Synthesis and Study of Covalently Bonded Self-Assembled Polymer Gel Nanoparticles

寻找新的大分子结构是大分子科学与工程创新的核心，也是我们研究的长期目标。聚合物凝胶是一类独特的大分子网络，其结构中含有大量的溶剂，如水。目前对聚合物凝胶结构的研究主要集中在体凝胶和微凝胶上。这项工作的目的是创造纳米结构的大块聚合物凝胶，并将这种结构与它们的物理性质联系起来。其核心思想是首先合成单分散的聚合物凝胶纳米颗粒，然后将它们自组装成三维网络，最后将它们共价键合。共价键有助于结构的稳定性，而自组装提供了衍射光的晶体结构，从而产生颜色。PI系统的自组装结构通过其两级结构层次进一步丰富：一级网络由每个纳米颗粒内的交联聚合物链组成，而二级网络是纳米颗粒的交联系统。作为一项可行性研究，PI合成了这种含有97%水的材料，显示出惊人的彩虹色，但柔软而有弹性。PI的方法由四个部分组成。首先，将合成几种具有代表性的聚合物凝胶纳米颗粒，如n -异丙基丙烯酰胺和羟丙基纤维素，并通过光散射方法作为模型构建块进行表征。其次，纳米粒子将自组装成各种结构。第三，将使用各种反应方案来共价键合这些组装体。第四，网络的物理性质，包括共价键、网目大小、两级结构层次、周期结构和弹性，将使用傅里叶变换红外（FTIR）光谱、色谱、紫外可见光谱和光散射方法进行研究。如果这项工作成功，将为在大分子材料中生成具有不同特征尺寸的稳定周期性3D结构提供一个框架。它使我们不仅可以从组成构件中获得有用的功能，还可以从表征这些结构的远程排序中获得有用的功能。创造这样的纳米结构材料在技术应用中也很重要，包括控制药物输送、生物材料、传感器、设备、色谱、生物粘合剂和显示。本科生和研究生都将参与这项研究。他们将在大分子科学和纳米技术的跨学科研究和开发中获得宝贵的技能。

The search for novel macromolecular structures is at the core of innovation in macromolecular science and engineering and is the long-term goal of our research. Polymer gels are a unique class of macromolecular networks that contain a large fraction of solvent such as water within their structure. Most current research on structures of polymer gels has focused on either bulk gels or microgels. The objective of this work is to create nanostructured bulk polymer gels and correlate such structures to their physical properties. The central idea is to first synthesize monodispersed polymer gel nanoparticles, then self-assemble them into 3D networks, and eventually covalently bond them. The covalent bonding contributes to the structural stability, while self-assembly provides the with crystal structures that diffract light, resulting in colors. The self-assembled structure of the PI's systems are further enriched by their two-level structural hierarchy: the primary network consists of crosslinked polymer chains inside each nanoparticle, while the secondary network is a crosslinked system of the nanoparticles. As a feasibility study, the PI's synthesized such a material that contains 97 wt% water, displays a striking iridescence but is soft and flexible. The PI's approach consists of four components. First, several representative polymer gel nanoparticles such as N-isopropylacrylamide and hydroxypropyl cellulose will be synthesized and characterized by light scattering methods as model building blocks. Second, the nanoparticles will be self-assembled into various structures. Third, various reaction schemes will be used to covalently bond these assemblies. Fourth, the physical properties of the networks, including covalent bonding, mesh size, two-level structural hierarchy, periodic structures, and elasticity, will be investigated using Fourier transform infrared (FTIR) spectroscopy, chromatography, UV-visible spectroscopy, and light scattering methods.%%%This work, if successful, will provide a framework to generate stable periodic 3D structures with varying feature sizes in macromolecular materials. It allows us to obtain useful functionality not only from the constituent building blocks but also from the long-range ordering that characterizes these structures. Creating such nanostructured material may also be of importance in technological applications including controlled drug delivery, biomaterials, sensors, devices, chromatography, bio-adhesives, and displays. Both undergraduate and graduate students will participate in this research. They will gain valuable skills in interdisciplinary research and development in macromolecular science and nanotechnology.