Scientists have developed a new chemical method to improve the accuracy of 3D printing technology. The new research, published in Advanced Functional Materials, offers an innovative approach. It takes advantage of photoinduced curing via an oxo-Diels–Alder cycloaddition among two reactants. This complex process, which is controlled by two distinct-colored light sources, enables 3D printed solid materials with sub-millimeter precision. UAB researcher Jordi Hernando, who led the study, worked alongside Prof. Christopher Barner-Kowollik’s group at the Queensland University of Technology in Australia.
This inventive process uses polymer-forming prepolymers that are UV light activated and that participate significantly in the formation of the polymeric material. Ultraviolet light initiates the polymerization process, and a second beam of red light stops the process entirely. By utilizing both light wavelengths, this two-light technique provides unique control over the polymerization process, letting scientists determine exactly where the material hardens.
Curing agents in this process are extremely multifunctional. These complexes go from a reactive state to a non-reactive state in response to light. Upon exposure to ultraviolet light, these curing agents are activated, setting off the chain reaction of polymerization. Shining them with red light makes them inactive, thereby stopping the reaction in its tracks. This powerful dynamic control mechanism enables one to create advanced complex solid features. These structures can be on the order of less than a thousandth of a millimeter.
The approach leverages unique irradiation patterns from the diverse light beams to define targeted areas within the polymer resin that cure. Solidification occurs only in regions illuminated only by ultraviolet radiation. This ensures that no spatial structure can develop in areas with simultaneous exposure to ultraviolet and red light. This precision lets researchers design intricate shapes with unmatched specificity, unlocking new opportunities in applications that demand delicate detail.