Kinetics and Mechanism of Stable Free Radical Miniemulsion Polymerization (SFRMP) and Application to the Preparation of Nanostructured Latex Particles

大多数具有特殊性质的聚合物材料具有窄的分子量分布(MWD)。在这个项目中，PI将使用一种新型的带有氮氧化物稳定自由基的自由基引发系统，这将促进具有窄MWD的聚合物的合成。最初在乳液聚合中使用这种引发剂系统的尝试没有成功，问题被追溯到大的单体液滴。为了克服这些问题，人们开发了一种细乳液聚合技术。单体首先以亚微米液滴的形式分散，在那里发生成核和聚合。成功地制备了固含量较高、粒径为100 nm的聚苯胶乳，并获得了较窄的分子量分布。了解这一独特的乳液聚合过程的动力学和机理是该项目的主要目标之一。将探索合成表面具有各种共价键合官能团(如羧基、氨基、环氧基)的胶乳粒子的新途径。PI还将利用聚合物链的“活性”特性，通过连续的单体添加步骤，研究如何制备具有所需表面结构/性能的多层胶体颗粒。这些材料的性能将被测量，预计将与传统聚合工艺制造的材料有很大不同。

Most polymeric materials with special properties have narrow molecular weight distributions (MWDs). In this project the PIs will use a novel free radical initiator system with nitroxide stable radicals that will promote the synthesis of polymers with narrow MWDs. Initial attempts to use this initiator system in emulsion polymerizations were unsuccessful, and problems were traced to large monomer droplets. To overcome these problems, a miniemulsion polymerization technique was developed. Monomer is first dispersed in the form of submicron droplets where nucleation and polymerization occur. Polystyrene latexes with relatively high solids content and with particle sizes of 100 nm were successfully prepared, and narrow MWDs were obtained. An understanding of the kinetics and mechanism of this unique emulsion polymerization process is one of the primary goals of this project. New avenues for the synthesis of latex particles with a variety of covalently bonded functional groups (e. g., carboxyl, amino, epoxy) at the particle surface will be explored. The PIs will also take advantage of the "living" character of polymer chains in an investigation of the preparation of multi-layered colloidal particles with desired surface structures/properties by sequential monomer addition steps. The properties of these materials will be measured and are expected to differ substantially from those being made by conventional polymerization processes.