The influence of oligomerisation on scale-up and tuneability of bio-inspired silica.

Silica is the world's most widely produced nanomaterial by mass. Current manufacturing methods have a fundamental trade-off – low-value silica nanomaterial can be manufactured at scale, but lacks the properties required for advanced applications. In contrast, high-value silicas require toxic chemicals, harsh conditions, and energy-intensive processes that are unsustainable and uneconomical.
Bio-inspired silica (BIS) has emerged as a promising solution, harnessing biological formation principles such as mild temperature, neutral pH, and minimal waste generation. Scalability has been demonstrated up to 40 litres. However, critical knowledge gaps remain in understanding how synthesis links to structure, property, and performance as BIS formation follows a non-classical pathway. Speciation and kinetics remaining insufficiently understood for predictable and tuneable scale-up.
This thesis investigates how oligomeric species impact BIS formation, through combining real-time experimental species quantification, and systematic kinetic modelling. In doing so, it establishes the first quantitative kinetic model for BIS formation, supporting a 2-oligomer sequential pathway (monomer → oligomer 1 → oligomer 2 → polymer) with fifth-order initial monomer consumption, indicating a nucleation-like cooperative process. Two closely performing models were identified, differing in the order of oligomer conversion. Time-resolved oligomer measurements are essential for resolving this ambiguity.
Dielectric spectroscopy was investigated as a novel real-time monitoring technique, but proved inadequate for aqueous BIS systems, where water signal overwhelmed subtle oligomeric changes.
Systematic mixing analysis involved multi-inlet vortex mixers (MIVMs) across three geometries and various flowrates. No single mixing parameter consistently predicted speciation trends or material property variations – indicating that end-point characterisation alone masks underlying process sensitivities. BIS scale-up should therefore be guided by pathway-level oligomer understanding rather than traditional bulk mixing descriptors.
This thesis advances BIS from a phenomenologically described process to a quantitatively modelled system, providing a foundation for scale-up with controllable properties and establishing principles for rational, sustainable nanomaterial manufacturing.