Effect of incorporated amide blocks on the glass transition in polyesteramides

Abstract

Incorporation of amide blocks is a common strategy used to promote the thermal and mechanical performances of polyesteramides. Meanwhile, glass transition temperature (Tg) is often used as one of the key parameters for measuring their physiochemical properties. Using a classical molecular dynamics approach, the Tg values of polyesteramides with a varying amide content are predicted by distinguishing their density variations with temperature. The predicted Tg values are in agreement with the measurements with an overestimation of about 2.6–6.5%. The incorporation of amide blocks favors the formation of interchain hydrogen bonds (HB). Although the relationship between Tg and HB formation has been well established, our simulations reveal that the entanglement of polyesteramide backbones leads to the Tg reduction at a high amide content, which is caused by the interplay between inter- and intra-chain HB numbers. The revealed molecular mechanism of Tg dependence on amide addition is helpful for the molecular design of functional polyesteramides.