Nonlinear optical epoxy-containing compositions and crosslinked nonlinear optical polymeric composition therefrom

The present invention discloses oriented optical epoxy compositions comprising a reaction product of arylhydrazones with a monomer copolymerizable therewith and to oriented crosslinked polymeric composition comprising the reaction product of an epoxy arylhydrazone or the epoxy composition of the invention with a curing agent. The present invention also discloses processes for making the said compositions.

The present invention relates to epoxy-containing compositions exhibiting 
nonlinear optical properties on orientation, and to oriented crosslinked 
polymeric compositions comprising the epoxy-containing compositions. 
BACKGROUND OF THE INVENTION 
Information may be more rapidly processed and transmitted using optical as 
opposed to electrical signals. Optical signals can be used to enhance the 
performance of electronic processors. For example, electronic wires 
interconnecting integrated circuits (ICs) can be replaced with optical 
interconnects and the information processed with IC driven electro-optic 
(EO) modulators. Optical signals in fiber optic communications can be 
encoded on the optical carrier using EO modulators. In both of these 
processes, nonlinear optical materials with second-order nonlinear optical 
activity are necessary to effect modulation of the light signal. 
Nonlinear optical materials can also be used for frequency conversion of 
laser light. Such a conversion is desirable in many applications. For 
example, optical memory media are presently read using 830 nm light from 
diode lasers. The 830 nm light wavelength limits the spot sizes which can 
be read and hence the density of data stored on the optical memory media. 
In fiber optic communications, light wavelengths of 1.3 .mu.m or 1.5 .mu.m 
are desirable due to the low transmission losses of glass fiber at those 
wavelengths. However, those wavelengths are too long for detection by Si 
based detectors. It is desirable to frequency double the 1.3 .mu.m or 1.5 
.mu.m wavelengths to 650 nm or 750 nm wavelengths where Si based detectors 
could be used. 
Nonlinear optical materials which have been used in electro-optic devices 
have in general been inorganic single crystals such as lithium niobate 
(LiNbO.sub.3) or potassium dihydrogen phosphate (KDP). More recently, 
nonlinear optical materials based on organic molecules, and in particular 
polar aromatic organic molecules have been developed. 
Organic nonlinear optical materials have a number of potential advantages 
over inorganic materials. First, organic nonlinear optical materials have 
higher NLO activity on a molecular basis. Organic crystals of 
2-methyl-4-nitroaniline have been shown to have a higher nonlinear optical 
activity than that of LiNbO.sub.3. Second, the nonlinear optical activity 
of the organic materials is related to the polarization of the electronic 
states of the organic molecules, offering the potential of very fast 
switching times in EO devices. The time response of the organic nonlinear 
optical system to a light field is on the order of 10 to 100 femtoseconds. 
In contrast, a large fraction of the second order polarizability in the 
inorganic crystals in EO applications is due to lattice vibrations in the 
crystal, slowing the time-response of the materials. In addition, the low 
dielectric constant of the organic materials (e.g., 2-5 Debye at 1MHz) 
compared to the inorganic materials (e.g., 30 Debye at 1MHz) enables 
higher EO modulator frequencies to be achieved for a given power 
consumption. Third, the organic materials can be easily fabricated into 
integrated device structures when used in polymer form. 
One of the promising and recent approaches to making stable nonlinear 
optically active organic materials involves forming highly crosslinked 
networks where polar molecules are polymerized directly into the polymer 
reagent matrix during the poling process. Eich et al., J. Appl. Phys., 
66(7), Oct. 1, 1989, pp 3241-3247, discloses the preparation of nonlinear 
optically active crosslinked polymer networks from the reaction of 
epoxides, with and without nonlinear optic dye moleties, and NLO active 
di- and tri-functional amines, in which the NLO amine is attached to the 
network by two chemical bonds. Jungbauer et al., Appl. Phys. Lett., 
56(26), Jun. 25, 1990, pp 2610-2612, discloses a crosslinked polymer 
network by reacting a diepoxide with a trifunctional amine in which the 
NLO active group is attached to the crosslinked polymer network by only 
one chemical bond. European Patent Application No. 0 474 402 A2 discloses 
multi-functional chromophore containing polymerizable compounds which are 
capable of being polymerized into a crosslinked network. 
Another approach to making nonlinear optically active organic materials 
involves side chain liquid crystalline polymers, with the NLO chromophore 
in the side chain as disclosed in U.S. Pat. Nos. 4,855,376, 4,948,532 and 
4,933,112. 
Still another approach is disclosed in Allen et. al., J. Appl. Phys., 
64(5), Sep. 1, 1988, pp 2583-2589, and involves making nonlinear optically 
active, single crystal structures of highly conjugated molecules based on 
substituted dihydropyrazoles. 
There is a continuing effort to develop new nonlinear optical polymers with 
increased nonlinear optical susceptibilities and enhanced stability of 
nonlinear optical effects. 
