Controlled scrambling reactions of polybutadiene and olefin-containing polyurethane prepared by step-growth or chain-growth polymerization were accomplished via macromolecular olefin cross-metathesis in the presence of Grubbs' second-generation catalyst to yield scrambled copolymers with different thermal and mechanical properties. In addition, naturally occurring polyisoprene and olefin-containing polyurethane were successfully scrambled, demonstrating that these polymers can be used to synthesize natural/synthetic hybrid materials by the cross-metathesis reaction. Effects of reaction time, solvent, and homopolymer structure on these scrambling reactions were investigated. This metathesis-based approach facilitates the precise control of the scrambling reactions under the applied reaction conditions, thus affording the desired polymer structures with compositions ranging from multiblock to random compositions and enhanced mechanical properties.
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