Sustainable and electrically conductive poly(glycerol) (meth)acrylate resins for stereolithography and volumetric additive manufacturing

Additive manufacturing (AM) has seen significant advances in recent years, and now encompasses various techniques, including stereolithography (SLA) and volumetric additive manufacturing (VAM), both belonging to the VAT photopolymerization branch of AM. SLA is a well-established technique, which constructs objects layer by layer using a photoactive resin and a light source. In contrast, VAM, a newer and less widespread method, offers distinct advantages by enabling the creation of objects in a single, cohesive process, allowing fabrication within approximately one minute. While these techniques have facilitated rapid prototyping and innovation, there is a pressing need for more sustainable, active and responsive materials to reduce the reliance on petrochemical-based resins as AM adoption grows. In this study, we explore the printability of poly(glycerol) 4 and 6 (meth)acrylates doped with multi-walled carbon nanotubes (MWCNTs) as sustainable and electrically conductive resin alternatives. Poly(glycerol), which is derived from glycerol, a biodiesel production by-product, was chosen due to its renewable nature and low environmental impact. As reported in our previous work (Meth)acrylate functionalities can be incorporated to make these poly(glycerol)-based materials photoactive, aligning with the widespread use of (meth)acrylates in the AM industry. The printability of these materials was tested and optimized in SLA; the resins doped with relatively small amounts of CNTs (<1wt%) yielded printed parts that were electrically conductive. The printed parts were also shown to have pressure sensing capabilities as their electrical conductivities change significantly based on applied pressure. VAM was then used to fabricate bespoke casings for the conductive printed parts.