CS200359B1 - 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. ^t • Similarly, a situation arose in the field of information policy. The ever-growing number of new information requires new approaches to optical data recording and processing. One possibility of recording optical information is holographic recording. This method differs from the classical amplitude record primarily 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 recording may have an amplitude or phase character depending on the absorption field or the refractive index of the material. For many applications, it is advantageous if these changes are reversible. ^Currently, a series of materials that can be used for continuous holographic recording, eg. photographic emulsion, light-curing and crosslinking materials. 2-e groups of reversible media it is necessary to mention photochromic systems, electro-optical materials, thermoplastic media, etc.

For example, photosensitive materials are used for reversible information recording

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200,359 photosensitive thermoplastic layers of conjugated polymers (Mylnlkov VC, ^A erenin ANi Doc. AN USSR 153 · 1381, 1963; Saneom A. Kozol ET, i Proc. Display, IEE Conf. P. 325, 1971) or rigid polymer metrics (polystyrene , poly (vinyl alcohol), poly (methyl methacrylate) polyacrylonitrile) in which the photochromic substance spiropyran is dissolved. The resolution of the most efficient photochromic layer - spiropyran in polystyrene - was 300 lines / mm. (LeřČienský M.> Record of Information in Organic Materials, Czechoslovak Academy of Sciences, 1974 and literature cited there).

^In many applications, it is advantageous in view of high diffraction efficiency, infrared recording capacity, and the ability to repeat recording using volume, phase holographic recording in reversible materials. Some electro-optical crystals have already proven effective in this group of substances, eg LiNbOy Preparation of these single crystals However, it is very demanding There have been efforts to exploit the great variability of organic structures for the preparation of new photosensitive materials, However, only a few substances are known for volume, phase and reversible recording, for example toluene sulphate, etilbene derivatives, etc. A great 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 malannic anhydride with some vinyl or alkene monomers, eg styrene, alkyl vinyl ethers, ethylene, etc.

The invention relates to photosensitive polymers of the general formula I

(X)

where R. CH ₂ -CH ₂ , CH-CHg,

R _x . H, SO2Na; R ₂ . H, OCH3

R ₃ . H, CH ₃ (CH ₂ ) _k , k - 0,1,3,7

R ₄ - CH ₃ (CH ₂ ) ₂ , Z - 0,1,3 n 10 ² - 10 ⁴

R ₅ - CH ₃ (CH _{2) m,} m - 1,3,5,11

200 359 x, y, z, are molar fractions that ee can vary in the following range: x - 0.10 - 0.99 y «θ, ΟΙ - 0.90 (x + y + z 1) z 0 0, 10 - 0.99

Botocitlivé polymers of formula I according to the invention prepared by the maleinhydridu the copolymer of formula II {f ^H * H ° - R) _n (II)

CO whatever Ran has the meaning given above acts by an aromatic amino-containing compound of the formula

 wherein R 1 and I 2 are as defined above, and the resulting product is solvolysed by reaction with a compound of formula R 2 OH, wherein R 2 is as defined above.

This system is forochromic and is prepared by reacting maleic anhydride copolymers and said monomers in solution with aromatic amino-containing aromatic compounds. The content of the photochromic component in the system can be controlled by the ratio of the two reaction components. The photosensitive polymers can be crosslinked with diamines.

Maleic anhydride copolymers with the above monomers are prepared by copolymerization of both reactants, preferably, e.g., in an equimolar ratio, according to methods described in the literature (e.g., L.Flett, Maleio Anhydride Derivatives, J. Willey & Sons, New York, 1952 and references cited herein). ). Example 1 gives a description of the preparation of a copolymer of maleic anhydride with styrene.

For chemical stability, it is preferable to hydrolyze the anhydride groups of the polymeric material or partially esterify them with an aliphatic alcohol in solution at elevated temperature. This modification of the polymer can be carried out directly in the reaction mixture after preparation of the light-sensitive polymer by reaction with an azo compound or by dissolving the already isolated photosensitive polymer. . by swelling the cross-linked polymer in a suitable solvent.

The photochromic polymers of the invention are generally reddish-colored solids. The color intensity depends on the content of the photochromic component in the system. The polymers are soluble in polar organic solvents such as tetrahydrofurene, dioxane, acetone, dimethylformamide. In preparing the photosensitive film, the polymer is dissolved in a volatile solvent such as tetrahydrofuran. The solution is poured onto a glass plate and the solvent is allowed to slowly evaporate at room temperature. The thickness of the photosensitive film can be controlled by the concentration of the tetrahydrofuran polymer solution.

The crosslinked polymers are insoluble and can be cast into suitable forums.

After irradiation with ultraviolet light, the trans-cis isomerization around the central double bond -Nos-N- occurs in aromatic azo compounds. The photoconversion to the cis isomer depends on the wavelength of the radiation used, the solvent, the temperature and other factors.

