# Conversion of Soluble Polyimines to Covalent Organic Framework Films and Composites

## TL;DR

Researchers developed a new method to convert soluble polyimines into covalent organic framework films and composites for advanced materials.

## Contribution

A versatile approach for synthesizing COFs using polyimines and vertex amines, enabling scalable fabrication and composite creation.

## Key findings

- Linear polyimines can be converted into high-crystallinity COF films via vapor annealing.
- The method allows solution-based processing and printing of COF films in desired shapes.
- COF composites, such as COF/CNT nanocomposites, can be easily fabricated using this approach.

## Abstract

Covalent organic frameworks (COFs) have been demonstrated
for promising
applications across research areas and industries. As research in
the field advances, there is an increasing need for processing techniques
for printing and fabricating COFs, as well as for synthesizing COF
composites for advanced materials. To achieve this goal, a versatile
approach allowing the synthesis of COFs through polyimines has been
developed. Specifically, linear polyimines derived from an aliphatic
diamine and aryl dialdehydes were synthesized and subjected to exchange
reactions with various vertex amines to generate high-crystallinity
imine-based COFs. These polyimines, also referred to as Schiff base
polymers, are soluble in organic solvents, enabling solution-based
processing and printing with vertex amines to create films of the
desired shapes. Highly crystalline COF films were then fabricated
by converting precursor films through vapor annealing. This process
enables the fabrication of COFs on both microscopic and macroscopic
scales. Furthermore, this method provides a straightforward approach
to creating advanced functional materials, such as COF/CNT nanocomposites.