Determination of the propagation rate coefficient for 3-[tris(trimethylsilyloxy)silyl] propyl methacrylate by pulsed-laser polymerization

Abstract

The free radical propagation rate coefficient of 3-[tris(trimethylsilyloxy)silyl] propyl methacrylate was measured by pulsed-laser polymerization over the temperature range 288–323 K. The activation energy and pre-exponential factor were determined, by fitting the propagation data to the Arrhenius equation, as 19.9 kJ/mol and 1.44×10 6 l mol −1 s −1, respectively. This value for the activation energy is significantly less than that obtained for the lower alkyl methacrylates and is similar to that previously reported for dodecyl methacrylate. The Mark–Houwink–Kuhn–Sakurada (MHKS) values for poly(3-[tris(trimethylsilyloxy)silyl] propyl methacrylate) in tetrahydrofuran were also determined using size exclusion chromatography with on-line viscometry and refractive index detectors. The molecular weight–intrinsic viscosity distributions were measured for forty-four independent samples yielding MHKS constants of 1.67×10 −5 dl/g and 0.74 for K and α respectively.