Synthesis and Self-Assembly of Amphiphilic Nanoparticles Based on Block Copolymers of Functionalized Vinylbenzocyclobutenes

技术总结纳米颗粒必须被订购成复杂的阵列，具有用于纳米和生物技术应用的生物系统的可控性和重复性。尽管不对称功能化的纳米颗粒有望在不需要模板辅助的情况下直接自组装成复杂的结构，但大多数纳米颗粒是具有各向同性表面的球形颗粒。因此，人们提出了一条新的路线，利用基于1-官能化的乙烯基苯并环丁烯的两亲嵌段共聚物，合成相对刚性的、具有杆状或哑铃状和三脚架形状的有机纳米粒子，以自组装成一维、二维和/或三维超结构，其中每个含有乙烯基苯并环丁烯的嵌段在显著不同的温度下进行异构化。因此，两亲性纳米颗粒将通过在准高稀释条件下的单独的分子内交联步骤逐步制备，该溶剂选择性地溶剂化非交联链(S)。块的长度将控制叶的大小，纳米颗粒预计在5-20 nm大小范围内。分子内的交联反应将通过核磁共振波谱中苯并环丁烯环的共振消失来监测，聚合物/纳米颗粒的尺寸和形状的变化将通过凝胶渗透色谱、光散射、透射电子显微镜(TEM)和/或原子力显微镜(AFM)来监测，这些样品是通过“液体化石组装”技术制备的。原子力显微镜将被用来确定单个纳米粒子的形状，它们的化学成分和形状的变化将通过电子显微镜、扫描电子显微镜和表面增强拉曼光谱来确定；这些技术也将被用来表征它们在液-液界面或在固体基质上的自组装结构。与较大的粒子相比，小到可以被认为是纳米粒子的粒子具有独特的性质。这些独特的性质正在导致独特的应用，这就导致了纳米技术领域的出现。然而，要在纳米技术应用方面取得重大进展，纳米颗粒必须能够有序地形成复杂的结构。尽管通过将纳米颗粒放置在已有复杂图案的表面上可以产生复杂的结构，但计算机研究表明，如果颗粒本身具有复杂的形状和/或复杂的表面属性，纳米颗粒应该能够在没有图案的表面上有序排列。例如，如果纳米颗粒表面的一半喜欢水，另一半排斥水，那么颗粒的这两个部分只会与周围颗粒上的相似部分相互作用，因此它们的组织受到它们的相似和不同的指导或限制。因此，提出了一种新的路线来创造具有复杂形状的纳米颗粒，例如哑铃形和三脚架形状，其中每个叶具有不同的表面属性。纳米颗粒的不同部分将通过化学反应逐步产生，每个不同的叶在不同的温度下发生反应。这些新的纳米粒子将提供真实的材料来测试理论，这些理论预测当纳米粒子具有不寻常的形状和不同的表面属性时，它们是如何组织的。这项拟议的研究将在日益重要的纳米技术领域培训学生研究人员，同时要求他们掌握基础化学和物理。本科生将在夏季通过一个REU(本科生研究体验)职位参加这个研究项目，该职位位于阿克伦大学由NSF赞助的REU聚合物科学与工程网站。此外，还将在阿克伦的国王小学为K-5年级的学生设立特别兴趣交易会。

TECHNICAL SUMMARYNanoparticles must be ordered into complex arrays with the control and reproducibility of biological systems for both nano- and biotechnology applications. Although asymmetrically functionalized nanoparticles are expected to self-assemble directly into complex structures without the need for template assistance, most nanoparticles are spherical in shape with isotropic surfaces. A new route is therefore proposed to synthesize relatively rigid, amphiphilic organic nanoparticles with rod or dumb-bell and tripod shapes for self-assembly into 1-D, 2-D, and/or 3-D superstructures, using amphiphilic block copolymers based on 1-functionalized vinylbenzocyclobutenes in which each of the vinylbenzocyclobutene-containing blocks undergoes isomerization at a significantly different temperature. The amphiphilic nanoparticles will therefore be fabricated step-wise by separate intramolecular crosslinking steps under pseudo-high dilution conditions in solvents that selectively solvate the non-crosslinking block(s). The lengths of the blocks will control the size of the lobes, and the nanoparticles are expected to be in the 5-20 nm size range. The intramolecular crosslinking reaction will be monitored by the disappearance of the resonances of the benzocyclobutene rings by NMR spectroscopy, and the change in the size and shape of the polymers/nanoparticles will be followed by gel permeation chromatography, light scattering, transmission electron microscopy (TEM), and/or atomic force microscopy (AFM) of samples prepared by a "fossilized liquid assembly" technique. Atomic force microscopy of "fossilized" samples will be used to determine the shapes of individual nanoparticles, and variations in their chemical composition as well as shape will be determined by TEM, scanning TEM and surface-enhanced raman spectroscopy; these techniques will also be used to characterize their self-assembled structures at a liquid-liquid interface or on a solid substrate.NON-TECHNICAL SUMMARY Particles that are small enough to be considered nanoparticles have unique properties compared to larger particles. These unique properties are leading to unique applications, which has led to the field of "nanotechnology". However, to make major advances in nanotechnology applications, the nanoparticles must be able to order into complex structures. Although complex structures can be generated by placing the nanoparticles on a surface with that complex pattern already built into it, computer studies have shown that nanoparticles should be able to order on a non-patterned surface if the particles themselves have complex shapes and/or complex surface properties. For example, if half of the nanoparticle surface likes water and the other half repels water, those two parts of the particle will only interact with similar parts on surrounding particles, such that their organization is directed or restricted by their similarities and differences. A new route is therefore proposed to create nanoparticles that have complex shapes, such as dumbbell and tripod shapes, in which each of their lobes have different surface properties. The different parts of the nanoparticle will be created stepwise using chemistry that reacts at a different temperature for each of the different lobes. These new nanoparticles will provide real materials to test theories that predict how nanoparticles organize when they have unusual shapes and varying surface properties. The proposed research will train student researchers in the increasingly important area of nanotechnology, simultaneously with requiring mastery of fundamental chemistry and physics. Undergraduate students will participate in this research program during the summer through an REU (research experience for undergraduates) position, in the NSF-sponsored REU Site for Polymer Science and Engineering at The University of Akron. In addition, a Special Interest Fair will be established for K-5 students at King Elementary School in Akron.