Physics and Applications of Active Complex Solids

活性复合固体的物理与应用

• 批准号: EP/E051251/1
• 负责人: Mark Warner
• 金额: $ 102.39万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FE051251%2F1
• 关键词: Physics; Applications; Active; Complex; Solids

SummaryLiquid crystal elastomers (LCEs) combine the nano-scale order of nematic and smectic liquid crystals, with the weak solid character of rubber. Thus there is orientational and layering order in the liquid crystalline polymers that are crosslinked to form these special rubbers. The ordering arises from the rods that are incorporated chemically into the polymers. Rubber, like liquid crystals, is fluid-like at the molecular level. It is thus capable of huge extensions that are more like the flow of a liquid.LCEs are the same as classical rubber, except that they take a macroscopic shape that reflects the anisotropy of their underlying polymers. They can extend by 100s% when cooling through the thermal isotropic to nematic transition. They contract again on heating. Such changes can be equally induced by shining light onto dye-containing LCEs, with subsequent recovery in the dark. We called these light actuated materials photo-elastomers.We aim to develop these materials for device applications, for instance actuation by light to make new types of microfluidic devices. We envisage channels that can be blocked by a light-operated micro-valve, or fluid pumped along channels by a light-driven peristaltic pump. Gratings and reflectors could be optically written into LCE films.The coupling of nano-order to mechanical properties can also be from its rotation instead of by its (temporary) destruction. Strains applied perpendicular to the ordering direction can induce the order to rotate, with shape deformations occurring sympathetically. In cholesteric rubber there is a periodic modulation of the refractive index. One gets a photonic band solid, analogous to an electronic band solid that gives one semi-conductors. In rubber these are deformable photonic band structures, with the consequence one gets a mechanically shifting laser colour. An object of this proposal is to understand how to make these band solids more perfect for tunable laser devices.The layered liquid crystals (Smectics) yield rubbers with even richer behaviour. Their mechanical response can be rubbery in the 2-dimensions of their layers, and solid-like in the third. In their tilted, chiral form, they are soft solid ferro-electrics, that is they have a direction of spontaneous electric polarisation. They are unique as ferro-electrics in that they are liquid-like at the local level, rather than being very hard ceramics. Their polarisation direction can be induced to rotate in response to particular shears. Inversely, applying an electric field causes the polarisation direction to rotate and hence shears to develop. The former could be a sensor, the latter an actuator. We aim to exploit these materials as devices.We have written Liquid Crystal Elastomers (OUP, 2003) which has become the standard research monograph in the field. The first chapter (along with the contents and preface) is available on the web (http://www.tcm.phy.cam.ac.uk/~mw141/) and summarises for a non-specialist audience the effects we aim to explore for their materials and device potential. There are links on the same page to films of thermal actuation, and to benders (both thermo- photo-elastomeric).

摘要液晶弹性体（LCE）结合了向列液晶和近晶液晶的纳米级有序性以及橡胶的弱固体特性。因此，交联形成这些特殊橡胶的液晶聚合物存在取向和分层顺序。这种排序是由通过化学方式融入聚合物中的棒产生的。橡胶与液晶一样，在分子水平上呈流体状。因此，它能够进行巨大的延伸，更像是液体的流动。LCE 与经典橡胶相同，只是它们采用反映其底层聚合物的各向异性的宏观形状。当通过热各向同性到向列相转变冷却时，它们可以延伸 100%。它们在加热时再次收缩。这种变化同样可以通过将光照射到含有染料的 LCE 上来诱导，然后在黑暗中恢复。我们将这些光驱动材料称为光弹性体。我们的目标是开发这些材料用于设备应用，例如通过光驱动来制造新型微流体设备。我们设想可以通过光控微阀来阻塞通道，或者通过光驱动蠕动泵沿着通道泵送流体。光栅和反射器可以光学写入LCE薄膜。纳米级与机械性能的耦合也可以来自其旋转，而不是通过其（暂时）破坏。垂直于有序方向施加的应变可以引起有序旋转，同时发生形状变形。在胆甾型橡胶中，折射率存在周期性调制。人们得到光子带固体，类似于电子带固体产生半导体。在橡胶中，这些是可变形的光子带结构，其结果是获得机械变化的激光颜色。该提案的一个目的是了解如何使这些带状固体更加完美地用于可调谐激光设备。层状液晶（近晶）产生具有更丰富行为的橡胶。它们的机械响应在其层的二维中可以是橡胶状的，而在第三维中则可以是固体状的。在其倾斜的手性形式中，它们是软固体铁电体，也就是说它们具有自发电极化的方向。它们作为铁电体的独特之处在于它们在局部水平上呈液体状，而不是非常坚硬的陶瓷。它们的偏振方向可以响应特定的剪切力而旋转。相反，施加电场会导致偏振方向旋转，从而产生剪切力。前者可以是传感器，后者可以是执行器。我们的目标是利用这些材料作为器件。我们撰写了《液晶弹性体》（OUP，2003），该书已成为该领域的标准研究专着。第一章（连同内容和前言）可在网上获取（http://www.tcm.phy.cam.ac.uk/~mw141/），并为非专业观众总结了我们旨在探索其材料和设备潜力的效果。同一页面上有热驱动薄膜和弯曲机（均为热光弹性体）的链接。

项目成果

Characterization of soft stripe-domain deformations in Sm-C and Sm-C* liquid-crystal elastomers.

Sm-C 和 Sm-C* 液晶弹性体中软条带域变形的表征。

• DOI: 10.1103/physreve.79.061705
• 发表时间: 2009
• 期刊: Physical review. E, Statistical, nonlinear, and soft matter physics
• 作者: Biggins JS

Textured deformations in liquid crystal elastomers

液晶弹性体中的纹理变形

• DOI: 10.1080/02678290902879224
• 发表时间: 2009
• 期刊: Liquid Crystals
• 影响因子: 2.2
• 作者: Biggins J

Elasticity of polydomain liquid crystal elastomers

• DOI: 10.1016/j.jmps.2012.01.008
• 发表时间: 2012-04-01
• 期刊: JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
• 影响因子: 5.3
• 作者: Biggins, J. S.;Warner, M.;Bhattacharya, K.
• 通讯作者: Bhattacharya, K.

Mechanical switching of ferroelectric rubber.

铁电橡胶的机械开关。

• DOI: 10.1103/physreve.79.061704
• 发表时间: 2009
• 期刊: Physical review. E, Statistical, nonlinear, and soft matter physics
• 作者: Adams JM