Thermoresponsive hybrid double-crosslinked networks using magnetic iron oxide nanoparticles as crossing points

Abstract

Double-crosslinked networks are a class of polymer materials that have recently started attracting attention. Herein, we report the successful fabrication of thermoresponsive hybrid double-crosslinked polymer networks which are able to rearrange under stimulation owing to the thermoreversibility of the Diels–Alder (DA) reaction. This new class of magneto-responsive networks is based on iron oxide nanoparticles (IONPs) as the nano-crosslinkers and difuran-functionalized poly(ethylene oxide) (PEO) as the diene partner for the thermoreversible DA reaction. The chemical and mechanical properties of the resultant networks were characterized. The rheological properties of 3D networks with and without IONPs were compared; the presence of IONPs in the network ensured that a gel-like structure was maintained after the retro Diels–Alder reaction (rDA). We attribute these characteristics to the establishment of a secondary network through covalently integrated IONPs. These synthetic materials may prove beneficial for the design and applications of polymer networks double-crosslinked with IONPs as magneto-responsive 3D networks for nanobiotechnology and nanomedicine.