Coumarin dyes and side-chain coumarin dye-substituted polymers which exhibit nonlinear optical properties

Coumarin dyes such as alkylaminocoumarincarboxamides which have functional hydroxyl groups or which are chemically attached to vinyl monomers such as methacrylic acid. The dyes which are chemically attached to vinyl monomers can be copolymerized, e.g. with acrylic monomers to produce a coumarin dye-containing polymer. The dyes which have functional hydroxyl groups can be reacted with an existing polymer or copolymer, e.g. a copolymer of styrene and acrylic acid to esterify the acid groups of the polymer to form a coumarin dye-containing polymer. Such coumarin dye-containing polymers are formed into films and fibers which when poled in an electric field yield a film or fiber with nonlinear optical properties.

BACKGROUND OF THE INVENTION 
This invention relates to the production of functional and polymerizable 
coumarin dyes for the preparation of side-chain coumarin dye-substituted 
polymers which exhibit nonlinear optical (NLO) properties. More 
particularly, the present invention is directed to the provision of 
functional coumarin dyes, polymerizable coumarin dyes and side-chain 
coumarin dye-containing polymers useful for the fabrication of organic 
polymeric nonlinear optical materials. 
The field of nonlinear optics is concerned with the interactions of 
electromagnetic fields with materials to produce new fields that are 
altered in phase, frequency, amplitude or other propagation 
characteristics from the incident field. See, for example, Y. R. Shen, 
"The Principles of Nonlinear Optics," John Wiley & Sons, N.Y., 1984. The 
best known nonlinear optical effect is second harmonic generation (SHG) or 
frequency doubling. Optically nonlinear materials are used in frequency 
doublers for lasers, optical communications and computing equipment, laser 
resistance devices, and in opto-electronic devices for other applications. 
See, for example, G. Boyd, J. Opt. Soc. of Am. B, 6(4) 685 (1989). 
Nonlinear optical devices such as frequency doublers have been based almost 
exclusively on inorganic materials, e.g. lithium niobate (LiNbO.sub.3) and 
potassium dihydrogen phosphate (KDP). Crystalline organic materials, e.g. 
methylnitroaniline (MNA), are also under development. The disadvantages of 
these materials include relatively poor laser damage resistance and 
difficulties in preparation and fabrication into opto-electronic devices. 
Additionally, single organic crystals are brittle and difficult to grow. 
Organic polymeric materials with large delocalized pi-electron systems 
exhibit very fast NLO responses, have large optical nonlinearities, and 
the chemical synthesis of these materials can be altered to optimize their 
desirable physical characteristics while preserving their NLO properties. 
See, for example, D. J. Williams, Agnew. Chem. Int. Ed. Engl., 23, 690 
(1984). Polymeric NLO materials can have very good mechanical properties. 
They can be mechanically tough and easily fabricated or processed into 
thin film geometries that are very desirable for integration with 
microelectronics. See, for example, G. H. Cross, et al., "Polymeric 
integrated electro-optic modulators," Proceedings of the SPIE, 1177, 79 
(1989). 
Two basic approaches exist for the synthesis of optically nonlinear 
polymers. One approach is to prepare guest-host materials by simply 
dissolving polarizable moieties (chromophores or dyes) as the guest in a 
polymeric host. This physical or solid solution may be severely limited in 
concentration of the chromophore due to limited solubility of the dye 
molecule. The other approach is to synthesize polymers that have 
chromophores chemically attached as either side-chain or main-chain 
substituents. These dye-substituted polymers have several distinct 
advantages over guest-host materials including higher limiting 
concentrations of the chromophore, reduced mobility and enhanced 
orientational stability of the chromophore, and improved optical, thermal 
and mechanical properties. See, for example, K. D. Singer, et al., Appl. 
Phys. Lett., 53(19), 1800 (1988). 
The methods used to synthesize dye-substituted polymers each have their 
separate advantages and disadvantages which should be considered. The 
attachment or substitution of chromophores onto preformed polymers is 
often complicated by limited reactivity of the chromophores and/or the 
polymer and/or poor solubility of the chromophore in the polymer. Steric 
interference or blocking of reactive sites on the polymer can also occur 
once some dye molecules have been attached to the polymer. The result is 
often poor control over the extend of reaction and less effective 
substitution of the polymer with chromophores. The polymerization of 
dye-substituted monomers is sometimes inhibited by side reactions, for 
example, in free radical polymerization the growing chain end may 
terminate by reaction with the dye. 
