Reminder to attend Hyeyoung Son's Preliminary Exam Seminar: MATERIALS ENGINEERING SEMINAR "Thin Polymeric Film Adhesion Through the Transition Between Surface Wrinkling and Delamination" By Hyeyoung Son Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Chelsea S. Davis ABSTRACT Thin polymeric film play an important role in many applications, including microelectronics, flexible displays, and protective film for products. Poor adhesion between a thin film and the underlying substrate can cause defects such as corrosion and delamination during processing and use. On the other hands, strong adhesion can result in sticky residue on the products. Therefore, controlling adhesion of thin film has been important in those applications. However, the adhesion of polymer thin films is hard to measure due to their brittleness, greatly complicating sample preparation and handling. Here, a method for measuring the adhesion of polymeric thin films to a soft elastomeric substrate is proposed which exploits the transition from wrinkling to delamination. In prior research, the critical strain for film delamination from a wrinkled surface has been well described mathematically and is affected by the thickness of the thin film, the critical strain energy release rate and the plane strain modulus of the thin film and substrate. Based on this critical delamination strain relationship, the critical strain energy release rate (a metric of the interfacial adhesion) is verified through the use of a well-characterized, model materials system (thin film (polystyrene, PS) and the substrate (poly (dimethyl siloxane), PDMS)) by determining the onset of delamination after wrinkling. In this work, the basic knowledge of the topic is discussed to better understand how the adhesion of polymer is interpreted as a viewpoint of fracture as well as the transition from wrinkling to delamination. Date: Monday, October 2, 2017 Time: 8:30 A.M. Place: ARMS 1021