SULFUR-CONTAINING POLYACRYLATES .4. THE EFFECT OF S-LINKAGE AND O-LINKAGE ON THE PHOTO INDUCED AND THERMALLY-INDUCED POLYMERIZATION OF DIMETHACRYLATES

The photo- and thermally induced polymerization of four analogous dimethacrylates-2,2'-thiobisethanol dimethacrylate, 2,2'-oxybisethanol dimethacrylate, pentanediol-1,5-dimethacrylate, and butanediol-1,4-dimethacrylate-was studied to determine the influence of - S - and - O - linkages on the polymerization course. Generally, the presence of the heteroatom in the monomer molecule results in higher reaction rates and yields but the extent of this influence highly depends on the polymerization conditions and the type of heteroatom. The effect of the thioether bond exceeds the effect of the ether bond at lower (40-degrees-C) temperature in the presence of oxygen but the reverse situation takes place at higher (75-degrees-C) temperature and/or in an inert atmosphere when photofragmentating and thermal initiators are used. The results are discussed mainly in terms of propensity of sulfides and ethers to act as hydrogen donors and chain-transfer agents. (C) 1993 John Wiley & Sons, Inc.