A new approach to produce polystyrene monoliths by gelation and capillary shrinkage

Polymeric monoliths are of great interest in a variety of applications. A new gelation approach to produce a mechanically stable polystyrene (PS) gel directly from its microemulsion is reported. To produce a PS gel, the as-prepared microemulsion is first demulsified by adding selected water-miscible organic solvents. The small PS latex particles liberated from the surfactant are assembled into a piece of bulk material at an appropriate temperature with a high degree of entanglement of the polymer chains. It is found that the d2T/η value is an important parameter to evaluate the gelation ability of the organic solvents and helps determine the gelation conditions. Finally, PS monoliths are obtained by capillary drying and their pore structures can be effectively tuned by changing the gelation time and the amount of solvent exchanged with water. This allows the controlled preparation of bulk PS artefacts with densities in the range of 0.06 to 1.14 g cm−3. This simple method of PS monolith production avoids the use of shaping tools or chemical templates, needs less energy, and is a promising alternative approach to design either integrated porous or compact polymer materials.