Sustainable chemistry & process engineering of bioinspired silica materials

Silica is the world’s most abundant mineral, occurring naturally in both geological formations and biological minerals. Artificially, silica is used in wide ranging applications e.g. polymer fillers, creating a US$6.9B/annum market. Current manufacturing methods require a silica salt and mineral acid for synthesis, achieving control over properties through careful modification of reaction conditions. Incorporation of non-reacting template molecules to the synthesis extends silica’s capability, imprinting complex and ordered porosity into the material, however this necessitates post-synthetic activation, stymieing commercialisation due to high environmental and processing costs. Taking inspiration from natural silica materials deposited by complex biomolecular templates, bioinspired silica (BIS) materials made using organic ’additives’ have been developed. These materials combine rapid, mild synthesis found in biological silicas with organic imprinted porosity found in templated silicas, bridging the gap between material families. This work develops new BIS synthesis methods to further explore the relationship between biological, templated, and bioinspired silica materials, and to develop BIS as a technology suitable for commercialisation. First, recent commercial feasibility calculations were validated by scaling up the synthesis and optimising it according to industrial feedback. Manipulation of BIS colloid chemistry was used to imprint mesopores of a uniform size into BIS structure for the first time. This is the first rapid (10 minute), room temperature, aqueous mesoporous silica synthesis (compared to several hours at high temperature in alcoholic solvents), greatly improving its behaviour and hence applications. Novel, room-temperature activation of BIS through acid extraction was also developed, the first such method for any templated silica. This enabled in-depth investigation of interfacial bonding, explaining BIS’s unusual surface chemistry and the mechanism of acid extraction, providing new insight into the relationship between additives and silica in BIS and other templated silicas. Finally, the ramifications of combining the above techniques is analysed along with the effect their development has on the large scale manufacturing techno-economics, establishing a clear route to commercialisation of the technology