Self‐healing nanocomposites from silica − polymer core − shell nanoparticles

A copolymer containing butyl methacrylate in a 10‐fold excess and furan‐protected maleimidopropyl methacrylate was synthesized via atom transfer radical polymerization ( ATRP ). Maleimide functionalities served as dienophiles for reversible crosslinking by Diels − Alder ( DA ) reactions. As counterpart to the linear polymer, silica − polymer core − shell nanoparticles with grafted furfuryl groups were prepared by surface‐initiated ATRP . Rheological measurements during the DA reaction at 80 °C showed an increase in storage modulus due to crosslinking within the nanocomposite. DSC allowed the detection of the endothermic retro‐ DA reaction above 120 °C, which provided the possibility to self‐heal scratches. Repeated curing/de‐crosslinking was detected using UV −visible spectroscopy and revealed the reproducibility of the thermoreversible crosslinking reaction, which is a prerequisite for the self‐healing mechanism. Finally, the scratch‐healing abilities of the material were verified on composite films.