Polymeric Multiporous Materials from Fibrillar Networks

Abstract

Poly(vinylidene fluoride) (PVF 2 ) 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 mm 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 N 2 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.

Unraveling the Effect of PEG Chain Length on the Physical Properties and Toxicant Removal Capacities of Cross-Linked Network Synthesized by Thiol–Norbornene Photoclick Chemistry

“…Due to the presence of larger pores in the surface as revealed by the SEM and TEM analyses, the widely used nitrogen adsorption–desorption technique could not be applied to measure the pore size of the as-synthesized gels . For these kinds of materials, mercury intrusion porosimetry (MIP) is known to provide more accurate and precise information of the pores due to its ability to resolve pores of a wide scale of diameters ranging from few nanometers to even micrometers. , Therefore, the pore size of G1 was evaluated by MIP (Figure S8) and pores of varying sizes (3–30 μm) were found to be distributed in the material. We believe that the presence of such large macropores in the network may be arising from the higher degree of intermolecular cross-linking in the material …”