Structure and Dynamics of Associative Polymers under Quiescent State and Flow

Author

• Rosita Sivaraj, Clemson UniversityFollow

Date of Award

8-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Committee Chair/Advisor

Dvora Perahia

Committee Member

Gary S. Grest

Committee Member

Stephen Creager

Committee Member

Brian N. Dominy

Committee Member

Jason McNeill

Abstract

Associative polymers, including ionizable polymers, are widely used in membranes, coatings, fuel cells, energy storage, and other advanced soft materials. Their properties are governed by ionic aggregation and associative interactions, which influence chain mobility, phase behavior, self-assembly, interdiffusion, and flow response. This dissertation employs large-scale molecular dynamics (MD) simulations to investigate the structure, dynamics, phase behavior, interdiffusion, and extensional flow response of ion-containing and associative polymer systems under quiescent and nonequilibrium conditions.

The influence of molecular architecture is first examined by comparing ring and linear associative polymers using the Kremer–Grest bead-spring model. In linear chains, their closed-loop architecture reduces interchain connectivity within associative networks. The extensional flow behavior of compressible and associative polymer melts is then investigated, demonstrating that strong extensional flow induces chain alignment, stretching, and a flow-induced transition accompanied by increased density and extensional viscosity. Associative interactions modify this response through transient physical crosslinks that restrict chain motion.

The interplay between ionic aggregation and flow is further explored in sulfonated polystyrene–poly(ethylene-r-propylene) (PSS–PEP) diblock copolymers, where increasing ionic content enhances aggregation, reduces chain extensibility, and alters stress growth and extensional viscosity. Finally, blends of polystyrene and sulfonated polystyrene (PS-PSS), together with thin films of associative polymers, reveal how ionic interactions regulate phase behavior, interdiffusion, and chain mobility.

Overall, this work establishes molecular-level relationships between ionic and associative interactions, dynamics, phase behavior, and flow, providing insights for the design of advanced polymeric materials.

Recommended Citation

Sivaraj, Rosita, "Structure and Dynamics of Associative Polymers under Quiescent State and Flow" (2026). All Dissertations. 4319.
https://open.clemson.edu/all_dissertations/4319

Author ORCID Identifier

0009-0006-0139-4728