Frozen polymerization for aligned porous structures with enhanced mechanical stability, conductivity, and as stationary phase for HPLC

Abstract

A directional freezing and frozen polymerization method is developed to prepare crosslinked aligned porous polymers with improved mechanical stability. Monomer solutions are directionally frozen in liquid nitrogen to orientate the growth of solvent crystals. The frozen samples are polymerized by UV irradiation. The solvent is removed under vacuum at room temperature to produce aligned porous structure. The mechanical stability is improved by two orders of magnitude compared to the usually freeze-dried porous materials. The materials are modified with graphene and a conducting polymer to achieve conductivity at 1.9 × 10⁻⁴ S cm⁻¹ and 5.2 × 10⁻⁶ S cm⁻¹, with the stable aligned pore structures maintained. The aligned porous monolith is also assessed by high performance liquid chromatography (HPLC), showing fast separation of hydrocarbon compounds with low back pressure at 59 bar.