Selective flux of organic liquids and solids using nanoporous membranes of polydicyclopentadiene

Abstract

Membranes were fabricated from the ring opening metathesis polymerization of dicyclopentadiene with the Grubbs first generation catalyst, and the permeability of twenty-one molecules through them was studied. Both polar and apolar molecules with molecular weights from 101 to 583 g mol⁻¹ permeated these membranes with values for flux of 10⁻⁵ to 10⁻⁶ mol cm⁻² h⁻¹ but selected molecules did not permeate them and had flux 10⁴ to 10⁵ times slower. The difference in flux was large between molecules that permeated and those that did not permeate, but no trend was observed that correlated flux with molecular weight or hydrophobicity. Rather, molecules that did not permeate the membranes had large cross-sectional areas that led to low rates of diffusion within the highly cross-linked polydicyclopentadiene membranes. The degree of cross-linking within the polydicyclopentadiene membranes was measured using infrared spectroscopy and approximately 84% of the dicyclopentadiene monomer had reacted to form cross-links. These are the first organic solvent nanofiltration membranes that separate molecules with molecular weights from 100 to 600 g mol⁻¹ based on cross-sectional areas.