Poly(methyl methacrylate)-block-polyethylene-block-poly(methyl methacrylate) Triblock Copolymers as Compatibilizers for Polyethylene/Poly(methyl methacrylate) Blends

High Resolution Image Download MS PowerPoint Slide Poly(methyl methacrylate)- block -polyethylene- block -poly(methyl methacrylate) (PMMA–PE–PMMA) triblock copolymers were prepared by a combination of ring-opening metathesis polymerization (ROMP), hydrogenation, and reversible addition–fragmentation chain-transfer (RAFT) polymerization. The number-average molar masses of the PMMA end blocks were varied ( M n = 1, 4, 12, and 31 kg mol –1 ), whereas that of the PE middle block was kept constant at M n = 13 kg mol –1 . The copolymers were evaluated as compatibilizers in PE/PMMA homopolymer blends containing PE in a 4:1 excess by weight. The compatibilized blends displayed significant improvements in elastic modulus, hardness, and scratch resistance as compared to uncompatibilized binary blends. The effects of the PMMA end-block molar mass and compatibilizer concentration on the blend morphology and mechanical properties were investigated. The triblock copolymer with the highest-molar-mass PMMA end blocks was most effective, presumably because of enhanced stress transfer between phases by virtue of a higher degree of entanglement of the end blocks with the PMMA dispersed phase.