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[COF Morphology Control] Self-Assembly of Super-Uniform COF Colloidal Particles into Multi-D Ordered Superstructures
Abstract:
1) The article introduces a novel strategy for synthesizing highly uniform COF colloidal particles and their self-assembly into complex, multidimensional superstructures, such as 1D supraparticles, 2D ordered layers, and 3D films.
2) The self-assembly techniques developed include emulsion solvent evaporation, air-liquid interfacial assembly, and drop-casting, which allow for the formation of superstructures without additional surfactants or chemical modifications.
3) The assembled structures retain the high porosity and specific surface area of the original COF particles, and the methods are applicable to various COF types, presenting a significant advancement in the field.
4) The methodology allows for precise control over particle size, a feature that surpasses previous works by simplifying the synthesis process and eliminating the need for extra surfactants or modifications.
Research Background:
1) Industry Problems: Traditional methods of synthesizing and assembling COF particles into multidimensional structures have faced challenges due to rapid reaction rates and harsh conditions, leading to kinetic traps.
2) Existing Solutions: Previous research has utilized various colloidal particles for self-assembly but has been limited by the lack of a simple, scalable method for fabricating COF superstructures across different dimensions.
3) Innovations by Authors: This paper presents a new approach to homogeneous nucleation for the controlled synthesis of COF colloidal particles and the development of several self-assembly techniques, overcoming the limitations of previous methods.
Experiments Details:
1) Synthesis of COF Colloidal Particles: Using a 2:3 molar ratio of TPB and DVA in ACN, followed by the addition of AcOH, resulted in the formation of yellow colloidal particles after 24 hours at room temperature.
2) Size Control of Particles: Systematic tuning of particle size by adjusting the amount of AcOH and PVP, with a decrease in particle size as AcOH increased and the addition of PVP preventing agglomeration.
3) Self-Assembly into 1D Supraparticles: Formation of spherical supraparticles through emulsion solvent evaporation, with the choice of solvent and particle concentration affecting the morphology of the supraparticles.
4) Self-Assembly into 2D Superstructures: Utilization of air-liquid interfacial self-assembly to create ordered monolayers, with the zeta potential and cleaning cycles influencing the assembly quality.
5) Self-Assembly into 3D Superstructures: Formation of 3D ordered superstructures through evaporation under heating, with the color of the films depending on the particle size.
Test and Analysis:
1) Particle Size Distribution: NTA measurements showed RSDs of <5%, indicating high uniformity.
2 )Crystalline Nature: PXRD confirmed the crystalline nature of COF particles, with computational simulation matching AA-eclipsed stacking patterns.
3) Pore Structure Characterization: BET surface areas of up to 986 m² g⁻¹ were determined through nitrogen adsorption-desorption isotherms, with pore-size distributions peaking at 2.92 nm.
4) Morphology of 1D and 2D Superstructures: SEM and FIB-SEM cross-sectional analysis revealed the internal layered structure and surface order of the supraparticles and monolayers.
5) Optical Properties of 3D Superstructures: The color variation of the films from red to violet with decreasing particle size indicates the formation of photonic crystals.
Summary:
1) The paper presents a versatile strategy for synthesizing and self-assembling super-uniform COF colloidal particles into multidimensional superstructures with preserved porosity and high specific surface area.
2) The self-assembly techniques developed are simple, scalable, and applicable to various COF types, enabling the creation of materials with long-range order and potential multifunctionality.
3) The findings pave the way for designing novel COF-based materials with applications in sensing, optoelectronics, and catalysis, among others.
4) It would be beneficial for the authors to conduct supplementary research on the integration of these superstructures into functional devices and explore their performance under real-world conditions.
Self-Assembly of Super-Uniform Covalent Organic Framework Colloidal Particles into Multi-Dimensional Ordered Superstructures
Authors: Wende Ma, Ning Zhang, Caicheng Long, Zhao Shu, Yacong Liu, Yue Lin, Dawei Lu, Qian Liu, Guibin Jiang
DOI: 10.1002/smll.202403331
Links: https://onlinelibrary.wiley.com/doi/10.1002/smll.202403331
