Process for producing homo- and co-polymers by RAFT miniemulsion polymerization

摘要

A novel process to produce homo- and co-polymers by RAFT polymerization in miniemulsion is here disclosed. The invention mixes to different existing technologies: miniemulsion and living free radical polymerization by RAFT. Miniemulsion provides the necessary radical segregation in order to reduce bimolecular terminations and to increase the polymerization rate. Moreover, since in miniemulsion oil droplets are directly nucleated, the transfer agent necessary to the RAFT process is already present at the beginning of the polymerization in the polymerization loci. The presence of the transfer agent assures the living mechanism, i.e. chains grow through the entire process in a highly controlled way. This generally leads to the production of low polydispersity polymers. It is worth noting that, since the RAFT reaction does not affect the radical concentration in the particle, the same polymerization rate as in a conventional polymerization process is obtained. Moreover, since polymer chains are still living at the end of the process, they can be restarted thus producing block copolymers.