Polymer blends exhibiting nonlinear optical response

In a preferred embodiment this invention provides novel organopolysiloxane/liquid crystalline polymer blends which exhibit nonlinear optical response. Illustrative of an invention composition is a blend of (1) organopolysiloxane corresponding to the formula: ##STR1## where n is an integer of at least 5; and (2) a liquid crystalline polymer corresponding to the formula: ##STR2## where m is an integer of at least 3.

BACKGROUND OF THE INVENTION 
It is known that organic compounds and polymeric materials with large 
delocalized .pi.-electron systems can exhibit nonlinear optical response, 
which in many cases is a much larger response than by inorganic 
substrates. 
In addition, the properties of organic compounds and polymeric materials 
can be varied to optimize other desirable properties, such as mechanical 
and thermoxidative stability and high laser damage threshold, with 
preservation of the electronic interactions responsible for nonlinear 
optical effects. 
Thin films of organic compounds or polymeric materials with large second 
order nonlinearities in combination with electronic circuitry have 
potential as systems for laser modulation and deflection, information 
control in optical circuitry, and the like. 
Other novel processes occurring through third order nonlinearity such as 
degenerate four-wave mixing, whereby real-time processing of optical 
fields occurs, have potential utility in such diverse fields as optical 
communications and integrated circuit fabrication. 
Of particular importance for conjugated organic systems is the fact that 
the origin of the nonlinear effects is the polarization of the 
.pi.-electron cloud as opposed to displacement or rearrangement of nuclear 
coordinates found in inorganic materials. 
Nonlinear optical properties of organic compounds and polymeric materials 
was the subject of a symposium sponsored by the ACS division of Polymer 
Chemistry at the 18th meeting of the American Chemical Society, September 
1982. Papers presented at the meeting are published in ACS Symposium 
Series 233, American Chemical Society, Washington, D.C. 1983. 
The above recited publications are incorporated herein by reference. 
Prior art of interest with respect to the present invention are 
publications relating to organopolysiloxane synthesis such as U.S. Pat. 
Nos. 2,716,128; 2,970,150; 3,159,662; 3,483,270; 3,694,478; 4,166,078; 
4,336,364: 4,370,365; 4,465,818; 4,472,563; and 4,578,494. 
Of particular interest are publications which describe organopolysiloxanes 
containing olefinically unsaturated substituents, such as U.S. Pat. Nos. 
3,498,945; 3,932,555; 4,077,937; and 4,530,989. 
Of related interest are publications which describe organopolysiloxanes 
having mesogenic side chain substituents, such as U.S. Pat. Nos. 4,358,391 
and 4,410,570. 
There is continuing interest in the development of organopolysiloxane 
polymers which exhibit exceptional properties for specialized 
applications. 
There is also a growing interest in the development of new nonlinear 
optical organic media for prospective novel phenomena and devices adapted 
for laser frequency conversion, information control in optical circuitry, 
light valves and optical switches. The potential) utility of organic 
materials with large second-order and third-order nonlinearities for very 
high frequency application contrasts with the bandwidth limitations of 
conventional inorganic electrooptic materials 
Accordingly, it is an object of this invention to provide novel 
compositions which are physical blends of an organopolysiloxane component 
and a liquid crystalline component. 
It is another object of this invention to provide novel nonlinear optical 
organic media. 
It is a further object of this invention to provide optical devices having 
a nonlinear optical component comprising a transparent solid medium of a 
physical blend of organopolysiloxane and liquid crystalline polymer 
components. 
Other objects and advantages of the present invention shall become apparent 
from the accompanying description and examples. 
This patent application is related to copending patent application Ser. No. 
923,501, filed Oct. 27, 1986. 
DESCRIPTION OF THE INVENTION 
One or more objects of the present invention are accomplished by the 
provision of a polysiloxane which is characterized by a recurring 
structural unit corresponding to the formula: 
##STR3## 
where R is an inorganic substituent or an organic substituent containing 
between about 1-12 carbon atoms; Z is a substituent selected from hydrogen 
and electron-donating and electron-withdrawing substituents; and the 
polysiloxane contains between about 2-2000 silicon atoms. 
Illustrative of R inorganic substituents are chlorine, fluorine, bromine, 
nitro, amino, hydroxyl, thiolo, and the like. 
Illustrative of R organic substituents are aliphatic, alicyclic and 
aromatic radicals such as methyl, trifluoromethyl, butyl, isobutyl, 
butenyl, ethoxyethyl, fluorohexyl, decyl, cyclopentyl, cyclohexenyl, 
phenyl, tolyl, benzyl, naphthyl, piperidyl, pyridyl, pyrazyl, and the 
like. 
In another embodiment this invention provides a polymer which is 
characterized by a recurring structural unit corresponding to the formula: 
##STR4## 
where R.sup.1 is a hydrocarbyl substituent containing between about 1-12 
carbon atoms; n is an integer of at least 5; and Z' is an 
electron-donating or electron-withdrawing substituent. 
When the polymer is a copolymer, preferably the above recurring structural 
units comprise at least about 25 weight percent of the copolymer. 
Illustrative of other recurring comonomeric units are dialkylsiloxyl, 
diarylsiloxyl, dialkylsilazanyl, oxyalkylene, and the like. The copolymer 
can have alternating comonomeric units, or be in the form of block 
copolymers with block units of the type described in U.S. Pat. No. 
3,483,270 and U.S. Pat. No. 4,586,997. 
In another embodiment this invention provides a polymer which is 
characterized by a recurring structural unit corresponding to the formula: 
##STR5## 
where R.sup.1 is a hydrocarbyl substituent containing between about 1-12 
carbon atoms; n is an integer of at least 5; X is an electron-donating 
substituent; and Y is an electron-withdrawing substituent. 
Illustrative of R.sup.1 substituents are C.sub.1 -C.sub.4 alkyl groups and 
C.sub.6 -C.sub.10 aryl groups, such as methyl and phenyl radicals. 
The term "electron-donating" as employed herein refers to organic 
substituents which contribute electron density to the .pi.-electron system 
when the conjugated electronic structure is polarized by the input of 
electromagnetic energy. 
The term "electron-withdrawing" as employed herein refers to 
electronegative organic substituents which attract electron density from 
the .pi.-electron system when the conjugated electronic structure is 
polarized by the input of electromagnetic energy. 
Illustrative of electron-donating substituents as represented by Z, Z' or X 
in the above formulae are amino, alkylamino, dialkylamino, 1-piperidyl, 
1-piperazyl, 1-pyrrolidyl, acylamino, hydroxyl, thiolo, alkylthio, 
arylthio, acyloxy, halo, C.sub.1 -C.sub.30 hydrocarbyl, C.sub.1 -C.sub.30 
hydrocarbyloxy, C.sub.1 -C.sub.30 hydrocarbylthio, and the like. 
