Amphiphile self-assembly and phase evolution in reactive environments

Liu, Deborah Yang-Hao

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https://hdl.handle.net/2142/117738 Copy

Description

Title

Amphiphile self-assembly and phase evolution in reactive environments

Author(s)

Liu, Deborah Yang-Hao

Issue Date

2022-10-25

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

Krogstad, Daniel V

Doctoral Committee Chair(s)

Evans, Christopher M

Committee Member(s)

• Leal, Cecilia
• Braun, Paul V

Department of Study

Materials Science & Engineerng

Discipline

Materials Science & Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Amphiphile
• Self-assembly

Abstract

In this work, we present two different systems of self-assembled amphiphile phase evolution under elevated temperatures. Characterization is largely performed with small-angle x-ray scattering. In the first system, a ternary mixture of block copolymer, epoxy resin, and ionic liquid is found to exhibit a wide variety of lyotropic phases typical to block copolymer self-assembly. The ionic liquid is found to modify the phase behavior of the block copolymer-epoxy mixture in a manner similar to selective solvent phase modification of block copolymers. The phase transitions exhibited in the ternary phase diagram can largely be understood through considerations of polymer volume and chain swelling. The system was then subjected to an elevated temperature such that the epoxy resin cured, and transformed from an unpolymerized liquid resin to a high molecular weight epoxy matrix. Phase transitions were observed at nearly every composition. In one case, an in-situ curing reaction wherein SAXS was performed continuously throughout the curing cycle revealed nearly continuous order-order transitions throughout the curing cycle. The variety of phase transitions observed suggests significant future opportunities in engineering materials with a wide variety of possible nanostructures. In the second system, a mixture of acylglycerols and long-chain alkyl oils was subjected to thermal breakdown in the presence of metal in autoclave experiments. This work was motivated by a gap in the understanding of how acylglycerols, which are materials of significant economic importance, cause the corrosion of metals. Systematic corrosion experiments were performed. Acylglycerols were found to break down readily in autoclave conditions, releasing significant amounts of decomposition products early in the process. These experiments informed follow-on experiments, which sought to design reverse micelle-forming solutions comprised of molecules found in acylglycerol thermal breakdown. By exploiting the amphiphilic nature of monoglycerides, we demonstrate that reverse micelles can incorporate both fatty acid and water into their structures. This work serves as preliminary experiments for the design of biofeedstock mixtures that neutralize corrosive species by sequestering the more corrosive (i.e. more polar) species.

Graduation Semester

2022-12

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Deborah Liu

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