Radical polymerization of capillary bridges between micron-sized particles in liquid bulk phase as a low temperature route to produce porous solid materials

Colloid Polym Sci. 2017 Oct;295(10):1773-1785. doi: 10.1007/s00396-017-4149-y. Epub 2017 Jul 18.

Abstract

We present a generic and versatile low temperature route to produce macro-porous bodies with porosity and pore size distribution that are adjustable in a wide range. Capillary suspensions, where the minor fluid is a monomer, are used as pre-cursors. The monomer is preferentially located between the particles, creating capillary bridges, resulting in a strong, percolating network. Thermally induced polymerization of these bridges at temperatures below 100 °C for less than 5 hours and subsequent removal of the bulk fluid yields macroscopic, self-supporting solid bodies with high porosity. This process is demonstrated using methylmethacrylate and hydroxyethylmethacrlyate with glass particles as a model system. The produced PMMA had a molecular weight of about 500.000 g/mol and dispersity about three. Application specific porous bodies, including PMMA particles connected by PMMA bridges, micron-sized capsules containing phase change material with high inner surface, and porous graphite membranes with high electrical conductivity, are also shown.

Keywords: Capillary bridges; Capillary suspensions; Membranes; Microparticles; Microscopy (optical, electron, force, fluorescence); Phase-change materials; Poly(methyl methacrylate); Properties; Radical polymerization; Spectroscopy; magnetic resonance: NMR/ESR; rheological.