Thermal, mechanical, and self-healing properties of polymer networks produced by photo-polymerizing α-cyclodextrin-glycidyl methacrylate adduct and poly(ethylene glycol) methacrylate

Self-healing polymer networks have attracted much attention because of the contribution to resource and energy savings by improving their service life. Herein, photo-polymerization reactions of α-cyclodextrin-glycidyl methacrylate adduct (αCD-GMA)/poly(ethylene glycol) methacrylate (PEGMA), β-cyclodextrin-glycidyl methacrylate adduct (βCD-GMA)/PEGMA, and αCD-GMA/3,4-dichlorophenyl isocyanate-end-capped PEGMA produced cyclodextrin/poly(ethylene glycol)-based network (CP, βCP, and DCP-CP, respectively) films. The thermal, mechanical, and self-healing properties of the CP films were compared with those of the βCP and DCP-CP films. The loss factor (tan δ) peak temperatures (− 9 to − 3 °C) measured via dynamic mechanical analysis (DMA), tensile strengths and moduli of the CP films decreased with increasing PEGMA content. Although all photo-polymerized films exhibited self-healing properties upon standing at room temperature for 24 h, the healing efficiencies in terms of tensile strength for the CP films were much higher than those for the βCP and DCP-CP films, in which the complexation of cyclodextrin-poly(ethylene glycol) (PEG) units is difficult. The CP film with the highest PEGMA fraction exhibited the highest healing efficiency and healed at least thrice. The 2D ¹H–¹H NOESY spectra of αCD-GMA/PEGMA and immersion of the self-healed CP film in PEG solutions suggested that the self-healing properties were imparted by reversible α-CD–PEG host–guest interactions.