麻豆淫院

Researchers at the UAB have developed a new chemical reaction to form solid polymeric networks using light (photocuring) which will allow the preparation of solid materials with controlled shapes measuring under a thousandth of a millimeter. The research is key for the development of new, performance-enhanced lithographic and 3D printing techniques.

At present, 3D printing is an increasingly widespread and accessible technology, typically involving the formation of solid polymeric materials in a specific region, either by extruding pre-formed polymers or by generating them in situ from their corresponding monomers, the molecules that make up polymers.

However, these techniques often suffer from several drawbacks, such as long printing times or low resolution, preventing the production of printed materials with micrometric dimensions.

To address these issues, polymer formation through light irradiation could be a promising solution, as photopolymerization reactions tend to be faster and can be induced with precise spatiotemporal control.

Most light-induced polymer material formation processes occur under irradiation from a single light source, which limits their temporal and spatial precision. For example, some photoactivated reagents may diffuse beyond the illuminated zone, or their lifetime may exceed irradiation time, thus limiting the spatiotemporal resolution of the photopolymerization process. Additionally, the maximum spatial resolution achievable with conventional optics is diffraction-limited, preventing such reactions from being confined to the nanometric scale.

To overcome these challenges, controlling photopolymerization reactions using two different-colored light sources has been proposed by several research groups, thus enabling the development of new lithographic and 3D printing techniques with enhanced capabilities. Although it is a promising solution, very few reactions of this type are currently known to exist.

Researchers from the UAB Department of Chemistry, led by Jordi Hernando, worked in collaboration with Prof. Christopher Barner-Kowollik's group at Queensland University of Technology, Australia, to develop a new photopolymerization reaction controlled antagonistically by two different colors of light. Specifically, one light beam promotes the formation of the polymeric material, while another beam halts the reaction. The research is in Advanced Functional Materials.

This chemical process involves photoinduced curing via an oxo-Diels鈥揂lder cycloaddition between two reactants. "On the one hand, we use prepolymers that are activated by ultraviolet light, and on the other hand, curing agents that change from a reactive to a non-reactive state depending on whether they are irradiated with ultraviolet or red light," explains Hernando.

With this new method developed by UAB researchers, light beams with distinct irradiation patterns can be used and therefore polymer resin curing occurs only in regions illuminated exclusively with ultraviolet light, while no solid material forms in areas exposed to both colors, making it possible to delimit the area where the polymer solidifies. The researchers were able to obtain solid polymeric materials in the laboratory with controlled shapes and with resolutions below millimeters.

"We are now exploring the use of this new methodology to improve the performance of 3D printing processes and reach sub-micrometer resolutions, which represents a significant step for this technology," says Hernando.