Rapid routes to highly branched, interfacially active silicones

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Silicone polymers are requisite materials in almost every technological area of developed societies, from antifoams, to wound dressings and intraocular lenses. Their susceptibility to acid and base means that facile and practical synthesis leads to complex mixtures of (lower value) materials with broad ranges of properties. MQ and MDTQ resins comprise one class of particularly high value silicone resins, with a market value of over USD$ 2 billion dollars/year. These are hyperbranched polymers that provide highly efficient reinforcement in elastomer and gel systems: in the latter case they also facilitate tack and adhesion, for example, on wound dressings. The Piers-Rubinsztajn reaction (PR) permits the rapid assembly of complex 3 dimensional (3D) structures. In the research project we propose to develop facile, industrially practical, short (1-3 steps) PR-based routes to hyperbranched polymers by creating libraries of precursor dendrons that can be combined in a 'mix-and-match' manner. The products will range in molecular weight (MW) from 3000-10000 g/mol and their physical properties will be documented and the optimal range(s) of branching and MW will be established for certain applications. Structure (MW, 3D structure, including geometry and rigidity)/property (adhesion, reinforcement) relationships will be established. This approach will supplant traditional industrial routes that lead to complex mixtures of poorer performing materials. The proposed work has benefits to Canada through the development of silicones for an Ontario company that can realize the benefits directly: Siltech currently exports most of its products to the US and elsewhere. In addition, the project will train market ready HQP because of the technical, critical thinking and problem solving skills they will learn through their research and direct interaction with our industrial sponsor.