| Abstract: | Styrene (St) and methyl methacrylate (MMA) were polymerized by azobisisobutyronitrile at 50°C. in the presence of silanes such as tetramethylsilane, trimethylcholorosilane, dimethyldichlorosilane, methyltrichlorosilane, and tetrachlorosilane. The polymerization rates of both St and MMA in the presence of silanes were nearly equal to those in the absence of silanes. On the other hand, the molecular weights decreased gradually as the concentration of chlorosilane increased. The chain transfer constants of all the silanes in the polymerization of St and MMA at 50°C. were calculated by Mayo's equation. The chain transfer constants of Me4Si, Me3SiCl, Me2SiCl, MeSiCl3, and SiCl4 were 0.31 × 10?3, 1.25 × 10?3, 1.78 × 10?3, 1.92 × 10?3, and 2.0 × 10?3, for St and 0.13 × 10?3, 0.22 × 10?3, 0.245 × 10?3, 0.27 × 10?3, and 0.30 × 10?3, for MMA, respectively. From these results, it was found that the Si? Cl bond was radically cleaved. The Qtr values of the silanes, in the same order as above, were found to be 1.03 × 10?4, 2.33 × 10?4, 2.83 × 10?4, 3.10 × 10?4, and 3.35 × 10?4, respectively and the etr values were +0.58, +1.30, +1.50, +1.48, and +1.43, respectively. |
