SynopsisPolymers having chloroacetate groups were prepared by addition reaction of various chloroacetic acids, such as mono-, di-, and trichloroacetic acids, to cis-1,4-polybutadiene under nitrogen atmosphere for obtaining photosensitive rubbers. The structure of products obtained was identified as a cyclized polybutadiene having pendent chloroacetate groups. The amount of the incorporated substituent increased up to the maximum of around 20 mol %, and the amount of the residual unsaturated groups in the polymer backbone decreased due to the cyclization of the double bond. Chloroacetylated polybutadiene had higher photocrosslinkability by UV irradiation than chloroacetylated chitosan or PVA owing to the high reactivity of the chloroacetate groups and the double bonds in the polymer. The photosensitivity depends both on the amount of the incorporated chloroacetate groups and the residual double bonds in the polymer and also depends on the glass transition temperature (T,) of the polymer, and the dependence of the crosslinking reaction on Tg was interpreted to be due to diffusion controlled reaction between excited dichloroacetate groups and olefinic groups in the polymer. INTRODUCTIONWe had found that1 when a chitosan whi'ch can be obtained by the hydrolysis of chitin having N-acetylglucosamide units was chloroacetylated, the chitosan could easily be photocrosslinked by UV irradiation. The mechanism of the photocrosslinking reaction was investigated by using isopropyl chloroacetates as model compounds. Moreover, the photosensitive chloroacetate groups were incorporated into poly(viny1 alcohol) for obtaining a new type of photopolymer.2Poly(viny1 cinnamate) -type photoresists and cyclized polydienes rubbers used together with photocrosslinking reagents, such as bisazides, are already commercialized and are widely used as photoresists.3-5 It is known that6 carboxylic acids add to olefinic compounds to yield the corresponding esters in the presence of acid catalysts, such as p-toluenesulfonic acid or perchloric acid. It had been reported that saturated carboxylic acids including acetic acid add to polydienes to yield cyclized polydiene rubbers having pendent carboxylate group^.^.^ Therefore, we made an attempt in order to obtain cyclized polydiene rubbers having cinnamate groups by using the reaction of polydienes with cinnamic acid in the presence of acid catalysts, which was reported in a previous paper.g It is known thatlOJ1 the glass transition temperature of photosensitive polymers greatly influences the photosensitivity, because the photocrosslinking reaction takes place in a solid state, where the mobility of the polymer influences the photochemical reaction. We had revealed the dependence of the photosensitivity on the glass-transition temperature of the polymer theoretically and experimentally in the case of the cyclized polydiene rubbers and linear polydiene rubbers having cinnamate groups.12-15 This paper describes the synthetic conditions of a new type of photoresist by means of the reaction of polybutadi...
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