Ultra-low density porous polystyrene monolith: facile preparation and superior application

Abstract

Ultra-low density porous polystyrene monoliths have been prepared via using water/styrene gel-emulsions, which were stabilized by a low-molecular mass gelator (LMMG), as templates. It was demonstrated that the porous materials as prepared possess a number of superior features such as highly adjustable internal structure and density, the lowest density could be lower than 0.01 g cm⁻³. Moreover, such materials can be used as excellent absorbents for many organic liquids including viscous oils like mineral oil and high-density oils such as dichloromethane. In particular, the absorption process is fast, selective and efficient when they are used in the purification of oil contaminated water. Importantly, the oils absorbed in the absorbent can be easily squeezed out, and furthermore the wet absorbent as obtained can be reused by suitable washing and natural drying. More importantly, the LMMG-based gel-emulsions employed as templates are simple in preparation, only mixing and agitation at ambient temperature are required. Moreover, further treatment of the wet porous materials as prepared from the templates is just washing and natural drying, which is completely different from those such as freeze-drying or supercritical drying widely adopted by others in the preparation of low density materials via routine approaches. It is believed that the LMMG-based gel-emulsion template method developed in the present work may have created a novel and facile way for preparing low density materials with ideal properties.