From the Solution Processing of Hydrophilic Molecules to Polymer-Phthalocyanine Hybrid Materials for Ammonia Sensing in High Humidity Atmospheres

Abstract

We have prepared different hybrid polymer-phthalocyanine materials by solution processing, starting from two sulfonated phthalocyanines, s-CoPc and CuTsPc, and polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), poly(acrylic acid-co-acrylamide) (PAA-AM), poly(diallyldimethylammonium chloride) (PDDA) and polyaniline (PANI) as polymers. We also studied the response to ammonia (NH3) of resistors prepared from these sensing materials. The solvent casted films, prepared from s-CoPc and PVP, PEG and PAA-AM, were highly insulating and very sensitive to the relative humidity (RH) variation. The incorporation of s-CoPc in PDDA by means of layer-by-layer (LBL) technique allowed to stabilize the film, but was too insulating to be interesting. We also prepared PANI-CuTsPc hybrid films by LBL technique. It allowed a regular deposition as evidenced by the linear increase of the absorbance at 688 nm as a function of the number of bilayers. The sensitivity to ammonia (NH3) of PANi-CuTsPc resistors was very high compared to that of individual materials, giving up to 80% of current decrease when exposed to 30 ppm NH3. Contrarily to what happens with neutral polymers, in PANI, CuTsPc was stabilized by strong electrostatic interactions, leading to a stable response to NH3, whatever the relative humidity in the range 10%–70%. Thus, the synergy of PANI with ionic macrocycles used as counteranions combined with their simple aqueous solution processing opens the way to the development of new gas sensors capable of operating in real world conditions.

Effect of Cobalt Phthalocyanine on Synthesis and Physicochemical Properties of Polyaniline

“…PCo1 ‐ PCo5 supramolecular structure change comparable to P1 is connected with the catalyst use in the polymer synthesis. It was previously reported that the use of phthalocyanines leads to a decrease in particle size and an increase in the homogeneity of the supramolecular structure of polyaniline, which is also observed for the studied samples.…”

Modulation of the organic heterojunction behavior, from electrografting to enhanced sensing properties

“…DMBz is the best MSDI developed in the laboratory. [16,26] Its sensitivity was of the same order of magnitude as the polymer-based devices [27][28][29][30][31] but lower than devices made from graphene [32] for which desorption is obtained by heating at ca. 200°C, or from hybrid materials, e.g.…”

Tetrasubstituted copper phthalocyanines: Correlation between liquid crystalline properties, films alignment and sensing properties

“…Using DFT calculations and spectral investigation, it has been shown that ammonia and amines interacts with the central metal ion inside the phthalocyanine ring and pr eferably forms a five-coordinated complex with MPcs with charge transfer to phthalocyanine molecule [49][50][51][52]. The electron charge transfers from electron donor NH 3 molecule to MPc resulting in a decrease of the holes density, hence causing a marked increase in the film's resistance [53].…”