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In the dark, a thermally activated back reaction to a more stable trans isomer takes place. radiation-induced isomerization and e manifested by a change in the ultraviolet spectrum. The absorption spectra of the azo compounds used in the tetrahydrofuran solution show, after irradiation, two characteristic bands of trans and cis isomer in the visible and near UV regions of the spectrum. E.g. in the case of 4-aminobenzene, the trans-isomer is absorbed at 390 nm, and the cis-form at 350 nm. Upon binding of the photochromic moieties with the polymer, the hypsochromic shift of the respective absorption bands occurs, but the characterization of the isomerization is the same as that of the free azo compounds. The figure shows the abscessive epectra of photosensitive substances in the dark and after irradiation also the curve 1-4 aminoazobenzene (in the dark), l '(for the irradiation), 2-styrene-malelnhydride-2 copolymer containing azo-crowns in the pheasant branches - in the formula - CHg, R 1 - R g HH, x O 0.55, y 0,4 0.45, z 0 0 «= 3000, curve £ (after irradiation).

The photoconversion to cis iaomer after irradiation is relatively high. b of the polymer kie B ' CH-CHg, R ' Rg ', x < 0.28, y < 0.72, z >

The thermally activated cis-trans reverse omeromerization is a first order kinetic reaction. At 20 ° C, the reaction rate constant value for each polymeric photosensitive system is po.

it is in the range of 0,4 0.4-2.5. 10 ^J min. The rate of reaction can be increased, for example, by catalysis with H ions.

The photosensitive polymers of the invention can be used to obtain a reversible holographic volume record with high resolution. For example, a polymer sheet, wherein R is CH-CH, Ri-Rg - Η x - 0.75, y «0.25, z - 0, η - 3.1Ο ³ showed resolution at a record 2000 lines / mm. Holographic recording is described in Example 5.

A more detailed process for preparing photosensitive polymers is shown in the following by way of example. ^x 'hese examples serve to ilustraol invention rather than limit its scope.

Example 1

38 parts by weight of maleic anhydride were dissolved in 500 parts by weight of benzene and 40 parts by weight of styrene and 0.16 parts by weight of the benzoyl peroxide initiator were slowly added. Dried nitrogen was bubbled through the reaction mixture for several minutes and then heated to 80 ° C under reflux. During the polymerization for 3 h, the reaction mixture was stirred. ^{And the} opolymer that precipitated from solution was washed with benzene and isolated by filtration. It was then dissolved in tetrahydrofuran not a 2% solution and successively precipitated twice with a 10-fold excess of benzene, respectively. heptane. The white, powdery product was dried to constant weight at 60 ° C under reduced pressure. The yield was 60% of the theoretical amount of styrene maleic anhydride copolymer.

Analysis for ^C 12 ^H 10 O 3 calculated C 71.3% H 5.0% H 23.7% found C 71.4% H 5.5% 23.1%.

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A mixture of 10 pbw of styrene-maleic anhydride copolymer and 10 pbw of 4-aminoazobenzene was dissolved in 180 pbw of anhydrous tetrahydrofuran. The solution was heated at 70 ° C for 8 hours under a reflux condenser equipped with a CaCl 3 drying tube. At the end of the reaction, the polymer was precipitated to a 20-fold excess of benzene. ^The product was extracted with benzene until the extract turned red in 4-aminoazobenzene. gotom the polymer was dissolved in tetrahydrofuran at 2% rortok, /

overheated with a 10-fold excess of heptane and sutured to constant weight under reduced pressure. The yield was 55% of the theoretical amount of the photosensitive polymer, where R is CH-CHg, R = eRgsH, x = 0.6, y = 0.4, z = 0.

IR (tetrahydrofuran solution) -1638 cm ^-1 (amide), 1730 cm ^-1 (carboxyl), 1775 and 1855 cm ¹ (anhydride).

UV (THP stream) - 360 nm (aza-trans binding).

Polymer Analysis - R = CH-CH ₂ , R 4 R 4 -H, x = 0.6, y = 0.4, z = 0 calculated: 71.3% Cf 5.0% H, 6.8% N Found: C, 70.6%, H, 5.5%, 6.8% », 17.1% O.

Example 2

Similarly, a copolymer of maleic anhydride and ethylene was prepared, which was prepared according to L. P.lett et al. Anhydride Derivatives (1952). In the resulting photochromic polymer, R = CH ₂ - CH ₂ .