The nonlinear optical properties of crystalline coumarin dyes have been 
previously reported and described, e.g. in U.S. Pat. No. 3,858,124. Thus, 
it has been disclosed that some coumarin dye single crystals have 
significant NLO properties, and that one specific example 
(7-diethylamino-4-methylcoumarin) showed frequency doubling ability that 
was at least as good as lithium niobate (LiNbO.sub.3). This crystalline 
coumarin also showed better laser damage resistance than LiNbO.sub.3. 
These reports also documented one major problem of coumarins that is 
common to many other crystalline materials used in NLO applications, that 
of difficulty in growing single crystals of sufficient size and high 
quality for evaluation. Further, nonpolymeric coumarin dye NLO materials, 
such as 7-dimethylamino-4-methylcoumarin, are limited in their usefulness 
by having poor mechanical properties. 
Dye-containing polymers for NLO applications have been reported. See for 
example U.S. Pat. Nos. 4,795,664; 4,779,961; 4,755,574 and 4,579,915. 
However, to applicants' knowledge, no coumarin dye-containing polymers 
having nonlinear optical properties have to date been produced or 
reported. 
One object of the invention accordingly is the provision of novel 
side-chain coumarin dye-containing polymers having nonlinear optical 
properties. 
Another object is to provide side-chain coumarin in dye-containing polymers 
which also have good thermal, mechanical and optical properties. 
A still further object is the provision of functional coumarin dyes and 
polymerizable coumarin dyes for the synthesis of the above coumarin 
dye-containing polymers having nonlinear optical properties. 
Yet another object is to provide coumarin dyes which have functional 
hydroxyl groups or which are chemically attached to vinyl monomers for use 
in producing coumarin dye-containing polymers having NLO characteristics. 
SUMMARY OF THE INVENTION 
The above objects are achieved according to the invention by the provision 
of coumarin dye-containing polymers, and monomeric functional coumarin 
dyes, and polymerizable coumarin dyes for synthesis of such polymers. The 
monomeric coumarin dyes include alkylaminocoumarin-carboxamides which have 
functional hydroxyl groups or which are chemically attached to vinyl 
monomers such as acrylic acid or methacrylic acid. The coumarin 
dye-containing polymers having nonlinear optical properties can be 
prepared by attaching the hydroxyl group of the coumarin dye-containing 
monomer to an existing polymer, or by copolymerizing the coumarin 
dye-containing vinyl monomer with another vinyl monomer, or by 
homopolymerizing the coumarin dye-containing monomer. 
The chemical attachment of the coumarin chromophores to polymers, 
particularly in the form of vinyl polymers such as polymethacrylate, 
restricts the mobility of the chromophores and improves their solubility 
in the polymers to which they are attached. A restricted mobility of the 
chromophores is important in the preservation of nonlinear optical 
properties. Good solubility of the dye in the polymer is important to the 
achievement of high chromophore concentrations while maintaining good 
physical and optical properties. Coumarin dye-containing monomers and 
coumarin dyes with reactive functional groups have excellent solubility in 
many common polymers of high optical clarity and they have sufficient 
reactivity to yield high degrees of chromophore incorporation into the 
polymer. Coumaromethacrylate monomers are very reactive in free-radical 
polymerizations and copolymerize well with a variety of vinyl monomers 
such as alkylmethacrylates and alkystyrenes to produce the novel coumarin 
dye-containing NLO polymers of the invention. 
The coumarin dye-containing polymers of the present invention are suitable 
for the fabrication of films and fibers by casting, extruding, or molding, 
and subsequent ordering or aligning of the attached molecular dipoles 
through electric field and magnetic poling techniques and 
Langmuir-Blodgett techniques known in the art. See, for example, M. A. 
Mortazavi, et al., "Second-harmonic generation and absorption studies of 
polymer-dye films oriented by corona-onset poling at elevated 
temperatures," J.Opt.Soc.Am. B, 6(4), 733 (1989), and G. L. Gaines, 
Insoluble Monolayers at Liquid-Gas Interfaces, Interscience: New York, 
1966. The resulting films exhibit strong, reproducible and stable 
nonlinear optical properties. 
