sry to combine in the proportions de~ired in the linear polymer vinyl sddition monomers corresponding to the repesting unit~. Polymerization csn be induced therm~lly or by exposure to ultrsviolet rsdiation (UV). For polymerization in the ne~r UV
(290 to 390 nm) portion of the spectrum 8g well ~8 the shorter w~velength (less thsn 550 nm) reglons of the visible spectrum conventional polymerizatlon initiators csn be employed A vsriety of conventionsl useful polymerizstion initi~tors sre listed in Scozzaf~Ys et al U.S. Pstent 4,485,161 snd in Principles of Polvmerizst~on, 2nd Ed., by G. Odi~h, John Wiley ~ Son~, 1981, pp. 194-206.
The opticslly sctive transmission medium need contain nothing in Qddition to the linesr polymer descrlbed sbove. In prsctice ~mall smounts of polymerizstion initistors, ususlly less thsn 1 percent by welght, b~sed on the weight of polymer, can remsin in the polymer when it i~ formed into the opticslly sctive trsn~mission medium. Bec~use of their low concentrstions, sbsorpt$on of rsdiation by re~idusl initiators sre normally too low to be significsnt. It i8 81~0 pos~ible, though not ususlly preferred, to combine the high x(2) linesr polymers described with other binders, such 88 opticslly psssive linesr polymers, in forming the tr~n~mission medium. Other - 35 binders csn be tolersted to the extent thst x~
for the tr~nsmission medium remain~ sbove 10 9 esu.
Molecular dipoles which sre not pendsnt group~ of 8 , , ~ 289;;~9S

polymer cfln be mixed wlth the high ~(2) llnesr polymers, if desired, but this is not requlred, since better control of the properties of the tr~nsmission medium i~ schieved when the molecular dipoles sre pendant groups of 8 linear polymer.
To fscilitate polar slignment of the molecular dipoles contsined within the optically sctive tran~mi~sion medium the high x(2) linesr polymers (and other binders, if present) must exhibit glass trsn~ition temperature~ sbove ~mbient temperstures. To sssure thst the trsnsmission medium is sufficiently rigid to lock the moleculsr dipoles in polar ~lignment under temperstures of use, it is preferred thst the high x~2) linesr polymers exhibit 8 glss~ trsnsition tempersture in the rsnge of from sbout 70C to 150C. Linesr polymers hsving still higher glsss trQnsition temperature~ can be employed, but sre not preferred becau~e of the high temperstures required for poling snd the resulting potential for thermsl degrsd~tion of the org~nic component~ of the opticsl trsnsmission medium.
The hi8h ~ linesr polymers prefer~bly have moleculsr weights (weight sversge, al80 designsted Mw) in the rsnge of from about 10,000 to 200,000, optimslly from sbout 15,000 to 120,000. Polymer moleculsr weights, unless otherwise indicst2d are understood to be mea~ured by gel permestion chromotogrsphy (GPC) using differential refrsctive index differentisl and poly~tyrene st~ndsrd~. A
molecular weight determination procedure of this type i~ described in detsil in "Modern Size Exclusion Chromotogrsphy", W.W. Ysu, J.J. Kirkland, and D.D.
Bly, Wiley Interscience, J. Wiley and Son~, 1979.
The ~pecific ~election of materisls forming the optically active trsn~mission media will be influenced by the wavelengths of electromsgnetic radistion the transmission be u~ed to propagate. The preferred opticsl srticles of thi~ lnvention sre those wh~ch exhibit the lowe~t possible sbsorptions of electromsgnetic r~diation in the opticslly active trsn~mlssion medium. For optlc~l srticles whlch are intended to propsgate u single wavelength or r~nge of w~velenths of electrom~gnetic radiation, transmission medis sre employed which exhibit sb~orption minima - within the wsvelength region of propagstion. Where the optical article itself receives electromagnetic rsdistion of one wsvelength and internslly produces for trAnsmission electromagnetic rsdistion of 8 differing wsvelength, the tran~mis~ion medium is prefer~bly chosen to exhlbit minimsl absorption~ in both spectral regions. For exsmple, if it is intended to employ sn opticsl article sccording to this invention for second harmonic generstion in respon~e to infrared radiation received from a ls~er, such ~8 8 laser emitting in the 800 to 1600 nm region of the spectrum, the linear polymers sre chosen to exhibit the lowest levels of ab~orption possible ~t the la~er wavelength in the infrared snd st the wavelength of the second hsrmonic in the visible ~pectrum.
ExsmPles The invention csn be better apprecisted by reference to the following specific exsmples:
Exsmple 1 N-(6-HYdroxYhexYl)-N-methYlaniline A mixture of 153 g ~1.43 mol) freshly distilled N-methylsniline, 200 8 (1.46 mol) 6-chlorohexsnol, 200 g (1.45 mol) pota~sium carbonste, 6 g potssslum iodide, and 750 mL n-butanol wa~ heated at reflux under nitrogen with vigorous mechanical stirring for 4 days. The solution wss cooled, filtered, and the solvent was removed st ~educed pressure. The residue was distilled in vscuo to 35 produce 210 g (71~) of a colorless oil, bp 153-166C
(0.10 mm).

