&lt;strong&gt;Polyaniline-Coated Polysulfone Membranes as Flexible Optical pH Sensors&lt;/strong&gt;

Umar

Ratemi

et al. 2016

Sensors

Self Cite

Abstract:A new optical pH sensor based on polysulfone (PSU) and polyaniline (PANI) was developed. A transparent and flexible PSU membrane was employed as a support. The electrically conductive and pH-responsive PANI was deposited onto the membrane surface by in situ chemical oxidative polymerization (COP). The absorption spectra of the PANI-coated PSU membranes exhibited sensitivity to pH changes in the range of 4-12, which allowed for designing a dual wavelength pH optical sensor. The performance of the membranes was assessed by measuring their response starting from high pH and going down to low pH, and vice versa. It was found that it is necessary to precondition the sensor layers before each measurement due to the slight hysteresis observed during forward and backward pH titrations. PSU membranes with polyaniline coating thicknesses in the range of «100-200 nm exhibited fast response times of <4 s, which are attributed to the porous, rough and nanofibrillar morphology of the polyaniline coating. The fabricated pH sensor was characterized by a sigmoidal response (R 2 = 0.997) which allows for pH determination over a wide dynamic range. All membranes were stable for a period of more than six months when stored in 1 M HCl solution. The reproducibility of the fabricated optical pH sensors was found to be <0.02 absorption units after one month storage in 1 M HCl solution. The performance of the optical pH sensor was tested and the obtained pH values were compared with the results obtained using a pH meter device.

Section: Resultssupporting

confidence: 61%

A Flexible Optical pH Sensor Based on Polysulfone Membranes Coated with pH-Responsive Polyaniline Nanofibers

Umar

Ratemi

et al. 2016

Sensors

Self Cite

“…The slight extra water uptake in SPEEK-PANI membranes could be attributed to the higher hydrophilicity of the polyaniline matrix. Polyaniline is a conductive polymer which has been utilized for pH sensing applications due to its pH-responsive nature [24][25][26][27]. The pH sensing property of polyaniline arises from the swelling/deswelling equilibrium upon pH change, during the doping/de-doping process.…”

Section: Resultsmentioning

confidence: 99%

Near-Infrared pH Sensor Based on a SPEEK–Polyaniline Polyelectrolyte Complex Membrane

2018

Iocn 2018

A polyelectrolyte complex (PEC) membrane based on sulfonated poly (ether ether ketone) and polyaniline (SPEEK-PANI) was developed for pH sensing applications. Aniline was polymerized in the presence of the SPEEK membrane by using in situ chemical oxidative polymerization to yield an ionically crosslinked SPEEK-PANI membrane. The fabricated membrane exhibited sensitivity in the physiological pH range of 2–8. The PEC membrane pH sensor showed good absorption properties in the near-infrared region (NIR). The membrane showed fast response during a de-doping process (≈90 s), while longer response times are essential for doping processes from the alkaline/neutral pH region to the acidic pH region, which is attributed to the presence of highly acidic sulfonic acid groups with a high buffering capacity in the PEC membrane. The SPEEK-PANI membrane exhibited slightly higher water uptake compared to the neat SPEEK membrane. The membrane exhibited good stability, as it was stored in 1M HCl solution for more than 2 years without physical or visual deterioration. A preconditioning step in 1M HCl ensured that the results were reproducible and allows the pH sensor to be used repeatedly. The PEC sensor membranes are suitable for applications that start at low pH values and move upwards to higher pH values in the 2–8 pH range.

“…In the case of electrochemical polymerization, aniline monomer is oxidized by the application of an electrical current and a thin layer of the resulted polymer is deposited on the surface of a conductive electrode. ,, Hence, the application electrochemical polymerization is limited to the conductive substrates such as metals, carbon, and conductive oxides. In comparison, in situ COP has been effectively employed to deposit the conductive polyaniline on both conductive and nonconductive substrates. − COP offers a simple, quick, and practical approach for preparation of polyaniline-coated substrates as it avoids the solubility problems of polyaniline that require the use of nasty and toxic solvents in cases such as dip coating or spin coating procedures.…”

Section: Background For Electrically Conductive Polymersmentioning

confidence: 99%

Chemical Oxidative Polymerization of Polyaniline: A Practical Approach for Preparation of Smart Conductive Textiles

2016

J. Chem. Educ.

104

Electrically conducting polymers are one of the promising alternative materials for technological applications in many interdisciplinary areas, including chemistry, material sciences, and engineering. This experiment was designed for providing undergraduate students with a quick and practical approach for preparation of a polyaniline-conducting polymer, demonstrating its application as a conductive coating for fabrication of smart, flexible, conductive textiles. Polyaniline was prepared by chemical oxidative polymerization (COP) of aniline monomer using ammonium persulfate as redox initiator. The polymerization was characterized by color change during the slow induction period, followed by sudden heat release during the polymerization stage due to the autoacceleration nature of this exothermic reaction. This polymerization system was used to demonstrate the heterogeneous precipitation polymerization technique. As a demonstration for the practical application of polyaniline in the area of smart conductive textiles, different nonconductive textile samples were coated with polyaniline by in situ COP and used as electronic textiles for operation of capacitive touch-screen displays.