Covalent organic frameworks (COFs) have gained considerable attention due to their design possibilities as the molecular organic building blocks that can stack in an atomically precise spatial arrangement. Since the inception of COFs in 2005, there has been a continuous expansion in the product range of COFs and their derivatives. This expansion has led to the evolution of three-dimensional structures and various synthetic routes, propelling the field towards large-scale preparation of COFs and their derivatives. This review will offer a holistic analysis and comparison of the spatial structure and synthesis techniques of COFs and their derivatives. The conventional methods of COF synthesis (i.e., ultrasonic chemical, microwave, and solvothermal) are discussed alongside the synthesis strategies of new COFs and their derivatives. Furthermore, the applications of COFs and their derived materials are demonstrated in air, water, and soil pollution management such as gas capture, catalytic conversion, adsorption, and pollutant removal. Finally, this review highlights the current challenges and prospects for large-scale preparation and application of new COFs and the derived materials. In line with the United Nations Sustainable Development Goals (SDGs) and the needs of digital-enabled technologies (AI and machine learning), this review will encompass the future technical trends for COFs in environmental pollution control.

The effect of individual and combined talc and glass fibers (GFs) on mechanical and thermal expansion performance of the filled high density polyethylene (HDPE) composites was studied. Several published models were adapted to fit the measured tensile modulus and strength of various composite systems. It was shown that the use of silane-modified GFs had a much larger effect in improving mechanical properties and in reducing linear coefficient of thermal expansion (LCTE) values of filled composites, compared with the use of un-modified talc particles due to enhanced bonding to the matrix, larger aspect ratio, and fiber alignment for GFs. Mechanical properties and LCTE values of composites with combined talc and GF fillers varied with talc and GF ratio at a given total filler loading level. The use of a larger portion of GFs in the mix can lead to better composite performance, while the use of talc can help lower the composite costs and increase its recyclability. The use of 30 wt % combined filler seems necessary to control LCTE values of filled HDPE in the data value range generally reported for commercial wood plastic composites. Tensile modulus for talc-filled composite can be predicted with rule of mixture, while a PPA-based model can be used to predict the modulus and strength of GF-filled composites.

Studies on the influence of drying processes on cellulose nanofiber (CNF) aerogel performance has always been a great challenge. In this study, CNF aerogels were prepared via two different drying techniques. The CNF solution was prepared via existing chemical methods, and the resultant aerogel was fabricated through supercritical CO₂ drying and liquid nitrogen freeze-drying techniques. The microstructure, shrinkage, specific surface area, pore volume, density, compression strength, and isothermal desorption curves of CNF aerogel were characterized. The aerogel obtained from the liquid nitrogen freeze-drying method showed a relatively higher shrinkage, higher compression strength, lower specific surface area, higher pore volume, and higher density. The N₂ adsorption capacity and pore diameter of the aerogel obtained via the liquid nitrogen freeze-drying method were lower than the aerogel that underwent supercritical CO₂ drying. However, the structures of CNF aerogels obtained from these two drying methods were extremely similar.

The search for wearable electronics has been attracted great efforts, and there is an ever-growing demand for all-solid-state flexible energy storage devices. However, it is a challenge to obtain both positive and negative electrodes with excellent mechanical strength and match positive and negative charges to achieve high energy densities and operate voltages to satisfy practical application requirements. Here, flexible MXene (Ti₃C₂T_x)/cellulose nanofiber (CNF) composite film negative electrodes (MCNF) were fabricated with a vacuum filtration method, as well as positive electrodes (CP) by combining polyaniline (PANI) with carbon cloth (CC) using an in-situ polymerization method. Both positive and negative free-standing electrodes exhibited excellent electrochemical behavior and bendable/foldable flexibility. As a result, the all-pseudocapacitance asymmetric device of MCNF//CP assembled with charge-matched between anode and cathode achieves an extended voltage window of 1.5 V, high energy density of 30.6 Wh·kg⁻¹ (1211 W·kg⁻¹), and 86% capacitance retention after 5000 cycles, and the device maintains excellent bendability, simultaneously. This work will pave the way for the development of all-pseudocapacitive asymmetric supercapacitors (ASC) with simultaneously preeminent mechanical properties, high energy density, and wide operating voltage window.