Radical Copolymerization of 2-lsopropenyl-2-oxazoline with Styrene in the Presence of Lewis Acids

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Abstract
Free-radical copolymerization of 2-isopropenyl-2-oxazoline (IPOZ) with styrene (ST) and methyl meth-acrylate (MMA) was carried out at 60°C. The reactivity of IPOZ (Q=0.81 and e=0.35) was nearly equal to that of MMA. In the radical polymerization of IPOZ in the presence of ZnCl2, the initial polymerization rate and the specific viscosity of the resulting polymer increased with an increase in the concentration of ZnCl2. The tacticities of the polymer determined by the NMR spectrum of the polymer obtained by radical polymerization showed that the content of syndiotactic triads of the polymer obtained in the absence of ZnCl2 was greater than that in the presence of ZnCl2. In the radical copolymerization of IPOZ (Mjand styrene (M2) in the presence of ZnCl2, the apparent reactivity ratio r1 increased with an increase in the ZnCl2 molar content, whereas r2 decreased. The apparent Q and e values of IPOZ increased markedly by the addition of ZnCl2. The radical copolymerizations in the presence of Lewis acids such as SnCl4, BF3, and HgCl2 gave copolymerization behaviors similar to those in ZnCl2. The white solid complexes isolated from IPOZ and Lewis acids were identified by spectroscopic (IR and NMR spectra) and elemental analyses. On the basis of these results, the reactivities of the complexed IPOZ monomer with Lewis acid and the radical derived from the complexed monomer are discussed.

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