Please consider attending the following: MATERIALS ENGINEERING SEMINAR “Visualizing Interfaces: Quantifying Adhesion Across Multiple Length Scales” By Naomi Deneke Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Chelsea S. Davis ABSTRACT Measuring adhesion is important in industries including paint, plastics, and electronics. Although there are test methods for quantifying adhesion such as the tape test, scratch test, blister test, and AFM test, they are often limited in length scale at observing adhesive properties. As a result, there presents an opportunity to better characterize adhesion and the effects of degree of contact (observed at the nano-length scale) on adhesion values. Forster Resonance Energy Transfer (FRET) is the transfer of energy from one molecule, Donor (D), to another, Acceptor (A), when they are between 10-100 Ȧ apart. This physical phenomenon can be used in conjunction with common adhesion tests to observe nanoscale displacements that may be perceived as true contact. In order to achieve this goal, a contact adhesion device has been developed to perform indentation experiments from which pull-off force can be determined for an axisymmetric hard probe (GPa range modulus) into contact with an elastic substrate (MPa range modulus). Surface energy and work of adhesion values can be calculated using force and displacement data acquired by the adhesion device in Johnson-Kendall-Roberts (JKR) theory for elastic contact. The materials used in the test are surface functionalized with either D or A fluorescent molecules to observe FRET and subsequently nanoscale displacements. Experiments are performed over an inverted fluorescence microscope to quantify FRET efficiency, ε (a distance, dependent measurable variable related to FRET), and thus provide insight visually and qualitatively on how degree of contact impacts adhesion. Date: Tuesday, August 14, 2018 Time: 11:00 A.M. Place: ARMS 1028