Photocrosslinking unsaturated poly

Kim S, Lee H, Ahn D, Park HW, Chang T, Lee W (2013) Direct sulfonation and photocrosslinking of unsaturated poly(styrene-b-butadiene-b-styrene) for proton exchange membrane of direct methanol fuel cell. J Membr Sci 427 85-91... 

Photocrosslinking. The second class of photopolymer chemistry that is used in some commercial products is based on the reaction of unsaturated moieties attached to an organic polymer. These photopolymer materials include the [2+2] cycloaddition of the ethylenic groups in poly(vinyl cinnamate) polymers and in the newer styryl pyridinium (10) and thiazolium (77) derivatives of poly(vinyl alcohol). The main advantage of this chemistry is that, unlike free-radical photopolymerization, they are insensitive to the presence of oxygen. This photopolymer mechanism is principally used in applications employing a washout development process (e.g. resists). 

Many modifications of poly(vinyl alcohol) were carried out to form photosensitive materials. Thus, unsaturation was introduced into the pendant groups for photocrosslinking. One example is a condensation with pyridinium and quinolinium salts ... 

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