Understanding molecular aspects of mass transport in charged and uncharged dense polymer networks

Sheridan, Grant S.

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https://hdl.handle.net/2142/115466 Copy

Description

Title

Understanding molecular aspects of mass transport in charged and uncharged dense polymer networks

Author(s)

Sheridan, Grant S.

Issue Date

2022-04-21

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

Evans, Christopher M

Doctoral Committee Chair(s)

Evans, Christopher M

Committee Member(s)

• Schweizer, Kenneth S
• Braun, Paul V
• Sing, Charles E

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)

• polymer
• polymer physics
• diffusion

Abstract

Polymer membranes are the future of separation, providing an energy efficient means of separation. Glassy polymer membranes have typically held the advantage over rubbery polymer membranes due to their higher selectivity; however, the work of this thesis aims to develop a molecular understanding of mass transport in dense rubbery polymer membranes to inspire the next generation of rubbery polymer membranes that can separate compounds based on size exclusion, combining the high permeability of rubbery polymer membranes with the high selectivity of glassy polymers. Imidazolium ionic liquid membranes were developed with varying ionic liquid moiety and crosslink density for the separation of toluene and heptane. TFSI- ionic liquid moieties showed improved toluene-heptane separation performance over their BF4- counterparts. Decreasing the crosslink density of the TFSI- polymerized ionic liquid membranes also led to a non-monotonic trend in permselectivity. The effect of crosslink density on mass transport was further investigated via probe diffusion in butyl acrylate polymer networks, where crosslinking significantly increased the glass transition temperature, reduced segmental dynamics, and reduced probe diffusion. Probe diffusion compared to segmental relaxation times revealed diffusion partially decoupled from segmental dynamics, where varying probe size led to a difference in diffusivity that could be accounted for by the inscribed probe volume. These results provide new insights regarding the effect of covalent crosslinks on probe diffusion necessary for the design and development of separation membranes.

Graduation Semester

2022-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Grant Sheridan

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