Step-wise polymerization-based microstructures of 1,5-cyclooctadiene modified polydicyclopentadiene for enhanced tensile strength and breaking elongation

The 1,5-Cyclooctadiene (COD) and dicyclopentadiene (DCPD) copolymers prepared by step-wise polymerization (CD-SP) can simultaneously enhance the tensile strength and breaking elongation of polymers, compared with those prepared by frontal polymerization (CD-FP). For example, the stress and strain of the 30%CD-SP are 2.7 times and 1.8 times that of 30%CD-FP, respectively. This step-wise polymerization (SP) is determined by the curing kinetic parameters and the conversion difference of COD and DCPD by non-isothermal DSC and non-model kinetics (MFK method), that is, SP: 35 °C, 4 h; 60 °C, 30 h. In addition, energetic composite materials consisting of 85% solid fillers and COD-DCPD copolymers are prepared by SP, and its mechanical properties are far better than those of traditional energetic composite materials. Specifically, the breaking elongation increases from less than 100% to more than 500%, and the tensile strength is higher than 1 MPa. It is expected to be used as a new binder in energetic composite materials and other composite materials.