Evolution of Self‐Assembled Lignin Nanostructure into Dendritic Fiber in Aqueous Biphasic Photocurable Resin for DLP‐Printing

Abstract

The design of lignin nanostructures where interfacial interactions enable enhanced entanglement of colloidal networks can broaden their applications in hydrogel‐based materials and light‐based 3D printing. Herein, an approach for fabricating surface‐active dendritic colloidal microparticles (DCMs) characterized by fibrous structures using nanostructured allylated lignin is proposed for the development of lignin‐based photocurable resins. With allyl‐terminated surface functionality of 0.61 mmol g−1, the entanglement between lignin‐DCM fibrils with a size of 1.4 µm successfully produces only lignin‐based hydrogels with structural integrity through photo‐crosslinking. The colloidal network of lignin dendricolloids reinforces the poly(ethylene glycol) (PEG) hydrogels during a digital light processing (DLP) 3D printing process by generating bicontinuous morphologies, resulting in six‐fold increases in toughness values with respect to the neat PEG hydrogel. The dual effectiveness of photoabsorption and free‐radical reactivity of lignin‐DCMs allow the light‐patterning of rather dilute PEG hydrogels (5–10%) with high geometric fidelity and structural complexity via DLP 3D printing. This study demonstrates a green and effective strategy for the design of 1D lignin‐DCMs that increases the versatility of the nanostructured biopolymer, opening up numerous opportunities for formulating functional hydrogels with robust structure‐property correlations.