Polymerization of Nonionic Surfactants: Poly(ethylene oxide) Macromonomers

摘要

A series of polymerizable macromonomers of co-methoxy poly(ethylene oxide)_n undecyl-a-methacrylate (PEO-R-MA-n, where n = 10, 15, 40) were synthesized. The critical micelle concentration of the PEO-macromonomer with n = 40 is 6.6 × 10~(-5) mol/L at 25℃. The kinetics of its polymerization in aqueous solution follows conventional solution polymerization, i.e., first and half order with respect to the concentrations of the PEO-macromonomer and K_2S_2O_8, respectively. The rate of its polymerization in water was extremely rapid as compared to its solution polymerization in benzene. The activation energies for the polymerization were 57 kJ/mol in water but 179 kJ/mol in benzene. The aqueous system produced polymers with a number-average degree of polymerization (DP_n) ranging from about 130 to 160, but it was around 7 for the benzene system, the results suggested that organized structures and compact cores of macromonomer micelles are responsible for the unusually rapid polymerization in aqueous solution.