Illustrative of electron-withdrawing substituents as represented by Z,Z' or 
Y in the above formulae are nitro, cyano, trifluoromethyl, acyl, carboxy, 
alkanoyloxy, aroyloxy, carboxamido, alkoxysulfonyl, aryloxysulfonyl, and 
the like. 
In another embodiment this invention provides a thermoplastic polymer which 
is characterized by a recurring structural unit corresponding to the 
formula: 
##STR6## 
where R.sup.1 is a hydrocarbyl substituent containing between about 1-12 
carbon atoms; X' is a C.sub.1 -C.sub.30 alkyl, alkoxy or alkylthio 
substituent; Y' is a substituent selected from nitro, cyano and 
trifluoromethyl groups; and the polymer contains between about 5-2000 
silicon atoms. 
In another embodiment this invention provides a thermoplastic polymer which 
is characterized by a recurring structural unit corresponding to the 
formula: 
##STR7## 
where R.sup.1 is a hydrocarbyl substituent containing between about 1-12 
carbon atoms; R.sup.2 and R.sup.3 are selected from hydrogen and C.sub.1 
-C.sub.30 alkyl groups, and R.sup.2 and R.sup.3 taken with the connecting 
nitrogen atom form a heterocyclic substituent; Y' is a substituent 
selected from nitro, cyano and trifluoromethyl groups; and the polymer 
contains between about 5-2000 silicon atoms. 
Illustrative of a heterocyclic structure formed by R.sup.2 and R.sup.3 
taken together with the connecting nitrogen atom is pyrrolidyl, 
imidazolidyl, oxazolidyl, thiazolidyl, and the like. 
Illustrative of specific organopolysiloxanes of the present invention are 
polymers represented by the following recurring structural units, wherein 
the polymers have a weight average molecular weight between about 
2000-100,000: 
##STR8## 
In another embodiment this invention provides a nonlinear optical medium 
comprising a noncentrosymmetric configuration of polymer molecules 
characterized by a recurring structural unit corresponding to the formula: 
##STR9## 
where R.sup.1 is a hydrocarbyl substituent containing between about 1-12 
carbon atoms; n is an integer of at least 5; and Z' is an 
electron-donating or electron-withdrawing substituent. 
Depending on the nature of the Z' substituents in the above polysiloxane 
formula, the nonlinear optical medium can exhibit a second order nonlinear 
optical response. Illustrative of a second order nonlinear optical 
response is an optical susceptibility .chi..sup.(2) of about 
1.times.10.sup.-7 esu at 1.91 82 m, and a Miller's Delta of about one 
square meter/coulomb. 
The term "Miller's delta" as employed herein with respect to second 
harmonic generation (SHG) is defined by an equation as elaborated by 
Garito et al in Chapter 1, "Molecular Optics:Nonlinear Optical Properties 
Of Organic And Polymeric Crystals"; ACS Symposium Series 233 (1983). 
The quantity "delta"(.delta.) is defined by the equation: 
EQU d.sub.ijk =.delta..sub..epsilon. .chi..sup.(1).sub.ii .chi..sup.(1).sub.jj 
.chi..sup.(1).sub.kk .delta..sub.ijk 
where terms such as .chi..sup.(1).sub.ii are representative linear 
susceptibility components, and d.sub.ijk, the second harmonic coefficient, 
is defined through 
EQU .chi..sup.(2).sub.ijk (-w.omega.; .omega., .omega.)=d.sub.ijk (-2.omega.; 
.omega., .omega.) 
The Miller's delta (10.sup.-2 m.sup.2 /c at 1.06 .mu.m) of various 
nonlinear optical crystalline substrates are illustrated by KDP(3.5), 
LiNbO.sub.3 (7.5), GaAs(1.8) and 2-methyl-4-nitroaniline(160). 
In another embodiment this invention provides a nonlinear optical medium 
comprising a centrosymmetric configuration of polymer molecules 
characterized by a recurring structural unit corresponding to the formula: 
##STR10## 
where R.sup.1 is a hydrocarbyl substituent containing between about 1-12 
carbon atoms; n is an integer of at least 5; and Z' is an 
electron-donating or electron-withdrawing substituent. 
A nonlinear optical medium with a centrosymmetric molecular configuration 
as defined above exhibits a third order nonlinear optical response. 
Illustrative of a third order nonlinear optical response is an optical 
susceptibility .chi..sup.(3) of about 1.times.10.sup.-12 esu at 1.91 
.mu.m. 
In another embodiment this invention provides an optical device, e.g., an 
electrooptic light modulator, with an organic nonlinear optical component 
comprising a transparent solid medium of a polymer which is characterized 
by a recurring structural unit corresponding to the formula: 
##STR11## 
where R.sup.1 is a hydrocarbyl substituent containing between about 1-12 
carbon atoms; n is an integer of at least 5; and Z' is an 
electron-donating or electron-withdrawing substituent. 
The term "transparent" as employed herein refers to an optical medium which 
is transparent or light transmitting with respect to incident fundamental 
light frequencies and created light frequencies. In a nonlinear optical 
device, a present invention nonlinear optical medium is transparent to 
both the incident and exit light frequencies. 
Synthesis Of Organopolysiloxanes 
A present invention organopolysiloxane polymer can be prepared by the 
reaction of a selected organosilicon structure having a silicon-bonded 
hydrogen atom with a selected acetylenic compound in the presence of a 
hydrosilylation catalyst: 
##STR12## 
The use of a platinum catalyst to promote the condensation of a silanic 
hydrogen-bonded siloxane with an unsaturated compound is described in U.S. 
Pat. Nos. 2,970,150; 3,159,662; 4,077,937; and 4,530,989. 
Organohydrogenpolysiloxanes are prepared in a general procedure as 
described in U.S. Pat. No. 4,370,365 by the hydrolysis of one or more 
organohalosilanes having silicon-bonded hydrogen such as 
methyldichlorosilane, followed by condensation of the hydrolysis product. 
The acetylenic starting material utilized for preparation of the present 
organopolysiloxanes can be synthesized by conventional procedures, such as 
by employing benzoin or cinnamic acid type of intermediates in the manner 
described in Organic Synthesis, coll. vol. III, 786 (1955) and coll. vol. 
IV, 857 (1963). 
The following flow diagram illustrates a reaction scheme for synthesis of 
an acetylene monomer: 
##STR13## 
Blends Of Polysiloxane And Liquid Crystalline Components 
In another embodiment this invention provides a composition which is a 
blend of components comprising: 
(a) a polysiloxane component which is characterized by a recurring 
structural unit corresponding to the formula: 
##STR14## 
where R is an inorganic substituent or an organic substituent containing 
between about 1-12 carbon atoms; Z is a substituent selected from hydrogen 
and an electron-donating and electron-withdrawing substituents; and the 
polysiloxane contains between about 2-2000 silicon atoms; and 
(b) a liquid crystalline component. 
