Sequential Dual-Cure Networks in Vat Photopolymerisation: Geometry Fixation, Secondary Network Formation and Property Homogenisation
Segurola, Juan
2026-08-27 · Report · Version 1.2
Vat photopolymerisation normally uses the same photochemical event both to define geometry and to establish a substantial fraction of the final polymer network. This coupling is convenient but restrictive. Optical attenuation, radical termination, oxygen inhibition, vitrification and mobility loss can generate non- uniform conversion through depth and between layers, while increasing exposure to compensate can degrade dimensional fidelity. Sequential dual-cure systems provide a different materials architecture. A first reaction is used to establish the printable geometry and mechanically stable intermediate state, while a second independently activated reaction subsequently modifies, completes or reorganises the network. Reported implementations include photochemical acrylate fixation followed by thermally activated radical or epoxy reactions, hybrid acrylate- epoxy interpenetrating networks, thermally strengthened interlayer interfaces, and wavelength-orthogonal radical/cationic photopolymerisation capable of producing spatial variations in mechanical properties from a single resin formulation. The central engineering distinction is that dual cure is not synonymous with conventional post-curing. Additional irradiation or heating that merely advances the same photopolymerisation reaction does not by itself establish a second curing mechanism. A dual-cure material contains deliberately separated reactive pathways whose sequence, latency and interaction influence the intermediate and final network states. This review develops an engineering framework for analysing such systems in vat additive manufacturing. It considers reaction orthogonality, latent stability, conversion gradients, interpenetrating-network morphology, polymerisation-induced phase separation, interlayer reinforcement, shrinkage and stress accumulation, and the relationship between the printable intermediate state and the final functional state. A stage-resolved qualification framework is proposed in which chemistry, dimensions and mechanical properties are measured after both the printing stage and the secondary cure.