Synthesis of methacrylic acid-acrylonitrile alternating copolymer using an extremely bulky methacrylate and the sequence-dependent thermal reaction behaviors

Abstract

In this work, we achieved the synthesis of the alternating copolymer composed of commodity monomer units, methacrylic acid (MAA) and acrylonitrile (AN), by using a bulky and transformable methacrylate carrying 2-ethylfenchyl ester group (EFMA). The low propensity of EFMA in radical homopolymerization and the high reactivity of AN radical to methacrylate monomer in radical copolymerization allowed the peculiar alternating propagation, which was supported by the low reactivity ratios [r1 = 0.03, r2 = 0.23 for EFMA (M1) and AN (M2)]. The resultant EFMA-AN alternating copolymer was quantitatively transformed into the MAA-AN counterpart via acidolysis, as supported by 1H and 13C NMR analyses in comparison with the corresponding 1:1 statistical copolymer. The MAA-AN alternating copolymer underwent thermal reaction between neighboring pendant groups in alternating sequence, which was different from the statistical copolymer composed of various sequence patterns.