title: Explanation for the apparent absence of collapse of polyelectrolyte brushes in the presence of bulky ions.
abstract: The conformational behavior of poly[2-(methacryloyloxy)ethyltrimethylammonium chloride] (PMETAC) brushes with different chain density in the presence of large benzyltributylammonium chloride (BTBAC) ions has been studied by a Quartz Crystal Microbalance with Dissipation (QCM-D) and Scanning Force Microscopy. Dense brushes do not collapse in the presence of BTBAC solutions of increasing ionic strength, contrary to what is observed in the presence of NaCl. Brush collapse can be observed for low-ionic-strength solutions of BTBAC when the brush density has been reduced. These phenomena can be explained by considering the Hofmeister series as well as ion size and free space in the brush.
authors.affiliation: The Nanoscience Centre, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Sergio E
authors.initials: SE
authors.lastname: Moya
authors.forename: Omar
authors.initials: O
authors.lastname: Azzaroni
authors.forename: Tim
authors.initials: T
authors.lastname: Kelby
authors.forename: Edwin
authors.initials: E
authors.lastname: Donath
authors.forename: Wilhelm T S
authors.initials: WT
authors.lastname: Huck
mesh_terms: D004573:Electrolytes / Q000737:chemistry*; D004583:Electrons; D007477:Ions / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
chemical_list: D004573:Electrolytes; D007477:Ions; D011108:Polymers