Fabrication and Characterization of Stable Hydrophilic Microfluidic Devices Prepared via the in Situ Tertiary-Amine Catalyzed Michael Addition of Multifunctional Thiols to Multifunctional Acrylates

In situ tertiary amine-catalyzed thiol-acrylate chemistry was employed to produce hydrophilic microfluidic devices via a soft lithography process. The process involved the Michael addition of a secondary amine to a multifunctional acrylate producing a nonvolatile in situ tertiary amine catalyst/comonomer molecule. The Michael addition of a multifunctional thiol to a multifunctional acrylate was facilitated by the catalytic activity of the in situ catalyst/comonomer. These cost-efficient thiol-acrylate devices were prepared at room temperature, rapidly, and with little equipment. The thiol-acrylate thermoset materials were more natively hydrophilic than the normally employed poly(dimethylsiloxane) (PDMS) thermoset material, and the surface energies were stable compared to PDMS. Because the final chip was self adhered via a simple chemical process utilizing the same chemistry, and it was naturally hydrophilic, there was no need for expensive instrumentation or complicated methods to "activate" the surface. There was also no need for postprocessing removal of the catalyst as it was incorporated into the polymer network. These bottom-up devices were fabricated to completion proving their validity as microfluidic devices, and the materials were manipulated and characterized via various analyses illustrating the potential diversity and tunability of the devices.