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Segmented polyurethanes (SPUs) based on PEG, PTMC and PLLA as macrodiols, HDI as diisocyanate and BDO as chain extender were synthetized and characterized with respect to composition, thermal and dynamical mechanical properties. The SPUs are heterogeneous and the thermal events observed in DSC and DMA analyses are related to the macrodiols components, being affected by the global composition.

Segmented polyurethanes based on poly(l-lactide)diol -PLLA, poly(ethylene-glycol) -PEG, poly(trimethylenecarbonate)diol -PTMC and hexamethylene diisocyanate were synthesized by a two-step polyaddition. Polyurethanes with variable compositions and molar mass were semi-crystalline and presented PLLA or PLLA + PEG crystalline phases and a heterogeneous amorphous phase. Sequential crystallization of PLLA and PEG resulted in a confined PEG crystallization into the PLLA crystalline phase. The random distribution of the segments in the polymer chains and the partial miscibility of the segments in the amorphous phase strongly influenced the morphology of the crystalline phase, and the kinetics of the crystallization. Morphology changed from not well-defined spherulites with Maltese cross to ring banded spherulites and axialites as the PLLA mass fraction decreased. PLLA nucleation and crystal growth rates varied with crystallization temperature similarly to homopolymers, presenting a bell-shaped curve, and the temperature for the maximum growth rate dependent on the polyurethanes composition.