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Silica based aerogel‐like materials obtained by quick microwave drying

2013; Wiley; Volume: 44; Issue: 5 Linguagem: Inglês

10.1002/mawe.201300140

1521-4052

Luísa Durães, Telma Matias, R. Patrício, António Portugal,

Mesoporous Materials and Catalysis

Abstract Aerogel‐like silica based materials were obtained by microwave drying of the gels synthesized with methyltrimethoxysilane (MTMS) precursor. The microwave drying is an alternative ambient pressure drying technique for these nanostructured materials that allows a fast fine drying stage and avoids the high temperature cycles of conventional evaporative drying. The gels were synthesized by a two‐step acid‐base catalyzed sol‐gel process following the procedures described in an earlier work. After 2 days of aging, they were placed in an oven at 60°C, during one day, and then washed with distilled water at 40°C. Finally, the gels were dried in a microwave oven, at 450 W, in three cycles of two minutes each with two minutes of interval. During drying, a reduction of the gel volume was observed, but the major part of this volume was recovered by spring‐back effect in 2 days, giving aerogel‐like materials with a density in the interval 60–80 kg/m 3 . The final materials are monolithic, flexible and have a thermal conductivity of ˜0.04 W/(m K), which make them suitable for insulation applications. Additionally, they exhibit high hydrophobicity (contact angle ˜150°) and surface area (414 m 2 /g), what can be beneficial for adsorption of some organic pollutants.