title: Tuning the electrochemical swelling of polyelectrolyte multilayers toward nanoactuation.
abstract: 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.
authors.affiliation: Laboratory of Biosensors and Bioelectronics, Institute for Biomedical Engineering, ETH Zurich , Zurich, Switzerland.
authors.forename: Raphael
authors.initials: R
authors.lastname: Zahn
authors.forename: János
authors.initials: J
authors.lastname: Vörös
authors.forename: Tomaso
authors.initials: T
authors.lastname: Zambelli
mesh_terms: D002266:Carboxymethylcellulose Sodium / Q000737:chemistry; D055664:Electrochemical Techniques; D005295:Ferrocyanides / Q000737:chemistry; D005296:Ferrous Compounds / Q000737:chemistry; D000075163:Metallocenes; D036103:Nanotechnology / Q000379:methods*; D010084:Oxidation-Reduction; D011073:Polyamines / Q000737:chemistry*; D011095:Polyethylenes / Q000737:chemistry; D011099:Polyglutamic Acid / Q000737:chemistry*; D058525:Quartz Crystal Microbalance Techniques; D000644:Quaternary Ammonium Compounds / Q000737:chemistry
chemical_list: D005295:Ferrocyanides; D005296:Ferrous Compounds; D000075163:Metallocenes; D011073:Polyamines; D011095:Polyethylenes; D000644:Quaternary Ammonium Compounds; D011099:Polyglutamic Acid; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride; C063994:polyallylamine; D002266:Carboxymethylcellulose Sodium; C004998:ferrocene