Fabrication of novel lightweight composites by a hydrogel templating technique

A non-conventional way of preparation of lightweight porous materials by templating hydrogels with a range of hydrophilic and hydrophobic scaffolding materials was explored. Sub-millimetre hydrogel slurries of polyacrylamide and gellan gum were templated with aqueous slurries of cement, gypsum and clay–cement mixtures or alternatively, dispersed in curable polydimethylsiloxane (PDMS). After the solidification of the scaffolding material, the evaporation of structured hydrogel produced porous composite material whose pores mimic the hydrogel meso-structure. We studied the density, volume contraction and the compression strength of the formed porous materials as function of the hydrogel initial volume fraction. This versatile hydrogel templating method can be applied very inexpensively to a range of scaffolding materials to yield lightweight porous materials with a great potential for use in the building industry in heat and sound insulation panels, an alternative to aerated concretes, lightweight building blocks, porous rubber substitutes and foam shock absorbers.

Graphical abstractWe explore a non-conventional way of preparation of lightweight porous materials by templating hydrogel slurries with a range of hydrophilic and hydrophobic scaffolding materials and demonstrate how the materials porosity, volume shrinkage upon drying and mechanical properties depend on the initial hydrogel content.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Hydrogel slurries templated with (1) cement slurries, (2) gypsum and (3) PDMS. ► Composite obtained after solidification of the templating phase and evaporation of the hydrogel. ► Very low volume shrinkage of porous PDMS and porous cement composites. ► In porous PDMS open 3D network formed in the material when >70 vol% gel. ► Up to 80% reduction in density of gel-templated samples of cement and PDMS.