,' ~` ` ., `

9s lH NMR (300 MHz, CDC13) ~ 1.44 ~m, 4H), 1.62 (m, 5H), 2.98 (s, 3H), 3.36 (t, 2H), 3.67 (t, 2H), 6.74 (m, 3H), 7.29 (t, 2H).
ExamPle 2 N-(6-Acetoxyhexyl~-N-methvlanillne A mixture of 210 g (1.01 mol) of N-(6-hy-droxyhexyl)-N-methylaniline (Exsmple 1), 112 g (1.10 mol) o~ scetic anhydride, snd 86 g (1.1 mol~ of pyr~dine w~s he~ted st reflux with stirring for 2 hours. After cooling, the solution W8S poured onto 500 g of ice snd extr~cted with ethyl ~cetate (4 x 300 mL). The combined extrscts were dried (MgSO4) snd the solvent was removed st reduced pressure. The residue WQS distilled in vscuo, collecting the frsction boiling st 130C (0.01 mm). Yield: 231 g (93%) of 8 colorless oil.
lH NMR (300 MHz, CDC13) ~ 1.40 (m, 4H), 1.65 (m, 4H), 2.08 (s, 3H), 2.96 (s, 3H), 3.37 (t, 2H) 4.07 (t, 2H), 6.75 (m, 3H), 7.23 (t, 2H).
ExsmPle 3 4-[(6-AcetoxYhexvl)methylsminolbenz-sldehYde Phosphorous oxychloride (145 g, 0.95 mol) wss sdded dropwise st 5C to 280 mL of stirred N,N - dimethylformsmide (DMF), snd the mixture wss ~tirred st 5C for 2 hours. N -(6-Acetoxyhexyl)-N-methylsniline ~Exsmple 2, 230 g, 0.93 mol) wss sdded 810wly, snd the resction mixture wss heated st 90C
for 3 hours. After cooling, the solution ws3 poured onto 500 g of ice snd the resulting mixture wss neutrslized to pH 5 with sodium scetste. The mixture W8S extrscted with dichloromethsne (4 x 200 mL), the combined extrscts were dried (MgSO4), snd the solvent wss removed st reduced pressure. The brown residue wss distilled in vscuo to provlde 186 g (73~) of 8 yellow oil, bp 195C (0.15 mm).
lH NMR (300 MHz, CDC13) ~ 1.38 (m, 4H), 1.60 (m, 4H), 2.02 (s, 3H), 2.98 (s, 3H), 3.37 (t, 2H), 4.02 (t, 2H), 6.65 (d, 2H), 7.66 (d, 2H), 9.70 (g, lH).

