Magnetic field effect on polymers and polymerization

Abstract

The influence of magnetic field on polymerization reaction, polymer structure and properties has been discussed in the light of the radical pair theory and the cage effect to explain the kinetics of polymerization and crosslinking reactions. The rate of polymerization and crosslinking increases due to the singlet (<img src='http://www.niscair.res.in/jinfo/leftrightarrow.gif' border=0>) triplet intersystem crossing mechanism. While the molecular weight increases, the molecular weight distribution decreases under magnetic field. The polymer microstructure viz., tacticity, copolymer composition and monomer sequence in the copolymer chain are also affected by the magnetic field. Polymerization of liquid crystal monomers under magnetic field results in highly oriented liquid crystal polymers. As a result, the polymer properties like crystallinity, chain flexibility, solubility, thermal behaviour are also changed. Conducting polyacetylene and magnetic polymers prepared under magnetic field also exhibit higher conductivity and magnetic properties respectively. Studies on biopolymers, solid state and plasma polymerization under magnetic field have also been reported.