Tunable encapsulations: Droplet-based microfluidics for the expansion of biodegradable polymer technologies

Harrier, Danielle D.

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https://hdl.handle.net/2142/115819 Copy

Description

Title

Tunable encapsulations: Droplet-based microfluidics for the expansion of biodegradable polymer technologies

Author(s)

Harrier, Danielle D.

Issue Date

2022-04-22

Director of Research (if dissertation) or Advisor (if thesis)

Guironnet, Damien S

Doctoral Committee Chair(s)

• Guironnet, Damien S
• Kenis, Paul J.A.

Committee Member(s)

• Leal, Cecilia
• Schroeder, Charles M.

Department of Study

Chemical & Biomolecular Engr

Discipline

Chemical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• microfluidics
• catalyst encapsulation
• biodegradable polymers
• ring-opening polymerization
• urea anion catalyst
• microfluidic emulsions

Abstract

Environmental plastic pollution has become a cause for concern over the past decades, motivated by an alarming accumulation of plastics in landfills and oceans. Biodegradable polymers have been gaining momentum as substitutes for non-biodegradable plastics as more sustainable and environmentally-friendly alternatives. Biodegradable polymers are synthetic compounds susceptible to degradation over time into environmentally acceptable substances. Despite the successful commercialization of many biodegradable thermoplastics, to date, there are still limitations in the applications. For example, aqueous polymer dispersions (i.e. emulsions) of biodegradable polymers are inaccessible due to the incompatibility of the emulsion polymerization process and the polymerization chemistry of biodegradable polymers. Biodegradable polymers are synthesized via a ring-opening polymerization (ROP) process which is water-sensitive. The water sensitivity of the polymerization chemistry prevents any technique using water as a solvent or dispersion media, which ultimately sets a limit on the polymeric material accessible. This thesis describes a droplet-based microfluidic encapsulation strategy that protects the water-sensitive catalyst from the aqueous phase, allowing the ROP to proceed in an aqueous dispersion. The success of this approach relies on simultaneous precise control of the kinetics of polymerization, the rate of mass transfer rates, and fluid mechanics. We report, for the first time, the production of biodegradable polymer particles dispersed in water. In this work, we systematically investigated the process and formulation parameters that govern the stability of the micro-droplets during generation, flow, and collection. More specifically, we tune droplet viscosity, surface tension, and hydrophobicity to further shield the ROP catalyst in the aqueous dispersion. Herein, a set of design rules for the tuning of catalyst protection efficiency within the aqueous dispersion are detailed, which ultimately allowed us to perform another water-sensitive ROP to produce polyether particles in water. To demonstrate the power and versatility of the encapsulation methodology, we crosslinked both chemistries to produce biodegradable elastomers and crosslinked polyethers in continuous flow. This project identifies the fundamental guiding principles to encapsulate water-sensitive polymerization catalysts to yield novel spherical polymer particles dispersed in water.

Graduation Semester

2022-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Danielle Harrier

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