MAGNETIC-FIELD EFFECT ON POLYMERS AND POLYMERIZATION

The influence of magnetic field on polymerization reaction, polymer st ructure and properties has been discussed in the light of the radical pair theory and the cage effect to explain the kinetics. of polymeriza tion and crosslinking reactions. The rate of polymerization and crossl inking increases due to the singlet (<->)triplet intersystem crossing mechanism. While the molecular weight increases, the molecular weight distribution decreases under magnetic field. The polymer microstructur e viz., tacticity, copolymer composition and monomer sequence in the c opolymer chain are also affected by the magnetic field. Polymerization of liquid crystal monomers under magnetic field results in highly ori ented liquid crystal polymers. As a result, the polymer properties lik e crystallinity, chain flexibility, solubility, thermal behaviour are also changed. Conducting polyacetylene and magnetic polymers prepared under magnetic field also exhibit higher conductivity and magnetic pro perties respectively. Studies on biopolymers, solid state and plasma p olymerization under magnetic field have also been reported.