In another embodiment this invention provides a thermoplastic composition 
which is a blend of components comprising: 
(a) a polysiloxane component which is characterized by a recurring 
structural unit corresponding to the formula: 
##STR15## 
where R.sup.1 is a hydrocarbyl substituent containing between about 1-12 
carbon atoms; n is an integer of at least 5; and Z' is an 
electron-donating or electron-withdrawing substituent; and 
(b) a liquid crystalline component. 
Characteristic of an invention composition is a blend which has a glass 
transition temperature above about 40.degree. C., and exhibits nonlinear 
optical response. 
The proportion of polysiloxane component in the composition can vary 
between about 10-90 weight percent of the total weight of components. 
The liquid crystalline component can be a low molecular weight compound or 
an oligomeric or polymeric liquid crystal. 
A liquid crystalline polymer component can be either a main chain or side 
chain liquid crystalline polymer. Illustrative of a liquid crystalline 
polymer component is a thermotropic liquid crystalline polymer containing 
recurring benzimidazole, benzthiazole or benzoxazole structures. 
The polysiloxane component and/or the liquid crystalline component of an 
invention composition blend can exhibit nonlinear optical response. 
An invention composition can be prepared by physically blending the two 
components, such as when both of the components are solids at ambient 
temperature. A solid admixture can be homogenized further by melting the 
physical blend, and then cooling to solidify the melt phase in the form of 
an organic alloy. 
An invention composition also can be prepared by dissolving the 
polysiloxane and liquid crystalline components in an organic solvent and 
then removing the solvent medium to provide the composition blend. 
An organic solvent solution of a composition can be utilized to cast films 
or to coat optical substrates. Suitable organic solvents include benzene, 
toluene, chloroform, tetrahydrofuran, N,N-dimethylformamide, 
N,N-dimethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, and the 
like. 
A spinning dope of an invention composition can be prepared and employed 
for the production of fibers. An invention composition in a molten state 
can be employed for molding or extruding of shaped articles. 
In another embodiment this invention provides a composition which is a 
blend of components comprising: 
(a) a polysiloxane component which is characterized by a recurring 
structural unit corresponding to the formula: 
##STR16## 
where R.sup.1 is a hydrocarbyl substituent containing between about 1-12 
carbon atoms; n is an integer of at least 5; X is an electron-donating 
substituent; and Y is an electron-withdrawing substituent; and 
(b) a liquid crystalline polymer component which is characterized by a 
recurring wholly aromatic structural unit corresponding to the formula: 
EQU --Ar--X--Ar-- 
where X is a divalent radical selected from estero, amido, azomethino, azo, 
azoxy, etheno and ethyno groups, and Ar is a divalent aromatic radical 
selected from phenylene, naphthylene and diphenylene groups, and aromatic 
radicals corresponding to the formula: 
##STR17## 
where Y is a carbonyl, sulfono, oxy or thio group. 
Illustrative of a wholly aromatic liquid crystalline polymer component is a 
copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. 
The term "wholly aromatic" as employed herein refers to a linear 
thermotropic liquid crystalline polymer in which each recurring monomeric 
unit contributes at least one aromatic nucleus to the polymer backbone. 
The term "thermotropic" as employed herein refers to polymers which are 
liquid crystalline (i.e., anisotropic) in the melt phase. Wholly aromatic 
thermotropic liquid crystalline polymers are disclosed in U.S. Pat. Nos. 
3,526,611; 3,991,013; 4,048,148; 4,057,597: 4,066,620; 4,067,852; 
4,075,262; 4,083,829; 4,107,143; 4,118,372; 4,122,070; 4,130,545; 
4,146,702; 4,153,779; 4,156,070; 4,159,365; 4,161,470; 4,169,933; 
4,181,792; 4,184,996; 4,188,476; 4,219,461; 4,224,433; 4,230,817; 
4,238,598; 4,238,599; 4,256,624; 4,332,759; and 4,381,389; incorporated 
herein by reference. 
In a further embodiment this invention provides a thermoplastic composition 
which is a blend of components comprising: 
(a) a polysiloxane component which is characterized by a recurring 
structural unit corresponding to the formula: 
##STR18## 
where R.sup.1 is a hydrocarbyl substituent containing between about 1-12 
carbon atoms; n is an integer of at least 5; X is an electron-donating 
substituent; and Y is an electron-withdrawing substituent; and 
(b) a side chain liquid crystalline polymer component which is 
characterized by a recurring structural unit corresponding to the formula: 
##STR19## 
where P is a polymer main chain unit, S is a flexible spacer group having 
a linear chain length of between about 0-20 atoms, M is a pendant mesogen, 
and where the pendant mesogens comprise at least about 10 weight percent 
of the polymer and the polymer has a glass transition temperature above 
about 60.degree. C. 
Side chain liquid crystalline polymers are disclosed in U.S. Pat. Nos. 
4,293,435; 4,358,391; and 4,410,570; incorporated herein by reference. 
Other literature describing side chain liquid crystalline polymers include 
J. Polym. Sci., 19, 1427 (1981); Eur. Polym. J., 18, 651 (1982); Polymer, 
26, 615 (1985); incorporated herein by reference. 
Side chain liquid crystalline polymers exhibiting nonlinear optical 
response are disclosed in copending patent application Ser. No. 822,090, 
filed Jan. 24, 1986; incorporated herein by reference. 
Liquid crystalline polymer technology is reviewed in "Polymeric Liquid 
Crystals", (Plenum Publishing Corporation, New York, 1985), and in 
"Polymer Liquid Crystals" (Academic Press, New York, 1982); incorporated 
herein by reference. 
A present invention composition blend of polysiloxane and liquid 
crystalline components can be shaped into a centrosymmetric or 
noncentrosymmetric optical medium such as a transparent film or coating, 
and employed as an organic nonlinear optical unit in a light modulator 
device, e.g., a laser frequency converter device. 
Nonlinear Optical Properties 
The fundamental concepts of nonlinear optics and their relationship to 
chemical structures can be expressed in terms of dipolar approximation 
with respect to the polarization induced in an atom or molecule by an 
external field. 
As summarized in the ACS Symposium Series 233 (1983) listed hereinabove in 
the Background Of The Invention section, the fundamental equation (1) 
below describes the change in dipole moment between the ground state .mu.g 
and an excited state .mu.e expressed as a power series of the electric 
field E which occurs upon interaction of such a field, as in the electric 
component of electromagnetic radiation, with a single molecule. The 
coefficient .alpha.u is the familiar linear polarizability, .beta. and 
.gamma. are the quadratic and cubic hyperpolarizabilities, respectively. 
The coefficients for these hyperpolarizabilities are tensor quantities and 
therefore highly symmetry dependent. Odd order coefficients are 
nonvanishing for all structures on the molecular and unit cell level. The 
even order coefficients such as .beta. are zero for those structures 
having a center of inversion symmetry on the molecular and/or unit cell 
level. 