It is an object of this invention to make polymeric compositions 
incorporating organic molecular structures which exhibit NLO activity upon 
orientation. It is an additional object of the present invention that the 
polymers comprising the NLO molecular structures or chromophores have 
relatively high glass transition temperatures. 
It is still a further object of the invention to provide organic polymeric 
materials with larger and thermally more stable second order nonlinear 
optical properties than presently used organic electro-optic materials. 
SUMMARY OF THE INVENTION 
In one aspect, the present invention is an oriented composition comprising 
the reaction product of: 
A) a compound corresponding to the Formula: 
##STR1## 
wherein Ar is an aromatic hydrocarbyl or heterocylic radical, substituted 
with at least one electron withdrawing group, and containing up to 30 
non-hydrogen atoms, and optionally substituted with an OR' group; A is 
independently at each occurrence either R or a C.sub.6-30 aromatic 
hydrocarbyl or heterocylic radical optionally substituted with an OR' 
group; R' is a hydrogen, epoxy or an alkylepoxy group; and R is a hydrogen 
or a C.sub.1 -C.sub.20 hydrocarbyl radical; provided there are at least 
two aromatically substituted OR' groups groups in the compound; and 
B) a monomer copolymerizable therewith. 
In another aspect, the present invention is an oriented polymeric 
composition comprising a reaction product of the compound of Formula (I) 
wherein R' is an epoxy or an alkylepoxy group, with a curing agent. 
In yet still another aspect, the present invention is an oriented 
crosslinked polymeric composition comprising a reaction product of the 
above epoxy composition with a curing agent. 
In yet still another embodiment, the present invention relates to a process 
for preparing an oriented crosslinked polymeric composition, comprising 
substantially simultaneously applying an external field and thermally 
annealing the reaction product of an epoxy composition with a curing 
agent, the epoxy composition comprising recurring moieties derived from a 
compound corresponding to the Formula I. The application of the external 
field and thermal annealing are carried out for a period of time 
sufficient to form a crosslinked composition having nonlinear optical 
properties. 
In yet still another embodiment, the present invention is a process for 
preparing an oriented crosslinked polymeric composition comprising 
simultaneously polymerizing and applying an external field to a reaction 
mixture of the compound Formula (I) wherein R' is an epoxy or an 
alkylepoxy group of a curing agent. 
In yet still another embodiment, the present invention is a device 
comprising the nonlinear optical epoxy-containing composition of the 
invention or the oriented polymeric composition of the invention. 
DETAILED DESCRIPTION OF THE INVENTION 
The term "orientation" as used herein refers to the alignment of molecular 
dipoles upon the application of an external field to a molecule or 
moleties derived therefrom according to the methods described herein, or 
by some other means, such that the molecule, or the moleties derived 
therefrom exhibit nonlinear optical activity. 
The phrase "oriented polymeric composition" refers to the polymeric 
composition following orientation as described above. 
The term "external field" as used 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. 
The phrase "aromatically substituted" herein refers to substituents that 
are directly attached to a hydrocarbyl or heterocyclic aromatic ring 
represented by radicals Ar and A. 
The term "electron donating" as used herein refers to organic substituents 
which contribute n-electrons to a conjugated electronic structure. 
The term "conjugated" group, as employed herein refers to a moiety 
containing alternating double or triple bonds which has the ability to 
transfer electronic charge. Conjugated moleties generally include groups 
which have, for example, a hydrocarbyl diradical comprising a single 
aromatic ring, multiple fused rings or multiple aromatic rings linked by 
carbon-carbon, carbon-nitrogen, or nitrogen-nitrogen double bonds. The 
conjugated groups may be substituted with pendant radicals such as alkyl, 
aryl, cyano, halo and nitro groups. 
The term "electron withdrawing", as employed herein, refers to any 
substituent which attracts the electrons from a conjugated electron 
structure, thereby providing a polarized resonating structure. A 
quantification of the level of electron-withdrawing capability is given by 
the Hammett .sigma. (sigma) constant. This well known constant is 
described in many references, for instance, J. March, Advanced Organic 
Chemistry, (McGraw Hill Book Company, N.Y., 1977 edition) pp. 251-259. The 
Hammett constant values are negative for electron donating groups 
(.sigma..sub.p =-0.66 for NH.sub.2) and positive for electron withdrawing 
groups (.sigma..sub.p =0.78 for a nitro group, .sigma..sub.p indicating 
para substitution.) 
Preferred electron withdrawing groups are those having a Hammett constant 
of (.sigma..sub.p) at least 0.50, and more preferably at least 0.60. 
Illustrative of the electron withdrawing groups useful in the present 
invention include: --NO.sub.2, --SO.sub.2 R", --SO.sub.2 CH.sub.2 F, 
--SO.sub.2 CHF.sub.2, --SO.sub.2 CF.sub.3, --S(NSO.sub.2 
CF.sub.3)CF.sub.3, --CF.sub.3, --CO.sub.2 R", --COCF.sub.3, cyano, 
cyanovinyl, dicyanovinyl, and tricyanovinyl, wherein R" is hydrogen or a 
C.sub.1 to C.sub.20 hydrocarbyl radical. 
