High T-g poly(ester amide)s by melt polycondensation of monomers from renewable resources; citric acid, D-glucono-delta-lactone and amino acids: A DSC study

摘要

We present a systematic, thermal study on the synthesis of poly(ester amide)s (PEAs) by the melt condensation of citric acid (CA), D-glucono-delta-lactone (GL) and various amino acids (AAs). The reactions were studied by differential scanning calorimetry (DSC) and it was found that the incorporation of amino acids into the previously investigated CA/GL system (de Jongh et al., 2017) results in a significant increase of the glass transition temperature (T(g)s) of the resulting PEAS as a result of the introduction of amide bonds. AAs with functional side chains (i.e. hydroxyl, thiol, carboxylic acid or amine) resulted in higher To than AM with hydrophobic, non-reactive side chains, which is attributed to additional crosslinking in the PEAs. The copolymerisation of proline (and two structural analogues), despite having no reactive side chain, yielded PEAS with significantly higher To than any other AA as a result of its cyclic structure.