Synthetic polyhydroxypolyamides from galactaric, xylaric, D ‐glucaric, and D ‐mannaric acids and alkylenediamine monomers—some comparisons

The condensation polymerization in a methanol solution of four different esterified aldaric acids (D-glucaric, meso-xylaric, meso-galactaric, and D-mannaric) with even-numbered alkylenediamines (C2–C12) gave polyhydroxypolyamides whose water solubilities and melting points were compared. In general, an increase in the alkylenediamine monomer length resulted in decreased polyamide water solubility. Differences in the polymer melting points and water solubilities were linked primarily to conformational differences of the monomer aldaryl units; for example, polyamides from meso-galactaric acid with an extended zigzag conformation aldaryl monomer unit had higher melting points and lower water solubilities than those from D-glucaric and meso-xylaric acids. The latter acid monomer units tended toward bent conformations that served to diminish intermolecular attractive forces between polymer chains, affecting polymer solubility and melting characteristics.