제 목 : MOLECULAR ASPECTS OF FRICTION BETWEEN POLYMER COATED SURFACES 연 사 : Prof. Andra Dėdinaitė 일 시 : 2019년 6월 18일(화) 오전 11시
장 소 : 화학관 2층 서병인강의실 (330226호실)
===================================================================================== MOLECULAR ASPECTS OF FRICTION BETWEEN POLYMER COATED SURFACES -the biolubrication perspective Andra Dėdinaitė KTH Royal Institute of Technology, School of Engineering Sciences in Chemistry, biotechnology and Health, Department of Chemistry, Surface and Corrosion Science, Drottning Kristinas väg 51, SE-10044 Stockholm, Sweden Nature has developed aqueous lubrication systems that perform close to perfect for many years under demanding conditions – sudden transitions from stagnant state to motion, shear under high loads and low speeds. These systems operate well lubricated and with minimal wear, if lucky, over 100 years. There is a need to look in detail at nature’s solutions in order to gain understanding of how man-made aqueous lubrication ought to be designed. With this purpose, we consider the complexity of a human synovial joint, joint lubricating fluids, architecture of individual components in these fluids and association structures. Next, we make attempts to mimic the nature and to understand principles of its operation in terms of friction control between surfaces. In order to do so we need to understand self-assembly at interfaces, and lubrication properties of key structural elements – bottle-brush and brush-on-brush polyelectrolytes, as well as polyelectrolye- surfactant aggregates. Examples will be discussed of how synthetically derived analogues of naturally available polyelectrolytes perform in aqueous environment as lubricating agents on solid surfaces. It will also be shown how extremely high friction forces between surfaces, induced between two negatively charged surfaces by oppositely charged polyelectrolyte bridging, can be modified by polyelectroyte association with the surfactant, leading to extremely low friction, even in presence of high adhesive force. Further, the case will be discussed when friction between the surfaces is high despite the absence on adhesion. For good lubrication, strong attachment of lubricant to surfaces is of importance. Thus polymers that contain blocks that lubricate and other blocks that provide strong anchoring to surfaces are desirable. To this end, we have, together with co-workers in Vilnius University, Lithuania, synthesized polyelectrolytes that carry resemblance to muscle-adhesive proteins and demonstrated how thin layers of these polyelectrolytes can withstand harsh attempts off wear without yielding to it.