Structure formation and hydrogen bonding in all-aliphatic segmented copolymers with uniform hard segments

Fully aliphatic segmented poly(ether ester amide) copolymers with uniform hard segments prepared by melt polycondensation of α,ω-hydroxyl end-functionalized polytetrahydrofuran and short glycine or β-alanine bisester-bisoxalamide units hold promise for biomedical applications. For polymers with the hard block contents varying from 10% to 27%, differential scanning calorimetry and atomic force microscopy reveal a highly phase-separated morphology, with ribbon-like nanocrystals dispersed in the soft segment matrix. To relate the polymer properties to the structure of the hard segment, the monomers were prepared and studied by optical and X-ray diffraction measurements. It was shown that the glycine and β-alanine carbonyl ester groups are tilted away from the oxalamide plane, which can affect the degradation rate via hydrolysis of the ester bond.