Nanoporous Crosslinked Polyisoprene from Polyisoprene-Polydimethylsiloxane Block Copolymer

The polyisoprene block of a polyisoprene-polydimethylsiloxane (PI-PDMS) diblock copolymer with 0.68 volume fraction of PI was tightly crosslinked with dicumylperoxide. The PDMS part of the obtained glassy material was subsequently quantitatively etched with anhydrous hydrogen fluoride or tetrabutylammonium- fluoride, in this way obtaining a nanoporous material. The fraction of the surviving double bonds was estimated by solid state NMR, while thermal analysis was used to characterize the glass transition temperature of PI as a function of crosslinking degree. Small angle x-ray scattering confirmed the existence of microphase separated cylinders of PDMS in a PI matrix and its conservation in the form of channels in the crosslinked matrix.