Polymeric multiporous materials from fibrillar networks

Abstract

Poly(vinylidene fluoride) (PVF₂) forms thermoreversible gels with liquid alkyl diesters as well as with camphor which is solid at room temperature. The diesters are replaced by another low boiling solvent cyclohexane by solvent exchange technique while camphor is dried just by exposing the material in vacuum to yield highly porous materials. Nano pores are generated as a result of solvent removal from polymer-solvent intercalates whereas macropores are contributed by percolation of polymer fibrils. The porosity thus created covers a wide range from 3 nm to 400 μm producing multiporous materials. Pores greater than 6 nm are measured by mercury intrusion porosimetry (MIP) and pores of diameter less than 6 nm is observed by N₂ adsorption porosimetry. The dried samples show two melting regions, low temperature hump for porous portion and high temperature peak for bulk portion. The porous materials have the ability to absorb water-soluble herbicides from around 10-ppm aqueous solution as indicated in UV spectrophotometric experiment.