时间：2012年10月22日星期一 下午16：00~17：00，请参加讲座的老师和同学提前15分钟入场
地点：华南先进光电子研究院，大学城校区理5栋二楼报告厅
报告人：荷兰皇家科学院院士Drik J. Broer 教授
讲座题目：Liquid Crystal Networks and Self-Organizing Hydrogels
讲座内容：Nanotechnology towards complex optics, soft actuators and nanoporous system

报告人简介：

Drik J. Broer 教授是世界著名的聚合物化学家，尤其在聚合物结构以及自组织聚合物网络领域卓有成就。Broer教授1973年加入荷兰皇家飞利浦，主要从事气相聚合方法，光学存储，通信纤维和液晶网络领域的研究工作。1990-1991年间，他在杜邦公司负责非线性光学材料以及p－共轭聚合物e气相沉积方法研究。1985年，Broer教授开始在液晶材料领域进行液晶单体的现场光聚合工艺开发。该领域研发以形成高密度、交联单一序列的液晶网络为目的。1991年后，他研发了LCD增强型光学薄膜。2000年，他在大屏幕液晶制造领域以及电子纸领域开始制造技术方面的工作。从2003年到2010年，他是飞利浦研究实验室的负责人之一，高级院士兼副总裁，尤其在生物医学器件以及聚合物材料应用领域卓有成就。1994年，他成为荷兰埃因霍温技术达学兼职教授，研究领域涵盖液晶材料，聚合物光导，太阳能，有机自组装，纳米蚀刻技术，软蚀刻以及生物微流体系统的聚合物动力装置等领域。2010年至今，他作为埃因霍芬技术大学的全职教授，功能有机材料及器件学部的负责人。研究方向主要是清洁能源技术以及水处理和健康保护。Broer教授是荷兰皇家科学院院士，迄今发表论问200多篇，Nature及Nature 子刊7篇，获得美国专利110项。

 

Abstract

    In-situ photopolymerization of liquid crystalline (LC) monomers has proven to be a valuable technique for the formation of well-ordered polymer networks. Their anisotropic properties led to a variety of applications in optics, electronics and mechanics. The use of light to initiate polymerization enables lithographic approaches for patterning. The LC behavior enables formation of complex morphologies on molecular level. Controlling the director profile of an LC network film in transversal direction gives geometrical morphing upon minor changes in order parameter. Examples of suited profiles of molecular orientation are twisted or splayed director configurations tied up in the network configuration. Reversible order parameter changes can be induced by a variety of means. It can be simply induced by temperature changes resulting in gradients in thermal expansion over the cross-section of the film. But more sophisticated and of interest for applications is a light induced change as a result of the E-Z isomerization of a built-in azo group. Rather than composing the monomers of covalent bonds alone, one can chose to replace some bonds by secondary interactions such as hydrogen bridges, thus providing responsive molecularly organized hydrogels. We applied the H-bridge based dimerization of benzoic acid to form nematic LC acrylate monomers. By a controlled and reversible rupture of the H-bridges mechanical responses can be initiated.

    Photopolymerization of smectic LC monomers lock in structures of different length scales. The first length scale is the resolution of lithography, and goes down to a few micrometers. The second length scale is set by the spacing of smectic

layers and is typically a few nanometers. The third length scale is the intermolecular distance in the layers, usually around 1 nm or below. By modifying smectic molecules with H-bridges the smectic periodicity can break-up into separated layers with a well-defined spacing, also in the nanometer range. The nanopores form by breaking the H-bridges at elevated temperatures or by contact with an alkaline solution. The integrity of the film is maintained by copolymerizing with fully covalent smectic crosslinkers.

 

Biography

    Dirk J. Broer is a polymer chemist and specialized in polymer structuring and self-organizing polymer networks. He joined Philips Research (Eindhoven, Netherlands) in 1973. Typical research topics he worked on were vapor phase polymerization, optical data storage, telecommunication fibers and liquid crystal networks. In 1990/1991 he worked at the DuPont Experimental Station (Delaware, USA) on nonlinear optical materials and vapor phase deposition of p-conjugated polymers. He started his work on liquid crystal materials in 1985 developing the process of in-situ photopolymerization of liquid crystal monomers to form densely crosslinked and monolithically ordered liquid crystal networks. From 1991 he developed at Philips Research optical films for LCD enhancement and in 2000 he started his work on new manufacturing technologies of LCDs for large area displays and electronic wallpaper. From 2003 to 2010 he was senior research fellow and vice president at the Philips Research Laboratories specializing on biomedical devices and applications of polymeric materials.

In 1996 he was appointed as part-time professor at the Eindhoven University covering research topics as liquid crystal orientation, polymer waveguides, solar energy, organic semiconductors, nano－lithography, soft lithography and polymer actuators for biomedical microfluidic systems. From 2010 he is appointed as fulltime professor in Eindhoven coordinating the department Functional Organic Materials and Devices with a research emphasis on clean technologies as energy harvesting, water treatment and healthcare.

Prof. Broer is member of the Royal Netherlands Academy of Arts and Sciences (KNAW). In total, he has around 200 publications in peer reviewed journals and 110 US patents.