Tunable latency by catalyst encapsulation for silicone crosslinking
Miller, Susannah
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https://hdl.handle.net/2142/122187
Description
Title
Tunable latency by catalyst encapsulation for silicone crosslinking
Author(s)
Miller, Susannah
Issue Date
2023-04-21
Director of Research (if dissertation) or Advisor (if thesis)
Guironnet, Damien S
Doctoral Committee Chair(s)
Guironnet, Damien S
Committee Member(s)
Rogers, Simon A
Peters, Baron G
Fout, Alison R
Department of Study
Chemical & Biomolecular Engr
Discipline
Chemical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Catalyst Encapsulation
Hydrosilylation
Immobilized Catalyst
Latency
Language
eng
Abstract
Catalyst encapsulation serves as a prominent means of enabling one-pot storage of crosslinkable silicone formulations with highly active, Pt-based hydrosilylation catalysts. Numerous approaches towards encapsulation of Pt-based hydrosilylation catalysts have been developed in the patent literature, but the challenge remains to achieve triggered catalyst release under mild heating conditions (< 100 °C) and minimal encapsulant loading while still maintaining robust storage stability (6 months at 25 °C) with no premature curing of the silicone formulation. Our work addresses these goals in two approaches. The first involves immobilizing Pt catalyst to functionalized silica nanoparticles to decrease diffusion of catalyst through its encapsulant and extend the shelf life of one-part crosslinkable silicone formulation, particularly for encapsulants of low glass transition or melting temperatures. We find that coordinating molecular platinum to silica nanoparticles functionalized with a high density of Pt-coordinating norbornene ligands causes unexpected latency of the catalytic activity in hydrosilylation reactions when compared to an identical reaction in which the norbornene is not tethered. We demonstrate that this latency is related to ligand density on the particle surface, chemical structure of the norbornene, and silica nanoparticle topology.
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