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS 
The coumarin dye-containing polymers produced according to the invention 
are characterized by a recurring monomeric unit corresponding to the 
formula: 
##STR1## 
where P is a polymer main chain unit, and 
where D is a coumarin dye; 
The polymer can be a homopolymer or a copolymer comprising any of a variety 
of polymer main chain units, including styrenic and acrylic units. 
Preferably a polymer contains from about 10 to 100 mole % of the recurring 
dye-containing monomeric unit . . . The polymer of this invention can be 
illustrated by the general formula: 
##STR2## 
where P is the group 
where F is --O--, --NH--, or --CH.sub.2 --O--; and, where R.sub.1 is H, an 
alkyl (including cyclic alkyls) of 1 to 22 carbon atoms, or other vinyl 
groups known in the art; 
where R.sub.7 is H or --COOR.sub.1 ; 
where D has the formula (1b) or (1c): 
##STR3## 
where R and R.sub.2 are H or an alkyl or alkenyl of 1 to 22 carbon atoms, 
e.g. methyl; 
where G is H, --CH.sub.3, or CF.sub.3 ; 
where A and B are H, alkyl or alkenyl of 1 to 22 carbon atoms, or the atoms 
necessary to complete a 6-membered heterocyclic ring containing N as the 
hetero atom; and, 
where n=2-18; 
where R.sub.3, R.sub.4, R.sub.5, and R.sub.6 are independently 
hydrogen,alkyl (including cyclic alkyl), alkenyl (including cyclic 
alkenyl), aryl, substituted aryl, cyano, amide, halogen, alkoxy, alkenoxy, 
or --COOR.sub.8, where R.sub.8 is hydrogen or an alkyl or alkenyl 
(including cyclic alkyl or alkenyl) of 1 to 22 carbon atoms; and, 
where y is at least 3 and y/(x+y+z) is about 0.10 to 1.0. 
The coumarin-containing vinyl polymers of formula (1) above can be prepared 
from alkylaminocoumarincarboxamide dyes which have functional hydroxyl 
groups, acrylic functional groups, or styrenic functional groups having 
the following general formula: 
##STR4## 
where E is --OH, the group 
##STR5## 
where R.sub.7 is H or --COOR.sub.1 ; 
where R, R.sub.1, and R.sub.2 are independently H or an alkyl or alkenyl of 
1 to 22 carbon atoms (e.g. methyl); 
where A and B are independently H, an alkyl or alkenyl of 1 to 22 carbon 
atoms, or the atoms necessary to complete a 6-membered heterocyclic ring; 
where n=2-18, preferably 2-6; and, 
where F is --O--, --NH--, or --CH.sub.2 --O--. 
Specific examples of hydroxy-functional coumarin dyes are set forth below 
in formulae (2a) and (2b), and specific examples of polymerizable coumarin 
dyes are set forth in formulae (2c) and (2d) below. 
##STR6## 
The preparation of the hydroxy-functional coumarin dye (2a) is set forth in 
Example 1 below. The hydroxy-functional coumarin dyes such as (2a) and 
(2b) can then be esterified with methacrylic acid to produce the 
polymerizable coumarin dyes (2c) and (2d), by procedure set forth in 
Examples II and III below. 
The alkylaminocoumarincarboxamide having the attached methacrylic ester 
grouping, compound (2c), is polymerized with methyl methacrylate, 
according to Examples IV and V below to produce the methacrylate copolymer 
(3) below. 
##STR7## 
where y is at least 3, y/(x+y) is 0.10 to 1.0, and n is as previously 
described. 
It is noted that the coumarin dye-containing polymer (3) above can also be 
prepared by reacting a hydroxy-functional coumarin dye (2a) with preformed 
polymer, e.g. a copolymer of methylmethacrylate and methacrylic acid. 
Furthermore, as illustrated in Example VIII below, a hydroxy-functional 
coumarin dye, e.g., as illustrated in Formula (2a), can be reacted with a 
copolymer of styrene and acrylic acid, to esterify some of the acid groups 
of the polymer and attach the coumarin dye to the polymer to form the 
coumarin dye-containing polymer shown below in Formula (4). 
##STR8## 
The formulae (5) and (6) below illustrate still further coumarin-containing 
polymers according to the invention. 