Equation (2) is identical with (1) except that it describes a macroscopic 
polarization, such as that arising from an array of molecules in a liquid 
crystalline domain: 
EQU .DELTA..mu.=.mu..sub.e -.mu..sub.g =.alpha.E+.delta.EE+.gamma.EEE+. . . (1) 
EQU P=P.sub.O +.chi..sup.(1) E+.chi..sup.(2) EE+.chi..sup.(3) EEE+. . . (2) 
Light waves passing through an array of molecules can interact with them to 
produce new waves. This interaction may be interpreted as resulting from a 
nonlinearity of the induced polymerization. For wholly optical processes 
such interaction occurs most efficiently when certain phase matching 
conditions are met, requiring identical propagation speeds of the 
fundamental wave and the harmonic wave. Birefringent crystals often 
possess propagation directions in which the refractive index for the 
fundamental .omega. and the second harmonic 2.omega. are identical so that 
dispersion may be overcome. 
The term "phase matching" as employed herein refers to an effect in a 
nonlinear optical medium in which a harmonic wave is propagated with the 
same effective refractive index as the incident fundamental light wave. 
Efficient second harmonic generation requires a nonlinear optical medium 
to possess propagation directions in which the optical medium 
birefringence cancels the natural dispersion, i.e., the optical 
transmission of fundamental and second harmonic frequencies is phase 
matched in the medium. The phase matching can provide a high conversion 
percentage of the incident light to the second harmonic wave. 
For the general case of parametric wave mixing, the phase matching 
condition is expressed by the relationship: 
EQU n.sub.1 .omega..sub.1 +n.sub.2 .omega..sub.2 =n.sub.3 .omega..sub.3 
where n.sub.1 and n.sub.2 are the indexes of refraction for the incident 
fundamental radiation, n.sub.3 is the index of refraction for the created 
radiation, .omega..sub.1 and .omega..sub.2 are the frequencies of the 
incident fundamental radiation and .omega..sub.3 is the frequency of the 
created radiation. More particularly, for second harmonic generation, 
wherein .omega..sub.1 and .omega..sub.2 are the same frequency .omega., 
and .omega..sub.3 is the created second harmonic frequency 2.omega., the 
phase matching condition is expressed by the relationship: 
EQU n.sub.107 =n.sub.2.omega. where n.sub..omega. and n.sub.2.omega. are 
indexes of refraction for the incident fundamental and created second 
harmonic light waves, respectively. More detailed theoretical aspects are 
described in "Quantum Electronics" by A. Yariv, chapters 16-17 (Wiley and 
Sons, New York, 1975). 
A present invention organopolysiloxane alone or in admixture with a liquid 
crystalline polymer typically is optically transparent and exhibits 
hyperpolarization tensor properties such as second harmonic and third 
harmonic generation, and the linear electrooptic (Pockels) effect. For 
second harmonic generation, the bulk phase of an organopolysiloxane of an 
admixture with a liquid crystalline polymer whether liquid or solid does 
not possess a real or orientational average inversion center. The 
substrate is a macroscopic noncentrosymmetric structure. 
Harmonic generation measurements relative to quartz can be performed to 
establish the value of second order and third order nonlinear 
susceptibility of the optically clear substrates. 
In the case of macroscopic nonlinear optical substrates that are composed 
of noncentrosymmetric sites on the molecular and domain level, the 
macroscopic second order nonlinear optical response .chi..sup.(2) is 
comprised of the corresponding molecular nonlinear optical response 
.beta.. In the rigid lattice gas approximation, the macroscopic 
susceptibility .chi..sup.(2) is expressed by the following relationship: 
EQU .chi..sub.IJK -.omega..sub.1,.omega..sub.2)=Nf.sup..omega.3 f.sup..omega.2 
f.sup..omega.1 &lt;.beta..sub.ijk (-.omega..sub.3 ; .omega..sub.1, 
.omega..sub.2) &gt; 
wherein N is the number of sites per unit volume, f represent small local 
field correlations, .beta..sub.ijk is averaged over the unit cell, 
.omega..sub.3 is the frequency of the created optical wave, and 
.omega..sub.1 and .omega..sub.2 are the frequencies of the incident 
fundamental optical waves. 
These theoretical considerations are elaborated by Garito et al in chapter 
1 of the ACS Symposium Series 233 (1983); and by Lipscomb et al in J. 
Chem., Phys., 75, 1509 (1981), incorporated by reference. See also Lalama 
et al, Phys. Rev., A20, 1179 (1979); and Garito et al, Mol. Cryst. and 
Liq. Cryst., 106, 219 (1984); incorporated by reference. 
The microscopic response, or electronic susceptibility .beta., and its 
frequency dependence or dispersion, can be experimentally determined by 
electric field induced second harmonic generation (DCSHG) measurements of 
liquid solutions or gases as described in "Dispersion Of The Nonlinear 
Second Order Optical Susceptibility Of Organic Systems", Physical Review 
B, 28 (No. 12), 6766 (1983) by Garito et al, and the Molecular Crystals 
and Liquid Crystals publication cited above; or by solvatochromism 
measurements as described in "Nonlinear Optics: A Molecular Basis For 
Electronic Susceptibility", by Buckley et al, A.C.S. National Meeting, New 
York, New York, April 17, 1986; published in A.C.S. Symposium Series. 
In the measurements, the created frequency .omega..sub.3 is the second 
harmonic frequency designated by 2.omega., and the fundamental frequencies 
.omega..sub.1 and .omega..sub.2 are the same frequency designated by 
.omega.. An applied DC field removes the natural center of inversion 
symmetry of the solution, and the second harmonic signal is measured using 
the wedge Maker fringe method. The measured polarization at the second 
harmonic frequency 2.omega. yields the effective second harmonic 
susceptibility of the liquid solution an thus the microscopic 
susceptibility .beta. for the molecule. 
External Field-Induced Molecular Orientation 
In the nonlinear optical media described hereinabove, the centrosymmetric 
or noncentrosymmetric configuration of Polysiloxane molecules alone or in 
association with liquid crystalline molecules can be external 
field-induced. 
The term "external field" as employed herein refers to an electric, 
magnetic or mechanical stress field which is applied to a substrate of 
mobile organic molecules, to induce dipolar alignment of the molecules 
parallel to the field. 
In a melt phase blend of a present invention polysiloxane in admixture with 
a liquid crystalline component, both types of molecules will align under 
the influence of an electric or magnetic field. The degree of orientation 
is determined by the orientational order parameter. 
For both nematic and smectic mesophases, the parameter is defined in terms 
of a director which is a vector parallel to the molecular long axis (and 
perpendicular to the plane of molecular layering in the case of the 
smectic mesophase). 
