RUI: Stabilization of Gold Nanoparticles in Solution by Poly(Vinyl Alcohol) Adsorption

技术综述聚合物在纳米颗粒上的吸附既具有技术意义，又具有科学意义。考虑到金纳米颗粒(AuNPs)的广泛应用，以及聚乙烯醇(PVOH)的无毒性和水溶性，令人惊讶的是，PVOH在AuNPs上的吸附研究尚未见文献报道。选择PVOH的另一个理由是，它可以在商业上获得，具有不同的相对分子质量和水解度，即不同量的残留聚醋酸乙烯酯(PVA)重复单元。一般柠檬酸还原法制备的AuNPs对PVOH和PVA链段的吸附分别由氢键和疏水相互作用驱动。主要的相互作用模式将取决于给定系统中两个过程的相对能量学。聚合物组成为吸附提供了一个额外的控制参数，并增加了探索吸附机理的复杂性(S)。了解PVOH/PVA在AuNPs上的吸附变化，如聚合物相对分子质量、纳米粒子的尺寸、聚合物组成、聚合物浓度和吸附时间，将使我们能够提出一种稳健的方法来提高AuNPs对溶液pH、离子强度和温度变化的稳定性。为了我们在聚合物薄膜中制备自组装纳米粒子的长期利益，PVOH可能太结晶，不能作为粒子形成有序阵列的合适的聚合物基质，而PVA在提供柔软性方面可能是重要的。以允许粒子在自组装中移动。在AuNP-PVOH体系中发展起来的理解和方法有可能推广到其他纳米颗粒-亲水聚合物偶联物。非技术性SUMMARY纳米颗粒由于其高比表面积/体积比而在溶液中容易形成聚集体，导致其独特的纳米特性的丧失。在纳米粒子上吸附一层薄的聚合物是一种在其应用中提供粒子稳定的有效方法。在这项拟议的工作中，一种水溶性和无毒的聚合物聚乙烯醇将从水溶液中吸附到纳米金颗粒表面，以防止纳米颗粒因环境中pH、离子强度和温度的扰动而聚集。这项提案中要求的资金将在未来三年支持派？S与曼荷莲学院的本科生和当地女高中生进行研究合作的努力。本科生和当地女高中生将参与这项提案中描述的工作的所有方面，从设计和合成到使用常规和复杂的仪器进行表征。在这个过程中，研究人员将被介绍到聚合物化学的跨学科领域，并接触到至关重要的纳米技术领域。让本科生接触研究对于教育和招生都很重要。建议的外展活动有哪些？让当地的女高中生参与前沿研究，让当地的中学生参与有趣的、启发性的聚合物工作坊？将激励和培养更多的女性成为未来的科学家和工程师。

TECHNICAL SUMMARYPolymer adsorption onto nanoparticles has both technological relevance and scientific significance. Considering the broad range of applications involving gold nanoparticles (AuNPs) and the nontoxicity and water solubility of poly(vinyl alcohol) (PVOH), it is surprising that adsorption studies of PVOH onto AuNPs have not been reported in the literature. An additional rationale for selecting PVOH is that it is commercially available with different molecular weights and extents of hydrolysis, i.e. different amounts of residual poly(vinyl acetate) (PVA) repeat units. The adsorption of PVOH and PVA segments onto AuNPs prepared by the common citrate reduction method is expected to be driven by hydrogen bonding and hydrophobic interactions, respectively. The dominant mode of interaction will depend on the relative energetics of the two processes in a given system. Polymer composition provides an additional control parameter for adsorption and increases the complexity of probing of the adsorption mechanism(s). Understanding the variants of PVOH/PVA adsorption onto AuNPs, such as polymer molecular weight, size of nanoparticles, polymer composition, polymer concentration, and adsorption time, will allow us to propose a robust method to impart the stabilization of AuNPs against variations in solution pH, ionic strength, and temperature. For our long-term interest of preparing self-assembled NPs in polymer thin films, PVOH may be too crystalline to function as an appropriate polymer matrix for particles to form organized arrays and PVA could be important in providing ?softness? to allow particle mobility in self-assembly. The understanding and methodologies developed in the AuNP-PVOH system are potentially extendable to other nanoparticle-hydrophilic polymer conjugates.NON-TECHNICAL SUMMARYNanoparticles have the tendency to form aggregates in solution, due to their high surface area-to-volume ratio, resulting in the loss of their unique nanoscopic characteristics. Adsorption of a thin polymer layer onto nanoparticles is an effective approach to provide particle stabilization in their applications. In the proposed work, a water-soluble and nontoxic polymer, poly(vinyl alcohol), will be adsorbed onto gold nanoparticle surfaces from aqueous solutions, to prevent nanoparticles from aggregating in response to environmental perturbations in pH, ionic strength, and temperature. The funds requested in this proposal will support the PI?s efforts in research collaborations with undergraduate students at Mount Holyoke College and local female high school students over the next three years. The undergraduate and local female high school students will be involved in all aspects of the work described in this proposal, from design and synthesis to characterization using both routine and sophisticated instrumentation. In the process, researchers will be introduced to the interdisciplinary field of polymer chemistry and be exposed to the vitally important area of nanotechnology. Exposure of undergraduate students to research is important for both education and recruitment purposes. The outreach activities proposed ? having local female high school students involved in frontier research and local middle school students engaged in fun and enlightening polymer workshops ? will inspire and prepare more women to be future scientists and engineers.