Lignin nanorods reinforced nanocomposite hydrogels with UV-shielding, anti-freezing and anti-drying applications

Abstract

Recently, natural polymers with brilliant features such as environment-friendly, biocompatibility, biodegradability and diverse applications, have attracted great attention. As the most abundant natural renewable aromatic polymer, the high-value utilization of lignin recently has become a research hotspot worldwide. In this work, lignin sulfonate nanorods (LSNs) prepared by a facile self-assembly method were creatively introduced into the polyacrylamide/polyacrylic acid (PAM/PAA) network in water/glycerol solvent system to construct a mechanically enhanced, UV-shielding and anti-freezing/anti-drying nanocomposite hydrogel. The fluorescence images of hydrogels showed that LSNs were well-distributed in the hydrogels network and the hydrogen bonds were formed between LSNs and polymer network of hydrogels, which dramatically enhanced the tensile strength and ultimate elongation of hydrogels from 20 to 62 KPa and 210–420 %, respectively. Moreover, hydrogels exhibited good UV blocking performance due to the presence of lignin. Simultaneously, in the presence of glycerol, the nanocomposite hydrogels could tolerate an extreme low temperature (−60 °C) for a week without freezing and keep the initial state after storage at ambient temperature (20 °C, 60 % relative humidity) for 15 days, exhibiting remarkable potential applications under extreme conditions. Therefore, preparing LSNs reinforced hydrogels with UV-blocking and anti-freezing properties would expand their applications in broader fields. LSNs reinforced hydrogels with excellent UV blocking, anti-freezing and anti-drying properties. • A facile self-assembly method to prepare lignin nanoparticles is presented. • Mechanical properties of hydrogel are enhanced by introducing lignin nanoparticles. • Hydrogel shows excellent UV resistance due to the presence of lignin nanoparticles.