Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Kundu, Santanu

Committee Member

Elmore, Billy B.

Committee Member

Meng, Dong

Committee Member

Toghiani, Hossein

Committee Member

Walters, Keisha B.

Other Advisors or Committee Members

Rai, Neeraj

Date of Degree

8-11-2017

Document Type

Dissertation - Open Access

Major

Chemical Engineering

Degree Name

Doctor of Philosophy

College

James Worth Bagley College of Engineering

Department

Dave C. Swalm School of Chemical Engineering

Abstract

Gels and hydrogels have attracted a great attention for potential applications in tissue engineering, drug delivery, actuators, and soft robots. There has been a significant progress to engineer hydrogels from both synthetic and natural precursors to be as tough as a solid and as stretchable as a rubbery material while maintaining high water/solvent content. Despite considerable advances in rationally designing hydrogels, our understanding of their complex nonlinear mechanical deformation behavior is incomplete. This is partially due to the difficulty in conducting mechanical characterization on slippery, soft and swollen gels. Thus, it is required to develop new experimental techniques in order to better characterize them. Further, analyzing the experimental observations and link it with the molecular networks is an important factor. With this perspective, in this dissertation, nonlinear mechanical properties of different gel like materials have been investigated. We chose different gels with varied molecular structure, from molecular gel to self-assembled copolymer gels with flexible chains, to semiflexible polysaccharide based polymers. By developing suitable experimental protocols, strain-stiffening behavior of these materials, similar to that observed in biological materials, have been captured. Chain flexibility is a dominant factor in mechanical behavior of gels. For example, gels with flexible chains dilate orthogonal to an external shear load, whereas gels with semilexible chains contract similar to biological gel-like materials. In order to investigate the failure mechanism in our gels, cavitation rheology technique was also applied. We found that cavitation phenomenon in gels is related to the molecular architecture of the gels. The present work provides a better understanding of the deformation behavior of soft gels when subjected to a large load.

URI

https://hdl.handle.net/11668/19984

Comments

Alginate||Molecular gel||Strain Stiffening||Cavitation||Rheology||Gel||Polymer

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