Epoxy compositions 
The epoxy compositions of the invention comprise recurring moieties derived 
from the arylhydrazone of Formula (I), which exhibit nonlinear optical 
properties upon orientation. The arylhydrazones are described in U.S. Pat. 
No. 5,208,299 , the entire contents of which are incorporated herein by 
reference. 
Illustrative of Ar radicals in the arylhydrazone of Formula (I) include: 
##STR2## 
wherein X is either hydrogen or OR'; Z is selected from a group consisting 
of O, S and NR; M is either a covalent bond or a divalent conjugated 
group; Y is an electron-withdrawing group; n is an integer from 1 to 4; 
and R and R' are as defined hereinabove. 
Illustrative of A radicals in the arylhydrazone of Formula (I) include: 
##STR3## 
wherein Q is selected from a group consisting of hydrogen, OR', R, RO, RS, 
R.sub.2 N, 
##STR4## 
where A, R, R', and Ar are as previously defined, and R" is a divalent 
substituted or unsubstituted hydrocarbyl group containing 1 to 20 carbon 
atoms. 
The arylhydrazones can be suitably prepared by the reaction of a suitable 
hydrazine with a compound containing one or more carbonyl groups, 
especially aldehyde or ketone. 
Illustrative but not limiting examples of the hydrazines include 
4-nitrophenylhydrazine, 2,4-dinitrophenylhydrazine, 
N'-methyl-N'-3-(hydroxy-4-nitrophenyl) hydrazine, 
N'-methyl-N'-4-(nitrophenylhydrazine), 6-nitro-2-benzothioazolylhydrazine, 
N'-methyl-N'[4-(p-hydroxyphenylsulfonyl)phenyl]hydrazine, 
2,4-dinitro-1,5-bis(N'-hydrazino)benzene, 
2,4-bis(methylsulfonyl)phenylhydrazine, 4-(methylsulfonyl)phenylhydrazine, 
and 4-(tricyanovinyl)phenylhydrazine. Preferred hydrazines useful for the 
present invention are substituted nitrophenylhydrazines. 
Suitable carbonyl groups containing reactants for the purpose of this 
invention are of the general formula: 
##STR5## 
where A is independently at each occurrence as previously defined. 
Illustrative but not limiting examples of such compounds are 
4,4'-dihydroxybenzophenone, 4,4'-bis-(4-hydroxyphenylthio)benzophenone, 
4-hydroxybenzaldehyde, 3-hydroxy-4-methoxybenzaldehyde, 
5,5'-methylene-bis-salicylaldehyde, 1,3-diacetylbenzene, 
4,4'-bis(4-hydroxyphenylsulfonyl)benzophenone and 
2,4-dihydroxybenzaldehyde. 
The methods of preparing the arylhydrazones are described in U.S. Pat. No. 
5,208,299 which has been incorporated herein by reference. The reaction of 
the above-described carbonyl compounds with the above-described hydrazines 
provides hydroxy arylhydrazones. 
The hydroxy arylhydrazones obtained from the above-described carbonyl 
compounds and the aryl-hydrazines are reacted with an excess of epoxide 
such as epihalohydrin, followed by dehydrohalogenation to obtain the epoxy 
arylhydrazones containing at least two epoxy or alkylepoxy groups. The 
alkyl group in the alkylepoxy is represented by a C.sub.1 -C.sub.20 
hydrocarbyl group. 
The epoxy arylhydrazone can be reacted with a difunctional monomer, using 
the well known procedure of epoxy resin chain extension. See for example, 
U.S. Pat. No. 4,438,254, and references contained therein. Alteration of 
the mole ratios of the difunctional monomer and the epoxy can provide 
products of varying molecular weight and varying end-group functionality, 
as can be predicted from the established kinetics of step-growth 
polymerization. The epoxy compositions of the invention are preferably 
prepared using a molar excess of the epoxy arylhydrazone to provide a 
composition that is statistically likely to contain epoxy end groups. 
Other epoxides listed hereinbelow may be advantageously added to the 
reaction mixture. 
The mole ratio of the epoxy to difunctional monomer is in the range of 2:1 
to about 1:1, such that at least about 10 mole percent of the mixture is 
derived from the epoxy arylhydrazone of Formula (I). 
The hydroxy arylhydrazones can also be reacted with a difunctional monomer, 
for example, diepoxides listed below, including the above-described epoxy 
arylhydrazones to obtain the epoxy compositions of the invention. Thus, 
the arylhydrazone represented by Formula (I) containing at least two 
aromatically substituted OR' groups can be suitably polymerized to obtain 
the epoxy compositions of the invention according to methods well known to 
those skilled in the art of epoxy resins. See, for example, Encyclopedia 
of Polymer Science and Technology, 2nd Edition, pp. 323-331. 