If theta is defined as the angle between the director and a chosen axis, 
then the orientational order parameter is defined as the average over all 
molecules of the second Legendre polynomial. The parameter ranges from 
-0.5 to 1.0 (1.0 corresponds to perfect uniaxial alignment along a given 
axis. 0.0 corresponds to random orientation, and -0.5 corresponds to 
random orientation confined in a plane perpendicular to a given axis). 
The order parameter thus defined does not distinguish between parallel and 
antiparallel alignment. Thus, a sample of asymmetric rod-like molecules 
would have an order parameter of 1.0 for both the case in which the 
molecules are colinear and all pointed in the same direction, and the case 
in which the molecules are colinear and form antiparallel pairs. 
The application of an orienting external field to an array of nematic 
liquid crystal molecules results in an order parameter of approximately 
0.65. Deviations from ideal order are due to nematic fluctuations on a 
micron length scale which accommodate characteristic defects. These 
fluctuations may be dynamic for small molecule liquid crystals or frozen 
for polymeric liquid crystals. 
Smectic liquid crystals may be aligned by application of an orienting 
external field, with a resulting order parameter exceeding 0.9. Unlike the 
nematic phase, characteristic defects are removed upon aligning the 
smectic phase and thereby forming a single liquid crystal phase. Such 
phases are known as monodomains and, because there are no defects, are 
optically clear. 
For both the nematic and smectic mesophases, application of a DC electric 
field produces orientation by torque due to the interaction of the applied 
electric field and the net molecular dipole moment. The molecular dipole 
moment is due to both the permanent dipole moment (i.e., the separation of 
fixed positive and negative charge) and the induced dipole moment (i.e., 
the separation of positive and negative charge by the applied field). 
The torque which results by the application of a DC electric field normally 
would only produce very slight alignment even for high dipolar and 
polarizable molecules at room temperature. The alignment torque is 
negligible in comparison with the disordering effect of thermally induced 
rotation (i.e., the Boltzman distribution of rotational eigenstates at 
room temperature). However, due to the unique associations developed by 
liquid crystalline molecules through intermolecular forces, long range 
orientational order on a micron length scale is present. Under these 
conditions, bulk orientation of the sample by application of aligning 
fields exceeding a few volts/cm can produce the degrees of alignment 
indicated above. 
Application of an AC electric field also can induce bulk alignment. In this 
case, orienting torque occurs solely due to the interaction of the applied 
AC field and the induced dipole moment. Typically, AC field strengths 
exceeding 1 kV/cm at a frequency exceeding 60 KHz are employed for the 
nematic phase. At these frequencies, rotational motion of aligned nematic 
regions is not sufficient to follow the field. As a direct result torque 
due to the interaction of the applied field and any permanent dipole 
moment over time averages to zero. However, electronically induced 
polarization is a very rapid process so that the induced dipole moment 
changes direction depending upon the direction of the applied field 
resulting in a net torque. 
Application of a magnetic field also can effect alignment. Organic 
molecules do not possess a permanent magnetic dipole moment. In a manner 
analogous to AC electric field, a magnetic field can induce a net magnetic 
dipole moment. Torque results from the interaction of the induced dipole 
moment and the external magnetic field. Magnetic field strengths exceeding 
10 Kgauss are sufficient to induce alignment for a nematic phase or 
smectic phase. 
Alignment of nematics by electric or magnetic fields are accomplished 
simply by application of the field to the nematic material. Alignment of 
the smectic phase is more difficult due to a higher viscosity which 
decreases rotational freedom. Formation of aligned smectic monodomains can 
be achieved by orienting a material in the nematic phase, and cooling the 
material into the smectic phase while maintaining the aligning field. For 
materials which have only smectic and isotropic phases and which lack a 
nematic phase, alignment can be accomplished in the smectic phase at an 
elevated temperature near the smectic to isotropic transition temperature, 
e.g., sufficiently close to the transition temperature so that the medium 
may contain smectic domains in an isotropic fluid. 
Mechanical stress induced alignment is applicable to both the smectic and 
nematic mesophases. Strong aligning mechanical stress propagates 
throughout a solid liquid crystalline material due to the natural tendency 
of these media to self align. Specific mechanical stress methods include 
stretching a thin film, or coating a composition surface with an aligning 
polymer such as nylon, polyethylene terephthalate, polyvinyl alcohol, and 
the like. Physical methods (e.g., stretching) rely upon the rigid and 
geometrically asymmetric character of certain molecules to induce bulk 
orientation. Chemical methods (e.g., coating the surface with an aligning 
polymer) rely upon strong intermolecular interactions to induce surface 
orientation. All of the methods described above to produce oriented 
materials generally apply to small molecule and polymeric liquid crystals 
and polysiloxanes. For polymers which possess a glass transition, the 
mobile phase of aligned molecules can be frozen by rapid cooling below the 
glass transition temperature. 
In melt phase blends of polysiloxane and liquid crystalline components, the 
degree and direction of polysiloxane molecular alignment in an external 
field is influenced directionally by the axial configuration of the liquid 
crystalline molecules. 
Publications relating to external field-induced molecular orientation 
include The Physics of Liquid Crystals, P. G. deGennes, p. 95-97, Oxford 
University Press, 1974: J. Stamatoff et al, "X-Ray Diffraction Intensities 
of a Smectic-A Liquid Crystal", Phys. Rev. Letters, 44, 1509-1512, 1980; 
J. S. Patel et al, "A Reliable Method of Alignment for Smectic Liquid 
Crystals", Ferroelectrics, 59, 137-144, 1984; J. Cognard, "Alignment of 
Nematic Liquid Crystals and Their Mixtures", Mol. Cryst. Liq. 
Cryst.:Suppl., 1982; incorporated herein by reference. 
The following examples are further illustrative of the present invention. 
The components and specific ingredients are derived in view of the 
foregoing disclosure within the scope of the invention.

EXAMPLE I 
This Example illustrates the preparation of polymethylhydrosiloxane in 
accordance with the procedure described in the Journal of High Resolution 
Chromatography and Chromatography Communications, 8, 516 (1985). 
Acetonitrile (2.5 ml) and water (2.5 ml) are added to methyldiethoxysilane 
(0.033 mole) and dimethyldimethoxysilane (0.033 mole) and the resulting 
solution is stirred for 1 hour. A solution of benzenesulfonic acid (0.1 M 
in H.sub.2 O) is added and the mixture is stirred under an argon purge for 
26 hours. An excess of hexamethyldisilazane is added and the solution is 
stirred at 20.degree. C. for 15 minutes. The temperature then is raised to 
80.degree. C. for 2 hours to remove the residual disilazane. 
The encapped polymer is dissolved in dichloromethane and precipitated with 
methanol. The fractionation process is repeated twice, and the dissolved 
polymer is filtered through a millipore filter. A colorless viscous oil 
remains after solvent evaporation, which has a weight average molecular 
weight of about 20,000. 
