The Fundamentals of Admicellar Polymerization

GRADY-9521985开发了一种称为胶束聚合的方法，该方法可以通过表面活性剂模板在表面形成一层非常薄的聚合物。在该过程中，在吸附在表面上的表面活性剂双层的疏水区中形成聚合物。通过PPG Industries和俄克拉荷马大学应用表面活性剂研究所的合作研究，已经表明在商业沉淀二氧化硅上形成的胶束聚合的苯乙烯-二烯共聚物显著改善了二氧化硅作为橡胶的填充剂的性能，该橡胶用作汽车轮胎的模型。白炭黑填充轮胎胎面胶可能比普通炭黑填充轮胎胎面胶具有优势，如较低的热量积累和更好的抗碎裂/块化性能。填充白炭黑的胎面还可以具有较低的滚动阻力，从而提高燃油经济性和减少温室气体排放，同时还可以改善潮湿路面的牵引力。这些轮胎一直不受欢迎，因为需要使用昂贵的有机硅烷偶联剂和增加混合时间。胶束聚合可以提供一种机制来生产具有相同性能优势的白炭黑填充胎面，但不需要偶联剂。本研究的目的是：(1)建立胶束聚合的动力学表达式，(2)了解聚合物组成对填料性能改善的影响，以及(3)确定二氧化硅孔结构与胶束聚合的关系。为了解决第一个目标，模型表面将被用来将动力学问题与孔扩散问题分开。由于胶束聚合表面上类似于乳液聚合，因此Smith-Ewart动力学将提供理论起点。第二个目标是由这样一个事实驱动的，即用苯乙烯-二烯共聚物改性的二氧化硅比用任一种均聚物改性的二氧化硅具有更好的填充性。该项目的第三部分将使用可控孔径的沉淀二氧化硅，结合散射和液体吸附测量来探索孔结构的影响，以量化孔径的变化。

Abstract - Grady - 9521985 A process called admicellar polymerization has been developed which can be used to form a very thin layer of polymer on a surface via a surfactant template. In this process a polymer is formed in the hydrophobic region of a surfactant bilayer absorbed on the surface. Through a cooperative research effort between PPG Industries and the Institute of Applied Surfactant Research at the University of Oklahoma, it has been shown that admicellar polymerized styrene-diene copolymers formed on a commercial precipitated silica significantly improve the properties of the silica as a filler for a rubber which serves as a model for automobile tires. Silica-filled tire treads may have advantages over normal carbon black filled tire treads, such as lower heat buildup and improved resistance to chipping/chunking. Silica-filled treads can also have a lower rolling resistance leading to better fuel economy and reduced emissions of greenhouse gases, while also having improved traction on wet pavement. These tires have not been popular because use of a costly organosilane coupling agent and increased mixing times are required. Admicellar polymerization might offer a mechanism for producing a silica-filled tread with these same performance advantages, yet a coupling agent is not required. The objectives of this research are to: (1) develop a kinetic expression for admicellar polymerization, (2) understand the effect of polymer composition on the improvement in filler properties, and (3) determine the relationship between silica pore structures and admicellar polymerization. To address the first objective, model surfaces will be used to isolate the kinetic problem from the pore diffusion problem. Since admicellar polymerization superficially resembles emulsion polymerization, Smith-Ewart kinetics will provide the theoretical starting point. The second objective is motivated by the fact that a silica modified with a styrene-diene copolymer has better filler properties than a silica modified with either homopolymer. The third part of the project will explore pore structure effects using controlled pore-size precipitated silicas in combination with scattering and liquid adsorption measurements to quantify changes in pore size.