The radical polymerization of a polystyrene macromonomer having a methacryloyl end group (with an M, of 2700), was investigated at various macromonomer concentrations ([M]), in order to study in detail the effect of [M] on the polymerization behaviour. The polymerization rate (Rp), the degree of polymerization (DP), the concentration of the propagating radical ([M*]), and the initiator efficiency (f) were evaluated by gel permeation chromatography, using an instrument equipped with a laser light scattering detector (1.s.-g.p.c.), and also by electron spin resonance (e.s.r.) spectroscopy. The viscosity of the polymerization solution (~/) was also measured, by using an Ubbelohde viscometer. The DP of the formed poly(macromonomer)s changes drastically with [M]. The order of Rp and Rp/?~/2, with respect to [M], was 2.2 and 1.3, respectively, where q~ is the ratio of ~/of the polymerization system to that of the solvent. This indicates that ~/alone is not responsible for an order of R o that is larger than unity. Values for the propagation rate constant (kp) were approximately constant with respect to [M], while those of the termination rate constant (kt) rapidly decreased with increases in [M]. These results are discussed in terms of [M], ~/, and the segment density around the propagating radical site.
Посилання на статтю:
Radical polymerization behaviour of macromonomers: 3. Effect of macromonomer concentration / Kiyoharu Tsutsumi and Yoshio Okamoto // Polymer. – 1994. – Vol 35. – P. 2205-2209.