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.

建议编号：CBET-0730692/CBET-0731319首席研究员：Mark D.Foster/David T.Wu大学/研究所：阿克伦大学/科罗拉多矿业学院：合作研究：使用支化和环状分子控制界面热力学和功能化这是与科罗拉多矿物学院CBET-0731319合作的项目。控制聚合物界面性质独立于本体性质在许多应用和工艺中至关重要，可以通过官能化分子丰富界面来实现。由于所需官能团在界面上可能不受青睐，因此需要一个促进这种浓缩的一般策略。我们的目标是使用新的非线性链结构来创造热力学驱动力，将功能化的分子带到界面上，而不依赖于界面寻找基团。福斯特的团队(U·阿克伦)已经证明，长链支化确实可以将聚合物驱离或驱离界面。这些实验只与吴(科罗拉多矿业学院)的平均场理论预测部分一致。此外，环状分子还被预测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。为了促进对本体和界面热力学的理解，将这一概念转化为有用的应用，它们将整合定义明确的分子的合成(Quirk，UA)、混合行为的实验测量(Foster)和新理论的发展(Wu)。智力上的优点：将发展一种新的自洽场形式，以在对(非平均场)水平上处理分子内和分子间的相互作用，以考虑显式的拓扑效应以及化学基团效应和链构象之间的相互作用。由于单体-单体相互作用，非线性链共混物的关键物理问题预计是膨胀/崩溃和拥挤。一个早期的目标将是解释关于支链混合物的表面偏析和相关的整体热力学的现有数据。首次用中子反射法和表面增强拉曼光谱测量了环链共混物的界面偏析和体相热力学相互作用参数。与支链共混物的新信息一起，这些数据将被比较并用于完善理论。通过阴离子聚合合成定义明确的支链和环状分子将使比较变得特别尖锐。还将与使用具有商业前景的格拉布斯催化剂进行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，他们将通过将具有表面避免的极性基团的聚合物表面功能化，将其连接到具有特殊设计的非线性结构的分子上。辐射影响：本研究实现的长支化和环状聚合物的热力学建模将适用于用于本体和表面流变性改性的添加剂的设计(例如在润滑油中和控制液滴形成或辅助加工)，用于粘合剂和密封剂(例如硅氧烷材料)，以及用于药物输送(例如树枝状聚合物)。它也将适用于含有支链和环状聚合物的生物体系，如多糖和核酸。教育将与研究相结合，让研究生加入合作大学和国家实验室的研究活动，并通过阿克伦大学的REU计划包括本科生。教职员工和研究生将与阿克伦全球聚合物学院一起准备视频模块，以网络和课堂为基础向K-12学生推广。这些模块将描述研究中的基本概念，例如分子混合和分离的原因，光和中子的散射如何揭示表面的结构，以及拉曼光谱如何对表面组成敏感。