Kong, Victoria
(2024)
Exploring Network Heterogeneity Effects on Butyl Acrylate Elastomers through a Double Network Approach.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
In the last decade, the double network approach has emerged as a novel way to overcome the challenge of engineering soft, but still tough, crosslinked polymer networks. However, much remains unknown about the structure-property relationships bridging first network molecular features and the bulk double network response. Recently, synthetic rules have been identified that allow for the synthesis of networks with precisely controlled topological features. Here, we utilize these design rules and synthesize multiple series of butyl acrylate networks with systematically varied topological features including crosslink heterogeneity, dangling ends, loops, and strand dispersity. The networks are then swollen into double net- works. Because all the first network samples are prepared in duplicate, we can characterize the uniaxial stress-strain response of the first networks and analyze their resulting effect on the prepared double networks. Our results show that changing features in the first network topology, for example crosslink distribution, can alter the modulus of the first network independent of the observed strain stiffening response in the double network. We also show that other network defects, such as loops and dangling ends, can also independently tune the modulus and onset of strain stiffening by changing the density of elastically effective strands, but not necessarily the lengths of the global percolated paths in the network. Finally, we present our attempts to synthesize mechanochemically active randomly and regularly crosslinked single and double networks. While we unfortunately ran into chemical incompatibilities with our mechanophore and network syntheses, we identify suspected degradation pathways, which can help to inform future mechanophore choices for these experiments. In summary, this thesis provides important fundamental insights about the relationship between first network molecular structure and the bulk double network stress-strain response. We expect that the findings presented herein will be helpful for informing future design of soft, tough, crosslinked polymer materials with precisely tuned stress-strain behavior.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
27 August 2024 |
| Date Type: |
Publication |
| Defense Date: |
22 April 2024 |
| Approval Date: |
27 August 2024 |
| Submission Date: |
2 May 2024 |
| Access Restriction: |
2 year -- Restrict access to University of Pittsburgh for a period of 2 years. |
| Number of Pages: |
222 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Chemistry |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
polymer, chemistry, network, elasticity |
| Date Deposited: |
27 Aug 2024 14:27 |
| Last Modified: |
27 Aug 2024 14:27 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/46381 |
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