Collaborative Project: GOALI: Acrylic Resins Product and Process Design through Combined Use of Quantum Chemical Calculations and Spectroscopic Methods

合作项目：GOALI：结合使用量子化学计算和光谱方法进行丙烯酸树脂产品和工艺设计

• 批准号: 1159736
• 负责人: Andrew Rappe
• 金额: $ 23.03万
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1159736&HistoricalAwards=false
• 关键词: Collaborative; Project; GOALI; Acrylic; Resins

Abstract1160169/1159736Soroush / RappeIntellectual Merit. In our recent successful GOALI work, we have made significant advances in understanding the spontaneous thermal polymerization of acrylates in the absence of any conventional thermal initiators. By combining efficient first-principles quantum-mechanical density functional theory (DFT) calculations with spectroscopic measurements of polymer samples, we have identified conclusively the mechanisms for monomer self-initiation and chain transfer reactions, including the reaction intermediates and transition states. We also calculated rate constants (frequency factors and activation energies) for the reactions in the gas phase.Now, building on these results, we propose to improve experimental control of the thermal spontaneous (without addition of conventional thermal initiators) polymerization of alkyl acrylates through coordinated and collaborative experimental and theoretical/computational research. To deepen our theoretical understanding, calculations will be performed with increasingly realistic solvent models, including multiple explicit solvent molecules in the quantum region and recently-developed van der Waals DFT functionals, to improve intermolecular potential energy surfaces. Concurrently, batch reactor polymerization experiments will be designed on the basis of the computational results and conducted to evaluate the influence of solvent type, monomer and solvent concentrations, and temperature on polymer-chain microstructural characteristics and polymerization rate.The specific goals of this project are: (a) We will develop a computationally efficient method of calculating reliable liquid-phase rate constants for spontaneous thermal acrylate polymerization reactions such as monomer self-initiation, co-initiation by monomer and solvent, and chain transfer. (b) We will design and conduct batch polymerization experiments and, using spectroscopic methods, measure the microstructural characteristics of the produced polymer chains to validate and refine our theoretical predictions. (c) Using the developed computational method and batch polymerization experiments, we will study the structure-reactivity relationship for various solvents and monomers with a ketone functional group. (d) We will use these theoretical and experimental understandings to guide our computational screening and experimental validation of novel thermal initiators (solvents that permit rapid but controllable thermal polymerization of acrylates). Our ultimate goal is to design high-performance acrylic resins and chemically self-regulated polymerization processes for the production of acrylic resins at attractive overall cost.Broader Impacts. The potential impacts of this project are societal (through improved safety), environmental, economic, and in human resource development, among others. Spontaneous thermal polymerization allows for the production of higher quality, environmentally friendlier solvent-borne paints and coatings at lower operating costs. Low molecular weight polymer and oligomer solutions have adequately low viscosity?even at high weight percent solids?thus requiring less solvent to be sprayable and brushable. The reduction or elimination of thermal initiators (e. g. azonitrile or organic peroxides, normally the most expensive component of a resin formula) and the increase of reaction rate both lower the operating costs. The elimination of residual groups due to the thermal initiators in the final product (which adversely affect polymer properties such as resistance to UV radiation) and the use of the quantitative understanding in optimal control of the polymerization reactors improve the resin quality. The PIs and Co-PI will train and mentor two doctoral research assistants as well as six undergraduate (REU) students, who will participate in broad range of research activities from quantum-level computations and supercomputing to laboratory experiments and spectroscopic methods. The project results will be released to the public at conferences and in journal and conference proceedings papers. As in our past research activities, students from under-represented groups will be selected, trained and mentored in this project.

摘要1160169/1159736Soroush / Rappe智力价值。在我们最近成功的 GOALI 工作中，我们在理解没有任何传统热引发剂的情况下丙烯酸酯的自发热聚合方面取得了重大进展。通过将有效的第一原理量子力学密度泛函理论（DFT）计算与聚合物样品的光谱测量相结合，我们最终确定了单体自引发和链转移反应的机制，包括反应中间体和过渡态。我们还计算了气相反应的速率常数（频率因子和活化能）。现在，基于这些结果，我们建议通过以下方法改进丙烯酸烷基酯热自发（不添加常规热引发剂）聚合的实验控制协调和协作的实验和理论/计算研究。为了加深我们的理论理解，我们将使用越来越现实的溶剂模型进行计算，包括量子区域中的多个显式溶剂分子和最近开发的范德华DFT泛函，以改善分子间势能表面。同时，根据计算结果设计间歇反应器聚合实验，评估溶剂类型、单体和溶剂浓度以及温度对聚合物链微观结构特征和聚合速率的影响。该项目的具体目标是：（a）我们将开发一种计算有效的方法来计算自发热丙烯酸酯聚合反应的可靠液相速率常数，例如单体自引发、单体和溶剂共引发以及链转移。 （b）我们将设计和进行间歇聚合实验，并使用光谱方法测量所产生的聚合物链的微观结构特征，以验证和完善我们的理论预测。 （c）利用开发的计算方法和间歇聚合实验，我们将研究具有酮官能团的各种溶剂和单体的结构-反应性关系。 (d)我们将利用这些理论和实验理解来指导我们对新型热引发剂（允许丙烯酸酯快速但可控热聚合的溶剂）的计算筛选和实验验证。我们的最终目标是设计高性能丙烯酸树脂和化学自调节聚合工艺，以有吸引力的总体成本生产丙烯酸树脂。产生更广泛的影响。该项目的潜在影响包括社会（通过提高安全性）、环境、经济和人力资源开发等。自发热聚合可以以更低的运营成本生产更高质量、更环保的溶剂型油漆和涂料。低分子量聚合物和低聚物溶液具有足够低的粘度——即使固体重量百分比高——因此需要较少的溶剂即可喷涂和刷涂。热引发剂（例如偶氮腈或有机过氧化物，通常是树脂配方中最昂贵的成分）的减少或消除以及反应速率的提高都降低了操作成本。消除最终产品中由于热引发剂而产生的残留基团（这会对聚合物性能产生不利影响，例如耐紫外线辐射），并在聚合反应器的最佳控制中使用定量理解，从而提高树脂质量。 PI 和 Co-PI 将培训和指导两名博士研究助理以及六名本科生 (REU)，他们将参与从量子级计算和超级计算到实验室实验和光谱方法的广泛研究活动。该项目的结果将在会议、期刊和会议论文集上向公众发布。与我们过去的研究活动一样，该项目将选择、培训和指导来自代表性不足群体的学生。