Alternative o-quinodimethane cross-linking precursors for intramolecular chain collapse nanoparticles

The benzothiophene dioxide derivatives as potential o-quinodimethane precursors with the ability to be incorporated as comonomers into linear polymer backbones and exhibit similar cross-linking characteristics as benzocyclobutene derivatives was investigated. The cross-linking unit was shown to be compatible with standard nitroxidemediated living free radical polymerization conditions, and the intramolecular chain collapse process of both polystyrene and acrylate polymers gave well-defined monodisperse nanoparticles in the 5-10 nm size dimension. A series of experiments to optimize reaction conditions for the preparation of the VBS cross-linking monomer were employed. A significant increase in the yield of the TMS-protected product was observed when the reaction was performed at 100 °C. It was observed that the novel cross-linking unit was compatible with nitroxide-mediated polymerization procedures that allowed the incorporation into polystyrene.