Quartz crystal microbalance electrode modified with thermoresponsive crosslinked and non-crosslinked N-isopropylacrylamide polymers. Response to changes in temperature

Abstract

Electrochemical quartz crystal microbalance (EQCM) electrode was modified with environmentally sensitive polymers. The polymer layers on the electrode were compos ed of eithe r crosslinke d or no n-crosslink ed thermoresponsive poly(N-isopropylacrylamide). For anchoring thin gel films on the electrode surface, the electrochemically induced free radical polymerization (EIFRP) was employed. The electroreduction of the peroxydisulfate anion led to generation of free radical. This radical initiated the free radical polymerization process that led to the formation of a thin gel layer attached to the electrode surface. To monitor in situ the growth of the polymer film the changes in resonant frequency of the quartz crystal were recorded. A significant decrease in the frequency (growth of the layer) was seen in the potential range where the reduction of peroxydisulfate anion took place. The morphology of the layers was examined with a scanning electron microscopy (SEM). The phenomenon of volume phase transition (shrinking/swelling process) in the gel layers initiated by a change in temperature was investigated. Unexpected big, sharp, and of negative sign minima appeared at the change-in-frequency vs. temperature plots. These minima were not seen in the plots obtained for the polymers without linker. That situation should be useful in the investigation of chemical interactions proceeding under the conditions of volume phase transition. The influence of volume phase transition on the transport of a member of a model red-ox system, ferro-and ferricyanide couple, and therefore on height of its voltammetric response was examined. The changes in electrochemical properties of the layers induced by volume phase transition were monitored with electrochemical impedance spectroscopy.

Comparison of the Adsorption of Linear and Cyclic Antimicrobial Peptides Onto Cellulosic Compounds-Reinforced Poly(Vinyl Alcohol) Films Using Qcm-D

“…AUT possesses thiol groups that bind to the gold coating of the sensors by strong metal-sulfur interactions (i.e., chemisorption), forming close-packed self-assembled monolayers, leaving the amine groups (-NH 2 , the other end of n-alkanethiols) free [28]. Most of these amine groups are protonated under neutral conditions (pKa ≈ 7.5), thus establishing electrostatic interactions with the weakly negatively charged acetate groups of PVA (≈ 12%) [29].…”

Quartz Crystal Microbalance Study of Adenosine as Inhibitor for Fe Corrosion in HCl Solution

“…From the Sauerbrey equation, the measured frequency change can be used to calculate the mass change (¦m) of the surface of the working electrode. 3 There were previous studies on the adsorption of various compounds [4][5][6][7] and corrosion test 8,9 conducted using the QCM. However, despite the popularity of researches into corrosion inhibitors for iron and its alloys (mild, carbon and stainless steels) in HCl solution, 10-14 the real-time adsorption of those inhibitor on a corroding surface of an iron working electrode in HCl solution was relatively unaddressed, especially using QCM.…”