EXAMPLE II 
This Example illustrates the preparation of 1,2-diphenylethylene compounds. 
A. 
To a stirred solution of 21.6 grams (0.1 mole) of 4-nitrobenzyl bromide in 
500 ml of toluene is added in several portions 26.2 grams (0.1 mole) of 
triphenyl phosphine. The solution is heated at reflux for one hour, during 
which time the Wittig salt forms and precipitates from solution. The 
reaction mixture is cooled to room temperature, and the salt precipitate 
is filtered from the toluene, washed with fresh toluene to remove any 
unreacted triphenyl phosphine and 4-nitrobenzyl bromide, and then dried in 
an open dish. 
B 
To a stirred solution of 44 grams of dry potassium carbonate in 500 ml of 
acetone is added 12.2 grams (0.1 mole) of 4-hydroxybenzaldehyde, and the 
resultant mixture is heated to reflux temperature. After a refluxing 
period of a half hour, 17.4 grams of n-octyl bromide (0.09 mole) is added 
to the mixture. The reaction medium is maintained at reflux for about 20 
hours, then the product mixture is cooled to room temperature and 
potassium salt precipitate is filtered off. The acetone is removed by 
vacuum distillation, and a residual crude product is recovered. 
4-octyloxybenzaldehyde product is purified by distillation under vacuum 
(bp. 140.degree. C. at 0.1 torr). 
C. 
To a stirred solution of 30 grams (0.063 mole) of Wittig salt as prepared 
in step A in 200 ml of dry toluene in a 500 ml flask fitted with a rubber 
septum, reflux condenser and addition funnel is added 39 ml of n-butyl 
lithium (0.63 mole) in hexane (1.6 M) through the septum using a syringe. 
The red solution is refluxed for a half hour, and then 14.75 grams of 
4-octyloxybenzaldehyde (0.63 mole) as prepared in step B in 50 ml of 
toluene is added dropwise through the addition funnel. 
The mixture is cooled to room temperature and dissolved in ether (500 ml). 
The resultant solution is extracted four times with distilled water to 
remove the triphenyl phosphine oxide and lithium bromide salts. The ether 
solution is dried over anhydrous magnesium sulfate, and after the 
magnesium sulfate is separated by filtration the ether is removed by 
vacuum distillation to yield a residual crude product. The 
4-octyloxy-4'-nitrodiphenylethylene product is purified by 
recrystallization from absolute ethanol. 
D 
A reaction flask equipped with a stirrer and condenser is charged with 200 
ml of N,N-dimethylformamide and 11.2 grams (0.1 mole) of potassium 
t-butoxide. The flask is sealed and flushed with argon. A 14.6 gram 
quantity of n-octyl thiol is added to the solution via syringe. The 
reaction medium is heated at 60.degree. C. for a half hour, then 12.1 
grams of 4-fluorobenzaldehyde are added via syringe. The mixture is 
stirred at 60.degree. C. for 4 hours, and after cooling 300 ml of water 
are added and the resultant aqueous solution is extracted three times with 
hexane. The hexane extracts are combined and dried over anhydrous 
magnesium sulfate. The magnesium sulfate and hexane are removed to yield a 
residual oil. The crude 4-octylthiobenzaldehyde product is purified by 
vacuum distillation (b.p. 149.degree. C. at 0.6 torr). 
E. 
Following the procedure of step C, 15.75 grams of 4-octylthiobenzaldehyde 
is reacted with 30 grams of Wittig salt to yield 
4-octylthio-4'-nitrodiphenylethylene product. 
EXAMPLE III 
This Example illustrates the preparation of diphenylacetylene compounds. 
A. 
To a stirred mixture of 90 grams (0.334 mole) of 
4-N,N-dimethylamino-4'-nitro-1,2-diphenylethylene in 3 liters of 1,2,3 
trichloropropane solvent in a 5 liter three-neck round bottom flask are 
added 59.0 grams (0.369 mole) of bromine in 200 ml of 
1,2,3-trichloropropane over a period of about a half hour. The solution is 
stirred for one hour, and then 4.1 grams (0.05 mole) of cyclohexene is 
added to react with any residual bromine. The solvent is removed in vacuo 
and the residual semi-solid product is washed with hexane to remove any 
remaining solvent and dibromocyclohexane. 
The semi-solid product is dissolved in 3 liters of absolute ethanol, and 
the solution is charged to a three-neck round bottom flask fitted with a 
reflux condenser, mechanical stirrer, and 500 ml addition funnel. 
A 150 gram (1.336 moles) quantity of potassium t-butoxide is dissolved into 
350 ml of absolute ethanol, and the solution is added slowly from the 
addition funnel to the refluxing solution of dibromodiphenylethane 
derivative, and the solution is refluxed for a half hour after the 
addition is completed. When the reaction medium is basic to pH paper, the 
reaction is stopped. The solution is hot filtered and allowed to cool. 
Solids are separated from the ethanol solution by filtration, and the 
ethanol solvent is removed in vacuo to yield a residual solid product. The 
4-N,N-dimethylamino-4'-nitrodiphenylacetylene product is recrystallized 
from ethyl acetate. 
B. 
Employing the same procedure, 4-octylthio-4'-nitro1,2-diphenylethylene is 
converted to 4-octylthio-4'-nitrodiphenylacetylene. 
C. 
Employing the same procedure, 4-hexadecyloxy-4'-nitro-1,2-diphenylethylene 
is converted to 4-hexadecyloxy-4'-nitrodiphenylacetylene. 
D. 
Employing the same procedure, 4-ethoxy-4'-cyano-1,2-diphenylethylene is 
converted to 4-ethoxy-4'-cyano-diphenylacetylene. 
EXAMPLE IV 
This Example illustrates the production of organopolysiloxane polymers in 
accordance with the present invention. 
##STR20## 
A 6.0 gram quantity of diphenylacetylene (33.7 mmoles) is dissolved in 45 
ml of dry toluene in a 100 ml round bottomed flask equipped with a 
stirrer, and then 2 grams of polymethylhydrosiloxane (33.3 mmoles of 
reactive sites) is added. The reaction medium is heated to reflux to 
degass the flask with vapors. The flask is then stoppered with a syringe 
septum, and maintained at 60.degree. C. with stirring. 
One drop of chloroplatinic acid solution (0.5 M platinum IV chloride in dry 
2-propanol) is introduced to the stirring solution via a 25 microliter 
syringe (about 3-4 microliters). The reaction mixture is stirred for 16 
hours at 60.degree. C. 