Suitable difunctional monomers for copolymerizing with the arylhydrazone of 
Formula (I) include diepoxides, diphenols, dithiols, diacids and 
difunctional amines. 
Diphenols which can be employed in the practice of the present invention 
include the bisphenols described in U.S. Pat. Nos. 5,115,075; 4,480,082 
and 4,438,25 4, and in copending U.S. applications Ser. No. 800, 340, 
filed on Nov. 26, 1991, now abandoned, and Ser. No. 884, 673, filed on May 
18, 1992, now U.S. Pat. No. 5,246,751, all of which are incorporated 
herein by reference. Preferred diphenols include 
4,4'-isopropylidenebisphenol (bisphenol A), 4,4'-sulfonyldiphenol, 
4,4'-oxydiphenol, 4,4'-methylenediphenol, 4,4'-thiodiphenol, 
9,9-bis(4-hydroxyphenyl)fluorene, 4,4'-biphenol, 
4,4'-dihydroxybenzophenone, hydroquinone, resorcinol, and 3,3', 
5,5'-tetrabromobisphenol A. More preferred phenols are 
4,4'-isopropylidenebisphenol (bisphenol A), 
9,9-bis(4-hydroxyphenyl)fluorene, hydroquinone, resorcinol, 
4,4'-sulfonyldiphenol, 4,4'-thiodiphenol, 4,4'-oxydiphenol, and 
4,4'-biphenol. Most preferred phenols are 4,4'-isopropylidenebisphenol 
(bisphenol A), 4,4'-sulfonyldiphenol, 4,4'-oxydiphenol, and 
9,9-bis(4-hydroxy-phenyl)fluorene. The diphenols may include the hydroxy 
arylhydrazone of the invention. 
Dithiols which can be employed in the practice of the present invention 
include those represented by the formula HS-R'"--SH, wherein R'" is a 
hydrocarbylene or a divalent aromatic moiety. Preferably, R'" is (1) 
alkylene or cycloalkylene which optionally contains a heteroatomic moiety 
such as oxygen, sulfur, sulfonyl, or sulfoxyl or (2) arylene which 
optionally contains a heteroatomic moiety and optionally substituted with 
alkyl, alkoxy, halo , nitro, cyano or cycloalkyl groups. More preferred 
dithiols include 1,4-butanedithiol, 1,5-pentanedithiol, mercaptoethyl 
ether, 1,6-hexanedithiol, and 4,4'-dimercaptodiphenyl ether (DMPE). The 
most preferred dithiol is DMPE. Dithiols and processes for preparing them 
are well known. See, for example, U.S. Pat. No. 3,326,981 and Sutter 
Scrutchfield, Journal of the American Chemical Society, Vol. 58, p. 54, 
1936. 
Dicarboxylic acids which can be employed in the practice of the present 
invention include 4,4'-biphenyldicarboxylic acid, 
2,6-naphthalenedicarboxylic acid, isophthalic acid and terephtalic acid. 
Preferred diacids include isophthalic acid and terephthalic acid. Most 
preferred diacid is terephthalic acid. 
Difunctional amines which can be employed in the practice of the present 
invention include amines having two reactive hydrogen atoms such as 
ethanolamine, propanolamine, 2-aminopropionamide, aniline, 
4-hydroxyaniline, anisidine, benzylamine, piperazine and 
2,5-dimethylpiperazine. 
Diepoxides which can be employed in the practice of the present invention 
include the 9,9-bis(4-hydroxyphenyl)fluorene, hydroquinone, resorcinol, 
4,4'-sulfonyldiphenol, 4,4'-thiodiphenol, 4,4'-oxydiphenol, 
4,4'-dihydroxybenzophenone, tetrabromoisopropylidenebisphenol, 
4,4'-biphenol, 4,4'-dihydroxybiphenylene oxide, 
bis(4-hydroxyphenyl)methane, 
.alpha.,.alpha.-bis(4-hydroxyphenyl)ethylbenzene, 2,6-dihydroxynaphthalene 
and 4,4'-isopropylidene bisphenol (bisphenol A). More preferred diglycidyl 
ethers are the diglycidyl ethers of 9,9-bis(4-hydroxyphenyl)fluorene, 
hydroquinone, resorcinol, 4,4'-sulfonyldiphenol, 4,4'-thiodiphenol, 
4,4'-oxydiphenol, 4,4'-dihydroxybenzophenone, 
tetrabromoisopropylidenebisphenol, 4,4'-biphenol, 
4,4'-dihydroxybiphenylene oxide, bis(4-hydroxyphenyl)methane, 
.alpha.,.alpha.-bis(4-hydroxyphenyl)ethyl-benzene, 
2,6-dihydroxynaphthalene and 4,4'-isopropylidene bisphenol (bisphenol A). 
