Logo: to the web site of Uppsala University

Porous organic materials (POMs), including metal-organic frameworks (MOFs), porous organic polymers (POPs) and covalent organic frameworks (COFs), are emerging functional porous materials with unique properties such as high surface areas, tunable porosities, and synthetic diversity. They have attracted significant interests for their potential applications in adsorption, separation, catalysis, energy harvesting, and storage. However, POMs are usually synthesized as insoluble and infusible powders, posing challenges in processing them into desired shapes and structures. As a result, the practical applications of POMs have been significantly hampered.

In order to address this issue, we have recently developed nanoengineering techniques with the assistance of cellulose nanofibers (CNFs) as the flexible substrate to process a range of POMs. For example, the interfacial synthesis enabled the formation of POM nanolayers on the surface of functionalized CNFs. The obtained hybrid CNF@POM nanofibers can be easily processed into freestanding and flexible nanopapers and aerogels. The features of renewability, high surface area, rich surface functionality, nanofibrous structure, good dispensability and processability in water of CNFs make them as excellent substrate or template for processing the POMs. The resulting nanocomposites find applications in flexible electrochemical energy storage, solar thermal energy harvesting, thermal insulation, fire retardancy, and E-waste recycling. These studies provided new routes for overcoming the difficulties in processing various POMs. It is expected that the transfer of knowledge from these studies into the areas of materials design and manufacturing could promote the development of fully sustainable, freestanding functional porous materials for versatile applications.