Strengthening silica aerogels with surface initiated ATRP cross-linked poly(methyl methacrylate)

•Aerogels based on silica surface modified with cross-linked poly(methyl methacrylate) were prepared.•Surface initiated atom transfer polymerization (ATRP) of methyl methacrylate and ethylene glycol dimethacrylate was used.•Super critical carbon dioxide drying resulted in high surface area aerogels.•ATRP modified aerogels were substantially stronger than un-modified aerogels.

Silica aerogels were strengthened by surface initiated atom transfer radical polymerization (SI-ATRP) of methyl methacylate (MMA) and ethylene glycol dimethacrylate (EGDMA) from ATRP initiators grafted to the gel before supercritical drying. Tetramethoxysilane (TMOS) was copolymerized in methanol with 2.67 mol% of the ATRP initiator, 3-(triethoxysilyl)propyl-2-bromo-2-methylpropanoate, to afford gels. After replacing the methanol with toluene and adding copper catalyst, MMA and EGDMA (1:1), highly cross-linked poly(MMA-co-EGDMA) was grown from the surface of the aggregated particles making up the gel. After supercritical carbon dioxide drying, the result was highly porous poly(MMA-co-EGDMA)-silica aerogel composites that were significantly stronger than silica aerogels or poly(MMA)-silica aerogel composites of the same density.