Browsing by Author "Preston, Daniel J"

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    Understanding and Leveraging the Temperature-Dependent Curing of Silicone Elastomers
    (2024-08-28) Yap, Te Faye; Preston, Daniel J
    Silicone elastomers offer a wide range of mechanical properties, and their inherent compliance renders them suitable for use in applications including medical devices, shock absorbers, water-repellant surfaces, and cookware. Moreover, in the past decade, silicone elastomers have facilitated significant progress in the field of soft robotics. However, knowledge of the curing duration at a given temperature for thermally polymerizable elastomers often relies on empirical trends, and furthermore, the curing parameters—typically determined through trial and error—are limited to specific geometries and elastomers. Additionally, over-curing elastomeric parts at elevated temperatures consumes excess energy and contributes to device failure due to subsequent weak adhesion between components. The lack of understanding of the curing behavior limits the accessible design space of elastomers. Building on a framework introduced in my prior research quantifying the inactivation reaction of viruses, in this thesis, I present a modeling framework based on thermo-rheological experiments and the Arrhenius equation to provide a new understanding of the temperature-dependent curing of platinum catalyzed elastomers. The experimental results reveal that the curing behavior exhibits self-similarity upon normalizing with the gelation time, and the reaction is characterized by a dimensionless reaction coordinate that represents the extent of curing. Next, I leverage this understanding of the curing kinetics to study the adhesion between elastomer layers only as a function of the extent of curing, which accounts for both duration and temperature, and demonstrate the utility of the reaction coordinate to pinpoint failure regimes. Adhesion between elastomeric components represents a longstanding problem in the field of soft robotics and soft lithography. New insight into improving adhesion will enable new fabrication methodologies. Finally, I investigate the effects of curing silicone elastomers at temperatures beyond room temperature on the mechanical properties. The corresponding experimental results highlight the feasibility of using temperature to control the speed of curing while maintaining the desired mechanical behavior. Overall, my thesis aims to understand and leverage the curing behavior of elastomers as a function of time and temperature, informed by reaction kinetics, to broaden elastomer processing beyond traditional casting, and expand the accessible design space for the manufacturing of elastomeric devices.