Colloquium Series: Dr. Joseph Dennis, U.S Army research Laboratory
Tuesday, March 18 @ 4:00 pm - 5:00 pm
Dr. Joseph Dennis
Polymer Chemist
U.S. Army Research Laboratory
Title: Adaptive Structural Adhesives: How do you design rapid response in a polymer glass or composite?
Abstract:
Structural resins are used ubiquitously across various industries as lightweight adhesives. As the automotive, aerospace and electronics industries look to increase performance, novel resin design becomes paramount. A cross-cutting need is improved ductility in glassy materials. Epoxy-amine based adhesives are an encouraging model platform because of high strength, and environmental stability, but they are intractable and suffer from brittle-like behavior well below the Tg. Adaptive glasses provide a relatively unexplored avenue to manage an “on-demand” mechanical response. Three response mechanisms will be outlined to provide a range of mechanical behaviors: (i) shape-changing functionalities which locally yield or soften the material to stimulate chain mobility; (ii) bond forming (or breaking) chemistries which increase (or decrease) the stiffness of the material; and (iii) energy absorbing groups which convert the incoming stimuli into a spatially controlled heating and result in a designed softening of the material. However, many challenges still remain in achieving controlled responses deep in the glassy state.
Bio:
Dr. Dennis is a polymer chemist stationed in Chicago as part of ARL Central within the US Army Research Laboratory. He is currently engaged with several universities in the Chicagoland area, focused on discovering and operationalizing adaptive polymer glasses for soldier, vehicle and weapon applications. His current role is actively collaborating with the external community and steering research to accelerate the discovery, innovation, and transition of technology to the Army.
Dr. Dennis graduated from the Macromolecules Innovation Institute at Virginia Tech in 2017 under the guidance of Professor Timothy E. Long, where he identified the delicate interplay between polymer topology and macroscopic properties in engineering thermoplastics. He then transitioned to a postdoctoral research position with IBM, focused on novel material designs for industrial applications ranging from microelectronics to sea floor piping. In some cases, he led interdisciplinary teams in collaborative projects as principal investigator with the group’s success evidenced in technology transfer though patents, and external recognition in peer-reviewed articles.
Dr. Dennis’ current research focus is in understanding and exploiting adaptive polymer networks. This relatively untapped area of material discovery presents challenging opportunities to understand the structure-property-response nexus and uncover rapidly-responding, adaptable materials for active armor, recyclable structural adhesives, and robotic technologies.