Synthesis and Structural Characterization of Oligo(carbonate diol)s and Oligo(urethane-carbonate diol)s via a Transesterification-Polycondensation Route.

Oligocarbonate diols (OCD) require tedious and time-consuming synthesis procedures. The most common ones use dimethyl carbonate or alkylene carbonate as starting materials. Considering the preparation of small batches of oligomerols with an atypical structure, this methodology is not convenient. Therefore, we developed a simple way to obtain OCDs and oligo(urethane-carbonate) diols (OUCDs) containing aliphatic, cycloaliphatic, aromatic or oxyethylene units based on commercially available OCDs (ETERNACOLL, UBE). The process was conducted in two stages combining transesterification/transurethanization and polycondensation reactions. It resulted in novel OCDs and OUCDs with an irregular structure. Their composition was characterized using FT-IR, NMR, and MALDI-TOF techniques. The hydroxyl values were determined by potentiometric titration. The numerical average molar masses of the oligomerols ranged from approx. 1000 to 3200 g/mol, making them attractive materials for the preparation of a variety of polyurethane products. Thanks to the presence of carbonate moieties that are resistant to hydrolytic and oxidative degradation, poly(carbonate-urethane)s could find applications as coatings, thermoplastic elastomers, and biomaterials. The influence of the structural variations of the oligomerols on the properties of polyurethanes is now under investigation.