A Polymer Generator Driven by Environmental Water Gradients

Dr. MA Mingming, University of Science and Technology of China

Detail:

People have been searching for methods to recover energy from waste heat and vibrations for many decades. By the process of energy harvesting (also called energy scavenging), small amount of energy is derived from ambient free energy sources such as solar energy, thermal energy, kinetic energy, mechanical vibration, biochemical energy and chemical gradients. Bio-mimicking energy harvesting devices that can utilize Gibbs free energy associating with chemical gradients have attracted considerable interest. Inspired by the crosslinked network structure of animal dermis, we have designed and synthesized a polymer composite film, by combining a rigid matrix (polypyrrole) with a dynamic network (polyol-borate). In an open environment, this strong and flexible polymer film actuator absorbs water from moist substrates and then ejects bound water into low humidity air; water absorption and release is accompanied by actuator expansion and contraction that results in rapid locomotion. The contractile stress reaches 27 MPa upon water release, which is 80 times more powerful than the strongest mammalian skeletal muscle. Upon water absorption, a free actuator can raise objects 380 times heavier or transport cargo 10 times heavier than itself. We have assembled an all-polymer generator by incorporating this actuator with a PVDF-based piezoelectric element. Driven by environmental water gradients, this polymer generator outputs alternating electricity at ~0.3 Hz, with a peak voltage of ~1.0 V. The electrical energy is stored in capacitors that could power micro- and nano-electronic devices.

在化学信号刺激下发生可逆形变的聚合物是目前功能高分子领域的研究热点。现有的工作大都集中在凝胶体系，难以同时实现快速响应和良好的力学性能。我们设计了一种具有聚吡咯和多元醇硼酸酯动态网络结构的高强度柔性薄膜材料，并发展了一种非水溶液电化学聚合反应方法来制备这一材料。这种新型有机聚合物材料保持了聚吡咯的有机半导体特性，并表现出优于普通聚吡咯材料的高强度和韧性。更重要的是，该薄膜材料还表现出多元醇硼酸酯动态网络所赋予的对水分的高响应性。在室温下，该薄膜可以自动并且持续不断的在潮湿基底上快速翻滚。我们深入研究并阐明了这一现象的机理：薄膜对水分的快速吸收和释放导致薄膜本身可逆的卷曲和舒张，从而将水分蒸发产生的化学浓度梯度（化学势能）转换为薄膜本身运动的机械能。该薄膜可以产生高达27 MPa的收缩张力，并能靠吸收水分举起自身重量380倍的物体。通过将该薄膜与压电PVDF材料复合，我们制备了以室温水分蒸发为能源的聚合物发电机，输出峰值电压可达1伏。在此基础上，我们力求提高该聚合物发电机的能量转换效率和输出功率，为探索其在可再生能源和微电子器件等领域的应用奠定基础。


个人简介：
马明明，1997年-2003年就读于清华大学化学系，获学士和硕士学位。2004年-2010年就读于美国俄亥俄州立大学化学系，获有机化学博士学位。2010年-2014年，在美国麻省理工学院Koch癌症研究所做博士后。2014年回国，加入中国科学技术大学化学系任教授。博士和博士后工作期间主要从事超分子化学和响应性聚合物材料的研究，已在Science，JACS，Adv. Mater.，Acc. Chem. Res.等国际著名学术期刊上发表论文19篇，相关研究成果已申请美国专利3项。2013年以第一作者身份发表于Science上的研究论文被美国麻省理工学院评选为“MIT Best of 2013”。