Self-supporting mesoporous silica thin films are generally fabricated by the first high-temperature thermal degradation of the pore-forming templates and the subsequent dissolution of the substrates. Herein, the poly-alpha-methyl styrene (PAMS) layers were treated as the sacrificial substrates for the preparation of nanoporous silica aerogel thin films, and the sacrificial substrates were eliminated by a low-temperature thermal degradation. In this work, the obtained self-supporting silica aerogel thin film had a large size of about 8 mm X 8 mm, and exhibited high flexibility. In addition, effect of the viscosity on the properties and microstructures of the films was also examined. (C) 2017 Elsevier B.V. All rights reserved.