Nitroxide-mediated living free radical miniemulsion polymerization of styrene

摘要

Living free-radical bulk polymerization using a stable free r; initiator system based on nitroxide stable radicals such as TEMPO (2,2 tetramethyl-l -piperidynyloxy) has permitted the synthesis of polymers molecular weight distributions only slightly broader than those obtained via ar polymerization (PDI < 1.3). Most recently we were able to successfully appl living free-radical polymerization in a miniemulsion polymerization process: prepare stable latexes with 20% solids and having relatively narrow mole weight distributions (1.14 - 1.6). Styrene miniemulsions were prepared using anionic surfactant Dowfax 8390 with hexadecane as costabilizer. The miniemu polymerizations were carried out at 125 degrees C in pressure bottles using be peroxide (BPO) and TEMPO. The kinetics of the living free radical miniemu polymerization were followed as a function of the [TEMPO]/[BPO] ratio in ore develop a mechanistic understanding of the nucleation and growth processes in disperse system. The development of particle number and the total numb polymer chains (through the molecular weight analysis) during the cour polymerizations in the presence and absence of TEMPO are used to deve comprehensive picture of the process. [References: 24]