New addition - fragmentation chain transfer agents synthesized by the Perkow reaction.

摘要

Studies were conducted in which α-styryl phosphorus esters, compounds easily synthesized using the Perkow reaction, were evaluated as a new class of addition-fragmentation chain transfer agents. In a series of experiments with methyl methacrylate, methyl acrylate, methacrylonitrile, and N-vinylpyrrolidone, 1-phenylvinyl diphenylphosphinate was found to be an effective chain transfer agent. The chain transfer constants (C _S) were calculated using the Mayo equation, and were found to be in the range of 0.1–0.5. 1-Phenylvinyl diphenylphosphinate was found to be less effective as a chain transfer agent in polymerizations of 2-vinylpyridine (C_S = 0.02). No chain transfer was observed in polymerizations of styrene conducted in the presence of 1-phenylvinyl diphenylphosphinate.; Studies were also conducted to determine the effectiveness of 1-phenylvinyl diphenylphosphinate as a chain transfer agent in polymerizations of methyl methacrylate performed using other free radical polymerization methods. These experiments indicated that this material was as effective in polymerizations conducted in solution, suspension, and photoinitiated polymerizations as in bulk polymerization. In experiments performed using an emulsion polymerization system, the chain transfer activity of 1-phenylvinyl diphenylphosphinate was found to be low, a reflection of its hydrophobic nature.; Studies with other 1-phenylvinyl phosphorus esters potentially capable of chain transfer by an addition-fragmentation mechanism such as 1-phenylvinyl dimethyl phosphate, 1-phenylvinyl diphenyl phosphate, 1-phenylvinyl methyl phenylphosphonate, and 1-phenylvinyl neopentylene phosphate were also conducted.; 31P-NMR spectra of polymers formed in polymerizations conducted in the presence of 1-phenylvinyl diphenylphosphinate suggest that phosphinate units are incorporated into the polymer chains. This indicates that fragmentation of the radical adduct resulting from addition of a propagating radical chain to the phosphinate is not quantitative. Furthermore, the hydrolytic stability of 1-phenylvinyl diphenylphosphinate was investigated using 1H-NMR spectroscopy.