Date of Award
6-26-2026
Date Published
August 2026
Degree Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Physics
Advisor(s)
James H Henderson
Second Advisor
Alexander Harvey Nitz
Keywords
3D Printing;Architected Structures;Fracture Energy;Shape Memory Polymers;Soft Matter;Tearing
Subject Categories
Physical Sciences and Mathematics | Physics
Abstract
This dissertation explores the mechanics of soft polymeric systems in which the mechanical response is strongly shaped by geometry, structural arrangement, and environmental coupling. The first system focuses on shape memory polymer (SMP)-based 3D printing, also known as 4D printing, where programmed strain is used to control shape shifting and the mechanical response of printed structures. The second system examines ultrathin polystyrene films floating on water, where fracture is influenced not only by the film itself, but also by folding, crack geometry, and the liquid interface. Two research chapters are dedicated to 4D printing-related work, while one chapter focuses on the ultrathin-film tearing project. Chapter 2 implements Programming via Printing (PvP), a single-step, single-material 4D printing approach in which tensile strain is trapped directly during extrusion and stored in the printed part. The effects of nozzle temperature, printing speed, and geometry on trapped strain and the resulting shape change are studied systematically to achieve high trapped strain in a controlled manner. A generalized fabrication strategy is then adopted to spatially vary trapped strain during fabrication. By programming the distribution of trapped strain, active and passive elements are successfully integrated within a single structure, enabling scalable designs for shape-morphing architectures. Chapter 3 extends the application of PvP to SMP-based architected structures that undergo thermally activated structural jamming through recovery-induced self-contact. In this system, shrinkage-driven contact between structural elements produces a stiff, load-bearing state without vacuum, pneumatic actuation, or other external hardware. The mechanical response is characterized through compression, three-point bending, and shear-like loading, showing how programmed recovery and contact can be used to achieve adaptable stiffness and enhanced load-bearing behavior. Chapter 4 shifts to ultrathin polystyrene films floating on water as a model system for studying tearing in the presence of a liquid substrate. In these experiments, a precut notch initiates tearing, while a large-amplitude fold forms opposite to the notch and guides the crack path during propagation. The tearing process is analyzed through geometric observables such as crack length and needle separation and interpreted using an energetic framework that balances fracture of the film with the surface energy associated with the exposed liquid interface. The experimental observations show that fold formation, film thickness, and geometric constraints influence crack initiation and propagation. Taken together, these studies show that soft matter systems with very different material platforms can nevertheless be understood through a common perspective: mechanics can emerge not only from the material itself, but also from geometry, structural arrangement, and the way the system interacts with its surrounding environment.
Access
Open Access
Recommended Citation
Iqbal, S M Asif, "Mechanics in Soft Matter: Experimental Studies of Bulk 3D-Printed Structures and Ultrathin Polymer Films" (2026). Dissertations - ALL. 2376.
https://surface.syr.edu/etd/2376
