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The Fabrication of Multi-Surface Polymer Nanocolloids Via Solvent Precipitation

Speaker: Chris Sosa
Series: Final Public Oral Examinations
Location: Eisenhart Room (E-Quad G201)
Date/Time: Friday, May 12, 2017, 2:00 p.m. - 3:30 p.m.

The heterogeneous structural ordering of chemical components on colloidal surfaces in nature often gives rise to functional capabilities not possible with homogeneous surface architectures. The asymmetric molecular structuring of naturally-derived surfactants and the anisotropic patterning of proteins on cell surfaces, for instance, allow for the emergence of complex colloidal behaviors such as interfacial assembly and targeted cellular interactions. The increasing functional requirements of colloid-based technologies in recent years have consequently generated significant interest in exploiting heterogeneous particle architectures for the enhancement of polymer colloid functionality. While many research efforts have succeeded in pursuing this objective, the commercial realization of anisotropically structured polymer colloids has been impeded by the limited availability of processing routes capable of simultaneously tailoring particle properties such as size, surface composition, and surface heterogeneity in a facile and easily scalable manner.

The research effort presented here therefore focuses on addressing this challenge by demonstrating the fabrication of two-faced “Janus”, tri-lobal “Cerberus”, and multi-surface “patchy” colloids from simple homopolymer starting materials via a single, continuous flow process. In particular, the thesis illustrates how the rapid displacement of a good solvent with a poor one under intense micromixing can induce the precipitation and phase-separation of polymer blends into colloids of a desired size with tailored domain composition and frequency.  The work also explores the physical factors such as polymer colloid assembly, phase-separation, and vitrification that help determine the formation of desirable Janus and multi-patch particle architectures. An application of a model biodegradable PLA/PCL Janus colloid to emulsion stabilization is furthermore discussed in the presented research.