Responsive polymeric nanoreactors

该项目的总体目标是通过将催化剂和试剂束缚或封装到新的“智能”纳米级聚合物支架上来创建和控制催化剂和试剂的特性和局部环境。这些小的离散分子或纳米颗粒（直径10-150纳米）在构建时，将通过在其壳、核或表面结构域中引入反应性基团而以“自下而上”的策略官能化，以允许具体检查周围环境对其反应性的影响。用于合成这些材料的这种“自下而上”的策略将允许在合成早期引入官能团和特定的响应性质，这有助于确保在整个过程中保持功能性，以提供定义明确的功能化纳米材料。提出了将这些纳米颗粒作为响应于外部触发/刺激以释放或螯合特定部分的纳米级载体/回收媒介物的研究，以使得能够在纳米颗粒内包装与周围介质或其他试剂不相容的反应性官能团，并且在需要时能够选择性和受控释放。纳米颗粒由许多聚合物“臂”组成，这些聚合物“臂”又具有亲水性（亲水性）和疏水性（疏水性）部分;这种聚合物被称为两亲共聚物。由于疏水和亲水部分的不同溶剂亲和力，这些聚合物将自身排列成具有核和壳结构的球状结构，称为胶束。例如，胶束在水（或任何与核心域不相容的溶剂）中的结构由胶束的外壳组成，所述外壳由与水直接接触的亲水聚合物链段组成，并且疏水聚合物链段隐藏在胶束核心内，从而使与溶剂的不利相互作用最小化（在有机介质中反之亦然）。这些胶束对浓度变化固有地不稳定，但它们可以在壳层中选择性地使用共价键合或交联化学来稳定，以提供稳健的纳米颗粒。必须仔细考虑交联程度，以确保形成坚固的纳米颗粒，但这种化学反应不应显着影响壳层的渗透性，并且仍然允许小分子通过该层扩散到位于核心内的功能性。域。这些纳米颗粒独特的核-壳形态赋予了新的性质，包括作为宿主或容器携带或螯合货物的能力，以及将反应性官能团嵌入纳米颗粒内同时保护其免受周围介质影响的能力。因此，这些纳米颗粒可以被设想为三维可改性的支持物，以提供独特的环境，其中可以发生小分子的选择性反应、包封或转化。本奖学金申请中提出的化学将探索这些聚合物材料的这两个方面。第一个项目将开发新的水溶性和响应性聚合物支架，这些支架包含不同的领域，其中可以发生选择性催化，以通过减少所需的昂贵和对环境有害的有机溶剂的量来开发更绿色的工业方法。还提出了在纳米颗粒内或表面上的特定环境内的反应的介导，以导致对产物的组成和性质的控制。第二种方法将利用响应性聚合物，以允许触发释放试剂或催化剂到周围介质中，用于受控的顺序反应。提出这些方法，使新的“智能”纳米反应器的催化和多步有机反应的发展。

The overall goal of the project is to create and control the properties and local environment of catalysts and reagents by tethering or encapsulating them to new 'smart' nanoscale polymeric scaffolds. These small discrete molecules or nanoparticles (10-150 nanometers in diameter) when constructed, will be functionalised in a 'bottom-up' strategy by the introduction of reactive groups in their shell, core or surface domain, to allow for the specific examination of the effect of surrounding environment on their reactivity. Such a 'bottom up' strategy for the synthesis of these materials will allow for the introduction of the functional groups and specific responsive properties early in the synthesis helping to ensure that the functionality is maintained throughout the process, to afford well-defined functionalised nanomaterials. Investigation of these nanoparticles as nanosized carrier/recovery vehicles that respond to external triggers/stimuli to release or sequester a specific moiety is proposed to enable packaging of reactive functionality, that is incompatible with the surrounding media or other reagents, within the nanoparticle and enable selective and controlled release when required. The nanoparticles are made up from many polymer 'arms', which in turn possess hydrophilic (water liking) and hydrophobic (water repelling) parts; such polymers are called amphiphilic copolymers. Due to the different solvent affinity of the hydrophobic and hydrophilic parts, these polymers arrange themselves into sphere-like structures, called micelles, with a core and shell structure. For example, the structure of a micelle in water (or any incompatible solvent for the core domain) consists of the micelle's outer shell which is made up of hydrophilic polymer segments in direct contact with water and the hydrophobic polymer segments are hidden inside the micelle core, minimising unfavourable interactions with the solvent (and vice versa in organic media). These micelles are inherently unstable to concentration changes but they can be stabilised using covalent bonding or crosslinking chemistries selectively in the shell layer, to afford robust nanoparticles. The degree of crosslinking must be carefully considered to ensure a robust nanoparticle is formed, but this chemistry should not significantly affect the permeability of the shell layer and still allow for the diffusion of small molecules through this layer to the functionality which is located within the core domain. The unique core-shell morphology of these nanoparticles imparts novel properties including the ability to behave as hosts or vessels to carry or sequester cargo and also the ability to embed reactive functionality within the nanoparticle whilst protecting it from the surrounding media. As a result these nanoparticles can be envisaged as 3-dimensional modifiable supports to provide unique environments in which the selective reaction, encapsulation or transformation of small molecules can occur. The chemistry proposed in this Fellowship application will explore these two aspects of these polymeric materials. The first will develop new water soluble and responsive polymeric scaffolds that contain distinct domains in which selective catalysis can occur to allow for the development of greener industrial methodologies, by reducing the amount of costly and environmentally damaging organic solvents required. The mediation of reactions within the specific environments within or on the surface of the nanoparticles is also proposed to lead to control over the composition and nature of products. The second approach will utilise responsive polymers to allow for the triggered release of reagents or catalysts into the surrounding media for applications in controlled sequential reactions. These methodologies are proposed to enable the development of novel 'smart' nanoreactors for catalysis and multi-step organic reactions.