The use of covalent organic frameworks as template for conductive polymer synthesis and their sensor applications

In this study, the synthesis of a mesoporous crystalline covalent organic framework (COF) based on melamine and 1,4-dibromo butane as COF-1,4 and its use as a template for in situ synthesis of conductive polymers such as poly(Aniline) (PANi) and poly(Pyrrole) (PPy) within the pores were reported. The synthesized COF-1,4/conductive polymer semi-Interpenetrating Network (semi-IPN) composites were characterized via FT-IR spectroscopy and thermogravimetric analyzer (TGA), and the conductivities of the prepared composites were determined with an electrometer. It was found that upon the in situ synthesis of the conductive polymers such as PANi and PPy within COF-1,4, the conductivity of bare COF-1,4 was increased 3 million-fold for COF-1,4/PANi, and 500 thousand-fold for COF-1,4/PPy, respectively. Furthermore, the potential sensor applications of these COF-1,4/conductive polymer semi-IPN composites were investigated against HCl and NH , and methyl orange (MO), and methylene blue (MB) dyes in aqueous solutions. The sensor studies revealed that the conductivity of bare COF-1,4 increased 20 and 7K-folds upon 15 min exposure to HCl and NH gases, respectively. Interestingly, an eightfold decrease in the conductivity of COF-1,4/PANi was observed upon 15 min exposure to NH gas vapor at ambient conditions. Also, the conductivities of prepared COF-1,4 and its conductive polymer composites changed after treatment with MO and MB dyes suggesting other potential sensor applications of these porous materials.