##STR9## 
Examples VI and VII below illustrate preparation of the coumarin 
dye-substituted tertiarybutyl styrene-methyl methacrylate copolymer of 
formula (6), by copolymerizing the polymerizable coumarin dye 2(c) above, 
with t-butyl styrene. 
In all of the compounds (2a) through (6) above, n ranges preferably from 2 
to 6. It is anticipated that the polymers of the present invention may be 
crosslinked by appropriate strategies. Crosslinking of these polymers may 
be carried out by reacting residual carboxylic acid groups or residual 
amino groups on the polymers with diepoxides, or by, thermal or U.V. 
treatment of one of the polymers of the present invention in the presence 
of a free radical generator to crosslink the polymer by reaction of alkyl, 
allylic or alkenylic groups in the polymer. 
The following are examples of practice of the invention.

EXAMPLE I 
Functional Dye Synthesis Preparation of (2a), n=2 
Hydroxy-functional and polymerizable coumarin dyes were prepared from 
3-carbomethoxy-7-diethylaminocoumarin (CMDEAC) which was prepared as 
follows. To a charge of 4-diethylaminosalicylaldehyde (6.12 g., 0.032 
mole) were added dimethylmalonate (4.17 g., 0.032 mole), 75 ml methanol, 
and 22 drops of piperidine. The solution was stored at room temperature 
for 4 weeks and then the solvent was removed on a rotary evaporator at 
room temperature. The remaining, fluorescent, viscous oil was 
chromatographed on 170 g. of silica using chloroform. The first fractions 
to elute were starting reactants. These were followed by 5.4 g. (61% 
yield) of CMDEAC which was recovered as a viscous oil. It was used without 
further purification. 
The hydroxy-functional coumarin dye 
N-(2-hydroxyethyl)-7-diethylaminocoumarin-3-carboxamide was prepared as 
follows. A charge of CMDEAC (6.12 g.) and ethanolamine (1.29 g.) was 
refluxed in 20 ml of benzene for 24 hours with stirring. The cooled 
solution was seeded and allowed to stand. Somewhat gummy crystals formed 
slowly. 
The crystals were washed once with cold benzene and recrystallized from 60 
ml of benzene with carbon decolorization. A yield of 1.78 g. with a 
melting point of 126.degree.-127.degree. C. was obtained. A second 
recrystallization from benzene yielded flat yellow needles with a melting 
point of 127.degree.-128.degree. C. Elemental analysis indicated 63.88% C, 
6.67% H, and 8.87% N (theoretical: 63.14% C, 6.62% H, and 9.21% N). 
EXAMPLE II 
Polymerizable Dye Synthesis Preparation of (2c), n=2 
A polymerizable, methacrylate ester of 
N-(2-hydroxyethyl)-7-diethylaminocoumarin-3-carboxamide was prepared as 
follows. To a charge of 
N-(2-hydroxyethyl)-7-diethylaminocoumarin-3-carboxamide (1.087 g.) were 
added 4-diethylaminopyridine (0.054 g.), 4-methoxyphenol (0.012 g.), and 
methylene dichloride (20 ml). To this solution were added methacrylic acid 
(0.4644 g.) in 5 ml methylene dichloride, followed by 
dicyclohexylcarbodiimide (1.045 g.) in a few ml of methylene dichloride. 
Within a few minutes dicyclohexylurea began to precipitate from solution. 
After standing overnight at room temperature, the urea was filtered off 
and washed with small volumes of methylene dichloride. The solvent was 
removed from the filtrate on a rotary evaporator. The dark yellow resin 
obtained was dissolved in 15 ml of benzene, treated with 15 ml of 
cyclohexane, and allowed to stand for 16 hours. The solution was then 
clarified by stirring with Celite and filtered. The Celite cake was washed 
with 6 ml of 1:1 benzene/cyclohexane. The filtrate was chilled to 
5.degree. C. and additional resin precipitated. The supernatant was 
decanted, the resin was triturated with 4 ml of cold mixed solvent, and 
the combined solutions were diluted with 10 ml of n-hexane. The turbid 
solution slowly deposited yellow crystals during several days at room 
temperature. After chilling for several more days at 5.degree. C., the 
supernatant was decanted from the crystalline solid which was then washed 
twice with cold 1:1:1 benzene/cyclohexane/n-hexane and dried under reduced 
pressure at room temperature. The product was a coarse yellow crystalline 
solid which melted 143.degree.-144.degree. C. Proton NMR and elemental 
analysis were consistent with the desired product. 
