Fabrication, analysis, application, and characterization of core-containing microparticles and hydrophilic microfluidic devices produced via the primary- and in situ tertiary-amine catalyzed Michael addition of multifunctional thiols to multifunctional acrylates
Doctor of Philosophy (PhD)
The objective of this research was to investigate amine-catalyzed thiol-acrylate chemistry for various novel applications that could fully utilize the untapped potential of this useful and robust chemistry. The use of this chemistry in each application solved a problem, improved on a disadvantage of current technologies, and decreased the level of complexity in association with required time, cost, and/or preparation conditions. The first novel application conceived, applied, and analyzed was in the field of microencapsulation. A novel approach for the preparation of microparticles via a dispersion polymerization using the primary amine-catalyzed addition of a trithiol to a triacrylate was realized and investigated. Various core materials were microencapsulated via this technique and introduced into appropriate systems to improve the desired characteristics of the given system. In a specific case, microparticles containing a borontrichloride-amine complex were observed to prevent the interaction between the Lewis acid initiator and fumed silica, hence improving the rheological properties of an epoxy system containing the initiator while maintaining the strength of the resulting polymer. Another application involved a novel approach to prepare stable hydrophilic microfluidic devices. Hydrophilic thiol-acrylate materials were fabricated with native stable water contact angles of ~60° via a two-pot soft lithography technique at room temperature, very rapidly, and with little equipment. The material hydrophilicity was modified from 10-85° via bulk- or post-modification techniques. These materials were prepared via the Michael addition of a secondary amine to a multifunctional acrylate, producing a nonvolatile tertiary amine utilized in the catalysis of the Michael addition of a multifunctional thiol to the multifunctional acrylate. Because the final chip was self-adhered via a chemical process utilizing the same chemistry, and it was naturally hydrophilic, there was no need for expensive equipment or methods to “activate” the surface. Also, due to the pre-synthesized monomer/catalyst molecule serving as the in situ catalyst, there was no need for post-processing removal of the catalyst as it was incorporated into the polymer network. Both novel applications facilitated great improvements by exploiting the major advantages of thiol-acrylate chemistry. The fabrication, analysis, application, and characterization of these novel amine-catalyzed thiol-acrylate microparticles and microfluidic devices are described.
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Bounds, Christopher O., "Fabrication, analysis, application, and characterization of core-containing microparticles and hydrophilic microfluidic devices produced via the primary- and in situ tertiary-amine catalyzed Michael addition of multifunctional thiols to multifunctional acrylates" (2012). LSU Doctoral Dissertations. 635.
Pojman, John A.