Synthesis and dynamic crosslinking of a hydroxyl-functionalized ethylene-propylene copolymer: Preparation of an elastomer with reprocessability and shape memory properties

The ternary copolymers of ethylene, propylene and 10-undecen-1-ol were prepared using a vanadium catalyst bearing an 8-anilide-5,6,7-trihydroquinoline ligand. By adjusting the concentration of 10-undecen-1-ol and polymerization temperature, the insertion rate of polar monomers was modulated with a maximum value of 3.8% achieved for 10-undecen-1-ol. With an increase in the hydroxyl insertion rate, the water contact angle of hydroxyfunctionalized ethylene-propylene copolymers decreased from 112.3° to 95.3°, indicating that the incorporation of 10-undecen-1-ol enhanced the hydrophilicity of the copolymers. Subsequently, a reprocessable ethylene-propylene rubber (EPR) with double dynamic bonds was synthesized through reaction between the hydroxyl group on functionalized ethylene-propylene copolymer and the crosslinking agent using isocyanate as chain end. The strength of functionalized ethylene-propylene copolymers was significantly improved through dynamic crosslinking. Significantly, the tensile strength of sample EP6-V-0.5 reached 14 MPa, which was 27 times higher than that of un-crosslinked EP6. The prepared functionalized ethylene-propylene rubber prepared exhibited not only reprocessability, but also remarkable shape memory and reshaping properties. Moreover, the conductive composite materials based on this rubber displayed great potential for application in motion sensors.