EXAMPLE III 
Polymerizable Dye Synthesis Preparation of (2d), n=3 
A polymerizable methacrylate ester of 1, 2, 4, 5, 3H, 6H, 
10H-tetrahydro-9-[N-(3-hydroxypropyl)] carboxamido [1]benzopyrano-(9, 9a, 
1-gh)quinolizin-10-one (Formula 2d) was prepared as follows. Coumarin 314 
(Eastman Kodak, 0.317 g.), 3-amino-1-propanol (0.118 g.), and 10 ml of dry 
benzene were added to a flask, stirred, and refluxed for 16 hours. An 
additional 10 ml of dry benzene was added to dissolve any crystallized 
material and the reflux was continued for an additional 8 hours. The 
solution was cooled to 5.degree. C. and the yellow solid was filtered, 
washed with cyclohexane, and dried. A yield of 0.246 g. of the 
intermediate was recovered, and showed a melting point of 
180.degree.-181.degree. C. This hydroxy-functional coumarin dye (2b) was 
then converted to the methacrylate ester (2d) using methacrylic acid, 
dicyclohexylcarbodiimide, 4-methoxyphenol, and 4-dimethylaminopyridine, in 
dichloromethane as described above in Example II. 
EXAMPLE IV 
Polymer Synthesis Preparation of (3), n=2 
A coumaromethacrylate (CMA) monomer 
N-(2-methacryloxyethyl)-7-diethylaminocoumarin-3-carboxamide (formula 2c) 
(1.0240 g, 0.00275 mol) was added to a 100 ml round bottom flask along 
with methyl methacrylate (1.0420 g, 0.01041 mol), azobisisobutyronitrile 
(0.0217 g), chlorobenzene (20 g), and benzene (6.55 g). The reagents were 
stirred magnetically with a stirring bar and dissolved completely in 
several minutes. The flask was connected to a reflux condenser, purged 
with nitrogen gas, and heated to a mild reflux for 16 hours under a dry 
nitrogen atmosphere. The solution was cooled to room temperature and 
slowly poured into 600 ml of rapidly stirring hexane. A yellow fluffy 
precipitate formed immediately and was isolated by suction filtration of 
the hexane mixture. A yellow solid was obtained and dried by heating to 
100.degree. C. under reduced pressure. 
The product was purified by preparative gel permeation chromatography (GPC) 
in chloroform with styragel columns which removed all unattached coumarin 
dye. The final product was isolated by evaporating the chloroform and 
drying the sample for an hour at 100.degree. C. under reduced pressure. A 
product yield of 0.8541 g (41%) was obtained. The sample was characterized 
by analytical GPC, proton nuclear magnetic resonance (NMR) spectroscopy, 
differential scanning calorimetry (DSC), and ultraviolet/visible (UV/Vis) 
spectroscopy. The GPC analysis indicated that the sample was high 
molecular weight (Number average Molecular weight (M.sub.n =84,000 g/mole, 
polydispersity=3.3). The NMR analysis indicated that sample had a CMA 
repeat unit mol fraction of 0.20. The DSC analysis indicated that the 
sample had a glass transition temperature (T.sub.g) of 110.degree. C., and 
the UV/Vis analysis indicated that the sample had an absorbance maximum 
(in chloroform solution) of 419 nm with a full-width, half-maximum of 44 
nm. 
