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

The effect of the poly(methyl methacrylate) (PMMA) block length of polystyrene(PS)-poly(methyl methacrylate) diblock copolymer on the interfacial adhesion between PS/PMMA 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, f(mono), are 1.69 x 10(-11) and 3.42 x 10(-11) N/monomer for PS/PMMA and PS/phenoxy, respectively. The higher value of f(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 kgmol(-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 kgmol(-1) and 10.9 kgmol(-1).