Powering smart materials by oscillatory chemical reactions

所有的植物和动物都有一定程度的适应环境的能力，例如，表现出向日性（一些花或叶子的表面跟随阳光的方向）或对热或疼痛做出反应。遵循同样的原则，而不是使用设计用于适应一系列条件的材料，而不是对其中任何一个单独的最佳材料，我们更喜欢能够感知其环境条件并进行相应调整的智能材料。我感兴趣的智能材料是显示化学机械响应的聚合物凝胶，即材料周围介质的化学变化导致材料通过膨胀或塌陷而占据的体积逐步变化。这种结构变化可用于迫使主体分子离开凝胶结构（塌陷）或进入凝胶结构（溶胀）。塌缩现象的应用之一是在药物输送系统中，该系统仅在某些环境条件下分配药物分子。另一方面，聚合物凝胶溶胀可用于在介质中包封不需要的反应抑制剂或病原体。智能聚合物凝胶的另一个应用是作为化学机械微阀，其中阀（凝胶）通过介质的变化来激活。一个示例是热激活微阀。在加热时，凝胶塌陷并且阀打开，而在移除热量时，凝胶膨胀并且阀关闭。这直接应用于微尺度系统中流体流动和混合的控制。智能材料应用中的一个基本要素是引起变化发生的刺激。拟议的研究调查钯催化的苯乙炔氧化羰基化（PCPOC）反应在甲醇设想其多功能的性质和重要的应用程序作为一个刺激的许多应用。这是一个非同寻常的化学系统，当在搅拌间歇反应器中操作时，其在pH和反应热输出方面表现出明显的振荡。作为一种化学振荡器，它福尔斯属于非线性化学动力学领域，研究与反应中一种或多种物质浓度的时间周期性或近周期性变化有关的现象。这类反应中最著名的是Belousov-Zhabotinsky反应。PCPOC反应是一个复杂性较高的振荡体系，是金属络合物催化反应中振荡行为的一个特例。PCPOC反应如此重要的原因有很多：它提供了一种新的但尚未被很好理解的pH振荡器;它代表了在催化体系中以振荡模式进行的由相对简单的试剂合成复杂分子的第一个例子;当在振荡模式下操作该体系时，与在非振荡模式下操作相比，可以实现高水平的产物选择性;除了振荡的pH值，同步振荡的热输出是存在的，它表现出两个相关的刺激，pH值和温度，它可能有应用在推进纳米器件通过产生振荡力时，与一块gel.This研究是针对合作的相互作用的实验和理论研究的应用，这种羰基化反应作为一种刺激。将开发PCPOC反应的预测物理化学模型，并将使用pH敏感聚合物、温度响应聚合物和对两者均敏感的材料研究该系统（即温度和pH响应性聚合物复合膜）作为：（1）含有智能材料的环境;（2）与包含智能材料的环境连通的封闭环境，以及（3）包含智能材料的封闭环境与目标环境连通。

All plants and animals have the ability to adapt to the environment to some extent e.g. exhibit heliotropism (some flowers or leaves surfaces follow the direction of sunlight) or react to heat or pain. Following the same principle, instead of using materials designed to suit a range of conditions while not being optimal for any of them individually, we would prefer smart materials that have the ability to sense the conditions in their environment and adjust accordingly. The smart materials I am interested in are polymer gels that show a chemo-mechanical response, i.e. a change in the chemistry of the medium about the material results in a stepwise change in the volume that the material occupies by causing it to swell or collapse. This structural change may be used to force host molecules out of the gel structure (collapsing) or into the gel structure (swelling). One of the applications of the collapsing phenomenon is in drug delivery systems that would dispense drug molecules only under certain environmental conditions. On the other hand polymer gel swelling may be applied for the encapsulation of unwanted reaction inhibitors or pathogens in the media. Another application of smart polymer gels is as chemo-mechanical micro-valves where the valve (gel) is activated by a change in the medium. One example is a heat activated micro-valve. Upon heating the gel collapses and the valve opens while upon removing the heat the gel expands and the valve closes. This has direct application in the control of fluid flow and mixing in micro-size systems.An essential element in the application of smart materials is the stimulus that causes the occurrence of the change. The proposed research investigates the palladium-catalysed phenylacetylene oxidative carbonylation (PCPOC) reaction in methanol envisioning many applications of its versatile nature and importantly application as a stimulus. This is an extraordinary chemical system that exhibits pronounced oscillations in pH and reaction heat output when operated in a stirred batch reactor. As a chemical oscillator it falls into the field of nonlinear chemical dynamics that studies phenomena related to the temporally periodic or nearly periodic variation of the concentrations of one or more species in a reaction. The best known reaction of this type is the Belousov-Zhabotinsky reaction. The PCPOC reaction is an oscillating system of higher complexity and an exceptional example of oscillatory behaviour in reactions catalysed by metal complexes. There are a number of reasons why the PCPOC reaction is of such great importance: it provides a novel and not well understood pH oscillator; it represents the first example of complex molecules synthesised from relatively simple reagents proceeding in a catalytic system in an oscillatory mode; when operating this system in an oscillatory regime high levels of product selectivity may be achieved compared to operating in a non-oscillatory mode; besides oscillations in pH, synchronised oscillatory heat output is present; it exhibits two relevant stimuli, pH and temperature; it may have application in propelling nano devices by generating an oscillating force when coupled with a block of gel.This study is aimed at the cooperative interplay between experimental and theoretical investigation into the application of this carbonylation reaction as a stimulus. Predictive physico-chemical models of the PCPOC reaction will be developed and this system will be researched with pH sensitive polymers, temperature responsive polymers and materials sensitive to both (i.e. temperature and pH responsive polymeric composite membranes) as: (1) an environment containing the smart material; (2) an enclosed environment communicating with the environment containing the smart material and (3) an enclosed environment containing the smart material communicating with the targeted environment.