The Melting Point of Crystalline Copolymers – Applying Materials Simulation

Abstract

The defect Gibbs energy of hydroxyvalerate comonomer inclusions into the crystals made up by random copolymers of poly(?-hydroxybutyrate-co-?-hydroxyvalerate) (PHB/HV) is calculated by means of the thermodynamic integration approach. The result obtained for a single inclusion is in excellent agreement with those obtained by fitting experimental melting temperature and cocrystal composition data. On decomposing the Gibbs energy, it is found that the crystallization entropy contributes the dominant part of the defect Gibbs energy. Our calculations on multi-inclusion crystals show that the Gibbs energy strongly decreases when the comonomers aggregate in a preferred pattern. Further information to the design of isomorphic copolymers is obtained from these calculations.