Random-Blocky Copolymers: Monomer Sequencing through Templated Chemical Coloring

拟议研究计划的中心主题是展示随机-嵌段共聚物(RBC)的能力，RBC是具有统计控制的单体序列分布的杂化聚合物，能够在整体上进行自组装并识别表面的化学模式。我们计划建立控制单体测序的统计性质就足以赋予RBC独特的组装和识别特性；这可能允许RBC执行类似于更复杂的生物分子的功能。通过调整均聚物在溶液中的旋转半径，然后对那些在空间上可以接触到“着色”部分的单体进行化学修饰(“着色”)，就可以合成RBC。根据均聚物的崩解程度(不良溶剂)或膨胀程度(良好溶剂)，RBC中的单体序列分布范围从块状(不良溶剂)到随机(良好溶剂)。我们提出了基于聚(苯乙烯-co-4-溴苯乙烯)和聚(甲基丙烯酸二甲氨基乙酯-co-烷基)的RBC的合成方案。我们发现，通过附加其他化学官能团，可以进一步对聚(苯乙烯-co-4-溴代苯乙烯)红细胞进行化学修饰。一系列分析探针，包括核磁共振、元素分析和克尔效应测量，将被用来确定红细胞中的化学组成和单体序列分布。分析方法将与使用蒙特卡罗模拟的建模研究相辅相成，这将揭示分子水平上对“着色”过程的本质的洞察。我们还提出了一种在二氧化硅小球表面制备红细胞的新方法。提出了一套全面的实验，旨在了解红细胞在溶液中的组装以及红细胞在溶液/固体和熔融/固体界面上的吸附。后一种方法的主要重点是研究共聚物序列分布、聚合物/固体相互作用和底物的化学非均质性之间的相互作用。高空间分辨率深度剖面技术，包括中子和X射线反射率、椭圆偏振光谱和离子束技术，将与选择性的氚标记相结合，用于探测红细胞在固/液和固/熔体界面的体积分数分布和面内分布。拟议活动的技术价值：这项工作的主要成果将是证明，尽管红细胞具有统计性质，但它能够执行与具有精确控制的单体序列分布的大分子相似的功能。我们将证明，可以使用简单的化学着色方法来生产具有广泛化学成分和官能团的红细胞。合成、实验和模拟的结合将为研究红细胞的溶液组装和界面活性提供非常强大的工具。拟议活动产生的更广泛的影响：红细胞可被认为是对“蛋白质前体”的最简单的模拟。研究它们的溶液自组装和界面性质有望揭示非常复杂的生物分子的行为。拟议项目的技术承诺包括但远远超出基于生物材料的应用的健康。了解这种大分子的界面性能为设计新的材料和结构提供了前所未有的手段，这些材料和结构可以在各种软凝聚物质应用中广泛使用，包括纳米反应器，它们是组织非聚合物纳米夹杂物的种子。我们还概述了我们在培养研究生方面的努力，概述了在北卡罗来纳州芒特艾里和波波斯的一所小学开展的外展活动，以吸引当地的K-12学生参与我们的跨学科研究努力。

The central theme of the proposed research plan is to demonstrate the ability of random-blocky copolymers (RBCs), heteropolymers with statistically controlled monomer sequence distributions, to undergo self-assembly in the bulk and perform recognition of chemical patterns on surfaces. We plan to establish that controlling the statistical nature of the monomer sequencing is sufficient in endowing the RBC with unique assembling and recognition characteristics; these may allow the RBCs to perform functions similar to those of more complex biomolecules. The RBCs will be synthesized by adjusting the radius of gyration of a homopolymer in solution, followed by chemical modification ("coloring") of those monomers that are sterically accessible to the "coloring" moiety. Depending on the degree of collapse (poor solvent) or expansion (good solvent) of the homopolyer, the monomer sequence distribution in the RBC will range from blocky (poor solvent) to random (good solvent). We propose synthetic schemes leading to RBCs based on poly (styrene-co-4-bromostyrene) and poly(dimethyl aminoethyl methacrylate-co-alkyl). We show that poly(styrene-co-4bromostyrene) RBCs can be further chemically tailored by attaching other chemical functionalties. A set of analytical probes, including NMR, elemental analysis, and Kerr effect measurements, will be applied to establish the chemical composition and monomer sequence distribution in the RBCs. The analytical methods will be complemented with modeling studies using Monte Carlo simulations, which will reveal molecular-level insight about the nature of the "coloring" procedure. We also propose a new method for preparing RBCs on the surfaces of small silica spheres. A comprehensive set of experiments is proposed that aim at understanding the assembly of RBCs in solution and the adsorption of RBCs at solution/solid and melt/solid interfaces. The main focus of the latter methods is to investigate the interplay between the copolymer sequence distributioin, the polymer/solid interactions, and chemical heterogeneities of the substrate. High spatial resolution depth profiling techniques, including neutron and X-ray reflectivity, spectroscopic ellipsometry, and ion beam techniques, will be applied in conjunction with selective deuterium labeling to probe the volume fraction profiles and the in-plane distributioin of the RBCs at solid/liquid and solid/melt interfaces. Intecllectual merit of the proposed activity: The major outcome of this work will be the demonstration that RBCs, in spite of their statistical nature, are capable of performing functions similiar to those of macromolecules with precisely controlled monomer sequence distributions. We will demonstrate that simple chemical coloring methods can be employed in order to produce RBCs with a wide range of chemistries and functionalites. The combination of the synthesis, experiment, and modeling will offer very powerful tools for studying the solution assembly and interfacial activity of RBCs. Broader impact resulting from the proposed activity: The RBCs may be considered the simplest mimics of "protein precursors". Studying their solution self-assembly and interfacial properties is expected to reveal important insight into the behavior of very complex biomolecules. The technological promise of the proposed project includes, but extends well beyond, the health of biomaterial-based applications. Understanding the interfacial performance of such macromolecules provides unprecedented means of designing novel materials and stuctures that can find widespread, use in a variety of soft-condensed matter applications, including nano-reactors, "seeds" for organizing non-polymeric nano-inclusions. We also outline our efforts in training graduate students, outline outreach activities in an elementary school in Mount Airy, NC, and popose to attract local K-12 students to take part in our interdisciplinary research endeavor.