Ultra-tough light-curing ionogels for UV shielding

Abstract

The mechanical properties of polyurethane ionogels prepared by UV light-curing are usually inferior to those of conventional polyurethanes. Highly entangled polymer chain networks with chemical crosslinking can potentially address this problem. Here, we prepare ionogels (PU-HRs) using UV curing technology with esterified rutin as a cross-linking agent. After optimization of the preparation process by response surface methodology, we obtain PU-HRs with a tensile strength of 34.96 MPa and toughness as high as 88.11 MJ m−3 (1.26-fold higher than that of silk from the silkworm, Bombyx mori (70 MJ m−3)). The high strength and toughness of PU-HR are mainly attributed to the three-dimensional cross-linked network structure formed by the “rigid-flexible” esterified rutin, the micro-phase separation structure between the soft-chain fragments, and the hard-chain fragments that form stable interfacial regions. These ionogels have great prospects in sunscreen coating applications, such as for sunscreen umbrellas and automotive or architectural sunscreen glass. Polyurethane ionogels can be made with UV light curing but suffer from low mechanical properties compared to conventional polyurethane. Here, robust UV light curable ionogels are made by using prepolymers containing carbon-carbon double bonds as monomers which cross-links to form entangled polymer networks.