Example 3 parts by weight of maleic anhydride-vinyl acetate copolymer (prepared according to literature data from S. de Wilde, GSSmets: J. Polym. Sci. 5,532 (1950)) and 10 parts by weight of 4-aminoazobenzene were dissolved in 400 parts by weight of dimethylformamide and heated. 8 h at 70 [deg.] C. 1 part by weight of 4,4-diaminodiphenylmethane was then added to the solution and the reaction mixture was further heated at 50 [deg.] C. for 24 h in a mold consisting of two glass plates between which a rubber gasket was placed. The crosslinked polymer was extracted with benzene and swollen in methanol where it was heated at 80 ° C for 72 h and finally dried very slowly at room temperature to obtain a polymer plate where R = CH -CH ₂ , R 4 = R 8 = H, R 4 = CH 3 with a thickness of 0.15-1 mm.

Example 4 parts by weight of styrene-maleic anhydride copolymer together with 1 part by weight of 4-amino-2,2-methoxyazobenzene were dissolved in 25 parts by weight of tetrahydrofuran. The reaction mixture was heated to reflux at 80 ° C for 4 h.

After the reaction of the polymer with photochrome was complete, 16 parts by weight of methanol were added to the solution, and the sample was heated at 80 ° C for 8 hours. Polymer, wherein R is CH-CH₂, R₁ is H, R ₂ is OCH _3, R is CH ₃ CH ₂ x - 0, y = 0.25, e-0.75 was isolated by precipitation into 10-fold excess of heptane and dried to constant weight.

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Example 5 parts by weight of maleic anhydride copolymers ee styrene e 3 parts by weight of 4-aminobenzenesulfonic acid sodium salt were dissolved in 130 parts by weight of dimethylformamide and heated at 80 ° C for 24 hours. The polymer was precipitated with diethyl ether:

petroleum ether 2) 3 and redissolved in a slightly alkaline aqueous medium. The solution was then dialyzed against distilled water for 24 hours. The lysed photochromic polymer was hydrolyzed by heating the aqueous solution at 100 ° C for 2 h, precipitated with dilute chlorine acid.

hydrogen and redissolved in tetrahydrofuran and precipitated with heptane. The prepared polymer has a composition corresponding to formula I, wherein R-CH-CHg, K-SO 2 Na, Rg * R, = H.

Example 6 parts by weight of butyl methacrylate and 2 parts by weight of maleic anhydride were dissolved in 5 parts by weight of acetone. The reaction mixture in the presence of 0.1 part by weight szoblsisobutyronitrilu heated under nitrogen at 70 ° C for Telia oo for 24 hours. After polymerizaoe solution was diluted by adding 12 parts of acetone ^with e polymer was precipitated into water (1000 parts) and dried from. The sample was heated to 80 ° C for final drying. In this way, a polymer of formula (II) wherein R 8 CH 8 CHCl 3 -,

CH,

R 3 R R 8 χ H, R ₄ = = CH ₃ (CH ₂ ) ₃ ³

Analogously, photochromic samples were prepared on the basis of methyl and ethyl methacrylate. CHjCHg.

Example 7

Hologrems were created by non-expanded argon laser beams of 51514.5 nm and simultaneously reconstructed by red light of 6632.8 nm, which hit the specimen at an angle satisfying the Bragg condition, the i-recording beams fell symmetrically to normal and formed an angle of 40 ° between them. °. The intensity ratio of both beams was 1 * 1. The thickness of the photosensitive layer was 50 µm.

Holograms at a beam angle of 60 ° were also recorded to determine the resolution of the material. In such an arrangement, holograms of a transparent object were obtained, depicting the ability of the photosensitive polymer sheet, where R is CH-CHg, RjwRgeH,

, x 0.75, y »0.25, z 0 0 is greater than 2000 lines / mm.

Claims (2)

SUBJECT OF THE INVENTION 1. The photosensitive polymers of the general formula I - « Γ Ί Γ * 1 . - CH - CH - ft - J-cn— -CH-R * what what what COOH, / 1 t COOH Lv J Ll * J ¹ -J O (I) CH. and R "= CH" _{O-CH, CH-O,} C - _O CH CH - CH _O CH - CH " Φ ^COOE <° · ' ⁵ R 1 = H, SO 3 Na = R ₂ - H, OCH ₃ , H, CH ₃ (CH ₃ ) _k , k = 0.1, 3.7; R ^CH CH ^CH CH - 0,1 0.1.3; R ₅ - CH ₃ (CH _{2) m,} m-1,3,5,11; η «10 ² - 10 ⁴ x, y, z There are molar fractions that can vary in the range: x = 0,10-0,99, y„ 0,01-0,90, z = 0,10-0 , 99 (x + y + z = 1). 2. A process for the preparation of photosensitive polymers according to claim 1, characterized in that the corresponding maleic anhydride copolymer of the formula II WHAT (II), where R and n are as defined above, acts by an aromatic azo compound containing an eminosulo of the formula Ί. Wherein R 1 and R 8 are as defined above, and the product obtained is solvolysed by treatment with a compound of formula R ₃ OH, wherein R ₃ is as defined above.