Synthesis and Characterization of Polypropylene-Based Polyurethanes

Abstract

A novel multiblock copolymer, polypropylene (PP)-based polyurethane (PU) (PbPU), has been successfully synthesized. Dihydroxyl end-capped macromonomers, prepared from the pyrolysis product of commercial PP followed by hydroxylation, reacted with polytetrahydrofuran (PTMEG) via a coupling reaction between the hydroxyl and isocyanate groups, to obtain multiblock copolymers with PP and PU segments. Here, a cheap and practical hydroxylation route using in situ generated amino borane was first applied for the functionalization of PP on a large scale, which was proven to be of high efficiency by 1H NMR measurement. PbPU copolymers with different compositions were prepared. The microstructure and basic properties of the resultant copolymers were studied by differential scanning calorimetry (DSC), atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), and mechanical testing. The PbPU copolymers presented excellent compatibilization for PP/PU blends, in which a significant enhancement in the interface adhesion and an improvement of mechanical properties can be achieved, regardless of the composition of the blends. Moreover, it is expected that the PbPUs can be used as a “versatile compatibilizer” for PP/polar polymer blends, considering that the PU segments in the copolymer show miscibility with many polar polymers, such as PP/poly(methyl methacrylate) (PMMA), PP/poly(vinyl chloride) (PVC), PP/poly(vinylidene difluoride) (PVDF), etc.