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

基于官能化乙烯基苯并环丁烯嵌段共聚物的两亲性纳米粒子的合成与自组装

• 批准号: 1006195
• 负责人: Coleen Pugh
• 金额: $ 53万
• 依托单位: University of Akron
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-03-01 至 2016-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1006195&HistoricalAwards=false
• 关键词: Synthesis; Self; Assembly; Amphiphilic; Nanoparticles

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.

技术概述纳米颗粒必须有序排列成复杂的阵列，具有生物系统的控制和再现性，用于纳米和生物技术应用。 虽然不对称官能化的纳米粒子预期直接自组装成复杂的结构而不需要模板辅助，但大多数纳米粒子的形状是具有各向同性表面的球形。 因此，提出了一种新的路线来合成相对刚性的两亲性有机纳米颗粒，其具有用于自组装成1-D、2-D和/或3-D超结构的棒状或哑铃形和三脚架形，使用基于1-官能化乙烯基苯并环丁烯的两亲性嵌段共聚物，其中每个含乙烯基苯并环丁烯的嵌段在显著不同的温度下经历异构化。因此，两亲性纳米颗粒将通过在选择性溶剂化非交联嵌段的溶剂中在伪高稀释条件下的单独分子内交联步骤逐步制造。嵌段的长度将控制叶的尺寸，并且纳米颗粒预期在5-20 nm的尺寸范围内。 分子内交联反应将通过NMR光谱法通过苯并环丁烯环的共振的消失来监测，并且聚合物/纳米颗粒的尺寸和形状的变化将通过凝胶渗透色谱法、光散射、透射电子显微镜（TEM）和/或原子力显微镜（AFM）对通过“结晶化液体组装”技术制备的样品进行跟踪。 将使用原子力显微镜对“样品化”的样品进行分析，以确定单个纳米颗粒的形状，并通过TEM、扫描TEM和表面增强拉曼光谱法确定其化学成分和形状的变化;这些技术也将用于表征它们在液-液界面或固体基底上的自组装结构。与较大颗粒相比，足够小以被认为是纳米颗粒的颗粒具有独特的性质。 这些独特的性质导致了独特的应用，这导致了“纳米技术”领域。 然而，要在纳米技术应用中取得重大进展，纳米颗粒必须能够有序地形成复杂的结构。 虽然复杂的结构可以通过将纳米颗粒放置在已经构建了复杂图案的表面上来生成，但计算机研究表明，如果颗粒本身具有复杂的形状和/或复杂的表面特性，则纳米颗粒应该能够在非图案化表面上有序排列。 例如，如果纳米颗粒表面的一半喜欢水而另一半排斥水，则颗粒的这两个部分将仅与周围颗粒上的相似部分相互作用，使得它们的组织受到它们的相似性和差异的指导或限制。 因此，提出了一种新的路线来创建具有复杂形状的纳米颗粒，例如哑铃和三脚架形状，其中每个叶片具有不同的表面特性。 纳米颗粒的不同部分将使用化学物质逐步产生，该化学物质在不同温度下对每个不同的叶进行反应。 这些新的纳米粒子将提供真实的材料，以测试预测纳米粒子在具有不寻常形状和不同表面性质时如何组织的理论。 拟议的研究将培养学生研究人员在日益重要的纳米技术领域，同时要求掌握基础化学和物理学。 本科生将在夏季通过REU（本科生研究经验）职位参加该研究项目，该职位位于阿克伦大学NSF赞助的REU高分子科学与工程网站。 此外，将在阿克伦的国王小学为K-5学生建立一个特殊兴趣博览会。