Lignin Enabling Facile 3D Printing of Rubber for All‐Weather Water Harvesting

ABSTRACT Soft materials, with high elasticity and low glass transition temperatures ( T g s), present significant challenges in fabricating finely structured components via 3D printing due to their inherent softness and slow curing kinetics. Current direct ink writing (DIW) methods for soft polymers typically rely on external stimuli (e.g., light and heat) or precious metal catalysts to ensure structural stability during printing, increasing process complexity and cost. Here, a simple DIW 3D printing strategy for rubber was developed by introducing modified lignin. By virtue of its rigid benzene ring structure and abundant reactive groups, the modified lignin forms covalently bonded crosslinked networks and intermolecular hydrogen bonds with rubber to enhance the viscoelasticity, and thixotropy of the ink. The addition of 30–50 wt% modified lignin increased the modulus of the ink by five orders of magnitude, which resulted in stable self‐supported printing during the printing process. Water‐collecting materials with a bionic cactus spine structure were fabricated utilizing 3D printing, which demonstrated superior capabilities for efficient fog capturing and photothermal evaporation, respectively. By combining these two water‐harvesting methods, a daily cycle can ideally deliver an overall water yield approximately 22 L m −2 , which will providing a high‐performance solution for all‐weather fresh water access.