Structure–Property Relationships of Poly(glycolic acid) and Poly(2-hydroxybutyrate)

Abstract

Conformational analysis of poly(glycolic acid) (PGA) and poly(2-hydroxybutyrate) (P2HB) has been carried out via molecular orbital (MO) calculations and NMR experiments on model compounds. The MO energies validated through comparison with the NMR data were introduced into the rotational isomeric state (RIS) scheme to yield the configurational properties of the two polymers. The spatial configuration of the P2HB chain with chiral centers was calculated by the RIS scheme combined with stochastic processes and expressed as a function of (S)/(R) or meso/ racemo ratio. The above results are compared with those obtained previously for poly(lactic acid) and discussed. The density functional theory calculations with a dispersion force correction were performed for PGA crystal under periodic boundary conditions and revealed the origin of its superior thermostability and mechanical strengths.