Most preferred diglycidyl ethers are the diglycidyl ethers of 
4,4'-isopropylidene bisphenol (bisphenol A), 4,4'-sulfonyldiphenol, 
4,4'-oxydiphenol, 4,4'-dihydroxybenzophenone, and 
9,9-bis(4-hydroxyphenyl)fluorene. Diepoxides also include the diglycidyl 
ethers of arylhydrazones described above. 
The incorporation of the NLO active moleties derived from the 
arylhydrazones has a number of advantages. High levels of NLO chromophore 
functionalization can be achieved without increasing the scattering losses 
of waveguides fabricated from the polymer. The addition of the groups 
which add to the NLO activity of the polymer do not plasticize the polymer 
and lower the polymer T.sub.g. In fact, such modifications can raise the 
polymer T.sub.g. Furthermore, the fact that the NLO chromophore is 
inherent to the polymer backbone increases the orientational stability of 
the NLO chromophores, reducing the temporal decay of the NLO activity with 
time. Thus, compositions containing this monomer have the advantage of 
high T.sub.g and increased orientational stability when fabricated into a 
nonlinear optical film or other NLO article in comparison to other NLO 
polymers. 
Crosslinked Polymer Compositions 
The crosslinked polymeric compositions can be obtained by curing the epoxy 
arylhydrazone of Formula (I) containing at least two epoxy or alkylepoxy 
groups or the above-described epoxy compositions with at least one curing 
agent by methods well known in the art. The polymeric compositions are 
then oriented as described below to obtain the oriented polymeric 
compositions of the invention. 
Generally, the amounts of the epoxy composition or the epoxy arylhydrazone 
and the curing agent employed herein are sufficient to provide a cured 
product. Usually the amounts of the epoxy composition or the epoxy 
arylhydrazone and the curing agent which provide a ratio of equivalents of 
curing agent per epoxy group from about 0.5 to about 1.2; preferably from 
about 0.95 to about 1.05 are used herein. 
The curing agents which can be employed herein include, for example, 
amines, acids or anhydrides thereof, biguanides, imidazoles, urea-aldehyde 
resins, melamine-aldehyde resins, phenolics, halogenated phenolics, 
sulfides and combinations thereof. These and other curing agents are 
disclosed in Lee and Neville's Handbook of Epoxy Resins, McGraw-Hill Book 
Co., 1967. The curing agent may be a compound which exhibits a NLO 
response. Nonlinear optical active amine curing agents, and crosslinked 
epoxy polymers thereof, exhibiting nonlinear optical activity are 
described in now allowed U.S. application Ser. No. 844,340, filed Mar. 3, 
1992 and now U.S. Pat. No. 5,279,870, U.S. Pat. No. 5,173,546, issued Dec. 
22, 1992, and U.S. Pat. No. 5,112,934, issued May 12, 1992. Suitable 
curing agents, for example, include 4,4'-diaminodiphenyl sulfone, 
p-nitroaniline, nitrobenzyl amine, Disperse Orange, methyl nitroaniline, 
amino nitropyrimidine, 2-6-diamine 4-nitrotoluene, 5-nitrobenzotriazole 
and combinations thereof, bisphenol A, tetrabromobisphenol A, 
phenolformaldehyde novolac resins, halogenated phenolformaldehyde resins, 
hydrocarbonphenol resins and combinations thereof. 
It may be advantageous to include commercially available epoxy resins to 
the polymerization mixture. Some commercial epoxy resins useful in the 
present invention include, for example, D.E.R..TM. 331, D.E.R..TM. 332, 
D.E.R..TM. 383, D.E.R..TM. 431, D.E.R..TM. 736, D.E.R..TM. 661, and 
Tactix.TM. 742, all commercially available from The Dow Chemical Company. 
The thermoset polymeric compositions of the present invention are 
preferably prepared by making a prepolymer by melt or solution 
polymerization methods known in the art. The prepolymer is used to form a 
film by methods described hereinbelow. The film so obtained is cured to 
provide the crosslinked thermoset polymeric composition of the present 
invention. 
The oriented polymeric composition can be prepared by applying an external 
field to the polymeric compositions described above. The polymeric 
compositions of the present invention can be in the form of sheets, films, 
fibers or other shaped articles formed by conventional techniques. 
Generally, films are used in testing, electro-optic devices and waveguide 
applications. 
Methods of fabricating films of NLO polymers and the methods of 
characterization of NLO activity are well known to those skilled in the 
art. Polymer films are typically fabricated by spin-coating or dip-coating 
a polymer solution onto a substrate. The substrate used depends on the 
poling method and method of characterization. For corona poling, a glass 
substrate such as a microscope slide is typically used. For parallel plate 
poling, a substrate with an electrically conductive surface is necessary, 
such as indium-tin-oxide (ITO) coated glass. The coated glass slides can 
be used directly for corona poling. The coated ITO slides for parallel 
plate poling require an electrically conductive overlayer, such as 
sputter-coated gold. 
