Macromolecules, Vol.52, No.18, 6953-6962, 2019
Supramolecular Elastomers with Movable Cross-Linkers Showing High Fracture Energy Based on Stress Dispersion
Highly flexible and tough elastomers were obtained from the bulk copolymerization of a peracetylated cyclodextrin (CD) monomer and small alkyl acrylate main chain monomers without a guest monomer. The main chains penetrated the cavity of the CD units, and the CD units on the polymer chain acted as movable cross-linking points in the obtained elastomer. In contrast, the copolymerization using a bulky main chain monomer with bulky side groups gave linear polymers. The CD units with the bulky main chain polymer cannot serve as movable cross-linking points. Introducing movable cross-linking into poly(ethyl acrylate) resulted in a higher fracture energy comparable to that of conventional rubbers because of the stress-dispersion properties related to the sliding motion of the movable cross-linking points. The movable cross-linkers disperse applied external stresses more effectively than an elastomer with reversible cross-linking at a high Young's modulus (150 MPa). Movable cross-linking can be introduced to enhance the fracture energy of polymeric materials.