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Since 2001, 3D microfabrication based on two‐photon polymerization (TPP) has drawn extensive attention and interest in biology, optics, photonics, material science, and high‐energy physics. The in‐volume fabrication capability due to the threshold behavior of two‐photon absorption enables TPP higher flexibility compared with other nanofabrication techniques. However, as determined by the in‐volume fabrication feature as well as various reaction dynamics, the writing characteristics of TPP, such as throughput, accuracy, surface quality, and fabrication capability, are still limited. Herein, a comprehensive study is performed on the spatiotemporal behavior of reaction dynamics during TPP fabrication, mainly focusing on spatiotemporal characteristics of radical diffusion, photothermal effect, microscale mechanics, and voxel stacking process. Based on the study, a nonsequential fabrication method is established to simultaneously improve key writing characteristics of TPP and realize sharp features, high speeds, large overhang structure, and smooth surfaces. The method established in this work can be applied to improve the performance of functional devices for various fields. [ABSTRACT FROM AUTHOR]

Fabrication of three-dimensional (3D) carbon-based structures at micro/nanoscale, mainly by pyrolysis of photocured resins, has recently drawn attention in battery development, material engineering, and catalysts. Upon pyrolysis, photocured 3D polymer structures undergo thermal decomposition and eventually carbonize while maintaining their 3D features. Herein, we systemically investigate the physical and chemical reactions that occur during the pyrolysis of methacrylate-based resin structures, yielding fundamental knowledge and an improved understanding of the pyrolysis processes. Based on our results, the pyrolysis process can be divided into three stages: monomer evaporation, chemical decomposition, and carbonization, in which the volume shrinkage mainly occurs in the first and third stages. The three stages have different effects on the mechanical properties of the pyrolyzed structures, with monomer evaporation and carbonization enhancing the Young's modulus while decomposition reduces the Young's modulus. Additionally, the surface smoothness of the photocured structures can be improved during pyrolysis due to the shrinkage of the polymer resins, which provides a potential approach to generating ultrasmooth carbon surfaces. [Display omitted] • Two-photon polymerized methacrylate was pyrolyzed under different conditions to reveal the property changes during the pyrolysis. • Monomer evaporation/decomposition, bond cleavage, thermal reflow, and carbonization occur during the pyrolysis. • Monomer evaporation/decomposition and carbonization enhance the Young's modulus and induce significant shrinkage. • Bond cleavage reduces the Young's modulus significantly while barely changes the morphology. [ABSTRACT FROM AUTHOR]