~289;~9S

~o--Example 4 4-MethYlmercaptobenzYl chlorlde To a stirred ~olutlon of 154 g (1.0 mol) of 4-methylmercaptobenzyl slcohol in 1 llter of dry benzene ws~ sdded dropwise 80 mL (1.1 mol) of thionyl chloride. The mixture tmmedlstely turned blue. After the addition of the thionyl chlorlde was completed, the mixture w~s heated at reflux for 2 hours. After - cooling, the benzene snd exce~s thionyl chloride were dl~t~lled at ambient pressure. The product w~s distilled in vacuo at 105C ~0.5 mm), to yield 160 g (93~) of 8 colorles~ liquid.
NMR (300 MHz, CDC13) ~ 2.49 (a, 3H), 4.57 ~8, 2H), 7.28 (dd, 4H).
ExsmPle S DiethYl 4--MethYlmercsPtobenzylPhosPhonste lS 4-Methylmercsptobenzyl chlorlde (Exsmple 4, 160 g, 0.94 mol) was sdded dropwlse, under nitrogen, with stirring to 183 g (1.1 mol) of trlethylphosphite which was hested st reflux. When the eddition of the 4-methylmercaptobenzyl chloride wa~ completed, the mixture W88 refluxed for additional 4 hours. The product was distllled ln V8CUO to yield 229 g (89S) of 8 colorless, vi~cous oil bp 142-145C (0.025 mm).
lH NMR (300 MHz, CDC13, ~): 1.27 (t, 6H), 2.49 (~, 3H), 3.13 (d, 2H), 4.04 (quintet, 4H), 7.66 (dd, 4H).
ExsmPle 6 Dieth~l 4-Meth~lsulfonYlbenzylPho~Phonste To a ~tirred solution of 174 g (0.60 mol) of dlethyl 4-methylmercaptobenzylphosphonate (Exsmple S) ln S00 mL of glscisl acetic acld was sdded dropwi~e 171 g (1.5 mol) of hydrogen peroxlde (30S in wster).
The mixture was heated st reflux for 2 hour~. After coollng, the water snd scetic scid were removed under reduced pressure snd the re~idue wss di~tilled to ~ yield 121 g (66S) of very viscous liquid bp 214-216C
-~ 35 (2 x 10-4 mm).
lH NMR (300 MHz, CDC13) ~ 1.23 (t, 6H~, 3.01 (8, 3H), 3.19 ~d, 2H), 4.02 (qulntet, 4H), 7.66 (dd, 4H)-:
: . ' ' '' - ' .

~3~5 ~1-- xsmPle 7 4'-[(6-HvdroxyhexYl)smlno-4-methYlsul-fonYlstilbene To ~ solution of 5 g (0.125 mol) 60% sodium hydride dispersion, 27.7 g ~0.1 mol) of 4-t(6-sce-toxyhexyl)methyl~mino]benzaldehyde (Example 3) ~nd 200mL of dry, fre~hly distilled 1,2-dimethoxyethane (DME) under nitrogen, st room tempersture, with vigorous - stirring w~s sdded 30.6 g (0.1 mol) of diethyl 4-methylsulfonylbenzylphosphonate (Ex~mple 6). The mixture immedi~tely turned yellow. The resction mixture was hested st reflux for 2 hours. The bright yellow solution wss poured over 400 g of crushed ice under ~ nitrogen bl~nket snd the resulting mixture wss extrscted with four 250 mL portions of dichloromethsne. The combined orgsnic extrscts were washed three times with 250 mL of wster, snd the solvent was removed at reduced pressure. The residue wss dissolved in 250 mL of 10~ (v/v) HCl in 1:1 ethsnol:water Rnd the solution wss hested st reflux for 4 hours. After cooling the ~olution wss neutrslized to pH 7 by the slow snd careful sddition of sodlum carbonste. The yellow solid thus formed w~s collected by filtrstion, washed with water snd sir dried. Recrystallizstion from methsnol yielded 31.4 g (81%) of 8 bright yellow solid. This msterisl contsined some ~cetste which w~s not hydrolized (-S~), however, 8 pure ssmple of the msterisl wss obtsined by chromstogrsphy. Thus, 5 g of the msterisl wss dissolved in 25 mL of 8 mixture of scetone:ethylscetste 1:5, snd loaded onto 8 dry sil~cs gel column (500 g, S cm dismeter). Elution gsve 4.5 g of pure msterisl which wss then recrystsllized from sbsolute methanol. mp 113-115C.
lH NMR (300 MHz, CDC13) ~ 1.45 (m, 4H), 1.63 (m, 4H), 3.01 (8, 3H), 3.09 (s, 3H), 3.39 (t, 2H), 3.69 (br t, 2H), 6.67 (d, 2H), 6.89 (d, lH), 7.18 (d, lH), 7.41 (d, 2H), 7.60 (d, 2H), 7.87 (d, 2H).

