Stabilization Mechanism of Emulsions and Latexes in CO2

乳液和乳胶在 CO2 中的稳定机理

• 批准号: 9905531
• 负责人: Keith Johnston
• 金额: $ 27.48万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-10-01 至 2003-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9905531&HistoricalAwards=false
• 关键词: Stabilization; Mechanism; Emulsions; Latexes; CO2

ABSTRACTCTS-9905531Johnston, Keith P.U. of Texas @ AustinThe objective is to develop a knowledge of colloid and interface science in compressed CO2-based systems in order to design surfactant for stable (1) organic polymer latexes and (2) emulsions composed of water and CO2. The adsorption of surfactant at organic-CO2 and water- CO2 interfaces will be described as a function of the balance between the surfactant's "CO2-philic" and "CO2-phobic" segments. Simultaneously, steric stabilization of latexes and emulsions will be controlled by varying the length and degree of solvation of the CO2-philic segment of the surfactant. The ability to relate interfacial properties and colloid stability to surfactant structure is of vital importance for the rational design of surfactants for these novel colloids in CO2.Novel types of diblock or triblock copolymer surfactant structure will be develop to stabilize an organic polymer latex in CO2, which can then be transferred to water form a stable aqueous latex. In CO2, the CO2-philic segment of the surfactant will provide steric stabilization. Upon transfer to water, this segment will collapse onto the surface, and another segment will ionize to provide electrostatic stabilization. The stability of the latex will be related to the adsorption of the surfactant in CO2 and water, the latex particle size, the CO2 density and the surface charge (in water) as a function of pH.A knowledge of the properties of surfactants at the water-in-CO2 interface will be developed to guide studies of the stability of water-in-CO2 (W/C) and CO2-in-water (C/W) emulsions. From measurements of the interfacial tension, the point where the "CO2-philic" and "CO2-phobic" or hydrophilic parts of the surfactant are balanced will be identified. This balance state will serve as crucial reference point to understand emulsion stability and type (curvature) (W/C or C/W) as a function of surfactant structure, pressure, temperature and salinity. Novel sub-micron emulsions will be formed where the interfacial tension is very low, and then the pressure or temperature will be adjusted to manipulate the stability of the emulsion.Emulsions composed of water and CO2 may be utilized for solvent-free coatings, reactions and separations of biomolecules, heterogeneous polymerization, enhanced oil recovery, formation of high surface area material, and cleaning of metals, fabrics, semiconductors, and contaminated soil. The potential for waste reduction is enormous given that more than 30 billion pounds of organic solvents are used worldwide each year.

ABSTRACTCTS-9905531Johnston, Keith P.U.德克萨斯州@奥斯汀的目标是发展基于压缩二氧化碳的系统中的胶体和界面科学知识，以便设计用​​于稳定的（1）有机聚合物乳胶和（2）由水和二氧化碳组成的乳液的表面活性剂。 表面活性剂在有机-CO 2 和水-CO 2 界面处的吸附将被描述为表面活性剂的“亲CO 2 ”和“疏CO 2 ”链段之间的平衡的函数。 同时，乳胶和乳液的空间稳定性将通过改变表面活性剂亲CO2链段的溶剂化长度和程度来控制。 将界面性质和胶体稳定性与表面活性剂结构联系起来对于合理设计这些新型胶体在CO2中的表面活性剂至关重要。将开发新型二嵌段或三嵌段共聚物表面活性剂结构来稳定CO2中的有机聚合物乳胶，然后将其转移到水中形成稳定的水性乳胶。 在 CO2 中，表面活性剂的亲 CO2 链段将提供空间稳定性。 转移到水中后，该片段将塌陷到表面上，而另一片段将电离以提供静电稳定性。 乳胶的稳定性与表面活性剂在 CO2 和水中的吸附、乳胶粒径、CO2 密度和表面电荷（水中）作为 pH 值的函数有关。将开发关于水包 CO2 界面表面活性剂性质的知识，以指导水包水 (W/C) 和 CO2 包水 (C/W) 乳液稳定性的研究。 根据界面张力的测量，将确定表面活性剂的“亲CO2”和“疏CO2”或亲水部分的平衡点。 这种平衡状态将作为了解乳液稳定性和类型（曲率）（W/C 或 C/W）作为表面活性剂结构、压力、温度和盐度函数的重要参考点。在界面张力非常低的情况下，将形成新型亚微米乳液，然后调节压力或温度来控制乳液的稳定性。由水和CO2组成的乳液可用于无溶剂涂料、生物分子的反应和分离、非均相聚合、提高采油率、高表面积材料的形成以及金属、织物的清洁、 半导体和受污染的土壤。 鉴于全球每年使用超过 300 亿磅的有机溶剂，减少废物的潜力是巨大的。