Synthesis and thermal properties of poly(ester-siloxane) multiblock copolymers

The goal of this research was the synthesis and thermal characterization of poly(ester-siloxane) multiblock copolymers. Poly(butylene terephthalate) (PBT) was the polyester block. α, ω-Diamino-terminated poly(dimethylsiloxane) (PDMS) was reacted with an excess of dimerized fatty acid to form a dicarboxy-terminated oligomer containing stable amide links. Multiblock copolymers were obtained in a three-stage process: oligomer preparation, transesterification, and polycondensation from the melt. A magnesium-titanate catalyst was used for transesterification and polymer formation (polycondensation). The synthesized oligomer was considered to be the soft segment and its content ranged from 20 to 45% by weight. Multiblock copolymers showed microphase separation as determined by differential scanning calorimetry (DSC). Their morphology was studied by optical microscopy (OM) and showed spherulitic ordering.