Vat photopolymerization (VP) of solvent-free carbon Nanoparticle-Acrylic nanocomposites

Digital light processing (DLP) based vat photopolymerization (VP) additive manufacturing (AM) offers high resolution and rapid printing capabilities, making it particularly well-suited for producing intricate geometries. However, the applications of DLP are limited by material options available, particularly due to their low mechanical properties. This study addresses this challenge by introducing a novel solvent-free method to incorporate various carbon-based nanoparticles into DLP resins. This approach ensures printability by maintaining nanoparticle stability in the solution while enhancing overall material properties. Ten acrylic monomers were carefully selected based on their Hansen solubility parameters to effectively disperse and stabilize the studied nanoparticles (graphite nanoparticles, GNPs, and edge oxidized graphene oxide, EOGOs). It was found that Tricyclodecane Dimenthanol Diacrylate (G1231) possessed similar interfacial energies with the nano-fillers, which prevented agglomeration within the matrix. This led to the creation of homogeneous nano-filled resins, which demonstrated stability for the seven-day observation period, suggesting potential stability beyond this timeframe. Additionally, this study explored the relationship between layer exposure time, nanoparticle concentration, and size on printability, as well as key characteristics such as viscosity, depth of cure, and mechanical properties. The optimal combination of parameters led to considerable improvements in mechanical properties, with the modulus of elasticity and tensile strength increasing by 18% and 17% respectively for nano-filled resins up to 0.07 wt%, with cure times up to 90 s. The solvent free method of incorporating carbon-based nanomaterials in resins is simple and efficient. It also demonstrates great potential for broader material selection and property enhancement in DLP resins, thereby paving the way for expanded applications across various fields.