Cellulose nanofiber/cationic conjugated polymer hybrid aerogel sensor for nitroaromatic vapors detection

A novel porous aerogel of cellulose nanofiber (CNF)/cationic water-soluble poly[9,9-bis[3′-(N,N-dimethy)-N-ethylammonium)propyl)-2,7-fluorene-alt-1,4-phenylene]dibromide (CPFD) is prepared by freeze drying. CNF can effectively prevent aggregation of the conjugated polymer CPFD backbones. The CNF/CPFD hybrid aerogel is use for the detection of nitroaromatic (NAC) vapors. Due to the porous structure, the CNF/CPFD hybrid aerogel possesses a large number of accessible cavities, which could be sufficiently large to allow the diffusion of NAC vapors into the aerogel. As a result, the CNF/CPFD aerogel sensor shows high sensitivity toward NAC vapors. For 120-s exposure, the fluorescence quenching efficiency of the CNF/CPFD aerogel sensor toward 2,4-dinitrotoluene vapor is up to 85.9%, which is much larger than that of the spin-cast CPFD film. Furthermore, the sensing performance of the CNF/CPFD hybrid aerogel is not heavily dependent on the thickness, and the sensing process of the CNF/CPFD aerogel sensor is reversible.