Synthesis of Oligo(butylene succinate)-based Polyurethanes

Biobased oligo(butylene succinate)-based thermoplastic polyurethanes (TPUs) were prepared following a two-step polymerization process: condensation of succinic acid and butanediol and the chain extension of resulting hydroxyl-terminated butylene succinate oligomers (OBS) in the presence of butanediol as chain extender and isophorone diisocyanate (IPDI) as coupling agent. Mechanical and thermal properties of the elaborated TPUs were evaluated in terms of hard segment and compared with those of commercial polybutylene succinate (PBS), Bionolle 1001. Whatever the compositions, the ultimate tensile properties of OBS-based TPUs and Bionolle 1001 were found to exhibit similar values ( ≈400%, σ ≈40 MPa), which can be explained by their close molecular weight (60000 g.mol-1 equiv. PS). Interestingly, a higher content of hard segments within OBS-based TPUs leads to materials exhibiting higher rigidity, smaller degree of crystallization, lower melting temperature and weaker stability of the materials with temperature. Such a trend was attributed to the presence of urethane functions and their ability to set up strong H-bonding interchain interactions.