Journal of Polymer Science Part A: Polymer Chemistry, Vol.40, No.20, 3350-3359, 2002
Living radical graft polymerization of methyl methacrylate to polyethylene film with typical and reverse atom transfer radical polymerization
Nickel-mediated atom transfer radical polymerization (ATRP) and iron-mediated reverse ATRP were applied to the living radical graft polymerization of methyl methacrylate onto solid high-density polyethylene (HDPE) films modified with 2,2,2-tribromoethanol and benzophenone, respectively. The number-average molecular weight (M-n) of the free poly(methyl methacrylate) (PMMA) produced simultaneously during grafting grew with the monomer conversion. The weight-average molecular weight/number-average molecular weight ratio (M-w/M-n) was small (< 1.4), indicating a controlled polymerization. The grafting ratio showed a linear relation with M-n of the free PMMA for both reaction systems. With the same characteristics, assumed for both free and graft PMMA, the grafting was controlled, and the increase in grafting ratio was ascribed to the growing chain length of the graft PMMA. In fact, M-n and M-w/M-n of the grafted PMMA chains cleaved from the polyethylene substrate were only slightly larger than those of the free PMMA chains, and this was confirmed in the system of nickel-mediated ATRP. An appropriate period of UV proirradiation controlled the amount of initiation groups introduced to the HDPE film modified with benzophenone, The grafting ratio increased linearly with the preirradiation time, The graft polymerizations for both reaction systems proceeded in a controlled fashion.
Keywords:atom transfer radical polymerization (ATRP);reverse atom transfer radical polymerization;controlled graft polymerization;high-density polyethylene;methyl methacrylate;surface functionalization