Kinetics and mechanism of the grafting of 2‐(dimethylamino)ethyl methacrylate onto hydrocarbon substrates

Abstract

AbstractThe kinetics of grafting a basic monomer, 2‐(dimethylamino)‐ethyl methacrylate (DMAEMA) to hydrocarbon substrates have been investigated. These systems were chosen as models for the grafting of a homopolymerizable monomer to polyolefins such as polyethylene. The reactions with squalane and n‐eicosane were initiated by an organic peroxide, 2,5‐dimethyl 2,5 dit‐butylperoxy)‐3‐hexyne; grafting yields become significant at high reaction temperatures and low monomer concentrations. In squalane, the order of reaction with respect to monomer increased from about 1.1 for 0.22−0.44M DMAEMA to almost 2 at 0.69M DMAEMA; the order with respect to initiator was 0.56. The overall activation energy in the 130−160°C temperature range was, however, surprisingly low, 42±5 kJ mol−1. When analytical data were used to separate the overall rate into those for grafting and homopolymerization, different kinetic paths were observed for the competing reactions. These results are interpreted in terms of two different mechanisms; intramolecular chain transfer plays an important role in grafting, while depropagation becomes a major factor in homopolymerization at temperatures above 150°C. © 1995 John Wiley & Sons, Inc.