EXAMPLE V 
Polymer Synthesis Preparation of (3), n=2 
A CMA monomer N-(2-methacryloxyethyl)-7-diethylaminocoumarin-3-carboxamide 
(formula 2c), 2(A)-n-2 (0.2610 g, 0.000701 mol) was added to a 50 ml round 
bottom flask along with methylmethacrylate (1.3310 g, 0.0133 mol), 
azobisisobutyronitrile (0.0157 g), and benzene (15.39 g). The flask was 
connected to a reflux condenser, purged with nitrogen gas, and heated to a 
mild reflux for 23 hours under a dry nitrogen atmosphere. The solution was 
cooled to room temperature and the solvent was evaporated. A yellow solid 
was obtained and dried by heating to 100.degree. C. under reduced pressure 
for one hour. The product was purified by preparative GPC in chloroform 
with styragel columns which removed all unattached coumarin dye. The final 
product was isolated by evaporating the chloroform and drying the sample 
for an hour at 100.degree. C. under reduced pressure. A product yield of 
0.637 g (40%) was obtained. The sample was characterized by analytical 
GPC, proton NMR spectroscopy, DSC, and UV/Vis spectroscopy. The GPC 
analysis indicated that the sample was high molecular weight (M.sub.n 
=38,000 g/mole, polydispersity=1.6). The NMR analysis indicated that 
sample had a CMA repeat unit mol fraction of 0.034. The DSC analysis 
indicated that the sample had a T.sub.g of 109.degree. C., and the UV/Vis 
analysis indicated that the sample had an absorbance maximum (in 
chloroform solution) of 419 nm with a full-width, half maximum of 44 nm. 
EXAMPLE VI 
Polymer Synthesis Preparation of (6), n=2 
A CMA monomer N-(2-methacryloxyethyl)-7-diethyl 
aminocoumarin-3-carboxamide, (formula 2c), (0.3639 g, 0.000977 mol) was 
added to a 50 ml round bottom flask along with t-butylstyrene (0.5494 g, 
0.00343 mol), azobisisobutyronitrile (0.0095 g), and benzene (25 g). The 
reagents were stirred magnetically with a stirring bar and dissolved 
completely in several minutes. The flask was connected to a reflux 
condenser, purged with nitrogen gas, and heated to a mild reflux for 10 
hours under a dry nitrogen atmosphere. The solution was cooled to room 
temperature and the solvent was evaporated. A yellow solid was obtained 
and dried by heating to 100.degree. C. under reduced pressure. 
The product was purified by preparative GPC in chloroform with styragel 
columns which removed all unattached coumarin dye. The final product was 
isolated by evaporating the chloroform and drying the sample for an hour 
at 100.degree. C. under reduced pressure. A product yield of 0.380 g (42%) 
was obtained. The sample was characterized by analytical GPC, NMR 
spectroscopy, DSC, and UV/Vis spectroscopy. The GPC analysis indicated 
that the sample was high molecular weight (M.sub.n =29,000 g/mole, 
polydispersity=1.8). The NMR analysis indicated that sample had a CMA 
repeat unit mol fraction of 0.26. The DSC analysis indicated that the 
sample had a T.sub.g of 132.degree. C., and the UV/Vis analysis indicated 
that the sample had an absorbance maximum (in chloroform solution) of 418 
nm with a full width, half-maximum of 45 nm. 
EXAMPLE VII 
Polymer Synthesis Preparation of (6), n=5 
A CMA monomer N-(5-methacryloxypentyl)-7-diethyl 
aminocoumarin-3-carboxamide (formula 2c) (0.3760 g, 0.00101 mol) was added 
to a 50 ml round bottom flask along with t-butylstyrene (0.5551 g, 0.00346 
mol), azobisisobutyronitrile (0.0095 g), and benzene (20 g). The reagents 
were stirred magnetically with a stirring bar and dissolved completely in 
several minutes. The flask was connected to a reflux condenser, purged 
with nitrogen gas, and heated to a mild reflux for 12 hours under a dry 
nitrogen atmosphere. The solution was cooled to room temperature and the 
solvent was evaporated. A yellow solid was obtained and dried by heating 
to 100.degree. C. under reduced pressure. 
The product was purified by preparative GPC in chloroform with styragel 
columns which removed all unattached coumarin dye. The final product was 
isolated by evaporating the chloroform and drying the sample for an hour 
at 100.degree. C. under reduced pressure. A product yield of 0.271 g (29%) 
was obtained. The sample was characterized by analytical GPC, NMR 
spectroscopy, DSC, and UV/Vis spectroscopy. The GPC analysis indicated 
that the sample was high molecular weight (M.sub.n =24,000 g/mole, 
polydispersity=1.7). The NMR analysis indicated that the sample had a CMA 
repeat unit mol fraction of 0.21. The DSC analysis indicated that the 
sample had a T.sub.g of 100.degree. C., and the UV/Vis analysis indicated 
that the sample had an absorbance maximum (in chloroform solution) of 418 
nm with a full-width, half-maximum of 45 nm. 
