Growth and Structure of Multifunctional Polymer Brushes from Ultra-thin Coatings

超薄涂层多功能聚合物刷的生长和结构

• 批准号: 1507409
• 负责人: Padma Gopalan
• 金额: $ 38.4万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1507409&HistoricalAwards=false
• 关键词: Growth; Structure; Multifunctional; Polymer; Brushes

NON-TECHNICAL SUMMARY:Polymer brushes are long stringy molecules that are chemically bonded to a surface to form dense, thin coatings that drastically change the properties of the surface. These coatings guide the behavior of cells for regenerative medicine, promote biocompatibility in implant devices, resist deposition of micro-organisms on ship hulls, or control flow of electricity in microelectronic devices. The structure of the polymer brushes provides the needed mechanical strength to form a stable coating and their chemistry provides the right functionality to interface/communicate between the substrate and the environment. This research program will develop new synthetic methodologies to make these polymer brushes and develop materials characterization techniques to promote a molecular-level understanding of the resulting structures. This methodology has the potential to be of broad impact since the chemistry is simple enough to be adapted by the coatings industries. The research program will serve to inspire and involve undergraduate students in polymer science and engineering research, by working with the PI and graduate student mentors through the REU program. K-12 educational modules developed through this research will be disseminated nationally by the PI and the graduate students by partnering with UW-Madison Institute for Chemical Education (ICE). Through the Women in Science and Engineering (WISE) Residential Program the PI will engage in mentoring underrepresented students to create a supportive environment by coordinating information, research and activities for and about women in the sciences and engineering.TECHNICAL SUMMARY: The research program will study the synthesis of a single-component crosslinked coating to grow homopolymers and mixed polymer brushes with excellent control over homogeneity of grafting sites, dispersities, chemical functionalities, graft to graft distance, ability to grow low to high molecular weights, and with stability to thermal annealing conditions. The growth of polymer brushes from these coatings is fundamentally different from growth from traditional self-assembled monolayers. A key aspect of this research will be to develop a mechanistic understanding of the growth process by combining depth profiling and angle resolved X-ray photoelectron spectroscopy (ARXPS) studies. The stratification effect as well as brush growth kinetics will be studied as a function of crosslink density and coating thickness by embedding specific elemental markers in the brush (Br and N). Combination of ARXPS, Atomic force microscopy and 3D tomography will provide useful morphological information on these polymer brushes. The brushes grown from these coatings will be floated off from the substrate as "polymer carpets" and 3D morphological insight obtained by 3D tomography. Melt self-consistent field theory (SCFT) predictions of phase diagrams for mixed polymer brushes are based on the assumption that the grafting densities are uniform. So far experimental means for meeting these assumptions have lagged behind. Using the unique chemistry for growth of well-defined brushes and the characterization methods developed in this proposal the SCFT predictions will be tested. Furthermore the simplicity of the chemistry is expected to allow arbitrary changes in composition to tune surface properties by incorporating appropriate comonomers. For these reasons the methodology developed here has the potential to have major impact by highly simplifying the way polymer brushes are grown.

非技术摘要：聚合物刷子是一种长而细的分子，它们以化学方式结合到表面上，形成致密、薄的涂层，从而极大地改变了表面的特性。这些涂层指导再生医学细胞的行为，促进植入设备的生物兼容性，防止微生物沉积在船体上，或控制微电子设备中的电流流动。聚合物刷子的结构提供了形成稳定涂层所需的机械强度，它们的化学成分提供了正确的功能，以便在衬底和环境之间进行接口/通信。这项研究计划将开发新的合成方法来制造这些聚合物刷子，并开发材料表征技术，以促进对所产生结构的分子水平的了解。这种方法有可能产生广泛的影响，因为这种化学方法足够简单，可以被涂料行业采用。该研究计划将通过REU计划与PI和研究生导师合作，激励和参与聚合物科学和工程研究的本科生。通过这项研究开发的K-12教育模块将由PI和研究生与威斯康星大学麦迪逊化学教育研究所(ICE)合作在全国传播。通过女性科学与工程(WISE)居留计划，PI将致力于指导未被充分代表的学生，通过协调科学和工程领域女性的信息、研究和活动来创造一个支持性的环境。技术摘要：该研究计划将研究单组分交联涂层的合成，以生长均聚物和混合聚合物刷子，该涂层对接枝点的均质性、分散性、化学功能、接枝到接枝的距离、生长低到高分子量的能力以及对热退火条件的稳定性具有良好的控制。这些涂层中聚合物刷子的生长与传统自组装单分子膜的生长有根本的不同。这项研究的一个关键方面将是通过结合深度剖析和角度分辨X射线光电子能谱(ARXPS)研究来发展对生长过程的机理理解。通过在刷子(BR和N)中嵌入特定的元素标记，将作为交联剂密度和涂层厚度的函数来研究层化效应以及刷子生长动力学。ARXPS、原子力显微镜和3D断层成像的结合将为这些聚合物刷子提供有用的形态信息。从这些涂层生长出来的刷子将作为“聚合物地毯”漂浮在基材上，并通过3D断层成像获得3D形态洞察。熔体自洽场理论(SCFT)对混合聚合物刷相图的预测是基于接枝密度均匀的假设。到目前为止，满足这些假设的实验手段一直落后。利用明确定义的刷子生长的独特化学和本提案中开发的表征方法，SCFT的预测将得到验证。此外，化学的简单性有望允许任意改变组成，通过加入适当的共聚单体来调整表面性质。出于这些原因，这里开发的方法有可能产生重大影响，因为它高度简化了聚合物刷子的生长方式。