Adhesion enhancement of polymer blend interfaces by reactive block copolymer brushes

The effects of reactive silane-terminated poly(styrene-b-dimethylsiloxane) block copolymer on the fracture toughness between a poly(dimethylsiloxane) elastomer and polystyrene substrate are measured by the JKR technique. Adhesion enhancement is not observed when the platinum hydrosilylation catalyst is poisoned with a thiol, confirming that adhesion enhancement is due to a hydrosilylation reaction between silane end groups and residual vinyl functionality in the elastomer. The fracture toughness increases with the block copolymer areal density, the molecular weight of the PDMS block and the concentration of residual vinyl groups in the elastomer. These results compare well with predictions of the Lake and Thomas theory for failure of crosslinked elastomers. Addition of 0.016 copolymer molecules/nm(2) to the interface leads to a sixteen-fold increase in the fracture toughness.