Modulating The Interfacial Properties Of Polyzwitterions Through In-situ Amplification Of Ion Specificities By Electrochemical Methods

In this article,the ion-doping/de-doping behavior of PEDOT with different crosslinking densities under voltage was monitored in situ by QCM-D,and the conformational changes were observed by grafting polymer brushes on them,which provided an approach for studying polymer surface interfaces and ion-specific effects.Meanwhile,the etching reaction of mercaptoethylamine(CS)on gold was found when grafting polymer brushes on gold flakes,the etching reaction mechanism of CS with gold was also investigated.The details are as follows:1.A series of PEDOT films were obtained by electrochemical copolymerization of EDOT and Br-EDOT in different molar ratios.The behavior of ion doping/de-doping of these PEDOT films was investigated under different conditions of ionic strength and ion species under applied voltage,and it was found that the main behavior was cation doping/de-doping.It is inferred that the reason for this behavior is the cross-linking of the copolymerized PEDOT,which leads to the motion of the large-sized anions being bound and thus unable to enter and exit freely.2.The effect of different crosslinking densities on the ion doping/de-doping behavior of PEDOT films was verified by designing EDOT crosslinkers,and it was found that only appropriate crosslinking densities could achieve more favorable effects,including a greater degree of ion doping/de-doping and a greater redox stability.Polyampholytic electrolyte brushes were also grafted on the PEDOT films to investigate the ion doping/dedoping behavior under applied voltage.3.QCM-D in situ monitoring studied the etching reaction of CS with gold.The etching reaction is verified as diffusion-controlled and shows a half-order reaction kinetics.It is demonstrated that intact thiol and amino on CS are both critical for its etching ability to gold.Applied potentials can affect the electron transferring and hence can be used to regulate the etching of gold.The experimental results also reveal that only two carbon atoms of the spacer between thiol and amino on CS are very critical to the excellent etching ability.