Synthesis and properties of polyurethanes based on polyolefin: 2. Semicrystalline segmented polyurethanes prepared under heterogeneous or homogeneous synthesis conditions

Synthesis and Structure - Property Relations of Latexes Containing Graft Copolymers between Telechelic Polybutadiene and Dodecyl Methacrylate

Latexes comprising novel copolymers were formed by second-stage emulsion polymerization of dodecyl methacrylate (DMA) onto a hydroxylated polybutadiene-based polyurethane prepolymer (PUD) as seed latex, with persulfate initiator. Morphology data from TEM imaging (including chemical fixation ultra-microtoming), glass transition temperature, dynamic mechanical analysis, and other mechanical-property data were all consistent with a system showing extensive grafting and compatibilization between the different polymeric components. Water adsorption and AFM measurements showed that samples with poorer film-forming properties had higher water sensitivity, greater mixing of the polymer phases, and poorer mechanical properties. These properties were related to a phase-inversion phenomenon occurring above a critical dodecyl methacrylate/prepolymer ratio. The compatibilization of the PUD and poly(DMA) given by these modifications resulted in a product with increased tackiness, although with a higher water sensitivity.