Open Readings 2021 • P6-28
THE PPY LAYER THICKNESS CONTROL FOR THE DEVELOPMENT OF THE SENSOR
Raimonda Bogužaitė1, Vilma Ratautaitė1, Ernestas Brazys2, Arūnas Ramanavičius1, 2
1 Center for Physical Sciences and Technology, Department of Functional Materials and Electronics, Laboratory of Nanotechnology, Sauletekio av. 3, Vilnius LT-10257, Lithuania
2 Vilnius University, Faculty of Chemistry and Geosciences, Institute of Chemistry, Naugarduko str. 24, LT-03225 Vilnius
[email protected]
Molecularly imprinted polymers (MIPs) are encouraging materials that can be used in the recognition process [1,2]. The technique of molecular imprinting enables the construction of selective molecular recognition sites in polymeric matrices that operate on the principle of a lock and key mechanism [3]. The functional monomers initially form a complex with the imprint molecules, and following polymerization, their functional groups are held in position by the highly cross-linked polymeric structure [4]. MIPs exhibits exceptional thermal and chemical stability [5]. In the development of MIPs pyrrole is one of the most used polymers. It is applied because of the simplicity, ability to form thin coatings, stability, and ability to electropolymerize [6].
Furthermore, usually it is necessary to control the thickness of the MIP layer in order to optimize the sensitivity [5]. The thickness can be partially controlled by changing the concentration of the monomer, the number of potential pulses. During the development of uric acid-imprinted polypyrrole-based sensor, MIP preparation was based on a single potential pulse of 1 V vs Ag/AgCl lasting for 10 s. The polymerization mixture consisted of 5 mM uric acid and 50 mM pyrrole solution in PBS [3]. On the other hand, to develop a pyrrole-based CO2 sensor, pyrrole was polymerized electrochemically on glass/ITO or glass/ITO(TEMS) electrode surface from a solution containing 10 mM of pyrrole and 0.1 M of LiClO4 as an electrolyte. Polymerization was performed in room temperature by 10 potential cycles in the range from -0.2 V to +1.0 V vs Ag/AgCl(3M KCl) at the sweep rate of 50 mV/s and step potential of 2.44 mV [7]. By choosing a higher polymer concentration and a lower number of potential pulses, or a lower concentration but a higher number of potential pulses, both methods lead to the formation of a sufficiently thin layer that can be adapted to the design of the sensor.
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