GOALI: New Generation of Acrylic Resins Produced through Spontaneous Thermal Polymerization

摘要：Masoud Soroush研究所：德雷克塞尔大学建议书编号：0651706标题：GALI：通过自发热聚合生产的新一代丙烯酸树脂智力优点：北美关于涂料挥发性有机化合物含量的法规要求将允许的挥发性有机化合物从1990年的480 g/L涂料降低到2010年的300 g/L以下。这些法规和类似法规正在推动涂料中树脂的基本性质发生变化。固含量为60-80%的低相对分子质量、高官能化聚合物和低聚物溶液取代了固含量为30-40%的高相对分子质量、无官能化聚合物溶液，成为涂料配方中的关键成分。制备低分子量聚合物溶液的一个很有前途的方法是在高温下进行聚合。在这些高温下，二次反应对聚合速率和分子结构的形成有很大的影响，而这些反应在低温下并不显著。例如，烷基丙烯酸酯在高于140℃的温度下发生显著的、持续的、可重复的、自发的均相和共聚，这是该团队在2002年首次报道的，几十年来，人们一直知道甲基丙烯酸酯和苯乙烯在高温下发生可重复的自发聚合。引发丙烯酸烷基酯自发热聚合链式反应的物种和引发机理尚不清楚。对这些二次反应的定量了解使人们能够设计出更安全、更环保的聚合工艺，从而生产出新一代更高质量的溶剂型树脂。在这个项目中，首先设计了一种有效的实验方法来识别(A)引发丙烯酸酯自发性聚合的痕量物种和(B)引发过程的机理。实验方法应保证引发物和反应参数的可识别性。其次，在精心控制的条件下，按实验方法进行了丙烯酸丁酯等丙烯酸酯的高温自发聚合，并对聚合物的结构进行了表征。第三，将这些结果与数学模型相结合，以完善机理路径并量化二次反应的动力学。第四，研究了所建立的反应网络参数的可辨识性，以确保测量类型、数量和质量的充分性。第五，建立了适用于丙烯酸烷基酯高温自由基聚合的通用模型，并用实验室实验数据进行了验证。最后，利用所建立的机理模型，采用博弈论的新方法对半间歇、连续搅拌槽(CST)和混合式(CST后半间歇)的反应器设计构型进行了筛选，并计算出每种最优设计构型的最优配方。广泛影响：该项目的潜在影响包括环境、经济和教育等。对二次反应的定量了解的提高导致了以较低的操作成本生产新一代更高质量、更环保的溶剂型涂料和涂料。低分子量聚合物和低聚物溶液即使在高质量百分比固体时也具有足够低的粘度，因此需要添加较少的有机溶剂。使用较少或不添加热引发剂(通常是树脂配方中最昂贵的成分)，以及在较高温度下反应时间较短，可降低操作成本。在最终产品中，热引发剂残留基团较少(这会对聚合物性能产生不利影响，如抗紫外线辐射)，并在分子性能优化控制中使用定量理解，可提高树脂质量。包括杜邦在内的树脂和涂料行业主要受益于该项目的科学成果。该项目为一名博士和两名本科生提供了在工业环境中获得研究经验的宝贵机会。它的结果在会议和期刊论文上向公众公布。

ABSTRACTPI: Masoud Soroush Institution: Drexel University Proposal Number: 0651706Title: GOALI: New Generation of Acrylic Resins Produced through Spontaneous Thermal PlymerizationIntellectual Merit: North American regulations on volatile organic content (VOC) of coatings require the reduction of allowable VOC's from 480 g/L of paint in 1990 to below 300 g/L by 2010. These and similar regulations are driving change in the basic nature of resin in coatings. Low molecular weight, highly functionalized polymer and oligomer solutions at 60 to 80 weight percent solids have replaced high molecular weight, non-functional polymer solutions at 30 to 40 weight percent solids as key components in coatings formulas. A promising method of producing low molecular-weight polymer solutions is to carry out the polymerization at high temperatures. At these high temperatures, secondary reactions, that are insignificant at low temperatures, have very strong effects on the polymerization rate and molecular structure formation. For example, alkyl acrylates undergo significant, sustained, reproducible, spontaneous homo- and co-polymerization at temperatures above 140.C, which was first reported by this team in 2002 methacrylates and styrene have been known for several decades to undergo reproducible spontaneous polymerization at high temperatures. The species that initiate the chain reactions in spontaneous thermal polymerization of alkyl acrylates and the initiation mechanism are yet unknown. A quantitative understanding of these secondary reactions allows one to design safer and environmentally-friendlier polymerization processes that produce a new generation of higher quality, solvent-borne resins.In this project, an effective experimental method is first designed to identify (a) the trace species that initiate the spontaneous polymerization of alkyl acrylates and (b) the mechanism of the initiation process. The experiment method should ensure the identifiability of the initiating species and the reaction parameters. Second, under carefully controlled conditions, high-temperature spontaneous polymerization of alkyl acrylates such as butyl acrylate is carried out according to the experiment method, and the polymer structure is characterized. Third, these results are combined with mathematical modeling to refine the mechanistic pathways and quantify the kinetics of the secondary reactions. Fourth, the identifiability of the parameters of the developed reaction network is investigated to ensure the sufficiency of the type, number and quality of measurements. Fifth, a general model applicable for high-temperature free radical polymerization of alkyl acrylates is constructed and tested against lab-scale experimental data. Finally, by using the developed mechanistic models, reactor design configurations such as semi-batch, continuous stirred tank (CST), and hybrid (CST followed by semi-batch) are screened using a novel game-theory-based method, and an optimal recipe for each optimal design configuration is calculated.Broader Impact: The potential impacts of the project are environmental, economic and educational, among others. The improved quantitative understanding of the secondary reactions leads to the production of a new generation of higher quality, environmentally-friendlier solvent borne paints and coatings at lower operating costs. Low molecular weight, polymer and oligomer solutions even at high weight percent solids have adequately low viscosity, thus requiring the addition of less organic solvents. The use of less or no added thermal initiators (normally the most expensive component of a resin formula) and the adequacy of shorter reaction times at higher temperatures lower the operating costs. The presence of less residual groups from thermal initiators (which adversely affect polymer properties such as resistance to UV radiation) in the final product and the use of the quantitative understanding in optimal control of molecular properties improve the resin quality. The resin and coating industries including DuPont benefit primarily from the scientific outcomes of this project. The project provides one Ph.D. and two undergraduate students with an invaluable opportunity to gain research experience in an industrial environment. Its results are released to the public at conferences and in journal papers.