Multifunctional light-responsive graphene-based polyurethane composites with shape memory, self-healing, and flame retardancy properties

It is a challenge to manufacture light responsive polymer composite that possesses shape memory, self-healing, and flame retardancy capacities. Herein, multi-functionalized graphene oxide (mfGO) wrapped with nitrogen-, phosphorus-, and silicon- containing units was prepared via in-situ polymerization and subsequently was incorporated into a diselenide-containing polyurethane (dPTD) matrix to fabricate composite. The successful functionalization of mfGO was initially confirmed by a series of measurements. Taking advantage of the crystallization-induced and photo-thermal effects of mfGO as well as the dynamic exchange characteristic of diselenide bonds, the dPTD-mfGO2 composite containing 2 wt% of mfGO exhibited admirable shape memory and self-healing behaviors under visible-near infrared light within 3 min, and its shape memory characteristics and healing efficiencies were kept above 90% and 76% after three cycles, respectively. Further combustion experiments demonstrated that dPTD-mfGO2 composite showed superior LOI (24.9%) and UL-94 rating (V-2) without flaming drips, owing to the synergistic catalyzing carbonization and barrier effect of mfGO. Additionally, the dPTD-mfGO2 composite possessed an improved water contact angle of 109.5 degrees. These findings suggest that the introduction of 2 wt% mfGO to the dPTD matrix can synergistically improve the toughness, shape memory, self-healing, flame retardancy, and water resistance as compared with the neat dPTD. This work provides a promising pathway to fabricate stimulus-responsive composite materials with versatile functions.