Graduation Year

2023

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Chemical Engineering

Major Professor

David S. Simmons, Ph.D.

Committee Member

Venkat R. Bhetanabotla, Ph.D.

Committee Member

Robert S. Hoy, Ph.D.

Committee Member

Christopher L. Alexander, Ph.D.

Committee Member

Ryan G. Toomey, Ph.D.

Keywords

Copolymer Sequence, Dynamical Gradients, Glass Formation, Molecular Dynamics, Molecular Weight

Abstract

The utilization of polymeric materials has endured since prehistory, at first unknowinglyin the form of natural biopolymers such as wood and leather, culminating and continuing through the development of the plastics industry in the early twentieth century. Polymers, along with other materials including silicate glasses, readily exhibit the glass transition upon quenching: a continuous but rapid change from viscous (liquid) to elastic (solid) behavior. The physics surrounding the glass transition have been studied for over a century; while considerable progress has been made, there remains no universally accepted predictive theory of the glass transition. Modern development of glassy materials consists of three distinct approaches: laboratory experimentation of new and uncharacterized materials, computer simulations guiding material fabrication and experimentation, and theories which prescribe why and how materials behave from atomic and molecular fundamentals.

Work here encompasses computer simulations of molecular dynamics that provide molec-ular insight for guiding experiment and theory in three avenues: molecular weight effects on the glass transition, polymer sequence effects on the glass transition, and the development of a novel forcefield for detecting the origins of glass transition in simple glass-formers. Results herein indicate where current, standard polymer glass theory fails to corroborate observed dynamical trends and guide continued research towards comprehensive understanding of the glass transition, particularly as it pertains to polymers.

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