A strategy of achieving two things at one stroke toward the lignin-based furfural resin for adhesive and photothermal conversion materials.

Traditional phenolic resins (PF) are extremely widely applied in industrial and daily life due to their low cost and outstanding adhesion. However, they are also limited by the toxicity of phenol and formaldehyde as well as the petroleum-based origin at the same time. Herein, a comprehensive strategy for the development of formaldehyde-free lignin-based furfural resin (LFR) with dual functions for adhesive and photothermal conversion materials was presented. Firstly, a newly developed phenolated lignin was obtained via the transesterification of 3,4-dihydrocoumarin (DHC) and aliphatic hydroxyl group of lignin under organocatalysis. Then, the phenolated lignin can be regarded as a highly versatile and precise building block polymer for the design and development of LFR. LFR exhibited excellent adhesion performance from 1.12 to 2.75 MPa on various substrates. Additionally, the low-temperature and wet adhesion strength of LFR were also investigated. Different from traditional thermosetting PF, LFR was hot-melt and possessed outstanding photothermal conversion and hydrophobicity properties, which provided the possibility for its use as a photothermal power generation coating and anti/de-icing material. The maximum temperature and output voltage as well as current of LFR-2 coating could reach 154 °C, 310 mV and 43.2 mA via a thermoelectric generator, respectively. Finally, the hydrophobic, smooth and self-cleaning surface of LFR-2 could effectively help melt and remove ice even in a - 20 °C environment, which was beneficial for the utilization of photothermal material in real environment.