Synthesis and structure-property studies of polysiloxane polyurethane isocyanate-functional polymeric silanes

A novel type of polymeric isocyanate-functional silane of polysiloxane was synthesized for the first time from an acrylate-functional silane. Also employed were acrylate-functional isocyanates, acrylate-functional polyether or polyester urethane isocyanates and polyhydrogen methyl siloxane which reacted Si-H with a vinyl group. The synthetic yields of the polymers were studied by HPLC and found to be higher than 96%. The molecular weights obtained were acceptable. The density and the intrinsic viscosity of the graft copolymers were measured by standard methods. The surface chemical structure of the graft copolymers was investigated by ATR-FTIR. Shown are the special structures for a 60% silane side chain especially for the polyether urethane polyisocyanate-functional polymers.The morphology of the graft copolymers was investigated by FTIR and DSC. Hydrogen bonding between NH and C=O groups resulted in a special arrangement of the polymeric isocyanate-functional silanes of polysiloxane. These graft copolymers had a high percentage of strong hydrogen bonding between NH and C=O groups. DSC showed the crystallization morphology of silane on the polysiloxane chain and a lot of phase separation. The SEM results supported surface morphology which had a roller-like crystallization or regular arrangement.Kinetic studies confirmed that the functional groups had a reactivity similar to that of monomeric groups. As coupling agents used in composite and adhesive systems, these polymers were superior to those formed from monomeric silanes. This strength of coupling can be explained by a three-component interpenetrating polymer network adhesion theory.