Reactions of Functional Polymers at Organic Interfaces

技术摘要：涉及聚合物的界面反应比涉及小分子反应物的反应要复杂得多，因为影响其分子结构和界面行为的变量范围很广。虽然界面反应是许多聚合物应用的一部分，但对影响它们的参数通常缺乏基本的了解。因此，拟议研究计划的科学目标是提供对影响聚合物在有机界面上反应的因素的基本和定量的了解。这一目标的实现是这个项目的成果：为聚合物界面反应的分子设计和随后对它们所带来的界面性质的控制提供了基本的基础。选择了两个模型反应系统进行研究，以代表实际中可能遇到的各种反应：官能化聚合物与含有互补官能团的有机表面之间的“标准”反应。与有机表面接触的聚合物之间的光接枝反应，其中一个含有能够将聚合物接枝到表面的光活性基团。研究所需的功能聚合物将通过原子转移自由基聚合来制备。拟议的研究调查了界面反应如何受到以下因素的影响：溶剂质量和浓度，包括整齐的聚合物；分子量；官能团的面密度；官能团沿聚合物主干的位置；表面相互作用参数的性质；聚合物的状态(即玻璃态或橡胶状)、光化学反应条件和反应时间。所使用的有机界面将在硅片或镀金晶片上制备，以便通过一系列技术来表征反应，这些技术包括：X射线光电子能谱、掠射反射红外、椭偏仪、接触角、MALDI-TOF质谱仪、荧光光谱和凝胶渗透色谱。该研究计划还包括验证一种新的概念，即逐层共价组装，其中多个聚合物层连续地建立在有机衬底上，其中每一层都与前一层共价结合。非技术摘要：链分子在中间相反应的长度的性质是许多涉及聚合物和生物大分子的应用的重要潜在方面。这种反应用于控制材料和涂层的表面性质，如附着力和润湿性，用于使磁性纳米颗粒溶于水，作为磁共振成像增强剂，并用于制造生物传感器，其中DNA、蛋白质、抗体和抗原与底物化学结合以形成诊断微阵列。所提出的研究方案将为此类反应的设计和优化提供科学基础，以便在这些应用中使用。这种使能技术将在制造廉价的DNA测序芯片、过滤有害病原体的服装以及识别危险病原体和抗原物的快速诊断方面发挥重要作用。拟议中的研究还将通过一系列项目对研究和教育产生广泛影响：培训本科生和研究生研究人员，主办一名研究界面反应的暑期高中化学教师，并与该教师一起开发适合在他的课堂上使用的聚合物化学模块。PI.还将通过担任驻校教授、与学生一起住在宿舍、与本科生和一位特邀嘉宾就与“社会与科技”系列主题相关的话题举行非正式晚宴等方式，继续向哥伦比亚大学本科生进行外联活动。

TECHNICAL SUMMARY:Interfacial reactions involving polymers are far more complex than reactions involving small molecule reactants because of the broad range of variables that can affect their molecular structure and behavior at interfaces. While interfacial reactions are a part of many polymer applications, a fundamental understanding of the parameters affecting them is generally lacking. The scientific goal of the proposed research plan is therefore to provide a fundamental and quantitative understanding of the factors that influence the reactions of polymers at organic interfaces. The achievement of this goal is the deliverable of this project: a fundamental basis for both the molecular design of polymer interfacial reactions and for the subsequent control of the interfacial properties they bring about. Two model reaction systems have been selected for study to represent the wide variety of reactions that may be encountered in practice: . a "standard" reaction between a functional polymer and an organic surface containing a complementary functional group . a photografting reaction between a polymer in contact with an organic surface, one of which contains a photoactive group capable of grafting the polymer to the surface.The functional polymers required for the research will be prepared by atom transfer radical polymerization. The proposed research investigates how interfacial reactions are influenced by factors such as: solvent quality and concentration, including neat polymers; molecular weight; areal density of functional groups; location of functional groups along the polymer backbone; the nature of the surface interaction parameter, state of the polymer (i.e., glassy or rubbery), conditions of the photochemical reaction and reaction time. The organic interfaces employed will be prepared on either silicon wafers or gold-coated wafers in order to enable characterization of the reactions by a barrage of techniques including: x-ray photoelectron spectroscopy, grazing incidence reflection infrared, ellipsometry, contact angle, MALDI-TOF mass spectrometry, fluorescence spectroscopy and gel permeation chromatography. The research program also includes validation of a new concept, covalent layer-by-layer assembly, in which multiple polymer layers are successively built up on an organic substrate wherein each layer is covalently bound to the previous layer.NON-TECHNICAL SUMMARY:The nature of how long chain molecules react at interphases is an important underlying aspect of many applications involving polymers and biomacromolecules. Such reactions are used to control surface properties of materials and coatings such as adhesion and wettability, are employed to make magnetic nanoparticles soluble in water for potential use as magnetic resonance imaging contrast enhancement agents, and are used in the fabrication of biosensors wherein DNA, proteins, antibodies and antigens are chemically bound to substrates to form diagnostic microarrays. The proposed research program will provide a scientific basis for the design of such reactions and their optimization for use in these applications. This enabling technology will play an important role in the manufacturing of inexpensive DNA sequencing chips, clothing that can filter out harmful pathogens and rapid diagnostics that can identify dangerous pathogens and antigens.The proposed research will also have a broad impact on research and education through a number of programs: the training of undergraduate and graduate researchers, hosting of a summer high school chemistry teacher researching interfacial reactions and with that teacher, the development of modules on polymer chemistry suitable for use in his classes. The P.I. will also continue his outreach efforts to Columbia University undergraduate students at large through his activities as a Professor in Residence, living amongst the students in a dormitory and hosting informal dinners with undergraduates and a special guest talking on a topic related to the series theme "Society and Technology".