Mechanical properties of polymer networks with polyrotaxane crosslinkers with different molecular structures based on polyethylene glycol and α-cyclodextrin

The modification of vinyl groups on polyrotaxane derivatives, obtained with polyethylene glycol as the axial molecule and alpha-cyclodextrin as the cyclic molecule, allows the production of crosslinkers that react with various monomers, facilitating the formation of polymer networks. In contrast to conventional polymer crosslinked networks using typical crosslinking agents, polymer networks employing polyrotaxane crosslinking agents allow for mobile crosslinking points. Consequently, the resulting polymeric crosslinked network may exhibit increased toughness, as external stress is uniformly distributed throughout the polymeric network. This distribution helps to avoid excessive stress concentration in specific areas. To optimize the mechanical properties of polymer networks formed using polyrotaxane crosslinkers, we investigated the impact of the molecular weight of the axial molecules and the number of crosslinking points of the cyclic molecules in the polyrotaxane crosslinkers on the mechanical properties of the resulting polymer networks. Our results show that the fracture strain, fracture stress, and fracture energy of the resultant polymer networks increase with increasing molecular weight of polyethylene glycol. We also observed that the fracture stress and toughness of the polymer networks increased when there was less than one modified vinyl group on alpha-cyclodextrin, compared to the case with multiple vinyl groups.