Date: Tuesday, December 15th 2015

Time: 1:00 PM

Location: Molecular Science and Engineering Building (MoSE) 1226

Title: Atomic force microscopy probing methods for soft viscoelastic synthetic and biological materials and structures.

Committee:

Prof. Vladimir V. Tsukruk Advisor, MSE

Prof. Ken Gall, ME/MSE, Duke University

Prof. Andres Garcia, ME

Prof. Jeffrey Streator, ME

Prof. Jeannette Yen, Bio

Abstract:

Mechanical properties of micro- and nanoscale viscoelastic soft materials can dictate their performance and function.  In this dissertation we focus on refining atomic force micrscopy (AFM) methods and data analysis routines to measure the viscoelastic mechanical properties of soft polymer and biological materials in relevant fluid environments and in vivo using a range of relevant temperatures, applied forces, and loading rates.

These methods are directly applied here to a several interesting synthetic and biological materials.  First, we probe poly(n-butyl methacrylate) (PnBMA), above, at and below its glass transition temperature in order to verify our experimental procedure.  Next, we use AFM to study the viscoelastic properties of coating materials and additives of silicone-based soft contact lenses in a tear-like saline solution.  Finally, a major focus in this dissertation is determining the fundamental mechanical properties that contribute to the excellent sensitivity of the strain sensing organs in a wandering spider (Cupiennius salei) by probing under in vivo conditions.

These strain-sensing organs are known to have a significant viscoelastic component.  Thus, the cuticle of living spiders is directly investigated in near-natural environments (high humidity, temperatures from 15-40 °C).