Radical polymerization of butyl acrylate and random copolymerization of styrene and butyl acrylate and styrene and methyl methacrylate mediated by monospiro-and dispiropiperidinyl-N-oxyl radicals

摘要

Radial polymerization of butyl acrylate (BA) and random copolymerizations of styrene (St) and BA and St and methyl methacrylate (MMA) in the presence of 7-aza-15-hydroxydispiro[5.1.5.3]hexadecane-7-yloxl (1) and 1-aza-2,2-dimethyl-4-hydroxyspiro[5.6]dodecane-1-yloxy (2) were carried out. Radical polymerization of BA at 120 deg C in the presence of 1 gave poly(BA) with M_n = 20200 and M_w/M_n = 1.30 at 23% conversion. The termination of polymerization observed around approx 20% conversion was solved to a certain extent by an addition of small amounts of dicumyl peroxide, and poly(BA) with M_n = 37400 and M_w/M_n = 1.33 was obtained in 46% yield. Random copolymerizations of St and BA and St and MMA in the presence of 1 and 2 at 80 deg C gave the corresponding random copolymers with narrow polydispersities of 1.12-1.38 at the molar fraction above 0.30 of St in feed. The kinetic study for the NO-C bond homolysis of the corresponding alkoxyamines prepared from 1 and 2 were carried out, and evaluation of the preexponential factors (A_act) and the activation parameters (E_act) showed that the steric factors of the nitroxides are reflected mainly on E_act.