A simple approach to preparation of polyhedral oligomeric silsesquioxane crosslinked poly(styrene-b-butadiene-b-styrene) elastomers with a unique micro-morphology via UV-induced thiol-ene reaction

We report an approach to the fabrication of nanostructured thermoplastic elastomeric composites based on poly(styrene-b-butadiene-b-styrene) (SBS) crosslinked by polyhedral oligomeric silsesquioxane (POSS). The crosslinking reaction took place between thiol functional groups from the POSS molecules and the double bonds within the soft block segment of SBS via UV-induced thiol-ene reaction. Unlike typical methods of constructing SBS composite systems, the triblock copolymer was directly used to produce SBS based composite materials with different loadings of POSS without any pre-chemical modification. In this system, the existence of covalent bonds between the inorganic nano-material (POSS) and the polymer matrix (SBS) promoted the compatibility of the composite material and POSS formed the cross-linking centers for the SBS. AFM measurements showed that good compatibility led the composite films to form well-ordered micro-phase separation at the nanoscale, and incorporation of POSS could effectively improve mechanical properties of SBS, including the storage modulus and strength without residual elongation in the cyclic tensile tests at very small loading.