CS200360B1 - Photo-sensitive polymers and method for their production - Google Patents

Description

The invention relates to photosensitive polymers for recording information.

With the rapid development of optoelectronics, it is necessary to prepare new materials whose optical properties (refractive index, absorption) can be controlled by light. The main reason is the creation of new optical elements in integrated optics and optical communication systems. A similar situation arose in the field of information policy. The increasing number of new information requires new approaches to optical data recording and processing. ^d ne of the possibility of recording the optical information is holographic recording. This method differs from the classical amplitude recording mainly in that it simultaneously records the phase of the light field. 2. advantages of this method include: higher recording capacity, possibility of obtaining spatial image, holographic interferometry, etc.

The hologram may be recorded either over the entire volume of the recording medium or may be formed by shape modulation of the surface. The volume record may have an amplitude or phase character, depending on whether the light field changes the absorption coefficient or the refractive index of the material. For many applications, it is advantageous if these changes are reversible. At present, a variety of materials are known which can be used for permanent holographic recording, such as photographic emulsions, light-polymerizing and cross-linking materials, and groups of reversible media need to be mentioned about photochronic systems, electro-optical materials, thermoplastic media, etc.

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From polymeric materials ee for re-exible data such as photosensitive thermoplastic layers of conjugated polymers (Mylnikov VC, Terenin AN: Dokl.AN USSR 153, 1361, 1963; Saneom A.Kozol ET, t Proc.Display, IEE Gonf. Etr 325, 1971) or a heavy polymer matrix (polystyrene, poly (vinyl alcohol), poly (methyl methacrylate), polyacrylonitrile) in which the photochromic substance apiropyran is dissolved. The resolution of the most effective photochromic layer - spiropyran in polystyrene - was 300 lines / mm. (Leščieneký M. with Rázný Information on Organic Materials, Czechoslovak Academy of Sciences, 1974 and references cited here).

For many applications, it is advantageous from the viewpoint of diffraction efficiency, kspscity of information recording and the possibility of repeated recording using volume, phase holographic recording in reversible materials. Certain of the anorgenic electro-optical crystals, e.g. However, the preparation of these single crystals is very demanding. Efforts have therefore been made to exploit the great possibilities of variability of organic structures for the preparation of new photosensitive materials. materials, the curiosities need not be prepared in the form of single crystals. However, so far only a few substances are known for volumetric, phase and reversible recording, for example toluene sulphate, stilbene derivatives, etc. The disadvantage of organic materials of this kind is their low sensitivity and rapid fatigue.

It has now been shown that these drawbacks can be overcome by reversible photosensitive materials of high diffraction efficiency based on polymers with a covalently bonded photochromic component, in particular copolymers of maleic anhydride with some vinyl or alkene monomers, e.g. styrene, alkyl vinyl ethers, ethylene etc.

The invention relates to photosensitive polymers of the general formula I

AND

where R = 10 ² to 10 ⁴

AND

I cooH

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R = CH-CH-, CH-CH 6

CH,

I 3

CH-CH., CH-CHI ^{C ά} COOR. O ⁴ I

CH-CHg

O

AND

COCH ^

R ₃ = H, CH ₃ (CH ₂ ) _k , k = 0,1,3,7;

R ₄ = CH ₃ (CH _{2) x,} / = 0,1,3;

R ₅ - CH ₃ (CH ₂ ) _m , m - 1,3,5,11 x, yz are molar fractions that ee can change in this range sx - 0 - 0,99 y 0,01 0,01 - 0,90 (x + y + z 1) z = 0 - 0.99

The photosensitive polymers of formula (I) according to the invention are prepared by the addition of the corresponding maleic anhydride copolymer of formula CH-CH-R,

CO CO where Ran is as defined above acts with an aromatic azo compound containing an amine group of the formula

-N'M-M »N - ^ 0 ^ —Hi.

and the product obtained is solvolysed by treatment with a compound of formula R ₃ OH, wherein R ₃ is as defined above.

These systems are photochromic and are prepared by reacting maleic anhydride copolymers and said monomers in solution with amino-containing aromatic azo compounds. The content of the photochromic component in the system can be controlled by the relative ratio of the two reaction components.

moleic anhydride copolymers with the above monomers are prepared by copolymerizing both reactants, preferably, e.g., in an equimolar ratio, according to methods described in the literature (eg, L.Flett, kaleic Anhydride erivstives, J. Willey & Sons, New York, 1952 and cited herein). literature).

The photochromic component in the polymer of the invention is 4,4bis (4-aminobenzen-1-azo) diphenyl. The haloazo compounds are synthesized by diazotization of benzidine, coupling with anilinomethanesulfonic acid sodium salt, and end group hydrolysis. The aniline-methanesulfonic acid salt is obtained from aniline and an equimolar adduct of KaHSC > ₃ with formaldehyde.

in view of chemical stability, it is preferable to carry out the hydrolysis of the anhydride groups of the polymeric material or their partial esterification with an aliphatic alcohol. T _{u-modification} polymer can be accomplished through swollen crosslinked polymer in a suitable solvent.

The cross-linked polymers of the invention are insoluble and can be cast into suitable molds.

