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<p>Polymer materials are receiving increased attention in the field of materials science, both in
academia and industry, with its widespread application from commercial plastics to advanced
biomaterials. These include composites in airplanes and automobiles, functional films on monitors
in mobile phones and computers, as well as adhesive and coating materials in civil engineering.
Despite significate efforts, the major questions and challenges in understanding key properties of
polymer materials are still not solved. Such lack of understanding hinders advances in delicate
design and controlling of polymers for advanced functional applications. The development of
polymer science began with the pioneering work made by Flory and his coworkers at 1950s as
commercial synthetic polymer industry started to develop and grow. During the following decades,
experimental work guided by theoretical predictions had been the major contribution of our further
understanding while the great challenges in experimental techniques at molecular level always
blurred critical information in polymer materials. With enhanced ability in computational science,
simulation starts to become an essential investigation method to provide thermodynamic insights
at this molecular level. Along with great progress in properties prediction with improved accuracy,
great challenges still exist in modeling processing of polymer systems, especially in accurate
description of dynamic evolution incorporated with various processing conditions resulting
macroscopic structural changes like carbon fiber processing from polyacrylonitrile (PAN)
precursor in which crystalline regions represent more than 55% of the material by volume. In terms
of crystallinity in polymers, with the heated debates over classical crystal-growth models, major
questions and challenges are still not solved including the control and determination of molecular
conformations and crystal structures as well as mesoscale morphologies, detailed understanding
of melting and crystallization. It is clear that molecular scale investigations on crystal structure
and crystallization mechanisms as well as predictive simulations of that will be a huge demand in
the near future to explore mechanical, optical, and other physical properties in polymeric materials.
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<p>The purpose of my dissertation is to summarize my major research contributions to our
current understanding of crystalline polymers in the aspects of crystal structure determination and
crystallization processes at molecular level, and to introduce our effort on simulation software
development and indicate possible future directions in the field of molecular modeling of polymer
crystals. Three major research topics will be included as the following
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<p>1. Crystalline and pseudo-crystalline phases of polyacrylonitrile from molecular dynamics;
2. Novel mode of non-crystallographic branching in the initial stages of polymer fibril<br></p></div></div></div><div><div><div>
<p>growth;<br>
3. Polymer crystal structure generator and analysis software (PolymerXtal). </p>
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| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/13541342 |
| Date | 14 January 2021 |
| Creators | Tongtong Shen (9953663) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/MOLECULAR_MODELING_OF_POLYMER_CRYSTALS_AND_CRYSTALLIZATION/13541342 |
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