Rapid 3D printing of unlayered, tough epoxy-alcohol resins with late gel points via dual-color curing technology

Additive manufacturing technologies and in particular vat photopolymerization promise complex structures that can be made in a fast and easy fashion for highly individualized products. While the technology has upheld this promise many times already, some polymers are still out of reach or at least problematic to print reliably. High-performance epoxide-based resins, which are regulated by chain transfer via multifunctional alcohols, are a typical example for resins with late gel points, which require long irradiation times and high light intensities to print. Therefore, we have developed a dual-colour printing approach where rapid radical curing of a soft, wide-meshed polymer network facilitates fast and easy 3D structuring of the subsequently slow curing step growth formulation at an orthogonal initiation-wavelength regime. Thereby the methacrylate system acts as a scaffold for an uncured epoxide alcohol system during the printing process, which is then cured with UV light post-printing. This way tough alcohol-regulated epoxy-systems become accessible to vat photopolymerization achieving outstanding high-resolution 3D printed parts without significant layering effects. The demonstrated wide-meshed matrix-assisted printing approach has the potential to make a multitude of slowly curing resins accessible to vat photopolymerization techniques, at low irradiation intensities and high curing speeds.