Robust and Flexible Rubber Composite with High Photothermal Properties Achieved by In Situ ZDMA Assisted Dispersion of Eumelanin and its Hydrophobic Photothermal Application

Eumelanin, a natural, biocompatible, and biodegradable photothermal agent derived from biomass, has attracted increasingly considerable attention due to its outstanding photothermal conversion efficiency. Unfortunately, its tendency to aggregate in flexible non-polar polymers, owing to its abundant polar groups on the surface, severely restricted the application of eumelanin in photothermal composite field. Herein, a feasible strategy is proposed to disperse eumelanin in non-polar rubber matrix via in situ generation of Zinc dimethacrylate (ZDMA). The graft-polymerization of ZDMA promotes the interfacial compatibility between styrene butadiene rubber (SBR) and eumelanin, achieving a uniform dispersion of eumelanin in SBR. The rubber composite exhibits a considerable tensile strength of 11.4 MPa, acceptable elongation at break of 146%, and outstanding photothermal conversion efficiency of up to 75.2% with only 1 wt% of eumelanin. Furthermore, based on the easy-processing of SBR matrix, the composite is treated with a sandpaper template technique and sprayed with trimethoxy(1H,1H,2H,2H-perfluorodecyl)silane (PFDTMS) to endow the material with near superhydrophobicity (water contact angle of 147.9°) capacity. Hydrophobicity provides excellent icing resistance, with droplet surfaces extending more than twice as long to freeze. Moreover, this hydrophobic photothermal material exhibits remarkable anti-frosting, de-frosting, and de-icing capabilities.