Responsive Films Derived from Weak Polyelectrolyte Multilayers

该项目的目标是探索将聚电解质多层膜（PEMs）转化为高功能pH，离子强度和/或温度响应涂层的原理和开发策略，该涂层可可逆地捕获或释放合成大分子和蛋白质。在这个项目中产生的关于在表面稳定聚合物薄膜的物理和化学方法的新知识将对材料和聚合物科学做出重大贡献。具体来说，该项目将为响应性聚合物自组装的构建块的分子设计、pem衍生为活性表面涂层以及基于pem的表面粘附和吸收性能调节的潜在能力等问题提供丰富的信息。我们的方法将基于分子工程和PEMs的聚合“构建块”的合成，其化学成分是进一步将PEMs转化为吸收膜所必需的。我们将探索几种使用静电或氢键聚合物多层膜作为起始材料生产表面附着活性吸收膜的途径。第一种方法将基于静电组装多层膜的组分在高浓度小离子下的解离，并结合其中一种膜组分的选择性“盐析”。在另一种情况下，我们将探索氢键多层的化学交联作为一种生产表面附着水凝胶的手段。将自组装的聚羧酸选择性交联，并进一步从交联的聚酸基质中释放出氢键聚合物，制备单组分聚羧酸水凝胶。双组分水凝胶将通过末端功能化的氢键聚合物与自组装聚酸的羧基反应得到。在后一种类型的吸收膜中，响应和吸收性能将通过氢键聚合物链之间的分子间粘附来调节。利用原位ATR-FTIR对薄膜组成、官能团电离和电荷平衡进行选择性监测。这些数据将与原位椭偏仪和原位原子力显微镜测量的薄膜膨胀结果相关联。聚合物相互作用如何响应环境刺激的问题，以及它们如何转化为膜密度和吸收特性的变化，将被解决。使用生产的薄膜作为可重新加载的基质，可以可逆和可控地吸收和解吸大分子和蛋白质，以应对环境刺激，特别有价值的分离，浓缩，以及控制化学物质和蛋白质在环境中的释放，这些环境具有表面的主导作用，如微流体通道。建议的研究结果将通过会议报告、项目负责人的邀请演讲、研究生的海报和口头报告以及档案文献向广泛的科学听众提供。教育方面的影响包括在史蒂文斯建立一个更强大的跨学科聚合物项目，为学生提供更好的培训。提议的研究结果将包含在最近开发的高级聚合物课程中，例如固体-液体界面的聚合物，以及研究生和本科生水平的其他核心实验室课程。还将通过支持两名女研究生来加强妇女对高级研究的参与。最后，由于我们小组在acs SEED项目中开展的活动，经济困难的高中学生将有机会接触到这项研究。

TECHNICAL EXPLANATION The objective of the project is to explore principles and develop strategiesfor transforming polyelectrolyte multilayers (PEMs) into highly functional pH-, ionicstrength- and/or temperature-responsive coatings which reversibly trap or releasesynthetic macromolecules and proteins. New knowledge generated in this project aboutphysical and chemical ways to stabilize polymer films at surfaces will be a significantcontribution to materials and polymer science. Specifically, the project will provide a wealth ofinformation on issues pertaining to molecular design of building block for responsive polymerself-assembly, derivatization of PEMs into active surface coatings and potential capabilitiesin PEM-based regulation of surface adhesion and absorption properties.Our approach will be based on a combination of molecular engineering and synthesis ofpolymeric 'building blocks' of PEMs with the chemical composition necessary for furthertransformation of PEMs into an absorbing film. We will explore several routes of producingsurface-attached active absorbing films using electrostatic or hydrogen-bonded polymermultilayers as a starting material. The first route will be based on the dissociation of componentsof electrostatically assembled multilayers at high concentrations of small ions combined withselective 'salting-out' of one of the film components. In another scenario, we will explorechemical crosslinking of hydrogen-bonding multilayers as a means to produce surface-attachedhydrogels. One-component hydrogels of polycarboxylic acids will be produced by selectivecrosslinking of self-assembled polycarboxylic acids and further release of hydrogen-bondedpolymers from the crosslinked polyacid matrix. Two-component hydrogels will be obtained byreacting end-functionalized hydrogen-bonding polymers with carboxylic groups of selfassembledpolyacid. In the latter type of absorbing films, response and absorbing properties willbe modulated through intermolecular adhesion between hydrogen-bonded polymer chains.Selective monitoring of film composition, ionization of functional groups and quantification ofcharge balance will be done using in situ ATR-FTIR. The data will be correlated with the resultsof film swelling as measured with in situ ellipsometry and in situ AFM. The question of howinterpolymer interactions respond to environmental stimuli, and how they are translated intochanges in film density and absorption properties will be addressed.NON-TECHNICAL EXPLANATION The use of produced films as re-loadable matrices that could reversibly andcontrollably absorb and desorb macromolecules and proteins from response to environmentalstimuli, specifically valuable for separation, concentration, and controlled release of chemicalsand proteins in environments with dominating effects of surfaces such as in a microfluidicchannel. Results of proposed research will be made available to a broad scientific audiencethrough conference presentations, invited talks given by the PI of this project, poster and oralpresentations of graduate students, and archival literature.The educational impact includes building a stronger interdisciplinary polymer program atStevens that will provide better training for students. The results of the proposed research will beincluded into recently developed advanced polymer courses, such as Polymers at Solid-LiquidInterfaces, and other core laboratory courses at both graduate and undergraduate levels.Participation of women in advanced research will be enhanced also through support of twofemale graduate students. Finally, economically disadvantaged high school students will begiven an opportunity to be exposed to this research due to activities our group sustains in theACS SEED program.