The fabricated NLO film must have a non-centrosymmetric alignment of the 
dipolar segments throughout the bulk of the polymer film. This is achieved 
by poling the filmy or applying an electric field across the film. In 
corona poling, the field results form a discharge between a wirer such as 
tungsten, suspended above the film and a grounded heater block. The corona 
poling technique is described further by M. A. Mortazavi et al., J. Opt. 
Sc. Am., B 6 (1989). In parallel plate poling a voltage is applied across 
the two electrode layers. In both procedures a voltage is applied at 
elevated temperatures, near the polymer T.sub.g (approximately 5.degree. 
to 10.degree. C. above the onset of T.sub.g as measured by DSC). The field 
is left on for at least a few minutes and the sample cooled with the field 
on to maintain the orientation of the dipolar segments. 
The oriented polymeric compositions of the invention can be prepared by 
substantially simultaneously applying an external field and thermally 
annealing the reaction product of the epoxy-containing composition 
comprising recurring moieties derived from the arylhydrazone of Formula I 
with a curing agent for a period of time sufficient to form a material 
having nonlinear optical properties. This process for producing a 
nonlinear optical polymeric film comprises poling the film to orient the 
NLO moieties by the methods described above, lowering the temperature to 
10.degree. to 50.degree. C. below the glass transition temperature, and 
annealing for a period of time whereby a stable NLO polymeric film is 
obtained. This "annealing" step is carried out so as to cause a reduced 
free volume in the film and thus less room for NLO moieties to randomly 
reorient themselves which lead to a decrease in the NLO signal. Thus this 
annealing process during the polymer orientation may advantageously 
improve the stability of the polymer. A specific example illustrating the 
advantages of thermally annealing and poling the polymeric film is set 
forth below. 
Another method of orientation of the thermoset polymer of the present 
invention for producing nonlinear optical materials includes polymerizing 
the prepolymer of a thermoset polymeric composition of the invention while 
the prepolymer is under an electric field such that the nonlinear optical 
moieties are aligned in the electric field before complete polymerization 
of the prepolymer takes place. This method of orientation will produce 
less stress on the ultimate polymer network than if the electric field is 
applied after the NLO moieties are incorporated into the backbone of the 
polymer. 
The oriented film fabricated from the polymers of this invention can be 
characterized for their NLO activity by a Maker Fringe Rotation Second 
Harmonic Generation Technique which is well known to those skilled in the 
art. See for example, Singer et al., Appl. Phys. Lett., 49, ( 1986 ) 
2448-250. 
The oriented polymeric film is used as a nonlinear optical medium in 
Mach-Zehnder intensity modulators, directional couplers, switches, 
frequency stabilizers, optical parametric devices, phase modulators, and 
passive waveguiding devices, as described in T. A. Tumolillo, Jr. 
"Multilevel registered polymeric Mach-Zehnder Intensity modulator array", 
Applied Physics Letters, 62(24), 14 Jun. 1993, U.S. Pat. No. 5,119,228, 
and G. R. Mohlmann et al., Nonlinear Optical Properties of Organic 
Materials III, SPIE Vol. 1337, (1990), the relevant portions of which are 
incorporated herein by reference. 
The following preferred specific embodiments are to be construed as merely 
illustrative, and not limitative of the remainder of the disclosure in any 
way whatsoever. In the following examples, all temperatures are set forth 
uncorrected in degree Celsius; unless otherwise indicated, all parts and 
percentages are by weight.

EXAMPLE 1 
Diglycidyl Ether of Bis(N'-methyl-4-nitrophenylhydrazone) of 
5,5'-methylene-bis-salicylaldehyde (I) 
##STR6## 
Compound I was prepared using bis(N'-methyl-4-nitrophenylhydrazone) of 
5,5'-methylene-bis-salicylaldehyde (BHBF) as the precursor diphenol. 
BHBF was prepared in accordance with the procedure described in Example 7 
of U.S. Pat. No. 5,208,299. A mixture of BHBF, epichlorohydrin (90 mL), 
and benzyltrimethylammonium chloride (0.15 g, 0.8 mmol) was stirred at 
85.degree. C. for 16 hours. The mixture was cooled to 0.degree. C. 
(ice/water bath) and sodium hydroxide (2 mL of a 50 percent aqueous 
solution) was added. The mixture was allowed to warm to room temperature 
and was stirred overnight. The mixture was diluted with dichloromethane 
and was washed with water. The organic layer was removed and dried over 
anhydrous magnesium sulfate, which was removed by filtration. Removal of 
solvents gave the product as a red solid. The product was purified by 
recrystallization from a hot chloroform/methanol mixture. The product was 
dried in a vacuum oven. .sup.1 H NMR (d6-DMSO) d 7.79 (dd, J1=171.0 Hz, 
J2=9.5 Hz, 4H), 7.83 (m, 1H), 7.24 (d, J=8.5 Hz, 1H), 7.07 (d, J=8.6 Hz, 
1H), 4.42 (d, J=11.5 Hz, 1H), 3-99 (m, 2H), 3.51 (s, 3H), 3.41 (m, 1H), 
2.87 (m, 1H), 2.77 (m, 1H). 13C NMR (d6-DMSO) 156.03, 153.12, 140.23, 
135.40, 133.74, 131.86, 126.81, 126.50, 124.81, 114.90, 114.57, 71.02, 
50.97, 44.93, 33.48. 
