The study presented here examines the effect of postcure on the mechanical properties of urethane acrylates as compared to vinyl ether functionalized polyurethanes. The vinyl ether systems cure via a cationic mechanism and are, therefore, expected to undergo dark reactions which may lead to noticeable postcure effects. Urethane acrylate systems, on the other hand, are not known to undergo postcuring reactions since these systems polymerize via the free radical mechanism. Recently, however, it has been reported that trapped free radicals exist in irradiated acrylate samples for periods as long as seventy days [1], and that radical entrapment occurs very early in the reaction at conversions as low as 10% [2] . It has also been reported that acrylate unsaturation continues to disappear for several days after irradiation [3]. These findings, important as they are, only reflect the spectroscopic behavior of UV cured acrylates using electron spin resonance and infrared absorption techniques. Although some studies relating mechanical property changes to postcuring of acrylate systems have been reported [4], no clear correlation between these parameters has been identified [5]. The comparative data reported here helps identify the effects and the nature of the postcuring process in both the acrylate and the vinyl ether systems.

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A series of eleostearic acid-resorcin phenolic resins were synthesized, mainly including eleostearic acid-resorcin-formaldehyde resin (I)(softening point:70-75°C), methyl eleostearate-resorcin-formaldehyde resin(II)(softening point:65-70°C), N-hydroxyethyl eleostearic amide -resorcin-formaldehyde(III)(softening point:85-90°C). The relative molecular weights determined by GPC method are M_n:5.0×10³-1.0×10⁴, M_w:1.0 ×10⁴-4.0×10⁴, D:3.0-6.0. The reaction products were characterized using I.R. and elemental analysis. A detailed investigation was made on the photosensitivity of the photopolymers formed from these phenolic resins and BAC-M. All these negative photoresists can be developed in dilute aqueous base. The minimum quantities of exposure energy required are between 10-20mj/cm². Clear etched image with 3μm line width was obtained. The photocured films have excellent resistance to acids.

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Polycarbonates containing thymine photodimer units were found to be decomposed by irradiation of deep-UV light at around 250nm, where thymine photodimer units dissociated to thymine units. In the presence of acid generator, the polycarbonates decomposed at both the thymine photodimer units and the carbonate units. Sensitivity as the chemical amplification resist was high. For this system, high sensitivity as EB resist was also found.

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The applicability of semi-empirical PPP and INDO/S molecular orbital calculations For indoanilines (3) was investigated under three structural points of view: syn/anti isomerization, resonance canonical structures, and non-planarity of the molecule.

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Ion-pair charge-transfer complexes were formed very slowly in 1, 2-dimethoxyethane solution of poly(tetrahydrofuran) containing 4, 4′-bipyridinium salts of tetrakis[3, 5-bis(trifluoromethyl)phenyl]-borate in the main chain. The excitation of a CT-band in deaerated organic solutions of polymers resulted in colour changes from pale yellow to blue owing to the photoinduced electron transfer reaction. The blue form decayed exponentially in the dark with the lifetime of about 17min at 20°C and was regenerated upon CT excitation. The colour changes were repeated reversibly for many times.

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We investigated the formation of index modulation for volume holograms consisting of poly-N-vinylcarbazole (PVCz), and achieved a new process that enables large holograms and uniform quality.
Conventionally PVCz holograms are developed by two sequential dipping process: first into good solvent, then into poor solvent. When a swollen PVCz film is dipped into poor solvent, PVCz molecules precipitate into small grains. In the upper layer small grains can pack closely, because the solvent in the film can escape outside. However, the solvent in the lower layer is prevented from escaping by the closely packed upper layer, and the remaining solvent forms gaps corresponding to the degree of swelling. As the result of the difference in swelling between highly exposed and low exposed areas, refractive index modulation appears. Based on the investigation above, we found a new process where the holograms are developed by single dipping process into a mixture of volatile good solvent and nonvolatile poor solvent. When the film swollen by the mixture is carried out, the solvent in the film becomes poor solvent rich and small grains are formed. With this new process all areas of a hologram can be developed under same conditions, so large holograms with uniform quality becomes possible.

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Holography with a blue sensitive photopolymer system and novel repolymerizing fixing methods are described. The photosensitive medium is composed of photosensitizing dye, chain transfer agent, initiator, monomer and polymeric film-forming binder. Coatings are cast from solution onto a washed glass plate.

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Chitosan-ammonium dichromate (CT-AD), chitosan- potassium dichromate (CT-PD) and chitosan-sodium dichromate (CT-SD) polymers were prepared and irradiated to UV light with a high pressure mercury lamp. It was found that photocrosslinking reaction may occur in all three polymers. Therefore, negative image can be obtained.
The developing process for this system was different from that for making positive image of the same system. It was carried out in two steps. Firstly, the unreacted dichromate was extracted from the irradiated photopolymer film by using an alkaline solution and then the developing process was carried out with an acidic solution. The images thus obtained showed comparatively high resolution.
Characteristic curves of chitosan-dichromates were obtained and investigated. In this paper, influences of film thickness and type or concentration of photosensitizers to photosensitivity of photopolymers will be discussed.

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The electrochemical behaviour of viologens and their complexes with acceptors was investigated. We found that there are three redox states for viologens, and four states for the complexes which depended on the concentration and the affinity of acceptor. Generally the number of redox states is only two. Additional redox states result from molecular interaction, exactly from the charge transfer interaction between molecules in the system. The affinity of the compound increased as a result of complexing with an acceptor. Particularly, the complexation of radical salt and acceptor was discussed in detail.

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Some p-N, N-dimethylamine substituted benzal ketone derivatives(ABK) are used as a new class of sensitizes for visible light induced radical photopolymerization of methylmethacrylate (MMA) by combination with diphenyliodonium salt (DPIO). The electron-transfer sensitized photolysis of DPIO- DABA system was studied by spectroscopy and rate of radical photogeneration was determined to be 94.59 (mol.l^-1 s^-1), The relative efficiency of various ABK for polymerization of MMA is in the order DABA>DABP>ABA. The polymerization rate was proportional to [DPIO]^0.37 [DABA]^0.16 and [MMA]^1.0. Photopolymerization was retarded by oxygen indicating a radical mechanism. Effect of several additives on the polymerization revealed that some heterocyclic thiol compounds exhibit significant role of rate acceleration.

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