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时间:2016/10/25 14:58:00 点击数:


报告题目:Macro-, Micro- and Nano-Actuators Based on Liquid Crystal Elastomers – a bottom-up molecular design




Artificial muscles are man-made materials that try to reproduce the two main characteristics of real muscle fibers, namely, elasticity and contractility. They respond to various external stimulations (ion concentration, electric field, temperature, light etc.) by a significant shape or size change. In addition to classical materials such as piezoelectric ceramics and shape memory alloys, polymer-based artificial muscles have become the most important muscle-like materials since the 1990s. They offer operational similarity to biological muscles in response to external stimulation. They are resilient and damage tolerant and they exhibit large actuation strains (stretching, contraction, or bending). Artificial muscle systems have many potential applications of great interest, including serving as the materials foundation for fabrication of sensors, microrobots, micropumps, and actuators with combinations of size, weight, and performance parameters beyond those currently achievable. In this talk, I discuss one particular kind of polymer-based artificial muscles, the nematic liquid crystal (LC) elastomers. LC elastomers combine the properties of LC systems with orientational ordering and those of polymer networks with rubbery elasticity. LC elastomers as artificial muscles were first proposed by P.-G. de Gennes. We present here a bottom-up strategy to make artificial muscles, using nematic side-chain and main-chain LC polymers as building blocks. The overall material response in these artificial muscles reflects the individual macromolecular response: the contraction/elongation of the material results from the individual macromolecular chain shape change, from stretched to spherical at the nematic to isotropic phase transition triggered by external stimuli. This approach is particularly interesting for the development of micro- and nano-sized actuators.
Min-Hui Li obtained her BS in 1986 and her MS in 1988 from Tsinghua University in Beijing. She received her PhD in Polymer Chemistry and Physical Chemistry from Pierre and Marie Curie University in Paris in 1993. After a post-doc in the French Institute of Petroleum, she joined the French National Center for Scientific Research (CNRS) as a tenure researcher in 1994. She served in the “Centre de Recherche Paul Pascal” in Bordeaux as an associate professor between 1994 and 1997, in the Curie Institute in Paris as an associate professor then a full professor between 1997 and 2014. Since 2015, she works in Chimie ParisTech (Ecole Nationale Superieure de Chimie de Paris). Professor Li’s current research interests are focused on soft matter chemistry; polymer self-assembly; smart and biomimetic materials, liquid crystal elastomers, polymer vesicles. She has published papers in high impact journals including PNAS, Adv. Mater., JACS, Phys. Rev. Lett., Chem. Commun., Macromolecules etc. Currently Prof. Li is also adjunct professor in Beijing University of Chemical Engineering and in Zhejiang University. She contributes actively to the educational and scientific cooperation between France and China (e.g., to the project of BUCT Sino-French Engineering School, to the “9+9” program between 10 ParisTech colleges and Top 12 Chinese universities).