12~39~9.5 ~2--ExamPle 8 4'--[(6-HYdroxYhexYl)methYlamln meth~lsulfonYla~obenzene A ~tirred suspension of 150 8 (0.88 mol) of 4-methylsulfonylaniline in 1 liter of 20~ hydrochloric acid at 0-3C wss treated dropwise with a solution of 66.5 g (0.96 mol) of sodium nitrite in 200 mL of water. N-(6-Hydroxyhexyl)-N-methylsniline (Exsmple 1, 218 g, 1.05 mol~ W8S sdded 810wly, msintsinin8 the temper~ture below 5C, and the mixture was stirred for 1 hour. Sodium acetate (119 g, 0.88 mol) wss sdded and stirring was continued for 3 hours. Concentrsted ammonium hydroxide (250 mL) was added, and the mixture W88 stirred for 64 hours. The precipitated product W8S recry~tsllized successively from ethsnol, from toluene, and then from toluene/isopropanol to produce 160 g (47~) of 8 red solid, mp 114-116C.
1H NMR (300 MHz, CDC13) ~ 1.4 (m, 4H), 1.6 (m, 4H), 3.07 (~, 3H), 3.08 (8, 3H), 3.43 (t, 2H), 3.64 (t, 2H), 6.72 (d, 2H), 7.88 (d, 2H), 7.98 (AB, 4H). 13C{lH} NMR (75.5 MHz, CDC13) ~ 25.7, 26.8, 27.1, 38.7, 44.6, 52.6, 62.7, 111.3, 122.7, 126.0, 128.4, 139.7, 143.4, 152.4, 156.5.
ExamPle 9 4 -~(6-acrYloxYoxYhexyl)methYlamin ~methYlsulfomlstilbene A stirred mixture of 4 -[(6-hydroxyhexyl)-methylamino]-4-methylsulfonylstilbene (Example 7, 20.0 g, 52 mmol), triethylamine (6.3 g, 62 mmol) and dry dichloromethane (DCM) was treated dropwise with acryloyl chloride (5.6 g, 62 mmol) in 50 mL of DCM at 23C under nitrogen. The resulting solution was stirred st 23C for 72 hours, and then filtered. The filtrate was washed succcessively with satursted NaCl, with satursted NHC03, and with water. The organic layer was dried (MgS04), and the ~olvent was removed st reduced pressure to deposit a yellow o~l which gradually crystallized. The product was recrystallized from tetrahydrofuran (THF)~hexanes to l~9~g5 yield 15.5 g (68%) of 8 yellow solid, mp 88-90C.
lH NMR (300 MHz, CDC13) ~ 1.40 (m, 4H), 1.70 (m, 4H), 3.00 (8, 3H), 3.06 (8, 3H), 3.37 ~t, 2H), 4.17 (t, 2H), 5.82 (dd, lH), 6.12 (m, lH), 6.40 (dd, lH), 6.70 (d, 2H), 6.91 (d, lH), 7.09 (d, lH), 7.44 (d, lH), 7.62 (d, 2H), 7.88 (d, 2H). 13C{lH}
NMR (75.5 MHz, CDC13) ~ 25.8, 26.7, 28.6, 44.6, 64.4, 121.4, 126.3, 127.2, 127.7, 128.3, 128.6, 129.5, 130.2, 130.4, 148.4 Anal. C~lcd for C25H31N3O4S: C, 68.00; H, 7.08; N, 3.17; S, 7.26. Found: C, 68.01; H, 6.86; N, 2.98; S, 6.89.
Example 10 4'-[(6-MethscrYloxvox~hexYl)methylam~nol-~methYl~ulfomlszobenzene A mixture of 141 g (0.362 mol) of 4'-t(6-hy-droxyhexyl)methylsmino]-4-methylsulfonylszobenzene (Exsmple 8), 37.0 g (0.366 mol) of triethylsmine, 400 mg of 3-t-butyl-4-hydroxy-5-methylphenylsulfide (inhibitor), and 500 mL of dry dichloromethsne wss treated with methacryloyl chloride (52.7 g, 0.504 mol) st 0C under nitrogen. The reaction mixture wss ~tirred for 1 hour at 0C snd then for 12 hours st 23C. The reaction mixture was washed with 500 mL of water to remove precipitated triethylamine hydrochloride, then with 500 mL of ssturated NHCO3, snd finally with S00 mL of water. The orgsnic lsyer was dried (Na2SO4) and the solvent was removed st reduced pressure to deposit a dark orsnge oil which crystsllized on trituration with hexanes. The product was recrystsllized from toluene snd then from THF/hexsnes to provide 124 g (75~) of orange powder, mp 78-80C.
1H NMR (300 MHz, CDC13) ~ 1.44 (m, 4H), 1.69 (m, 4H), l.9S (s, 3H), 3.09 (s, 6H), 3.45 (t, 2H), 4.16 (t, 2H), 5.56 (8, lH), 6.10 (s, lH), 6 74 (d, 2H), 7.90 (d, 2H), 8.00 (AB, 4H). 13C{lH}
NMR (75.5 MHz, CDC13) ~ 18.3, 25.9, 26.7, 27.0, 28.6, 38.7, 44.6, 52.5, 64.5, 111.3, 122.7, 125.1, i~.ss~ss 126,0, 128.3, 136.5, 139.8, 143.5, 152.4, 156.4, 167.4. FD-MS: 457 (M~). Anal. Calcd for C24H31N3O4S: C, 63.00; H, 6.83; N, 9.12; S, 7.01. Found: C, 62.96; H, 6.56; N, 9.12; S, 7.83. ExamPle 11 CoPolymerizatlon of 4 -[~6-scrYloxyoxY-hex~l)methl~minol 4-methYlsulfonYl~t bene with methYlmethacrylate A mixture of 4'-[(6-acryloxyoxyhexyl)methyl-amino]-4-methylsulfonylstilbene (Exsmple 9, 0.75 g, 1.7 mmol), distilled methylmethacrylste (2.00 g, 20.0 mmol), distilled chlorobenzene (15 mL), and 2,2 -szobis-(2-methylpropionitrile) (AIBN, 38 mg) was degassed by standsrd freeze/thaw techniques snd hested in a sealed ampoule under nltrogen at 60C for 48 hours. The resulting vi~cous solution was cooled and poured into 100 mL of vlgorously sgitated methanol to precipitste the polymer as 8 fine yellow powder, which was isolated by centrifugatlon. The polymer W8S
purified by repeated reprecipltation from dichloromethane into methsnol, snd was dried ~n vacuo at 80C for 48 hours. Yield: 2.35 g (80~).
GPC (THF, polystyrene ~tandards, differential refractive index detection): Mn = 25300 Mw = 111000. Tg = 109C (DSC).
Example 12 CoPolYmerization of g'-r(6-acryloxY-oxYhexYl)methYlaminol ~ methylsulfon stilbene with 4-t-butyl~tYrene A solution of 4'-tacryloxyoxyhexyl)methyl-amino]-4-methyl~ulfonylstilbene (Exsmple 9, 5.00 g, 11.3 mmol), distilled 4-t-butylstyrene (15.0 g, 93.6 mmol), and AIBN (0.182 g, 1.1 mmol) in 100 mL of d$stilled chlorobenzene was degassed by standard freeze/thaw techniques and then W8S heated st 60C for 15 hours. The polymer was precipitated into 1500 mL
of vigorously stirred methanol and purified by reprecipitation from dichloromethane into methanol. A
yellow powder was obtained, mass 10.0 g (50~).

