Global specialty
silica production is over 3 million tonnes per
annum with diverse applications across sectors and an increasing demand
for more complex material structures and surface chemistries. Commercial
manufacturing of high-value silica nanomaterials is energy and resource
intensive. In order to meet market needs and mitigate environmental
impacts, new synthesis methods for these porous materials are required.
The development of the bioinspired silica (BIS) product system, which
is the focus of this review, provides a potential solution to this
challenge. BIS is a versatile and greener route with the prospect
of good scalability, attractive process economics and well controlled
product materials. The potential of the system lies not only in its
provision of specific lead materials but also, as itself, a rich design-space
for the flexible and potentially predictive design of diverse sustainable
silica nanomaterials. Realizing the potential of this design space,
requires an integrative mind-set, which enables parallel and responsive
progression of multiple and dependent research strands, according
to need, opportunities, and emergent knowledge. Specifically, this
requires development of detailed understanding of (i) the pathways
and extent of material diversity and control, (ii) the influences
and mechanisms of scale-up, and (iii) performance, economic and environmental
characteristics and sensitivities. Crucially, these need to be developed
for the system overall, which sits in contrast to a more traditional
research approach, which focuses initially on the discovery of specific
material leads at the laboratory scale, leaving scale-up, commercialization,
and, potentially, pathway understanding to be considered as distinctly
separate concerns. The intention of this review is to present important
recent advances made in the field of BIS. Specifically, advances made
along three research themes will be discussed: (a) particle formation
pathways, (b) product design, and (c) scale-up and manufacture. These
advances include first quantitative investigation of synthesis-product
relationships, first structured investigation of mixing effects, preparation
of a broad range of functionalized and encapsulated silica materials
and continued industrial engagement and market research. We identify
future challenges and provide an important foundation for the development
of new research avenues. These include the need to develop comprehensive
and predictive product design models, to understand markets in terms
of product cost, performance and environmental considerations, and
to develop capabilities enabling rapid prototyping and scale-up of
desired nanomaterials.