For irradiation with ultraviolet light, the geometric isomerization of trens-cis around the central double bond -N ' The photoconversion to the cis isomer depends on the wavelength of the radiation used, the solvent, the temperature and other factors. In the dark, a thermally activated back reaction to a more stable trans isomer takes place. Irradiation-induced isomerization is manifested by a change in the ultraviolet spectrum.

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The absorption spectra of the azo compounds used show, in the tetrahydrofuran solution, two characteristic bands of the trans and cis isomers in the visible and near UV regions of the spectrum _after irradiation.

Rapř. in the case of 4-aminoazohenzene absorbs the trans-isomer at 390 nm, and at 350 tons the ois-form. When the photochromic groups are attached to the polymer, a hypsochromic shift of the respective absorption bands occurs, since the isomerization pattern is the same as that of the free azo compounds.

The photoconversion to the cis isomer after irradiation is relatively high.

In the case of a crosslinked polymer according to the invention, where R CH - CH, R, - CH 1, x - 0, y - 0.05, z> 0.95 reaches 30%.

The thermally activated reverse isomerization of cis-trans is kinetic to the 1st order reaction. At 20 ° C, the reaction rate constant for each polymeric light-sensitive system is in the range of »0.4 - 2.5. 10 ”min“ ^. The reaction rate can be increased, for example, by catalysis with H ⁺ ions.

Said materials can be used to obtain a reversible holographic volume record with a high resolution.

A more detailed process for preparing photosensitive polymers is exemplified below. These examples serve to illustrate the invention and do not limit its scope.

Example

10.7 parts by weight of NagSgOs were dissolved in 8.4 parts by weight of 37% formaldehyde, 10.8 parts by weight of aniline were added with stirring, and diluted by 65 parts by weight of water. The mixture was heated at 75 ° C for 6 h. The end of the reaction was detected by Ehrlich's reagent, which upon reaction with the free amino group forms a colored Schlff base. Tetrazotized benzidine was added to the anilinomethanesulfonic acid salt solution thus prepared while stirring. During the coupling, the acidity of the solution was blunted with sodium acetate for 6 h and the temperature maintained below 14 ° C. Tetrazotized benzidine was prepared by dissolving 10 pbw of benzidine in 55 pbw of dilute HCl (9 pbw of concentrated HCl) heated to 70 ° C. of the solution was charged with 43 pbw of 2.5 M NaNO 3 and ice-cooled to 10-12 ° C for about 20 minutes. The product obtained after coupling was filtered and boiled for 5 h in 5% NaOH, washed thoroughly with water, dried, recrystallized from methanol and dried again to constant weight.

Analysis (Mass Spectrometry) - fragmentation of the sample corresponds to 4,4'-bis (4-aminobenzene-1-azo) diphenyl.

74 parts by weight of maleic anhydride-butyl vinyl ether copolymer (prepared according to the data of Dubin and Strausa in J.Phys.Chem. 74, 2842 (1970)) was dissolved in 150 parts by weight of dimethylformamide and 1 part by weight of azo crosslinker 4,4-bis (4) was added. Crosslinking of the polymer was accomplished by heating the reaction mixture in glass form at 60 ° C for 2 h. After removal from the mold, the polymer was where R = CHg-CH-O (CHg) 2-CH 0.96, 0.04, 0.10 extracted with benzene and then dried

Said polymer sample was swollen in butyl and resp. of octyl alcohol and heated in the solvent at 80 ° C for 72 h. Esterification modified polymer, wherein

R-CHg-CH-O-Rj-Rj-CH3CHgI, Rj-CH3CHgJR, RJ-CH3CHgJYx0, y0.04, ζ 9.96 was slowly dried on teflon washer at room temperature.

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Analogously, photochromic samples were prepared from the starting copolymers of maleic anhydride with ethyl, hexyl and dodecyl vinyl ether, where R ^CHCHCH ^CHgCH CHCHCHCH))), respectively. CH 3 (CH 2> 11) These starting copolymers were synthesized according to literature data (Dubin, Strauss, J. Phye. Hem. 74, 2842 (1970), H. Isatsuda et al. Reporte on Progression in Pol. Phys. In Japan 14, 51 (1971).

Claims (2)

OBJECT OF THE INVENTION · What is claimed is: 1. A photosensitive polymer of the general formula I wherein R @ 1 R. CHg-CHg, CH-CHg, CH-CHg, CH-CHg, CH-CHg W, COOR, O R _c COOCH, R ₃ = H, CH ₃ (CH ₂ ) _k , k = 0,1,3,7 5 r ₄ = ch ₃ (ch ₂ ), - 0,1 ^ 5 R ,. CH CH ₃ (CH ₂ ) _m , m- 1,3,5,11 x, y, z, are molar fractions which can vary in the range 4 x = 0-0,99, y 0,01 0,01-0 , 90, z = 0, -0.99, where x + y + z> 1. 2. A process for the preparation of photosensitive polymers according to claim 1, characterized in that the corresponding meleinic anhydride copolymer of the formula II -CH «-CH-RCO CO“ (II), where Ran is as defined above, is treated with an aromatic azo compound containing an emino group. formulas The HgN and the product obtained are aolvolysed by treatment with a compound of the formula R @ ₃ H, wherein R @ 3 is as defined above.