GPC (THF, polystyrene st~nd~rds, dlfferentisl refractive index detection): Mn339500;
MW=166000. Tg=127C (DSC).
ExamPle 13 HomoPolymerlzstlon of 4'-[(6-scrYloxY-ox~hexYl)methYlsmlnol-4-methyl~ulfonYl-stllbene A solution of 4'-t(6-~crYloxYoxYhexyl)-methylamlno]-4-methylsulfonylstilbene (Exsmple 9, 2.29 g, 5.00 mmol), snd AIBN (0.042 g, 0.~6 mmol) ln 10 mL
of dist~lled chlorobenzene W8~ degsssed by stsndsrd freeze/th~w technique~ and then wa~ he~ted st 60C for 48 hour~. The polymer W8~ precipitsted into 300 mL of vigorou~ly ~tirred methsnol snd purified by reprecipitstion from dichloromethsne into methsnol.
An orange powder wss obtslned, msss 2.09 g (90~).
GPC (THF, polystyrene ~tsndsrds, dlfferentlsl refractlve index detection): Mn=22100;
MW-56500. Tg-101C (DSC).
Exsmple 14 CoPolYmerization of 4'-[(6-scrYloxY-hexYl~methYlsminol-4-methYlsulfon~l-szobenzene with methYlmethacrYlste A stlrred solutlon of 75.0 g (0.164 mol) of 4'-t(6-methscryloxyoxyhexyl)methylsmino~-4-methylsul-fonylszobenzene (Exsmple 10), 75.0 g (0.749 mol) of dlstilled methylmethacrylate, snd 2.50 g (0.0091 mol) of AI8N ln 500 mL of dlstllled chlorobenzene wss degss~ed by bubbllng nltrogen through the mlxture.
The solutlon was hested st 60C for 48 hours and then poured lnto excess methsnol (sgltated ln 8 blender) to preclpltste the polymer. The product wss reprecipitsted from dichloromethane lnto methsnol and - then from THF into deionized wster. ~fter drying to constsnt weight ln vscuo, 141 g (94~) of sn orsnge powder was obtsined.
GPC (THF, polystyrene stsndsrds, differential refrsctlve lndex detectlon): Mn~3360Q;
Mw~92000. Tg~109C (DSC).

