Hybrid organic-inorganic gels that are melting gels

Ever since the observation in 2001 that some organic-inorganic silica hybrid gels are rigid at room temperature but soften and flow around 100 °C, there has been interest in so-called melting gels. Following heating to 150 °C or higher, the gels no longer soften and are considered consolidated hybrid glasses. The catalog of melting gels has grown over the past 20 years. Longer chain substitutions and other functional groups have been attached to the ≡Si-O-Si≡ molecular species. The substitutions make it possible to adjust the glass transition, the viscosity, and the temperature range of their usefulness.