REACTIVITY OF A POLYMERIZABLE AMINE ACTIVATOR IN THE FREE-RADICAL COPOLYMERIZATION WITH METHYL-METHACRYLATE AND SURFACE-PROPERTIES OF COPOLYMERS

The relative reactivity of a polymerizable tertiary amine in free radi cal polymerization is analysed through the study of its copolymerizati on with methyl methacrylate initiated by benzoyl peroxide at low tempe rature. Copolymers of N,N-dimethylaminobenzyl methacrylate with methyl methacrylate were prepared in solution at low temperature (30 and 35 degrees C) by using the polymerizable acrylic amine/BPO redox system a s initiator. The reactivity ratios were calculated according to the ge neral copolymerization equation from composition data of copolymer sam ples determined by H-1 n.m.r. spectroscopy, and by using both lineariz ation methods and the non-linear least square analysis of Tidwell and Mortimer. The values obtained indicated that this system approaches to the ideal behaviour. Wetting experiments were carried out at room tem perature in air to determine the surface energy of the copolymers. It was found that the surface energy increased with the content of N,N-di methylaminobenzyl methacrylate in the copolymer, the copolymers becomi ng more hydrophobic as the fraction of this monomer increased in the c opolymer. (C) 1997 Elsevier Science Ltd.