, ' ' "' ' -, ~ : ' . ' ' ~ ~ .

, .

12B9;~95 ~6--ExamPle 15 OPticsl Cell PrePsrstion for CoPolvmer 4 -~(6-scr~lox~oxvhexYl~methl~mlnol-4-methylsulfonYlstilbene with methYl-methscrYlste (Ex~mple 11) The polymer (0.35 g) W8S di~solved in 2 mL of dichloromethsne snd spin costed Qt 250 rpm onto 125 ~m gsp side-by-side chromium electrodes by flrst sstursting the surfsces before spinning. The ssmples were dried for 16 hours st 40C, producing sn opticslly clesr, smorphous film. The film wss oriented by hesting to 125C snd spplying 8 pollng field of 2.4 X 104 V/cm scross the chromium electr~des. The ssmple w8~ cooled to room tempersture and the field W88 removed.
ExsmPle 16 OPticsl Cell PrePsrstion for CoPolvmer 4'-[(6-scrYloxYhexvl)methylsminol 4^
methYlsulfonYlazobenzene with meth~l-methscrYlate (Example 14) Sod~ lime glss~ overed on one side with 25 nm of indium tin oxide (IT0) wss obt~ined commercislly.
A SiO2 film 0.2 ~m thlck wss sputtered onto the side of the sods llme glsss covered wlth IT0. Next, a polymer film W~8 spin costed over the SiO2 l~yer follows: The polymer (10 wtS) was dissolved in purified 1,2,3-trlchloropropsne. The soluton wss dropped onto the substrste until the substrste was completely covered. The substrste was spun st 500 rpm for 10 seconds and then the speed wss increased to 2000 rpm for 60 sec. The fllm was subsequently plsced in a v~cuum oven snd hested to 120C for about 12 hr in order to remove residusl solvent. Thls trestment resulted in a film approximstely 1.25 ~m thick.
Next, a 1 ~m monomeric gl~ss film wss therm~lly evsporsted over the polyer. Finslly, ~ 200 nm thick MgIn electrode w~s thermslly ev~porsted on top of the monomer glass.

