Homopolymers of 1-and 2-naphthyl acrylate and methacrylate have been synthesized, and their photochemistry and fluorescence behavior have been studied in THF at 25 °C. All four polymers undergo a photo-Fries reaction which leads to the introduction of quenching groups on the polymer chain. The polymers also exhibit intramolecular excimer fluorescence, with the ratio of excimer to monomer emission greater in the more flexible poly acrylates. Quantum yields of photochemical reaction are of the same magnitude as those of fluorescence. Irradiation of methacrylate homopolymers or copolymers with vinyl ketone monomers leads to random chain scission with low quantum yield, a process which enables determination of the Mark-Houwink viscosity laws for each polymer. The polyacrylates undergo cross-linking in competition with chain scission. Variations between the monomer fluorescence decay functions of the four polymers are attributed to differences in the nature of the chromophores and, to a lesser degree, to differences in chain flexibility.

fert-Butyl peresters based on aromatic hydrocarbon and aryl ketone chromophores with lowest lying tt-tt* transitions have been synthesized and tested as photoinitiators in radical processes. The systems designed are of varying efficacy, with the nonketonic systems serving as better initiators with higher concentrations of aromatic monomers such as styrene.Acknowledgment. This work has been supported by the National Science Foundation, DMR 8103100. We are most grateful for this support. The authors also acknowledge many helpful discussions with Professor Satyendra Gupta.Registry No. 1, 2, 3, 4, 88475-88-1; 5, 88475-89-2; 4-(bromomethyl)benzoyl chloride, 52780-16-2; pyrene, 129-00-0; 4-carbomethoxybenzoyl chloride, 7377-26-6; 4-[(1 -pyrenyl)carbonyl]benzoic acid, methyl ester, 88475-90-5; 4-[(l-pyrenyl)carbonyl]benzoic acid, 88475-91-6; pyrene-l-carboxylic acid, 19694-02-1; 4-carboxyfluorenone,

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The effect of tacticity upon the photodegradation of poly(acry1ophenone) in fluid solution has been investigated. The quantum yield of main-chain scission via the Norrish type I1 reaction was found to be approximately 0.40 for both isotactic and atactic homopolymers in toluene solution. The behavior is rationalized on the basis of identical local conformations for the biradical intermediates. The ineffectiveness of low levels of an added Lewis base in enhancing the quantum yield may be attributable to an intramolecular biradical stabilization mechanism. IntroductionThe effect of tacticity on polymeric photoprocesses has only recently come under intensive investigation. Most studies in this regard have dealt with excimer formation in polystyrene. Vala et al. ' have reported that the solution fluorescence spectra of polystyrene is independent of tacticity. However, subsequent results published by indicate that the ratio of

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