Poly vinylbenzophenone

The poly(benzophenone) diradical (5.27) easily abstracts hydrogen from hydrogen-donor molecules (RH) or from a polymer molecule (PH) giving the poly(benzophenone) ketyl radical (5.2S)  

Termination of two poly(benzophenone) ketyl radicals gives inter-(3.138) or intra-(3.139) crosslinked structures with benzophenone pinacol groups  

Photodegradation of poly(vinylbenzophenone) is accompanied by chain scission and crosslinking, which occur simultaneously [522]. 

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Holden and Guillet (54) have reported the photoaddition of a variety of olefins to thin films of poly(vinylbenzophenone) ... 

PVB = poly(vinylbenzophenone) PMVK = poly(methylvinyl-ketone) PVP = poly(vinylphthalimide) see Table 1 for other abbreviations. 

Ferrocene-CCl4 complex accelerates photodegradation of polyethylene [2326], poly(vinyl chloride) [1271] and poly(vinylbenzophenone) [1884]. The chain scission reaction can be initiated by free radicals formed from CCI4 however, FeClj may also participate in this process (cf. section 5.5). 

Electron transfer processes from an alkali metal to poly(vinylnaphthalene) is another kind of addition reaction. It is easy to perform in THE solution, and yields radical ion sites distributed at random along the chain (Scheme 12). However, initiation of anionic polymerizations by radical ion species proceeds by electron transfer to the incoming monomer. As a consequence this pathway cannot be used for the purpose of grafting, with the single exception of oxirane. The same is true of polymeric radical anions obtained upon metalation of poly(vinylbenzophenone) with alkali metals. ... 

Energy transfer from polymeric sensitizers such as poly(vinylbenzophenone) has been undertaken in order to examine whether molecular size influenced the ability to transfer energy to acceptor molecules. To this end we have investigated the ability of poly(vinylbenzophenone) to sensitize the solution photoisomerization of cis- and /mn5-stilbene [37]. 

Poly[styrene-co-(2-hydroxy-4 -vinylbenzophenone)] was less efficient in PS than 2-hydroxy-4-methoxybenzophenone [334]. Similarly, PE films doped with 4-dodecyloxy-2-hydroxybenzophenone (0.1 mol%) were more stable than PE doped with copolymers of ethylene with polymerisable benzophenones having a comparable content of chromophores [54]. The efficiency of a SAN type LS, a terpolymer of 2-hydroxy-4-(4-vinylbenzyloxy)benzophenone with acrylonitrile and styrene did not exceed that of conventional LS [84]. No efficiency loss of 2-hydroxy-4-methacryloyloxybenzophenone in ABS was observed after bonding into a terpolymer with styrene and acrylonitrile. The homopolymer was slightly inferior to both the monomer and terpolymer [84]. A better protection of PP was provided by poly[(2-hydroxy-3-allyl-4-methoxyphenylbenzophenone)-co-dibutyl maleate] than with 2-hydroxy-3-allyl-4-methoxybenzophenone [335] (stabilization tests were performed in the presence of phenolic antioxidants). A comparable or better light stabilizing efficiency of poly[vinyl acetate-co-(5-methylacryloyloxy salicylate)] or poly(2-allylphenyl salicylate-co-dioctyl maleate) than that of alkyl-phenyl salicylates was observed in polyolefins [335]. 

UV irradiation of poly(4-vinylbenzophenone) [poly(VBP)] in benzene solution, and in the presence of isopropanol as hydrogen donor, gives rise to a more complex picture [12,13]. Indeed, intra- and inter-molecular coupling reactions by the side-chain benzophenone ketyl radicals (K ) markedly change the macro-molecular morphology with the occurrence of cyclic and network structures as well as chain scission processes (Scheme 5). 

Furthermore, copolymers of 4-vinylbenzophenone with 4-(A/, A-dimethyl-amino) styrene [poly(VBP-co-DMAS)] are found [18,22,53] to exhibit even lower photoinitiation activity (Table 12) than poly(ABP-co-DMAS). 

TABLE IS. Properties of Cycloadducts between Poly(styrene-co-Vinylbenzophenone) and Various Olefins ... 

Second viiial coefficient of poly(styrene-co-4-vinylbenzophenone)... 

Poly(styrene-co-2,4-dihydroxy-4-vinylbenzophenone-iror-styrene) ... 

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