EXAMPLE VIII 
Polymer Synthesis--Preparation of (4), n=2 
An hydroxy-functional coumarin dye 
N-(2-hydroxyethyl)-7-diethyl-aminocoumarin-3-carboxamide (formula 2a) 
(1.2158 g, 0.00399 mol) was added to a 50 ml round bottom flask along with 
a copolymer of styrene and acrylic acid (1.0164 g, 0.00328 mol of acid), 
dicyclohexylcarbodiimide (0.6924 g, 0.00336 mol), 4-dimethylaminopyridine 
(0.0519 g, 0.000425 mol), and tetrahydrofuran (21.03 g). The reagents were 
stirred magnetically with a stirring bar and dissolved completely in ca. 
10 minutes. The flask was connected to a reflux condenser, purged with 
nitrogen gas, heated to a mild reflux, and stirred for 2 hours under a dry 
nitrogen atmosphere. The solution was then cooled to room temperature and 
poured slowly into 600 ml of rapidly stirring cyclohexane. A yellow fluffy 
precipitate formed immediately and was isolated by suction filtration of 
the cyclohexane mixture. A yellow solid was obtained and dried by heating 
to 80.degree. C. under reduced pressure. 
The product was purified by preparative GPC in chloroform with styragel 
columns which removed all unattached coumarin dye. The final product was 
isolated by evaporating the chloroform and drying the sample for an hour 
at 80.degree. C. under reduced pressure. A product yield of 0.952 g was 
obtained. The sample was characterized by analytical GPC, NMR 
spectroscopy, DSC, and UV/Vis spectroscopy. The GPC analysis indicated 
that the sample was high molecular weight (M.sub.n =31,000 g/mole, 
polydispersity=1.8). The NMR analysis indicated that the sample had a 
coumarin dye-substituted repeat unit mol fraction of 0.10. The DSC 
analysis indicated that the sample had a T.sub.g of 93.degree. C., and the 
UV/Vis analysis indicated that the sample had an absorbance maximum (in 
chloroform solution) of 421 nm with a full-width, half-maximum of 45 nm. 
EXAMPLE IX 
Polymer Synthesis 
In a procedure essentially the same as the procedure described in Example 
VIII above, an hydroxy-functional coumarin dye is added to a preformed 
copolymer of styrene and maleic anhydride to form a coumarin 
dye-containing polymer. 
EXAMPLE X 
Film Formation 
An optically nonlinear polymer film was prepared from the material 
described above in Example IV as follows. The coumarin dye-containing 
polymer (150 mg.) was dissolved in chlorobenzene (2 ml). A glass 
microscope slide (BK7) was thoroughly cleaned with several water washings 
followed by rinses with acetone and methanol. The slide was placed on the 
chuck of a photo-resist spinner and the spinning speed was set at ca. 800 
rpm. Several drops of the polymer solution were placed in the center of 
the slide and the slide was then spun for 30 seconds at room temperature. 
The spinner was stopped and the slide was removed and placed in an 
air-circulating oven at 140.degree. C. for 2 hours and in a vacuum oven at 
140.degree. C. for 24 hours to remove the solvent. The thickness of the 
cast film measured with a profilometer and determined to be ca. 836 nm. 
The UV/Vis spectrum of the film was recorded (.lambda..sub.max =425 nm, 
A.sub.max =1.46) with a spectrometer and the sample was prepared for 
electric field poling. 
The glass-supported film was placed on the grounded aluminum heated stage 
of a corona-poling apparatus and heated to 155.degree. C. A thin tungsten 
wire electrode was suspended 1 cm above the film and an electric field 
(ca. 5500 VDC, ca. 1.7 uA) was applied between the wire electrode and the 
grounded electrode. The film was held at 155.degree. C. for 5 min. and 
then cooled to room temperature while in the presence of the electric 
field. The UV/Vis spectrum of the film was measured again 
(.lambda..sub.max =425 nm, A.sub.max =1.09) and a chromophore orientation 
factor of 0.25 was calculated. Second harmonic generation (SHG) was 
utilized as a measure of the NLO properties of the sample. The SHG 
measurement was performed using a fundamental wavelength of 1064 nm and 
the amount of light produced at 532 nm was measured and compared to that 
from a quartz standard. The amount of second harmonic produced was used to 
calculate a d.sub.33 of ca. 19 pm/V. A second order nonlinear 
susceptibility .beta. was calculated for the film (using MO ver.5, by: 
J. J. P. Stewart, Frank J. Seiler Research Laboratory, U.S. Air Force 
Academy, Colorado Springs, Colo.) to be about 20.5.times.10.sup.-30 esu. 
