Morphology and properties of high molecular weight polyisobutylene and thermoplastic polyurethane elastomer

High molecular weight polyisobutylene (PIB) was modified by a mild and facile melt-mixing process with thermoplastic polyurethane elastomer (TPU) in the presence of a compatibilizer, i.e., polypropylene-g-maleic anhydride (PP-g-MAH). Scanning electron microscopy (SEM) in combination with solvent etching revealed a significantly phase-separated morphology due to different polarity of PIB and TPU. An evolution from dispersed phase to continuous phase for TPU was observed with the increase of TPU content, leading to an enhanced tensile strength of PIB/TPU blend in comparison to PIB. This phase-separated morphology of PIB/TPU blend was confirmed by FTIR and thermal analysis. Rheological studies suggested that the PIB/TPU blend (30 wt% of TPU) exhibited a typical non-Newtonian fluid behavior. More importantly, PIB/TPU blend was shown to possess enhanced thermal and oxidative/hydrolytic stability in comparison to TPU. SEM combined energy dispersive spectrometer (EDS) further elucidated that the surface chemical composition of PIB/TPU blend can be tailored through annealing, which further improved the biocompatibility as well as the oxidative/hydrolytic stability.