Upgrading of thermosets and composites via sequential frontal ring-opening metathesis polymerization and radical reactions

Frontal ring-opening metathesis polymerization (FROMP) of dicyclopentadiene (DCPD) shows promise for manufacturing thermosets and composites. To widen the applications, this work develops a novel approach for the upgrading of polydicyclopentadiene (PDCPD) and fiber-reinforced composites via sequential FROMP and radical reactions to achieve high performance. Herein, we mixed DCPD, Grubbs catalyst and radical initiators in one pot, and initiated FROMP, a self-perpetuating reaction, to obtain FROMP-prepared PDCPD. Then, the further radical reactions were carried out at elevated temperature. With our strategy, the performances of PDCPD and its composites were dramatically upgraded. For instance, the T_g of PDCPD could be significantly improved from ~171 °C to ~240 °C. The T_g, flexural strength and modulus of FROMP fabricated composite were successively increased from 141 °C, 135.3 MPa and 36.9 GPa to 262 °C, 467.1 MPa and 43.2 GPa, respectively. We believe that this novel strategy will greatly improve the performance of PDCPD and composites, and open new avenues to apply FROMP to wider applications.