Enhancing Functional and Structural Properties of Polymer Nanocomposites by Controlling Dispersion and Interfaces

技术摘要：将纳米颗粒（如碳纳米管）分散在聚合物基体中，为创造具有新性能的新材料提供了一种很有前途的方法。不幸的是，大多数纳米颗粒在聚合物基体中不能均匀分散，因此制备的混合物很少达到目标性能。该项目将通过了解聚合物和原始纳米管之间的分子间相互作用如何完成和优化来克服这一限制。这将通过确定各种聚合物结合的官能团与原始单壁纳米管（SWNT）形成电子供体-受体（EDA）相互作用的能力，并将这种相互作用的性质和程度与聚合物基质中SWNT的分散以及最终纳米复合材料的结构和功能特性相关联来实现。此外，与SWNT形成EDA配合物的最有前途的官能团将作为次要组分并入共聚物中。在这些纳米复合材料中，将监测纳米复合材料中非共价相互作用形成的程度，并将其与纳米填料在聚合物基体中的分散和纳米复合材料的性能相关联。这种共聚将扩大聚合物结构的范围，从而扩大目标功能，从而可以纳入分散良好的聚合物纳米复合材料。实验设计建立在我们之前的nsf支持的工作基础上，该工作表明，优化聚合物和纳米级填料之间的非共价相互作用（氢键）可以显著改善所得到的纳米复合材料的分散性、热学、电子和结构性能。因此，我们将完成一系列的实验，利用我们在非共价聚合物-纳米填料相互作用方面的专业知识，开发合理调整纳米填料和聚合物基体之间的界面相互作用的方法，以改善所得纳米复合材料的均匀性和性能，同时保留目标功能所需的界面结构。非技术摘要纳米级填料与聚合物的均匀混合可以生产出具有一系列性能的新材料，这些性能仅用聚合物是无法获得的。例如，在聚合物基体中加入粘土已被证明可以提高其热变形温度、阻燃性、透气性和强度。另外，在共轭聚合物基体中加入碳富勒烯或纳米管可以提高其将阳光转化为能量的能力。不幸的是，制造这种聚合物和纳米颗粒的均匀混合物是困难的，因为大多数纳米颗粒不能有效地分散在聚合物基质中。通过改变纳米颗粒的表面可以改善混合性能，但这种改变往往会导致其预期性能的降低。该项目将寻求通过开发方法来克服这一限制，在不改变纳米颗粒结构的情况下，将聚合物和纳米颗粒之间的吸引相互作用结合起来，最终目标是利用这些吸引相互作用来改善纳米颗粒在聚合物基体中的分散和最终纳米复合材料的性能。该项目还将对当地高中科学教师进行聚合物方面的培训，通过一个公共宣传网站（www.factofthematter.org）向公众宣传材料对技术进步的贡献，并通过与工业界合作，加快将从该项目中获得的指导方针和基本理解转化为商业上可行的技术。

TECHNICAL ABSTRACTDispersing nanoparticles, such as carbon nanotubes, in a polymer matrix offers a promising method to create new materials with novel properties. Unfortunately, most nanoparticles do not homogeneously disperse in a polymer matrix, and thus the fabricated mixtures rarely attain the targeted properties. This project will seek to overcome this limitation by developing an understanding of how intermolecular interactions between polymer and pristine nanotubes can be accomplished and optimized. This will be realized by determining the ability of various polymer-bound functional groups to form electron donor-acceptor (EDA) interactions with pristine single-walled nanotubes (SWNT) and correlating the nature and extent of this interaction to the dispersion of the SWNT in a polymer matrix and to the structural and functional properties of the ultimate nanocomposite. Additionally, the most promising functional groups that form EDA complexes with SWNT will be incorporated into copolymers as a minor component. In these nanocomposites, the extent of non-covalent interaction formation in the nanocomposite will be monitored and correlated to the dispersion of the nanofiller in the polymer matrix and to the nanocomposite properties. This copolymerization will broaden the range of polymer structures, and thus targeted functionality, that can be incorporated in well-dispersed polymer nanocomposites. The design of the experiments builds on our previous NSF-supported work that demonstrates that optimizing non-covalent interactions (hydrogen bonding) between polymer and nanoscale filler can dramatically improve the dispersion and thermal, electronic, and structural properties of the resultant nanocomposite. Thus, a series of experiments will be completed that utilizes our expertise in non-covalent polymer-nanofiller interactions to develop methods to rationally tune the interfacial interaction between a nanofiller and polymer matrix to improve the homogeneity and properties of the resultant nanocomposite, while preserving the interfacial structure required for a targeted functionality.NON-TECHNICAL ABSTRACTHomogeneous mixing nano-sized fillers with a polymer enables the production of new materials with a range of properties that are not accessible with polymers alone. For instance, the inclusion of clays in a polymer matrix has been shown to improve its heat deflection temperature, flame resistance, gas permeability and strength. Alternatively, the incorporation of carbon fullerenes or nanotubes in a conjugated polymer matrix improves its ability to turn sunlight into energy. Unfortunately, creating this homogeneous mixture of polymers and nanoparticles is difficult, as most nanoparticles will not effectively disperse in the polymer matrix. Improved mixing behavior has been realized by modifying the surface of the nanoparticle, however this alteration often results in a decrease in its desired properties. This project will seek to overcome this limitation by developing methods to incorporate attractive interactions between the polymer and nanoparticle, without altering the structure of the nanoparticle, with the ultimate goal of using these attractive interactions to improve the dispersion of the nanoparticles in the polymer matrix and the properties of the final nanocomposite. This project will also train local high school science teachers in polymers, educate the public regarding the contribution of materials to technological advances via a public outreach website (www.factofthematter.org), and expedite the transfer of the guidelines and fundamental understanding garnered from this project to commercially viable technologies by collaborating with industry.