Collaborative Research: Control of interfacial thermodynamics and functionalization using branched and cyclic molecules

合作研究：使用支链和环状分子控制界面热力学和功能化

• 批准号: 0731319
• 负责人: David Wu
• 金额: $ 14.3万
• 依托单位: Colorado School of Mines
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-10-01 至 2011-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0731319&HistoricalAwards=false
• 关键词: Collaborative; Research; Control; interfacial; thermodynamics

Proposal Number: CBET-0730692 / CBET-0731319 Principal Investigator: Mark D. Foster / David T. WuUniversity/Institution: University of Akron/Colorado School of MinesTitle: Collaborative Research: Control of Interfacial thermodynamics and functionalization using branched and cyclic molecules This is a collaborative project with CBET-0731319, Colorado School of Mines.Control of polymer interfacial properties independent of bulk properties is crucial in many applications and processes, and can be achieved by enrichment of the interface by functionalized molecules. Since desired functional groups may not be favored at the interface, a general strategy is needed for promoting this enrichment. Our goal is to use novel nonlinear chain architectures to create a thermodynamic driving force to bring functionalized molecules to an interface without relying on interface-seeking groups. Foster's group (U. Akron) has shown that long-chain branching can indeed drive a polymer to or away from an interface. These experiments are only in partial agreement with mean-field theory predictions by Wu (Colorado School of Mines). Cyclic molecules are moreover predicted to produce an interfacial driving force independent of chemical group and polydispersity. The investigators will make the first measurements on blends containing cyclic molecules. To advance the understanding of both bulk and interfacial thermodynamics needed to move this concept to useful applications, they will integrate synthesis of well-defined molecules (Quirk, UA), experimental measurement of blend behavior (Foster), and development of new theory (Wu).Intellectual merit: A new self-consistent field formalism will be developed to treat intra- and inter-molecular interactions at the pair (non-mean-field) level, to account for explicit topological effects as well as interplay between chemical group effects and chain conformation. The critical physical issues for blends of nonlinear chains are anticipated to be swelling/collapse and crowding due to monomer-monomer interactions. An early objective will be to explain existing data on surface segregation and related bulk thermodynamics for mixtures with branched chains. Experimental measurements of interfacial segregation with neutron reflectometry and surface enhanced Raman spectroscopy, as well as of the bulk thermodynamic interaction parameter, will be made on blends of cyclic chains for the first time. Together with new information on blends with branched chains, these data will be compared with and used to refine theory. Synthesis of well-defined branched and cyclic molecules by anionic polymerization will enable particularly incisive comparisons. Comparison will also be made with blends containing polydisperse cyclic chains synthesized using ring-opening polymerizations with a Grubbs catalyst that has commercial promise. To demonstrate our approach, they will functionalize a polymer surface with surface-avoiding polar groups by attaching them to molecules with specifically designed nonlinear architectures.Broader impacts: The thermodynamic modeling of long-branched and cyclic polymers enabled by this study will be applicable to the design of additives for bulk and surface rheology modification (e.g. in lubricant oils and to control droplet formation or aid processing), for adhesives and sealants (e.g. siloxane materials), and for drug delivery (e.g. dendronized polymers). It will also be applicable for biological systems containing branched and cyclic polymers such as polysaccharides and nucleic acids. Education will be integrated with research by having graduate students join in research activities at the partner university and national laboratories, and by including undergraduates through U. Akron's REU program. Faculty and graduate students will prepare video modules with the Akron Global Polymer Academy for web and classroom-based outreach to K-12 students. These modules will describe basic concepts from the research, such as reasons for the mixing and demixing of molecules, how scattering of light and neutrons revealsstructure,and how Raman spectroscopy can be sensitive to the composition of surfaces.

提案编号：CBET-0730692 / CBET-0731319 首席研究员：Mark D. Foster / David T. Wu 大学/机构：阿克伦大学/科罗拉多矿业学院 标题：协作研究：使用支链和环状分子控制界面热力学和功能化 这是与科罗拉多矿业学院 CBET-0731319 的合作项目。控制聚合物界面性能独立于体积特性在许多应用和工艺中至关重要，并且可以通过功能化分子富集界面来实现。由于所需的官能团在界面上可能不受青睐，因此需要一种通用策略来促进这种富集。我们的目标是使用新颖的非线性链结构来创建热力学驱动力，将功能化分子带到界面上，而不依赖于界面寻找基团。 福斯特的研究小组（U. Akron）已经证明，长链支化确实可以驱动聚合物进入或离开界面。这些实验仅与吴（科罗拉多矿业学院）的平均场理论预测部分一致。此外，预计环状分子会产生与化学基团和多分散性无关的界面驱动力。研究人员将对含有环状分子的混合物进行首次测量。为了加深对本体热力学和界面热力学的理解，将这一概念转化为有用的应用，他们将整合明确分子的合成（Quirk，UA）、共混行为的实验测量（Foster）以及新理论的开发（Wu） ).智力价值：将开发一种新的自洽场形式主义来处理分子对（非平均场）水平上的分子内和分子间相互作用，以解释明确的拓扑效应以及化学基团效应之间的相互作用和链构象。非线性链共混物的关键物理问题预计是由于单体-单体相互作用而导致的膨胀/塌陷和拥挤。早期的目标是解释有关支链混合物的表面偏析和相关整体热力学的现有数据。将首次利用中子反射计和表面增强拉曼光谱对界面偏析以及整体热力学相互作用参数进行实验测量。连同有关支链混合物的新信息，这些数据将被比较并用于完善理论。 通过阴离子聚合合成明确的支链和环状分子将能够进行特别深入的比较。还将与具有商业前景的使用格鲁布斯催化剂开环聚合合成的含有多分散环链的共混物进行比较。为了演示我们的方法，他们将通过将聚合物表面连接到具有专门设计的非线性结构的分子上，用避免表面的极性基团对聚合物表面进行功能化。更广泛的影响：本研究支持的长支链和环状聚合物的热力学模型将适用于设计用于本体和表面流变改性（例如在润滑油中并控制液滴形成或辅助加工）、粘合剂和密封剂（例如硅氧烷材料）以及药物输送的添加剂（例如树枝状聚合物）。它还适用于含有支链和环状聚合物（例如多糖和核酸）的生物系统。通过让研究生参加合作大学和国家实验室的研究活动，以及通过阿克伦大学的 REU 项目纳入本科生，教育将与研究相结合。教师和研究生将与阿克伦全球聚合物学院一起准备视频模块，以便通过网络和课堂向 K-12 学生进行宣传。这些模块将描述研究中的基本概念，例如分子混合和分层的原因、光和中子的散射如何揭示结构以及拉曼光谱如何对表面的组成敏感。