Resin design for deterministic control of volumetric 3d printing*

Volumetric 3D Printing is a type of additive manufacturing in which 2D patterns of light are projected into a rotating volume of photosensitive polymer resin, locally crosslinking the material, resulting in a desired gelled 3D part. Polymerization is typically inhibited below a critical dose in radically-initiated resins due to the presence of dissolved atmospheric oxygen which is consumed prior to significant polymerization. This inhibition threshold is exploited to control which regions solidify in photopolymer 3D printing methods including stereolithography. However, oxygen levels cannot typically be modified, providing limited control over the inhibitory dose. We introduce a resin design scheme that provides deterministic control over the inhibition threshold dose in such resins. Since high resin viscosity is often desirable to limit transport, we show that the existence of a sharp inhibitory threshold sets an upper limit on viscosity through the Smolokowski diffusion limit.