Ionic liquid-directed self-assembly of block copolymers

在过去的二十年里，对充足和更发达的能源和数据存储的需求引发了工业界和学术界的新兴研究领域。能源存储在当今时代至关重要，特别是在存储由可再生资源产生的清洁能源方面。必须开发新的材料来满足这种不断增长的需求，自组装嵌段共聚物可以用来生成所谓的离子凝胶(包括固定在交联聚合物基质中的离子液体(IL)的凝胶材料)，这是一类很有前途的材料。由于离子液体具有高离子导电性和高的热稳定性和化学稳定性等独特性质，离子液体的使用为储能应用提供了有利条件。数据存储是离子液体聚合物系统可以提供重大进展的另一个重要领域。根据2018年IDC白皮书(US44413318)，2018至2025年间，全球数据球体预计将增长530%，达到175泽字节(1.75x1023字节)。为了应对这种天文般的增长，我们必须生产具有不断增加的面密度(数据存储密度)的存储设备。要做到这一点，我们必须产生具有低于10 nm结构域的纳米管，而强分离嵌段共聚物(BCP)提供了一条潜在的途径来实现这样的小特征。BCP是使用两个或两个以上化学上不同的单体合成的聚合物，它们可以排列在一系列不同的序列中，从而产生不同的分类。一种可用于开发这种BCP的合成技术是可逆加成-断裂链转移(RAFT)聚合。使用RAFT可以对聚合过程进行严格控制，例如控制分子量和多分散性，从而使得到的聚合物非常明确。使用RAFT的一个关键优势是，该过程可以使用范围广泛的功能单体进行反应。人们对RAFT介导的聚合诱导自组装(PISA)越来越感兴趣，这是一种将在本项目中频繁使用的合成所需BCP的技术。与其他成熟的自组装路线相比，PISA具有优势，这些路线通常需要额外的后聚合步骤。本项目将专注于在ILS中合成和表征具有两亲性的BCP(即至少包含一个亲IL和一个IL-恐惧性嵌段)。重要的是，工业来源的(巴斯夫)ILS将被用于最大限度地提高IL-聚合物配方的商业相关性。将开发出诱导BCP自组装的配方，包括在溶液中(以获得用于储能应用的离子凝胶)和在体相(以产生用于纳米电子学的具有非常小的磁区尺寸的有序材料)。小角X射线散射(SAXS)将是一种重要的表征技术来确定所得到的自组装物种的大小和形状(即形貌)。块状自组装需要溶剂蒸气退火、热退火或自旋浇注，最终观察到的纳米图形可能取决于是否存在IL。低分子量嵌段共聚物表现出很强的微相分离能力，由于它们能够将微相分离到非常小的(&lt；10 nm)区域，因此引起了研究人员的极大兴趣。在离子液体存在下的溶液自组装产生离子凝胶，极大地改善离子液体的机械性能，同时提供相同的最佳性能(例如离子导电性)，因此具有用于能量存储应用的潜力。

The necessity for sufficient and more developed energy and data storage has triggered emerging research fields over the past two decades in both industry and in academia.Energy storage is vital in this day and age, particularly for storing clean energy produced from renewable resources. Novel materials must be generated to meet this ever-growing demand, and self-assembled block copolymers can be used to generate so-called ionogels (gel materials comprising an ionic liquid (IL) immobilised in a cross-linked polymer matrix) which are a class of materials that offer much promise. The use of ILs offers benefits for energy storage applications due to their unique properties including high ionic conductivity and high thermal & chemical stability.Data storage is another important area in which IL-polymer systems can offer significant advances. According to a 2018 IDC White Paper (US44413318), the Global Datasphere is predicted to increase by 530 per cent to 175 zettabytes (1.75x1023 bytes) between 2018 and 2025. To tackle this astronomical rise, we must produce storage devices with ever-increasing areal density (data storage density). To do this, we must generate nanopatterns with sub-10 nm domains, and strongly segregated block copolymers (BCPs) offer a potential route to such small features. BCPs are polymers synthesised using two or more monomers that are chemically distinct, and they can be arranged in an array of different sequences giving rise to different classifications. A synthetic technique that can be used to develop such BCPs is reversible addition-fragmentation chain transfer (RAFT) polymerisation. Utilising RAFT enables stringent control on the polymerisation process such as controlling the molecular weight and polydispersity such that the resulting polymers are very well-defined. A key advantage of using RAFT is that the process is that the reactions can be carried out using a wide range of functional monomers. There has been increasing interest in RAFT-mediated polymerisation-induced self-assembly (PISA), a technique that will be frequently used in this project to synthesise the desired BCPs. PISA has shown to be advantageous relative to other well established self-assembly routes which customarily involve additional post-polymerization steps.This project will focus on the synthesis and characterisation of BCPs with amphiphilic character in ILs (i.e. containing at least one IL-philic and one IL-phobic block). Importantly, industrially-sourced (BASF) ILs will be used to maximise the commercial relevance of the IL-polymer formulations. Formulations will be developed to induce BCP self-assembly, both in solution (to obtain ionogels for energy storage applications) and in the bulk (to generate ordered materials with very small domain sizes for nanoelectronics). Small-angle X-ray scattering (SAXS) will be an important characterisation technique to determine the size and shape (i.e. the morphologies) of the resulting self-assembled species.Bulk self-assembly requires solvent vapour annealing, thermal annealing or spin casting, and the final observed nanopattern can be dependent on whether an IL is present or absent. Low molecular weight block copolymers that exhibit strong microphase separation have yielded great interest amongst research due to their ability to microphase separate into very small (< 10 nm) domains. Solution self-assembly in the presence of ILs yields ionogels, which vastly improve the mechanical properties of ILs, whilst offering the same optimal properties (e.g. ionic conductivity) and thus have the potential to be used in energy storage applications.