Abstract
Cotelomers of 4-vinylpyridine (VP) and methyl acrylate (MA) prepared in a telogen of 1-dodecanethiol (LSH) or 1-dodecanol (LOH) were characterized. Ls-VP-MA accounting for 6.110.9 of the degree of polymerization (Pn) was a brown viscous liquid. The ratio of LSH to monomers (VP+MA) in the feed (β) was proportional to 1/Pn. A plot of MA to VP (α) vs. the chain-transfer constant (Cs) gave a straight line from which the following formula (1) was derived.
1/Pn= {4.6×10-1/ (1+α) +8.4×10-2} β+2.5α×10-3+7.6×10-2 (1)
The monomer composition of Ls-VP-MA was not effected by β, and the reactivity ratios of rVP and rMA calculated using the Fineman-Ross equations were 1.9 and 0.25, respectively. Lo-VP-MA prepared at 70°C was a yellow precipitate and 85211 of Pn, and that prepared at 175°C was a brown precipitate and 1244 of Pn. An approximately linear relationship was found between β and 1/Pn and the following equation was consequently derived.
1/Pn= {5.3×10-3/ (1+α) +7.8×10-4} β+4.5α×10-3-5.0×10-3 (2)
The monomer-cotelomer composition curve for Lo-VP-MA was similar to that of Ls-VP-MA. The reactivity ratios of rVP and rMA were 2.1 and 0.23, respectively. The reciprocal of Pn of Ls-VP-St (styrene) and Lo-VP-VAc (vinyl acetate) increased with β, and their reactivity ratios were essentially the same as those for the copolymerization of VP-St or VP-VAc.
