Understanding In-Situ Chemical Transformations of Polymer Brush-Modified Surfaces

这项先进材料研究的主要目标是了解通过化学反应转化表面附着的聚合物层即所谓的聚合物刷子的能力如何受表面密度、界面上链条的程度、在自由溶液中存在的官能剂的大小以及反应时间和条件等性质的影响。虽然反应性聚合物刷子引起了广泛的兴趣，但指导选择合适的条件整合官能团的设计规则仍然没有开发出来，而且在很大程度上还没有被探索。为了解决这一知识差距，将在现场创建和修改反应性聚合物刷子，还将研究化学修饰的界面层成核矿物相生长的能力。所有这些研究都将加强功能性聚合物界面涂层的设计，为细胞生长的生物材料支架、传感器、微阵列或膜中的活性层以及润滑性、耐磨性或防污染涂层的设计带来新的长期机会。智能优点：了解安装在界面层中的官能团的位置和分布是一个复杂而具有挑战性的命题，因为纳米级结构及其被化学转化的能力是紧密耦合的：层中化学标记的分布和官能化程度的变化影响界面层的结构和性质。为了应对这一挑战，将研究以聚(甲基丙烯酸叔丁酯)和聚乙烯基二甲基内酯为基础的反应性聚合物刷子。使用大小从齐聚物到聚合物的多组分子的非催化和催化反应都将被研究。将使用中子反射率来确定改性刷子的纳米结构，并将创造性地应用同位素标记和对比度匹配策略来确定安装在刷子中的官能团的局部密度。为了研究化学基元的显示如何影响层的功能能力，我们将研究改性聚合物层中方解石相的成核和生长，为合成聚合物基质中钙矿物相的形成提供迫切需要的观点。这些活动将受益于一项新的国际合作，该合作带来了聚合物基质中钙矿化的专业知识。广泛影响：表达聚合物刷子的纳米级结构如何与层中显示的官能团的排列、大小和密度相耦合的设计规则将促进基于界面聚合物层的有用设备和结构的高效和优化设计。例如，了解聚合物支架中功能基元的展示与钙矿物相生长之间的联系，可能会促进仿生结构的发展，有助于缩小合成材料和天然复合材料(如骨)之间的差距。基础研究可分为界面高级界面材料研究、生物医学先进材料和传感器可能长期应用的材料。除了通过参与研究促进研究生和本科生以及博士后学者的培训外，与国家实验室和瑞士洛桑联邦理工学院的科学家合作将促进相关研究人员的专业成长和发展，部分得益于计划中的交流访问。在该计划中开展的研究活动将辅之以外展和指导活动，以支持来自代表性不足群体的学生的招生、留住和成功。最后，研究活动的结果将通过出版物和参与该计划的所有参与者的演讲进行交流，并将为即将召开的全国会议组织一次关于反应性聚合物界面的研讨会。

ABSTRACT#1133320Kilbey, S. MichaelUNDERSTANDING IN-SITU CHEMICAL TRANSFORMATIONS OF POLYMER BRUSH-MODIFIED SURFACESThe overarching goal of this advanced materials research is to understand how the ability to transform surface-attached polymeric layers so-called polymer brushes by chemical reaction is impacted by properties such as surface density, extent of the chains tethered at the interface, size of the functionalizing agent present in free solution, and reaction time and conditions. While reactive polymer brushes are of widespread interest, design rules that guide selection of appropriate conditions for integrating functional groups remain undeveloped and largely unexplored. To address this gap in knowledge, reactive polymer brushes will be created and modified in situ, and the ability of the chemically-modified interfacial layers to nucleate the growth of mineral phases will also be investigated. All of these studies will enhance the design of functional polymeric interfacial coatings, leading to new long term opportunities for the design of biomaterial scaffolds for cell growth, active layers in sensors, microarrays or membranes, and lubricious, wear-resistant, or anti-fouling coatings. Intellectual Merit: Understanding the location and distribution of functional groups installed in interfacial layers is a complex and challenging proposition because the nanoscale structure and its ability to be chemically transformed are intimately coupled: changes in the distribution of chemicaln tags in the layer and the degree-of-functionalization impact the structure and properties of the interfacial layer. To address this challenge, reactive polymer brushes based on poly(tert-butyl methacrylate) and poly(vinyl dimethylazlactone) will be studied. Both uncatalyzed and catalyzed reactions using sets of molecules ranging in size from oligomeric to polymeric will be investigated. The nanoscale structure of the modified brushes will be determined using neutron reflectivity, and a creative application of isotopic labeling in concert with contrast matching strategies will be used to determine the local density of functional groups installed in the brushes. To investigate how the display of chemical motifs affects the capacity of a layer to function, the nucleation and growth of calcite phases in modified polymer layers will be examined, providing a much-needed view of how calcium mineral phases form in synthetic polymer matrices. These activities will benefit from a new international collaboration that brings expertise in calcium mineralization in polymer matrices.Broader Impacts: Design rules that express how the nanoscale structure of polymer brushes is coupled to the arrangement, size and density of functional groups displayed in the layer will promote the efficient and optimal design of useful devices and constructs based interfacial polymer layers. For example, understanding the links between the display of functional motifs in polymer scaffolds and the growth of calcium mineral phases may advance the development of biomimetic constructs that help close the gap between synthetic and natural composite materials such as bone. The fundamental research can be classified as advanced interfacial materials research at and for interfaces, bio-medical advanced materials, and materials for possible long term sensor applications.In addition to promoting the training of graduate and undergraduate students and a postdoctoral scholar through engagement in research, collaborations with scientists at national laboratories and from Ecolé Polytechinque Fédérale de Lausanne (Switzerland) will enhance the professional growth and development of researchers involved, aided in part by planned exchange visits. Research activities undertaken in this program will be supplemented with outreach and mentoring activities that will bolster the recruitment, retention, and success of students from under-represented groups. Finally, results from the research activities will be communicated through publications and presentations by all participants involved in the program, and a symposium on reactive polymer interfaces will be organized for an upcoming national meeting.