Controlled Radical Polymerization for Novel Soft Materials

可逆去活化自由基聚合（RDRP）作为活性聚合（LP）方法的一种可行的替代方法在过去的二十年中出现，以生产具有可控微观结构的聚合物。几乎所有现代技术都依赖于具有明确分子特性的材料；聚合物对于微电子（定向自组装、光刻）、生物材料（如光刻）至关重要。控释，膜)和结构材料（涂料，密封剂，热塑性弹性体）。RDRP相对于LP的主要优势在于，它在表面上模仿LP的特征（聚合程度与转化程度的线性进展，窄分子量分布，活性链端），而无需应用后者所需的严格纯化和条件。此外，RDRP可以在水中进行，并结合LP无法完成的单体。该研究计划将RDRP应用于开发新材料，主要使用一种称为氮氧化物介导聚合（NMP）的变体，该变体避免了金属配体催化剂残留物或硫基链转移剂在其他常见RDRP工艺中存在的树脂变色。计划在未来5年的项目将重点使用NMP进行：1)定向自组装锥形/梯度共聚物，用于微电子的图案表面；2)通过点击化学获得水凝胶和自修复聚合物的新功能材料；3)合成用于动态水合物抑制剂/促进剂的两亲性嵌段共聚物。定向自组装已经在介电材料（IBM的AirGap技术）中得到了应用，被认为是光刻技术的后继微电子技术，在光刻技术中，通过缩小波长来获得更小的特征尺寸变得更加困难。我们将使用梯度共聚物而不是嵌段共聚物，因为从一个嵌段过渡到另一个嵌段时避免了中间纯化步骤。然而，更分散的界面有趣的自组装挑战。我们将探讨如何获得更小的特征尺寸，同时以可控的方式编程接口宽度。NMP在采用click化学和水凝胶等正交功能化方法方面落后于其他RDRP方法。我们还将研究基于新设计的引发剂改性，这些设计可以使甲基丙烯酸酯均聚并干净地交叉到其他单体家族，从而产生新材料。同时，我们还将采用正交功能化策略，如点击化学，以获得比早期NMP更广泛的材料特性。最后，我们最近报道了两亲性水溶性嵌段共聚物作为动态水合物抑制剂（KHIs）是非常有效的。水合物的形成是天然气管道流动保障面临的最关键问题之一。我们最初的尝试将用于发展结构-性能关系，并最终设计可生物降解的无毒KHIs。

Reversible de-activation radical polymerization (RDRP) has emerged over the past two decades as a viable alternative to living polymerization (LP) methods to produce polymers with controlled microstructure. Virtually all modern technologies depend on materials with defined molecular properties; polymers are critical for microelectronics (directed self-assembly, lithography), biomaterials (eg. controlled release, membranes) and structural materials (coatings, sealants, thermoplastic elastomers). RDRP's key advantage over LP is it mimics superficially hallmarks of LP (linear progression of degree of polymerization vs. conversion, narrow molecular weight distribution, active chain ends) without applying the stringent purification and conditions required of the latter. Further, RDRP can be done in water and combine monomers that otherwise could not be done by LP. The research program applies RDRP to develop new materials, using mostly a variant termed nitroxide mediated polymerization (NMP), which avoids resin discolouration  from metallic ligand catalyst residues or sulfur-based chain transfer agents that are present in other common RDRP processes. The program planned for the next 5 years will focus on using NMP for: 1) directed self-assembly of tapered/gradient copolymers towards patterning surfaces for microelectronics; 2) new functional materials via click chemistry for hydrogels and self-healing polymers; 3) synthesizing amphiphilic block copolymers for application in kinetic hydrate inhibitors/promoters. Directed self-assembly is already exploited in dielectric materials (IBM's AirGap technology) and is considered the successor microelectronics technology to photolithography, where it becomes more difficult to obtain smaller feature sizes by shrinking the wavelength. We will use gradient copolymers instead of block copolymers as an intermediate purification step is avoided when crossing from one block to the other. However, the more diffuse interface interesting self-assembly challenges. We will explore how to obtain smaller feature sizes while programming the interfacial width in a controlled manner. NMP has lagged behind other RDRP methods in adopting orthogonal functionalization methods like click chemistry and hydrogels. We will also examine initiator modification based on new designs which can homopolymerize methacrylates and cross-over cleanly to other monomer families, yielding new materials. Concurrently, we will also adopt orthogonal functionalization strategies like click chemistry to access a wider range of material properties than that was possible earlier by NMP. Finally, amphiphilic water-soluble block copolymers as kinetic hydrate inhibitors (KHIs) were recently reported by us to be quite effective. Formation of hydrates is one of the most critical problems facing flow assurance in gas pipelines. Our initial forays will be used to develop structure-property relationships and eventually design biodegradable non-toxic KHIs.