The Fabrication of Multi-surface Polymer Nanocolloids via Solvent Precipitation

Abstract

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.