Abdulhafez, Moataz Magdi Mahmoud Amin
(2022)
Laser Processing of Polymers for Controlled Carbonization and Folding.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Since the development of lasers, their applications have been continuously growing, and one emerging area of fundamental and applied research focuses on laser processing of polymers. This is due to the transformative potential of laser techniques, which are versatile and reliable methods for rapid and direct-write processing of soft materials to locally modify their geometry, physical and chemical properties. The combined potential of recent developments in polymer science and the commercialization of capable laser processes naturally lend themselves to the emerging area of manufacturing flexible electronics, soft-robotics and flexible neural probes. This powerful combination provides a platform of free form fabrication methodologies that enable both three-dimensional shaping in the millimeter-to-centimeter scale and local synthesis of graphene-related materials in the nanometer-to-micrometer scale. Hence, this thesis research focuses on understanding the fundamentals of such methodologies with specific application to graphene electrode fabrication by direct laser carbonization of polymers, as well as to self-folding of pre-strained polymers by laser-induced viscoelastic relaxation.
Laser carbonization of polymers is an emerging technique that enables directly patterning conductive nanocarbon electrodes directly on polymer films enabling a plethora of flexible devices. These laser-induced nanocarbon (LINC) patterns exhibit hierarchical porous and fibrous graphene-based morphologies. Nevertheless, the fundamental mechanisms underlying the formation of specific LINC morphologies are still missing. In this work, we develop different approaches to investigate these mechanisms through lasing polyimide with spatially controlled gradients of optical energy flux, combined with imaging and analytical/numerical modeling methods to elucidate the mechanisms of carbonization. From the analysis, we aim to correlate the process parameters to the electrical, electrochemical and surface properties of the nanocarbons.
Light induced bending/folding of specific types of polymers is also a powerful technique for creating complex three-dimensional shapes from either two-dimensional sheets. Of particular interest is inducing self-folding of pre-strained polymer sheets based on the interplay between spatiotemporal thermal gradients and viscoelastic relaxation. In this work, we develop a new approach for controlled self-folding of shape memory polymer sheets based on direct laser processing. Our work aims at understanding and describing the mechanics of folding through experimental and simulation techniques.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
10 June 2022 |
| Date Type: |
Publication |
| Defense Date: |
10 December 2021 |
| Approval Date: |
10 June 2022 |
| Submission Date: |
2 December 2021 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
174 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Industrial Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
direct laser writing, laser-induced graphene, flexible electronics, Shape memory polymers, self-folding |
| Date Deposited: |
10 Jun 2023 05:00 |
| Last Modified: |
10 Jun 2023 05:00 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/41990 |
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