Methyl 10-undecenoate as a raw material for the synthesis of renewable semi-crystalline polyesters and poly(ester-amide)s

Castor oil was efficiently used as a raw material for the synthesis of polyesters and poly(ester-amide)s. Aliphatic diols containing monoester, diester, ester-amide, monoamide and diamide linkages were synthesized from methyl 10-undecenoate through transesterification, amidation and thiol–ene reactions. These diols were then reacted with a bio-based methyl diester in the presence of TBD as a transesterification catalyst, yielding polyesters or poly(ester-amide)s with relatively high molar masses. These polyesters were characterized by FTIR, SEC and 1H-NMR spectroscopy and showed good accordance in terms of chemical structure with the theoretical compositions. Most of the polyesters displayed good thermal stability with temperature at 5% weight loss in the range 330–350 °C. Due to the fully aliphatic nature, the glass transition temperature of these materials was well below room temperature. However the incorporation of amide functions in the polyester backbone resulted in semi-crystalline materials with melting points ranging from 22 °C to 127 °C and complex melting behaviors due to polymorphism and melting–crystallization processes. Tensile properties of these polyesters were also investigated revealing a large increase of Young's modulus from 83 to 363 MPa with increasing ratios of amide functions.