EXAMPLE 2 
Epoxy Composition from D.E.R..TM. 332 and BHBF(II) 
A 100 mL minireactor, equipped with mechanical stirrer, condenser, and 
N.sub.2 inlet, was charged with D.E.R..TM. 332 epoxy resin (5.543 g, 16.2 
mmol, 2 equivalent s/diphenol, 171.22 g/equiv e.e.w., washed), BHBF (4.489 
g, 8.09 mmol,), and ethyltriphenyl-phosphonium iodide (0.34 g, 0.81 mmol, 
10 mol percent). DOWANOL.RTM. PM glycol ether (25 mL) was added under 
N.sub.2 and the mixture was heated to reflux for 24 hours. The mixture was 
allowed to cool and DMF (20 mL) was added to dissolve the orange slurry. 
The product was isolated by pouring the solution into water and collecting 
the product by suction filtration. The product was allowed to air dry, and 
was then vacuum dried for 5 hours. Vacuum drying was started at 75.degree. 
C. but the product began to fuse and drying was continued at room 
temperature. Obtained 8.40 g product (84 percent yield). .sup.1 H NMR 
(d6-DMSO).delta.8.10, m; 7.82, s, br; 7.47, m; 7.20, m; 7.05, m; 6.83, m; 
5.44, s; 4.3-4.0, m; 3.80, m; 3.42, m; 2.83, t; 2.70, m; 1.58, s; 1.50, s. 
13C NMR (d6-DSMO) 156.18, 155.91, 155.87, 155.07, 151.81, 151.79, 142.58, 
138.90, 133.81, 133.04, 132.97, 130.56, 127.31, 127.25, 125.38, 125.15, 
123.58, 119.46, 113.82, 113.78, 113.35, 113.17, 70.30, 69.06, 68.75, 
67.38, 49.63, 43.66, 41.04, 32.19, 32.14, 30.58. 
EXAMPLE 3 
Epoxy Composition from I and 9,9-bis(4-hydroxyphenyl)fluorene (BHPF) (3:2) 
(III) 
This epoxy composition was prepared in the manner described above for 
Example 2, using 3 parts of compound I and 2 part (BHPF). The .sup.1 H and 
13C NMR spectra of the product were consistent with the expected 
structure. 
EXAMPLE 4 
Epoxy Composition From Bisphenol A Diglycidyl Ether and 
4-nitro-phenylhydrazone of bisphenol K (NPHBK) (IV) 
This epoxy composition was prepared in the manner described above for 
Example 2, using 2 parts bisphenol A diglycidyl ether and one part NPHBK. 
NPHBK was prepared as described in Example 1 of U.S. Pat. No. 5,208,299. 
The .sup.1 H and 13C NMR spectra of the product were consistent with the 
expected structure. 
Preparation of Films for NLO Activity Measurement 
Thin films (about 1-5 .mu.m) were prepared by spin coating from either a 
prepolymer or epoxy composition using a Solitec Model 5100 spin coater. 
Typically, the solids content of the solution was about 30-33 weight 
percent. Solvents used are listed below for each example. Substrates were 
ITO coated borosilicate glass from Donnelly Applied Films Corporation. 
The cast films were air dried for at least 24 hours, followed by drying at 
elevated temperatures in a nitrogen atmosphere and under vacuum, and film 
thicknesses were measured on a Tencor Instruments Alpha Step 200 
profilimeter. Films were then coated with 140-250 .ANG. gold for parallel 
plate poling experiments. The d33 values were determined by second 
harmonic generation (SHG) measurements using the Maker Fringe rotation 
method, (see K. D. Singer et al., Appl. Phys. Lett., 49, 248 (1986)). A 
fundamental wavelength of 1579 nm was used. A y-cut quartz crystal was 
used as a reference. 
Oriented Crosslinked Polymeric Compositions 
Examples 5A-8 describe the preparation of the oriented crosslinked 
polymeric compositions of the invention. 
EXAMPLE 5A 
A solution containing compound II (2.0 g, 0.0032 epoxide eq) and 
4,4'-diaminodiphenyl sulfone (DADS) (0.20 g, 0.0032 amine eq) was prepared 
in 5 ml dimethylacetamide (DMAc). This solution was used directly to 
prepare films by spin coating at 1500 rpm for 40 sec and allowing the 
films to air dry for about 24 hours. The films were then dried in a 
nitrogen purged oven for 1 hour at 100.degree. C. and 1 hour at 
150.degree. C., and further dried for 1 hour at 150.degree. C. under 
vacuum. The films were then simultaneously poled and cured at 150.degree. 
