Poly(alkyl itaconates): 8. Observations of dual glass transitions and crystallinity in the dialkyl ester series diheptyl to di-eicosyl

Abstract

A series of poly(di-n-alkyl itaconic acid esters) with side chain lengths from 7 to 20 carbon atoms have been prepared. For derivatives with chain lengths of 7 to 11 carbons, two glass transition temperatures have been detected. The transition occurring at the lower temperature T 2 g originates in the side groups and is a result of the independent cooperative relaxation of the alkyl side chains, while that observed at higher temperatures T 1 g reflects the glass-rubber transition of the main chain backbone and the cooperative motion of the total molecule. Derivatives with chain lengths ⩾12 carbon atoms display melting temperatures T m , and measurement of the enthalpy of fusion ΔH f indicates that side chain crystallization takes place with part of each side chain entering into a regularly packed hexagonal lattice.