Formulation and 3D Printing of PVDF-Containing Photocurable Resins for Digital Light Processing

Additive manufacturing of electroactive polymers offers transformative potential for flexible electronics and smart devices, yet preserving the microstructure responsible for the electroactive property during processing remains a challenge. Here, we report a digital light processing (DLP) approach formulated without any volatile organic solvent to prepare poly-(vinylidene fluoride) (PVDF)-based composites under ambient conditions, employing 1,6-hexanediol dimethacrylate (HDDMA) as a polymerizable matrix and phenylbis-(2,4,6-trimethylbenzoyl)-phosphine oxide (BAPO) as an efficient visible-light photoinitiator. Unlike conventional solvent-based methods relying on PVDF dissolution, this formulation enables direct dispersion of PVDF particles in the photocurable resin without the use of organic solvents that are typically used in the processing of PVDF. Formulation optimization enabled stable suspensions of PVDF up to 35 wt %, with rheological and optical properties leading to high-fidelity DLP printed samples. Atomic force microscopy (AFM) of cross sections of the 3D printed sample revealed uniform dispersion of PVDF-rich domains. Comprehensive characterization of the 3D printed sample using differential scanning calorimetry (DSC), infrared spectroscopy (IR), and X-ray diffraction confirmed the retention of the pristine PVDF's semicrystalline phases postprocessing. Preprinting modification of the PVDF and postprinting modifications of the 3D printed composite were conducted to confirm this observation. For instance, solvent-precipitated PVDF with enhanced β phase fraction, which is often associated with electroactivity, was used in the formulation without phase degradation during photopolymerization and postprint annealing of the 3D printed composite provided additional phase tuning, underscoring the versatility of this approach. This work establishes DLP as a robust platform for the additive manufacturing PVDF-based composites, allowing for precise control and retention over crystalline phase content and complex architectures, potentially relevant for electroactive applications in next-generation flexible electronics.