Photosensitizer groups, pendant

Novel Synthesis and Photochemical Reaction of the Polymers with Pendant Photosensitive and Photosensitizer Groups... 

Accordingly, the synthesis of novel cinnamate polymers with high functionality and performance is very important from the viewpoint of both polymer chemistry and practical use. Recently, we have reported the synthesis of polymers with pendant photosensitive moieties such as cinnamic ester and suitable photosensitizer groups by radical copolymerizations of 2-(cinnamoyloxy) ethyl methacrylate with photosensitizer monomers (9), by copolymerizations of chloromethylated styrene with the photosensitizer monomers followed by the reactions of the copolymers with salts of... 

This article reports on the synthesis of photosensitive polymers with pendant cinnamic ester moieties and suitable photosensitizer groups by cationic copolymerizations of 2-(cinnamoyloxy)ethyl vinyl ether (CEVE) (12) with other vinyl ethers containing photosensitizer groups, and by cationic polymerization of 2-chloroethyl vinyl ether (CVE) followed by substitution reactions of the resulting poly (2-chloroethyl vinyl ether) (PCVE) with salts of photosensitizer compounds and potassium cinnamate using a phase transfer catalyst in an aprotic polar solvent. The photochemical reactivity of the obtained polymers was also investigated. 

PCEVE-NPEVE with 10 mol-% of pendant photosensitizer unit was also prepared by the cationic copolymerization of 90 mol-% of CEVE with 10 mol-% of NPEVE under similar reaction conditions used for the copolymerization of CEVE with NPVE. In contrast, a copolymer with pendant photosensitizer group could be obtained from the cationic copolymerization of CEVE with... 

The relationship between the thickness of polymer films containing about 10 mol-% of pendant photosensitizer groups and the conversions of the —C bonds after 10 min. irradiation is shown in Figure 5. The photochemical reactivity of PCEVE-NNVE decreased slightly with increasing thickness of the film. Interestingly, the reactivity of PCEVE-NPVE was not influenced by the thickness of the film in contrast to the self-sensitized polymers previously... 

Nishikubo, T, Kawashima, T., Inomata, K., and Kameyama, A., Design of multifunctional polymeric photosensitizers containing pendant (nitroaryl)oxy groups and quaternary onium salts for photochemical valence isomerization of potassium 3-phenyl-2,5-norbornadiene-2-carboxylate, Macromolecules, 25, 2312-2318, 1992. 

Fig. 4. Chemistry of poly(vinyl cinnamate) negative-acting resist. Initial light absorption by the photosensitizer is followed by energy transfer to produce a pendant cinnamate group in a triplet electronic state. This combines with a second cinnamate on another polymer chain, forming a polymer—polymer...

Syntheses of Self-Sensitized Polymers by Cationic Copolymerizations. The cationic polymerizations of several vinyl ethers containing pendant ester groups such as cinnamic ester 12), methacrylic ester 16), acrylic ester (77), and crotonic ester 18) have been reported. Based on these reports, cationic copolymerizations of CEVE with photosensitizer monomers such as NPVE, NNVE, VNP and NPEVE were carried out using TFB as a catalyst in toluene at — 65 °C. Each copolymer was obtained with high yield except in the case of copolymerization of CEVE with VNP as summarized in Table I. 

The reactions of PCVE with PNP are quantitative under these reaction conditions, and polymeric photosensitizers such as poly[2-chloro-ethyl vinyl ether-co-2-(4-nitrophenoxy)ethyl vinyl ether] (PCVE-NPVE) containing about 4, 10, 19, 28, 37, and 46 mol-% of pendant 4-nitrophenoxy (NP) groups were prepared (Table II). Although the reactions of PCVE with PNN were carried Table II. Reaction Condition and Results of the Syntheses... 

As shown in Figure 2, PCEVE-NPVE and PCEVE-NNVE containing about 10 mol-% of pendant sensitizer groups prepared from the reactions of PCVE with potassium cinnamate and PNP or PNN have photochemical reactivity equal to PCEVE-NPVE and PCEVE-NNVE prepared from the cationic copolymerizations, however, their photochemical reactivities were changed by the contents of photosensitizer units in the copolymers. 

Recently, a further example of photopolymerization of a donor-acceptor substituted monomer (methyl-2-octadecanamidopropenate) without any additive has been described [16]. The co (polyacrylates) containing electron-acceptor moieties as pendant groups are also photosensitive [17,18]. Their photosensitivity coincides with the charge-transfer absorption band peak and, therefore, such compounds possess a photoinduced memory effect. 

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