It will be understood that various vinyl monomers can be employed for 
polymerization with the coumarin dye monomers, such as (2c), to form the 
coumarin-containing polymers of the present invention, and various 
vinyl-containing monomers can be copolymerized with acrylic acid or 
methacrylic acid to form vinyl copolymers, e.g. acrylic acid and styrene 
copolymers, for reaction with hydroxy-functional coumarin dyes such as 
(2a) and (2b). Additional examples of such vinyl monomers are isopropyl 
fumarate, acrylonitrile, acrylamide, vinyl napthaline, acenapthalene, 
vinyl chloride, vinylidene fluoride, maleic anhydride, phenyl vinyl ether, 
vinyl benzoate, maleimide, butadiene, cyclohexyl methacrylate, adamantonol 
methacrylate, and borneol methacrylate. 
The coumarin dye-substituted polymers of the present invention have 
excellent processing characteristics which include solubility in common 
organic solvents, adhesion to substrates, mechanical toughness, thermal 
stability, and a high laser damage threshold. These characteristics 
translate into an ability to form rugged, high quality, uniform films 
which may be oriented by electric field poling techniques and crosslinked 
during the poling process. 
When an NLO polymer is synthesized by attaching a coumarin dye to a 
polymer, the resulting material has many physical properties that can be 
quite similar to those of the same polymer having no dye attached. These 
similarities include retention of T.sub.g, mechanical toughness, and other 
general physical and thermal properties. This permits the design of many 
useful coumarin dye-containing NLO materials. Although all of the polymers 
prepared in the examples were amorphous, it is possible that some of the 
polymers of the invention may form liquid crystalline phases depending 
also upon the comonomer used and the spacer length, n, in the coumarin 
monomer. 
Another very advantageous feature of coumarin dye-containing polymers is 
their broad window of transparency to visible light. This permits the use 
of these polymers in films for use in devices for eye and sensor 
protection. At high intensities, a portion of visible light may undergo 
frequency doubling into the ultraviolet spectrum. Films of these polymers 
may also be used as electro-optic switches and modulators. See, for 
example, P. Kaczmarski, et al., "Design of an integrated electro-optic 
switch in organic polymers," IEE Proceedings, 136, Pt. J. (3), 152 (1989). 
The relaxation of the alignment of (guest-host) dissolved chromophores in 
poled films results in a loss of NLO properties. See, for example, K. D. 
Singer, et al., Appl. Phys. Lett., 53(19), 1800 (1988). An additional 
advantage of coumarin dye-containing polymers of this invention is their 
high orientational stability which in turn provides high NLO property 
stability. Coumarin dye-containing polymers have a significant ability to 
resist chromophore realignment as evidenced by the results of accelerated 
aging experiments and the crosslinking of these polymers will increase 
their stability to an even greater extent. 
Another advantageous feature of attaching coumarin dyes to polymers for NLO 
applications is the high chromophore concentrations that may be obtained. 
Simple solutions of dyes in polymers are often restricted to very low 
concentrations of the dye (1 to 5%) due to immiscibility. By attaching the 
chromophore to the polymer through a polymerizable dye or a 
post-polymerization reaction, a single phase, homogeneous material with a 
much higher chromophore concentration is achievable. 
The excellent thermal, mechanical, optical and NLO properties of the unique 
coumarin dye-containing polymers of the present invention are 
substantially different from both crystalline coumarin compounds and the 
other dye-containing polymers of the prior art. 
From the foregoing, it is seen that the invention provides for the 
preparation of a novel class of monomeric coumarin dyes and a novel class 
of coumarin dye-containing polymers having excellent nonlinear optical 
properties, as well as other important advantages. 
Since various changes and modifications can be made in the invention 
without departing from the spirit of the invention, the invention is not 
to be taken as limited except by the scope of the appended claims.