Laser Ultrafast In Situ-Integrated COF Crystals

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) synthesis is hindered by slow imine bond dynamics and high activation energies.
• Traditional solvothermal methods for COF crystallization are time-consuming (hours to days) and lack precise control.

Purpose of the Study:

• To develop a rapid, controlled, and in situ crystallization strategy for COFs.
• To overcome the limitations of conventional solvothermal synthesis for dynamic covalent materials.

Main Methods:

• Utilized a 473 nm continuous-wave laser to create a photothermal microreactor at the solid-liquid interface.
• Employed Gaussian focusing to generate localized hotspots and steep temperature gradients for nonequilibrium crystallization.
• Achieved dynamic covalent exchange in an ultrafast, far-from-equilibrium regime.

Main Results:

• COF-300 nucleated and grew in situ within seconds, without catalysts.
• Demonstrated real-time, deterministic control over nucleation and crystal growth using laser power and exposure.
• Enabled direct laser writing of ordered COF microstructures with submicrometer spatial confinement.

Conclusions:

• Established an accessible nonequilibrium crystallization strategy for dynamic covalent materials.
• Presented a generalizable method for rapid, programmable crystallization of COFs.
• Opened possibilities for on-demand, in situ integration of COF microcrystals for photonic applications.