Two-way shape memory properties study of crosslinked cycloolefin/dicyclopentadiene copolymer

The two-way shape memory polymers (2 W-SMPs) have garnered significant interest from researchers due to their great performance and wide range of applications. In this study, we present the synthesis and assessment of crosslinked copolymers P(CDD- co -DCPD) and P(COE- co -DCPD) using dicyclopentadiene and different comonomers via ring-opening metathesis polymerization (ROMP). The two-way shape memory behavior of these copolymers was altered by not only varying the species and incorporation level of a second comonomer, but also by adjusting the concentration of the second comonomer. The results indicated that the melting and crystalline temperature of the crosslinked copolymer decreased with increasing content of DCPD. Additionally, it was observed that the P(CDD- co -DCPD) copolymers exhibited one-way shape memory function rather than two-way shape memory performance under constant stress. With the increasing content of DCPD in the copolymers, the shape recovery ratio exhibited an upward trend and reached a maximum of 94.44%. Additionally, the shape fixation ratio of the P(CDD- co -DCPD) copolymers also surpassed 95%. In contrast, the P(COE- co -DCPD) copolymers demonstrated both one-way and two-way shape memory functions, particularly, when the molar content of DCPD was 4 mol%, the shape recovery ratio reached a maximum of 95.03% and the shape fixation ratio exceeded 90%. Graphical