STRUCTURE AND PROPERTIES OF AB CROSS-LINKED POLYMERS

Hydroxy-terminated oligomers, such as polyester, polyether, or castor oil, were reacted with toluene diisocyanate to form isocyanate-terminated prepolymers, which were then reacted with 2-hydroxyethyl acrylate to obtain vinyl-terminated prepolymer (VTP). A series of AB cross-linked polymers (ABCP) was synthesized by free radical copolymerization of these VTPs and vinyl monomers using photo- or redox initiators. The effects of the cross-link density, component ratio, network structure and defect, hydrogen bond, and monomer structure on the glass-transition temperature, relaxation, and mechanical properties of ABCPS were studied. The morphologies and dynamic mechanical properties of an ABCP and an interpenetrating polymer network (IPN) with the same composition were compared. The results showed that the degree of phase separation of the ABCP is lower than that of the IPN.