C. for 1 hour with an applied field of 50V/.mu.m. 
EXAMPLE 5B 
Another set of films was prepared by spin coating with the above-obtained 
solution. The films were dried at 100.degree. C. for 1 hour, 150.degree. 
C. for 1 hour, and 180.degree. C. for 1 hour. The films were then poled at 
150.degree. C. for 10 minutes with an applied field of 50 V/.mu.m. The 
resulting films were about 2.0 .mu.m thick. 
EXAMPLE 6 
A solution containing compound II, (1.97 g, 0.0032 epoxide eq), 
methyltetrahydrophthalic anhydride (MTHPA) (0.54 g, 0.0033 anhydride eq) 
and benzyldimethyl amine catalyst were prepared (BDMA, 0.014 g) in 5 ml 
DMAc. The solution had limited stability at room temperature once the BDMA 
was added and was therefore used immediately to spin coat films at 1,000 
rpm for 40 seconds, which were allowed to air dry for about 24 hours. The 
films were then dried in a nitrogen purged oven for 1 hour at 100.degree. 
C. and 1 hour at 150.degree. C. The films were then dried for 1 hour at 
150.degree. C. in a vacuum oven and then 1 hour at 180.degree. C. in the 
nitrogen purged oven. The resulting films were 2.1 .mu.m thick. 
Then films were poled for 10 minutes at 150.degree. C. with an applied 
field of 50 V/.mu.m. 
EXAMPLE 7 
Compound III (3.5 g, 0.0021 epoxide eq), D.E.R..TM. 332 epoxy resin (0.38 
g), commercially available from The Dow Chemical Company, and DADS (0.13 
g, 0.0021 amine eq) were dissolved in 9 ml DMAc. The solution was used to 
spin coat films at 1,000 rpm for 40 seconds, which were allowed to air dry 
for about 24 hours. The films were then dried in a nitrogen purged oven 
for 1 hour at 100.degree. C. and 1 hour at 150.degree. C. The films were 
then dried for 1 hour at 150.degree. C. in a vacuum oven and then 1 hour 
at 180.degree. C. in a nitrogen purged oven. The resulting films were 
about 5.0-5.2 .mu.m thick. 
The films were then poled for 10 minutes at 190.degree. C. with an applied 
field of 50 V/.mu.m. 
EXAMPLE 8 
Preparation of DADS/Compound I/Tactix.TM. 742 Prepolymer 
Compound I (2.02 g, 0.0058 epoxide eq), Tactix.TM. 742 (1.33 g, 0.0083 
epoxide eq), commercially available from The Dow Chemical Company, DADS 
(0.89 g, 0.014 amine hydrogen eq), and 10 ml DMAc were added to a 100 mL 
3-neck round bottom flask and purged on a Schlenk line for about 30 
minutes with argon. All solids did not dissolve at room temperature. 
Heating was commenced and by 90.degree. C. all solids had dissolved. The 
solution was refluxed for 5 hours at 160.degree. C. 
Films were spin coated from the above solution at 1,000 rpm for 30 seconds. 
After air drying overnight, they were dried in a N.sub.2 purged clean room 
oven for 1 hour at 100.degree. C., then 1 hour at 150.degree. C. in a 
vacuum oven. The resulting film thicknesses were about 1.8 .mu.m. 
The films were simultaneously poled and cured in a nitrogen-purged oven for 
1.5 hours at 180.degree. C., 1 hour at 200.degree. C., and 1 hour at 
216.degree. C. The poling field of 50 V/.mu.m was applied after 35 minutes 
at 180.degree. C. 
The d.sub.33 values for Examples 5A-8 were determined using a fundamental 
wavelength of 1579 nm, as described above. The values obtained are set 
forth in Table I below. 
TABLE I 
______________________________________ 
d.sub.33 
Example (10.sup.-9 esu) 
Parallel Plate Poling 
______________________________________ 
.sup. 5A 9 during cure 
5B 9 after cure 
6 6 after cure 
7 10 after cure 
8 6 after cure 
______________________________________ 
Stability of Thermoset Polymers 
The thermal stability of three polymers was evaluated by monitoring the SHG 
signal as the temperature was increased at a rate of 5.degree. C./minute 
from room temperature to 150.degree. C. and 180.degree. C., for Example 
5A, 7 and 8, respectively. The results are set forth in Table II below. 
TABLE II 
______________________________________ 
Depoling Data for Thermoset Polymers 
Temperature Relative SHG Signal 
(.degree.C.) 
Example 5A Example 7 Example 8 
______________________________________ 
22 1.00 1.00 1.00 
80 1.00 1.00 0.97 
100 1.00 0.96 0.94 
140 0.80 0.85 0.95 
150 0.56 0.82 0.79 
170 -- 0.60 0.66 
175 -- 0.54 0.63 
180 -- 0.38 0.58 
______________________________________