After cooling the product solution is filtered through a fluted filter 
paper into an excess of ice-cold methanol (about 1 liter). The crude 
polymer product is a viscous off-white precipitate which gradually 
coagulates on standing in the methanol medium. The methanol is decanted, 
and the residual crude polymer product is redissolved in toluene and the 
methanol precipitation procedure is repeated. The recovered polymer is 
dried in a vacuum oven at 120.degree. C. for one hour. The final product 
is a clear hard glassy polymer which readily subdivides into small pieces. 
##STR21## 
Employing the same procedure, 0.5 gram (1.88 mmoles) of 
4,N,N-dimethylamino-4'-nitrodiphenylacetylene is reacted with 0.11 gram of 
polymethylhydrosiloxane (1.83 hydrogen equivalents). 
After two precipitations in methanol solvent as described in section A 
above, the resultant viscous red polymer is dissolved in dichloromethane. 
The solvent is allowed to evaporate off at room temperature, and the 
resultant polymer product is dried in a 120.degree. C. vacuum oven. 
##STR22## 
Following the same procedure, 1.0 gram (3.76 mmoles) of 
4-N,N-dimethylamino-4'-nitrodiphenylacetylene and 0.72 gram (2.8 mmoles of 
a 50:50 copolymer of methylphenylsiloxane and methylhydrosiloxane are 
reacted to form the above illustrated organopolysiloxane polymer. 
##STR23## 
Following the same procedure, 1.0 gram (3.76 mmoles) of 
4-N,N-dimethylamino-4'-nitrodiphenylacetylene and 0.45 gram (3.36 mmoles) 
of a copolymer of dimethylsiloxane and methylhydrosiloxane are reacted to 
form the above illustrated organopolysiloxane polymer. 
The polymer precipitations are conducted in a hexane solvent, because the 
polymer is soluble in the methanol solvent employed in the above 
preparations. 
##STR24## 
Following the same procedure, 1.0 gram (3.76 mmoles) of 
4-N,N-dimethylamino-4'-nitrodiphenylacetylene and 0.41 gram (3.37 mmoles) 
of polyphenylhydrosiloxane are reacted to form the above illustrated 
organopolysiloxane polymer. 
EXAMPLE V 
This Example illustrates the preparation of a thin substrate of 
polysiloxane polymer with a macroscopic noncentrosymmetric molecular 
orientation in accordance with the present invention. 
A polysiloxane polymer prepared in accordance with Example I is compression 
molded to form a film of about 500 micron thickness. 
The molding is accomplished in a 30 Ton press (Wabash Metal Products, Inc. 
Model #30-1010-2TMX) with programmed heating and cooling, and adjustable 
pressure. The platen temperature is set at 200.degree. C. The polymer in 
particulate form is placed between two Kapton (DuPont polyimide) sheets 
and positioned between the two platens. The platens are closed and 6 tons 
pressure is applied for 2 minutes. The platens are then cooled, the 
pressure is released, and the film sample is retrieved from the press. 
X-ray diffraction patterns from this transparent film sample, recorded by 
using nickel filtered CuK.sub..alpha. radiation and flat plate 
photographic techniques, indicate a random orientation of polymer molecule 
axes. The film exhibits a third order nonlinear optical response. 
Molecular alignment of the polymer molecule axes is achieved in the 
following manner. The film sample is sandwiched between two Kapton films 
of 0.002 inch thickness which in turn are sandwiched between two metal 
plates of 0.25 inch thickness, each having a ground flat surface and a rod 
attached to one side which serves as a contact for application of voltage 
in the alignment procedure. The sub-assembly is covered on top and bottom 
with a double layer of Kapton sheets of 0.002 inch thickness and providing 
a 0.004 inch electrical insulating layer against each platen. 
The whole assembly is placed between the platens of the press previously 
employed for preparing the unoriented precursor film sample. The platens 
are preheated to 200.degree. C., then closed and a pressure of 6 tons is 
applied. Wires from a DC power supply are attached to the rods of the 
electrode plates and a voltage of 700 V is applied for two hours while 
maintaining temperature and pressure. 
The press is cooled while pressure and voltage are maintained, then the 
voltage is reduced to zero and the pressure released. The molecularly 
aligned film sample is retrieved from the mold, and X-ray diffraction 
patterns are recorded with nickel filtered CuK.sub..alpha. radiation and 
wide-angle photographic flat plate techniques. Orientation functions are 
determined utilizing a polar table and a microdensitometer interfaced with 
a LeCray computer. 
The data demonstrate that the molecular alignment process results in a 
rotation of essentially all of the molecular axes of the polymer molecules 
out of the film plane into a direction parallel to that of the external 
field. This type of molecularly aligned polysiloxane film is 
noncentrosymmetric and can function as a second-order harmonic-generating 
nonlinear optical medium for a high intensity light field to which the 
medium is optically clear, e.g., as the nonlinear optical component in a 
laser frequency converter device, with a X.sup.(2) susceptibility of at 
least about 1.times.10.sup.-7 esu and a Miller's delta of at least about 
one square meter/coulomb. 
EXAMPLE VI This Example illustrates the preparation of 
poly-[6-(4-nitrobiphenyloxy)hexyl methacrylate]. 
##STR25## 
A. 4-Hydroxy-4'-nitrobiphenyl 
(1) 4-benzoyloxybiphenyl 
To 500 ml of pyridine in a 1000 ml three-neck flask is added 170 g of 
4-hydroxybiphenyl. The mixture is cooled to 10.degree. C., and 155 g of 
benzoyl chloride is added dropwise while keeping the mixture temperature 
below 20.degree. C. After complete addition, the mixture is heated 
gradually to reflux and maintained at this temperature for 30 minutes. The 
reaction mixture is then cooled to room temperature. 
The solidified product subsequently is admixed with 250 ml HCl and 250 ml 
water, then additional HCl and water are added and the slurry is mixed 
thoroughly in a blender. The particulate solid is filtered, washed with 
water to a neutral pH, and air-dried overnight. The crude product is 
recrystallized from n-butanol, mp 149.degree.-150.degree. C. 
(2) 4-benzoyloxy-4'-nitrobiphenyl 
4-Benzoyloxybiphenol (40 g) is mixed with 310 ml of glacial acetic acid and 
heated to 85.degree. C. Fuming nitric acid (100 ml) is added slowly while 
maintaining the reaction medium temperature between 85.degree.-90.degree. 
C. After complete addition, the reaction is cooled to room temperature. 
The resultant solid is filtered and washed with water and methanol. The 
crude product is recrystallized from glacial acetic acid, mp 
211.degree.-214.degree. C. 
(3) 4-Hydroxy-4'-nitrobiphenyl 
4-Benzoxyloxy-4'-nitrobiphenyl (60 g) is mixed with 300 ml of ethanol and 
heated to reflux. A solution of 40 g KOH in 100 ml of water is added 
dropwise at reflux. After complete addition, the mixture is refluxed 30 
minutes and cooled overnight. The resultant blue crystalline potassium 
salt is filtered and dried. 
