The block length effect of polystyrene-block-poly(methyl methacrylate) on the interfacial adhesion between polystyrene-poly(methyl methacrylate) and between polystyrene/phenoxy

Abstract

The effect of the poly(methyl methacrylate) (PMMA) block length of polystyrene(PS)-poly(methyl methacrylate) diblock copolymer on the interfacial adhesion between PS/PMM A and between PS/phenoxy has been investigated. When the block copolymer with the PMMA block length of 6.6 kg mol-1 is reinforced at the interfaces, the fracture behavior follows the pure chain pull-out mechanism, and the estimated monomer friction coefficient, ∫mono, are 1.69×10-11and 3.42 × 10-11 N/monomer for PS/PMMA and PS/phenoxy, respectively. The higher value of ∫mono in PS/phenoxy arises from the specific interaction between the PMMA block chain and phenoxy homopolymer. When the block copolymer with the PMMA block length greater than 10.9 kg mol-1 is added to the interfaces, the fracture behavior of both PS/PMMA and PS/phenoxy follows the craze formation followed by the chain scission, indicating that the entanglement molecular weight of PMMA lies in between 6.6 kg mol-1 and 10.9 kg mol-1.