~ .

~9~ 9 The polymer fllm wss poled by spplylng 430 volts scro~ the IT0 snd MgIn elec~rodes (IT0 po~ltive) for 5 minute~ while the film was st 8 tempersture of 111C. With the volt~ge still spplied, the film w~ then slowly cooled to room tempersture.
ExsmPle 17 Second Hsrmonic Generstion from Polymer 4V-[(6-scrYloxyoxyhexYl)methlsminol 4 methvl~ulfonYlstilbene with methYl-methacrylate (Example 11) The film of polymer 4 -[(6-acryloxyoxy-hexyl)methlamino]-4-methyl~ulfonyl~tilbene with methylmethscrylste (Exsmple 11) prepared as described in Example 15 W88 probed with 1064 nm lsser light snd 8 ~econd hsrmonic signsl st 532 nm wss detected which W8~ not present in the unpoled msterisl. The ~ignsl intensity wss found to be proportionsl to the squsre of the poling field strength. The sign~l inten~ity was referenced to thst of a qusrtz crystal, giving 8 vQlue for the second order susceptibility:
~(2) ~ 1 x 10-9 e~u.

The ratio between the two su~ceptibilities ~zzzlxxxx wss messured to be 2.9, very clo3e to the theoreticsl vslue of 3Ø The ~econd hsrmonic signsl wss completely stsble for 24 hours.
ExsmPle 18 Second Hsrmonic Generstion from PolYmer 4'-- r ( 6--8crYlOxyhexYl )methYlaminO 1~
methYlsulfonylszobenzene with methyl-methacrYlste (Example 14) The fllm of polymer 4'-t(6-scryloxyhexyl)-methylsmino]-4-methylsulfonylszobenzene with methyl methscrylste (Example 14) prepared as described in - Example 16 wss probed with 1064 nm lsser light snd 8 second hsrmonic signsl st 532 nm W88 detected which 3S W8~ not present in the unpoled ssmple nor in 8 previously poled ssmple heated above the glss~
transition temperature of the polymer. The ~ignal ~392~

inten~ity was found to be proportlonsl to the square of the poling field strength. The ratio between the two ~usceptibilities xzzz/~xxx was measured as 3.0, in accordance with theory.
Example 19 ElectrooPtic Mea~urements on Polymer 4'-[(6-scryloxyhexvl)meth~laminol-4-methyl~ulfonyl~zobenzene with methYl-- methacrylste (Exsmple 14) The elsctro-optic effect of the polymer cont~ining multilayer structure of Example 16 W8~
observed u~ing an ellipsometer An ellipsometer is sn optic instrument which measure~ the relative amplitude snd phase change of light polarized in snd normal to the plsne of incidence upon reflection from a surfsce. U~ing Fresnel's equstions, the electro-optic response of the multilayer structure was modeled to obtain the second order polarization susceptibility of the polymer film. A second order polarization susceptibility (x2) of 2 X 10 7 esu results in a curve which closely fits the measured response.
The invention has been described in detail with psrticular reference to preferred embodiments thereof, but it will be understood that variations snd modifications can be effected within the spirit and scope of the invention.

Claims (20)

1. An optical article containing, for the transmission of electromagnetic radiation, a medium exhibiting a second order polarization susceptibility greater than 10-9 electrostatic units comprised of a linear polymer containing as pendant groups polar aligned noncentrosymmetric molecular dipoles having an electron donor moiety linked through a conjugated .pi.
bonding system to an electron acceptor moiety to permit oscillation of the molecular dipole between a ground state exhibiting a first dipole moment and an excited state exhibiting a differing dipole moment, characterized in that the linear polymer contains repeating units derived from vinyl addition polymerization, at least 5 percent of the repeating units incorporate the molecular dipoles as pendant groups, and the molecular dipoles include a sulfonyl electron acceptor moiety.

