(660h) Reaction-Diffusion Control within High-Speed AM to Achieve Nano-Resolution Patterning

Polymeric materials containing hierarchical structures ranging from micrometer to nanometer feature sizes play a significant role in accelerating transport properties, critical for energy-water and biomedical applications. Major advances in high-speed, high-resolution additive manufacturing (AM) have demonstrated the capability of creating architected materials at the micrometer resolution. However, challenges existed in achieving sub < 500nm nanostructure control due to the limitation in projection optics and writing speed, as well as limited understanding of preservation and evolution of nano-morphologies during photo-patterning. In this research, we aim to address this challenge with two approaches. In the first part of the talk, we will focus on the introduction of dual-wavelength 3D printing platform coupled with controlled living radical polymerization to tackle the diffraction-limited patterning. The critical timescales of reaction-diffusion mechanism are elucidated with experiment and simulation. It was found that at the diffusion-limited printing time, the patterning resolution is dictated by the diffusivity and lifetime of the macroradicals. To achieve sub-500nm resolution, macroradical reactivity and projection optics exposure time needs to be simultaneously controlled to enter reaction-limited regime. In the second part of the talk, we will focus on a bottom-up approach using macromolecular-amphiphilic templates for controlling self-assembly nano-morphologies formation during rapid photo-crosslinking in AM platforms. The nano-morphologies preservation before and after printing are elucidated with SAXS, SEM, and DSC. It was found that without effective functionalized amphiphilic templates, the onset of polymerization driven microphase separation occur due to the thermodynamic depletion effect, leading to nano-morphologies coarsening of the bi-continuous micellar domains. Functionalized amphiphilic macromolecules are introduced to control the evolution of nanostructure formation. Taken together, the research builds on fundamental reaction-diffusion control with two different approaches to achieve sub-500 nm resolution within scalable AM platform, and provides a fundamental understanding towards the enhancement of patterning resolution with low-energy laser systems.