The dried salt is dissolved in a minimum amount of boiling water, and a 
50/50 HCl/water solution is added until an acidic pH is obtained. The 
crude yellow product is filtered and washed with water until neutral, and 
then recrystallized from ethanol, mp 203.degree.-204.degree. C. 
B. 4-(6-Hydroxyhexyloxy)-4'-nitrobiphenyl 
To 400 ml of ethanol is added 21.5 g of 4-hydroxy-4'-nitrobiphenyl and the 
mixture is heated to reflux. A solution of 7.1 g of KOH in 30 ml of water 
is added dropwise at reflux temperature. After complete addition, a 21.7 g 
quantity of 6-bromohexanol is added, and the reaction medium is refluxed 
about 15 hours. Then the reaction medium is cooled and the ethanol is 
removed in a rotary evaporator. 
The solid residue is slurried with water in a blender and the particulate 
solid is filtered, washed with water, and air dried. The crude product is 
recrystallized from ethanol, mp 117.degree.-119.degree. C. 
C. 4-(6-Methacryloxyhexyloxy)-4'-nitrobiphenyl 
4-(6-Hydroxyhexyloxy)-4'-nitrobiphenyl (22 g) is dissolved in 500 ml of dry 
dioxane and heated to 45.degree. C. A 14 g quantity of triethylamine is 
added, then a solution of 10.5 g of methacryloyl chloride in an equal 
volume of dioxane is added dropwise while maintaining the reaction medium 
temperature at 45.degree. C. 
The reaction medium is stirred at 45.degree. C. for about 24 hours. The 
dioxane then is removed under vacuum, and the solid residue is slurried in 
water in a blender. The particulate solid is filtered, washed with water, 
and air dried. The crude monomer product is recrystallized from ethanol, 
mp 53.degree.-56.degree. C. 
D. Poly[6-(4-nitrobiphenyloxy)hexyl methacrylate] 
The monomer (2 g) is dissolved in 20 ml of degassed benzene in a reactor, 
and 1 mole percent of azodiisobutyronitrile is added to the reaction 
medium. The reactor is heated at 60.degree. C. for 4 days. During this 
period, polymer product separates as a solid precipitate from the reaction 
medium. After the polymerization is completed, the precipitate is 
recovered and slurried with methanol in a blender. The solid polymer is 
filtered, washed with methanol, and vacuum dried. 
EXAMPLE VII 
This Example illustrates a poling procedure for producing a second order 
nonlinear optical medium of polysiloxane and liquid crystalline components 
in accordance with the present invention. 
A. Poling Cell Construction 
A poling cell is constructed from electrically conductive glass plates, 
such as Donnelly Mirror PD 5007-7. The glass plates are washed with 
sulfuric acid, isopropanol, 1-dodecanol, and isopropanol, with a distilled 
water rinse between each washing step. 
The poling cell is a sandwich type cell in which the conductive glass 
surfaces are in facing proximity and are separated by a polyimide film of 
approximately 25 micrometer thickness. A thin layer of epoxy adhesive is 
applied on the surfaces of the polyimide film to hold the glass plates. 
After the epoxy is completely cured, the cell is washed with isopropanol 
and rinsed with distilled water. After drying, the cell is stored in a dry 
box. 
B. Filling The Poling Cell 
A mixture of polysiloxane of Example I (30 weight %) and 
poly[6-(4-nitrobiphenyloxy)hexyl methacrylate] of Example V (70 weight %) 
is placed in a vacuum oven and maintained in a melt phase at a temperature 
of about 150.degree. C. for about 4 hours to eliminate entrained air 
bubbles from the polymer melt. 
The melt phase polymer blend is introduced into the space between the glass 
plates by charging a drop of the polymer melt to one of the openings of 
the poling cell space and placing the cell assembly in a vacuum oven 
maintained at a temperature approximately 10.degree. C. above the clearing 
temperature of the polymer blend. The cell space fills gradually by 
capillary action. The space filling period is about 4 hours for a 0.5 cm 
long space. The polymer melt in the filled cell is bubble-free. 
C. Electric Field Induced Orientation 
Two lead wires are attached to each of the conductive glass surfaces using 
electrically conductive epoxy adhesive. The poling assembly is placed in a 
microscope hot stage (Mettler FP-82 with FP-80 Central Processor), and the 
sample is observed with a polarizing microscope (Leitz Ortholux Pol) for 
alignment. 
The microscope is switched into a photodiode (Mettler Photometer No. 17517) 
to record the change of light intensity upon application of an electric 
field. The two lead wires are connected to an AC voltage amplifier 
(Electro-Optic Developments LA10A), which amplifies the voltage signal 
from a signal generator (Hewlett-Packard No. 3310B). 
The poling cell first is heated to bring the polymer blend to the isotropic 
phase. The assembly then is cooled at a rate of 0.2.degree. C./min. until 
the photodiode signal registers an abrupt increase which indicates that 
the melt has undergone a transition into a liquid crystalline phase. The 
temperature is further lowered by 2.degree. C. and then maintained at this 
temperature. 
The AC voltage source is set at 500 V, and the frequency is set at 2000 Hz. 
The power to the poling cell is turned on to apply an electric field 
across the polymer blend sample. The field strength is calculated to be 
approximately 2.times.10.sup.5 V/cm. About three seconds after the 
electric field is applied, depending on the composition of the polymer 
blend the photodiode signal drops close to the baseline, indicating that 
orientation development induced by the electric field is completed. At 
this point, the cooling is resumed until the temperature reaches 
35.degree. C., and the poling assembly is disconnected from the power 
source. 
When the poling assembly is removed from the microscope hot stage, by 
visual observation the polymer blend in the cell space is transparent. 
This is an indication that the molecular orientation is uniform and 
homogeneous throughout the sample. Orientation of the sample is further 
ascertained utilizing a wide angle X-ray diffraction technique, and the 
Hermann's orientation factor of the sample is approximately 0.9. 
D. High Field Poling For Symmetry Control 
The oriented polymer blend sample is subjected further to a higher electric 
field to develop a noncentrosymmetric orientation of nonlinear optical 
moieties which are a part of the side chains of the two polymer types. 
The poling cell assembly is heated until it is approximately 5.degree. C. 
below the glass transition temperature of the polymer blend. Then the lead 
wires of the poling assembly are connected to a DC voltage source (Kepco 
OPS-3500) and the voltage is turned up slowly until it reaches 2000 V. At 
this point, the electric field strength across the sample is about 
8.times.10.sup.5 V/cm. The sample is maintained at this field strength 
level for 10 hours, then the sample is cooled and the voltage source is 
disconnected. A noncentrosymmetrically oriented polymer blend matrix is 
obtained in this manner. 
From the measurements, there is an indication that a major proportion of 
the nonlinear optical moieties are aligned parallel to the electric field 
direction, and the rest are oriented antiparallel to the electric field 
direction.