Surface Interactions in Polymeric and Biological Materials at the Micro and Nano Scales

Featuring Hongbo Zeng, Ph.D.
Department of Chemical Engineering and Materials Research Laboratory
University of California, Santa Barbara

Location:  McDonnell Douglas Engineering Auditorium
Free and open to the public

Abstract:
Soft materials are central to a wide range of engineering and biomedical applications. Examples include polymers, biopolymers, and soft biogenic materials (articular cartilage, cornea, cell membrane, etc.). Many of the properties and applications of soft materials are strongly based on the weak (non-covalent) but long-range interactions among the molecular or supramolecular constituents. However, it is still poorly understood how and why these interactions lead to hierarchical structures of soft materials and, in most cases, time-dependent physical and engineering properties. Improving our fundamental understanding of the interactions of polymer surfaces and biological systems at the micro and nano scales is needed to develop new materials and further techniques in materials science, bioengineering, chemistry and nanotechnology.

Here Zeng reports some recent progress in: (1) adhesion and detachment mechanisms of polymer surfaces and thin films, especially transient surface deformations, flows and dynamics during both detachment and attachment (coalescence or spreading) of two polymer films. It is found that there is a continuous transition between the failure modes of viscous liquids and glassy solids. A new type of self-organized periodic transient surface fingering pattern and instability was also found to generally exist during adhesive contacts, spreading and coalescence of thin films of soft materials; (2) understanding the interactions between biological surfaces (of mussel and gecko adhesive systems) and non-biological substrates; establishing their surface properties and mechanical function; extending the fundamental physical and chemical understanding into development of advanced materials and devices with novel engineering and biomedical applications.

About the Speaker:
Hongbo Zeng received his B.S. and M.S. degrees in polymeric materials and chemical engineering at Tsinghua University in China in 2001 and 2003, respec­tively. He received his Ph.D. degree from the Chemical Engineering Department at the University of California, Santa Barbara in December, 2007, under the supervision of Prof. Jacob Israelachvili and Prof. Matthew Tirrell. His Ph.D. research involved the intermolecular and surface interactions (i.e., adhesion, friction, lubrication, and failure) of soft materials, including polymers/biopolymers and lipid bilayers. Currently, Zeng works as a research associate in the Materials Research Laboratory and Chemical Engineering Department at UCSB. His current research focuses on the mussel and gecko adhesive systems, nanomechanics of actin filaments, and development of bio-inspired advanced functional polymers and nano-structured biomaterials. Zeng is the recipient of the Peebles Award of the Adhesion Society in 2007, and the Materials Research Society (MRS) Graduate Student Award (Silver Medal) in 2007.