Abstract
Polypyrrole (PPy) has been widely used as a sensing material in many studies as PPy gives out noticeable reactions towards varieties of vapours of acids, bases, alcohols, alkanes, and chemical warfare agent (CWA) simulants. However, due to dispersion and mechanical properties limitation, PPy in nanoparticles (PPy NPs) has been introduced. The combinations between PPy NPs and nanosized metal oxide have shown promising improvement in the sensitivity of a sensor due to the larger total surface area of detection. In this study, the potential of PPy NPs and polypyrrole-iron oxyhydroxide (PFFs) nanocomposite as sensing materials in detecting the CWA simulant, dimethyl methylphosphonate (DMMP), is investigated. PPy NPs and modified PFFs nanocomposite were successfully synthesised using chemical oxidative polymerisation. The formation of PPy NPs and the effect of iron-oxyhydroxide (FeOOH) on the chemical interaction, morphology, and size of PPy NPs were investigated using attenuated total reflection-Fourier transform infrared (ATR-FTIR), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). ATR-FTIR analysis showed that the modified PFFs nanocomposite was successfully produced through the presence of a sharp –OH peak. The size of the prepared PPy NPs and PFFs nanocomposite was observed in the range of 50 to 70 nm and 110 to 160 nm, respectively, through TEM analysis. The electrochemical behaviour of PPy NPs and PFFs nanocomposite towards DMMP was investigated using cyclic voltammetry (CV) where, in the presence of DMMP, PPy NPs and PFFs nanocomposite showed 24% and 21% current signal reduction, respectively. This suggests that both PPy NPs and PFFs nanocomposite are able to discriminate an electrical signal both with and without the presence of DMMP.
Highlights
Polypyrrole (PPy) is one of the conducting polymers (CPs) that exhibit optical and electrical properties of both semiconductors and metals and are known as a distinctive group of organic materials [1, 2]
PPy in nanoparticles (PPy NPs) and PFFs nanocomposite were successfully synthesised using a chemical oxidative polymerisation technique with two different periods of sonication time. e one-hour sonication time produced finer nanoparticles compared to three hours of sonication. e polymerisation of the pyrrole monomer was confirmed by the broadening of the sharp peak of –NH stretching at 3217 cm−1 while the interaction between FeOOH and PPy
field emission scanning electron microscopy (FESEM) imagery showed that the 5 wt% FeOOH nanocomposite possessed iron metals that were well distributed without agglomeration in the PPy NPs compared to the 10 wt% FeOOH. e size of the prepared PPy NPs and PFFs nanocomposite was between 50 and 70 nm and between 110 and 160 nm, respectively. e potential of PPy NPs and PFFs nanocomposite as sensing materials in detecting dimethyl methylphosphonate (DMMP) was demonstrated using cyclic voltammetry (CV)
Summary
Polypyrrole (PPy) is one of the conducting polymers (CPs) that exhibit optical and electrical properties of both semiconductors and metals and are known as a distinctive group of organic materials [1, 2]. As described by Rao et al [12], FeCl3 is commonly chosen as an oxidant due to its stabilisation oxidation process with the pyrrole monomer as is shown in equation (1), and it is able to give higher conductivity properties compared to other oxidants [13]. En, to further enhance the synthesis, surfactants play an important role in the polymerisation process by improving the physical properties of polymers such as their solubility in solvents, stability, and conductivity [14]. As reported by Xing and Zhao [17], SDBS has been commonly utilised as a surfactant compared to any others as it can enhance the stabilisation of PPy NPs in terms of its dispersion state
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