Cellulose nanocrystal enhanced, high dielectric 3D printing composite resin for energy applications

Photocuring-based 3D printing becomes an emerging technology in various applications owing to their advantages of high design flexibility and low cost. Developing 3D printing resins with high dielectric constant is important for enabling on-demand manufacturing of energy storage materials. Herein, we report a scalable and simple approach for preparing ultraviolet (UV) curable resin composite with high dielectric constant, through the introduction of cellulose nanocrystals (CNCs) as bio-fillers into methacrylate malate photocurable resins (MMPR). MMPR resin was synthesized by reacting methacrylic acid (MAA) with malate resin (MR), while CNCs were also grafted to MAA for allowing the uniform dispersion of fillers in the polymer matrix. Subsequently, high dielectric constant composite resin CNCs-MAA/MMPR was prepared by simply mixing CNCs-MAA with MMPR and the dielectric constant of materials can be manipulated by varying the content of CNCs-MAA particles. Specifically, with the addition of 1 wt% CNCs-MAA, the dielectric constant increases from 4.0 (MMPR) to 10.9 at 1 MHz, which can be attributed to the interfacial effect between CNCs-MAA and MMPR matrix and the abundant presence of polar groups (-OH) from CNCs surface. The prepared resin composite can be directly used for conventional 3D printing technologies. Specifically, practical use of CNCs-MAA/MMPR composites for energy storage was demonstrated, which the capacitance of MAA/MMPR resin with 1 wt% CNCs increases more than 132% compared to pristine MMPR. This work provides an industrially feasible method for preparing photocurable resin composites with high dielectric constants for 3D printing.