Tuning the Electrochemical Swelling of Polyelectrolyte Multilayers toward Nanoactuation

• Published in: Langmuir Vol. 30; no. 40; pp. 12057 - 12066
• Main Authors: Zahn, Raphael, Vörös, János, Zambelli, Tomaso
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 14.10.2014
• Subjects: Carboxymethylcellulose Sodium - chemistry; Electrochemical Techniques; Ferrocyanides - chemistry; Ferrous Compounds - chemistry; Metallocenes; Nanotechnology - methods; Oxidation-Reduction; Polyamines - chemistry; Polyethylenes - chemistry; Polyglutamic Acid - chemistry; Quartz Crystal Microbalance Techniques; Quaternary Ammonium Compounds - chemistry
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la503051n

We discuss physicochemical determinants of electrochemical polyelectrolyte multilayer swelling that are relevant to actuator usage. We used electrochemical quartz crystal microbalance with dissipation monitoring (EC-QCM-D) and cyclic voltammetry to compare the electrochemical swelling of two types of ferrocyanide-containing polyelectrolyte multilayers, poly­(l-glutamic acid)/poly­(allylamine hydrochloride) (PGA/PAH), and carboxymethyl cellulose/poly­(diallyldimethylammonium chloride) (CMC/PDDA). We showed that ferrocyanide oxidation causes the swelling of PGA/PAH multilayers whereas it results in the contraction of CMC/PDDA multilayers. This behavior can be attributed to the presence of a positive and a negative Donnan potential in the case of PGA/PAH and CMC/PDDA multilayers, respectively. Using multilayers consisting of PGA and poly­(allylamine) ferrocene (PGA/PAH-FC), we applied EC-QCM-D and demonstrated potentiostatic thickness control with nanometer precision and showed that the multilayer’s thickness depends linearly on the applied potential within a certain potential range.