2. An optical article according to claim 1 further characterized in that means are provided for directing electromagnetic radiation to said transmission medium.

3. An optical article according to claim 1 further characterized in that biasing means are provided for placing an electric field across said transmission medium.

4. An optical article according to claim 3 further characterized in that said biasing means includes at least one transparent electrode in contact with said transmission medium.

5. An optical article according to claim 1 further characterized in that said transmission medium lies in contact with a linear waveguide for electromagnetic radiation.

6. An optical article according to claim 1 further characterized in that the transmission medium exhibits a x(2) of at least 10-8 electrostatic units.

7. An optical article according to claim 1 further characterized in that the linear polymer is a homopolymer.

8. An optical article according to claim 1 further characterized in that the repeating units incorporating the molecular dipoles form from 5 to 35 percent of the repeating units of the linear polymer.

9. An optical article according to claim 1 further characterized in that the linear polymer exhibits a molecular weight in the range of from

10,000 to 200,000 on a weight average basis.
10. An optical article according to claim 9 further characterized in that the linear polymer exhibits a molecular weight in the range of from 15,000 to 120,000 on a weight average basis.

11. An optical article according to claim 1 further characterized in that the molecular dipoles include an electron donor moiety linked to the sulfonyl electron acceptor moiety through a conjugated .pi. bonding system consisting of two terminal carbocyclic aromatic rings linked through 1 to 3 vinyl groups or two aza groups.

12. An optical article according to claim 11 further characterized in that the molecular dipoles are represented by the formula:
where A is a sulfonyl electron acceptor moiety;
D is an electron donor moiety;
E is a stilbenoid conjugated .pi. bonding system;
and L is a flexible spacer moiety.

13. An optical article according to claim 12 further characterized in that D is a secondary or tertiary amino moiety.

14. An optical article according to claim 12 further characterized in that A is :
where R is L or an optionally substituted hydrocarbon moiety.

15. An optical article according to claim 12 further characterized in that the molecular dipole is represented by the formula:
where A is a sulfonyl electron acceptor moiety;
D is an electron donor amino moiety;
L is a flexible spacer moiety;
Ra represent hydrogen, subsituents which, together with the electron acceptor moiety, collectively enhance the electron acceptance of the phenyl ring to which they are attached, or, optionally in one occurrence, represent a bonding site for L;
Rd represent hydrogen, subsituents which, together with the electron donor amino moiety, collectively enhance the electron acceptance of the phenyl ring to which they are attached, or, optionally in one occurrence, represent a bonding site for L;
G is independently in each occurrence a methine or aza moiety, with the proviso that no more than two aza moieties are next adjacent; and n is an integer of from 1 to 3.

16. An optical article according to claim 1 further characterized in that the linear polymer contains repeating units derived from the vinyl addition polymerization of a styrenic monomer.

17. An optical article according to claim 1 further characterized in that the linear polymer contains repeating units derived from the vinyl addition polymerization of 2-alkenoate esters.

18. An optical article according to claim 17 further characterized in that the repeating units containing the molecular dipoles are represented by the formula:

where A is a sulfonyl electron acceptor;
E is a 4,4'-stilbene linking moiety;
r is an integer of from 1 to 12;
R1 is hydrogen or methyl; and R2 is hydrogen or a hydrocarbon containing from 1 to 6 carbon atoms.

19. An optical article according to claim 18 further characterized in that remaining repeating units of the linear polymer are represented by the formula:

where R1 is hydrogen or methyl;
R5 is -CN or -C(O)OR6; and R6 is alkyl of from 1 to 6 carbon atoms.

20. An optical article according to claim 18 further characterized in that remaining repeating units of the linear polymer are derived from styrenic monomers.