Preparation and evaluation of polymer brushes
Université de Bretagne-Sud, Lorient

Yves Grohens is professor and director of the Laboratoire Polymères, Propriétés aux Interfaces et Composites at the University of South Brittany Lorient, France. His research interests include the preparation and characterization of polymer thin films (glass transition, density, cooperativity and confinement, chain conformation, and orientation).

Located in Lorient and Vannes (France) close to the sea, the Polymer, Interfaces Properties and Composites Laboratory belongs to the French ministry of teaching and research. 30 researchers including 12 graduate students are working in very good conditions in a new building and many technical facilities.

Brushes will be prepared in co-operation with the group at Lyon, led by Professors Eric Drockenmuller (photo right) and Jean-Paul Chapel.

The elaboration of tuneable well-defined polymer brushes involves the Langmuir-Blodgett reactive anchoring of an amphiphilic polymerization mediator to a functional substrate (below left) and consequent "grafted from" copolymerization of functional monomers (below right). These surfactant initiators (e.g. nitroxide or dithioester) include an alkylated spacer and a polar self-condensing triethoxysilane.

The well-controlled homogeneous growth of these confined thin-films are directly related to the degree of polymerization and the grafting density. Brush thickness can be measured by ellipsometry in air as a function of the molecular weight of polystyrene chains either grafted from or onto the silica surface.

For a given molecular weight, the grafting from approach (combined with the LB deposition technique) is very much more efficient for producing thick and then dense layers than the regular onto approach.

Relevant publications

Overview of relevant factors affecting the glass transition of supported thin polymer films. Y. Grohens, L. Mamon, G. Reiter, Y. Holl the European Journal Physical Journal E, 8, 217-224, 2002

Ion crater healing and variable temperature ellipsometry as complementary probes for the glass transition in thin polymer films Y. Grohens, R.M. Papaléo, L. Hamon the European Journal Physical Journal E, 12, 20, 2003

Cooperativity in stereoregular pmmas observed by molecular simulation A. Soldera, Y. Grohens Polymer, 45/4, 1307, 2004

Nanoscale characteristic length at the glass transition in confined syndiotactic poly(methyl methacrylate) Tuan Anh Tran, Sylvere Saïd, Y. Grohens Macromolecules, in press

Controlled polystyrene brushes on AFM tip. C. Devaux J. P. Chapel, E., Beyou, P. Chaumont Eur. Phys J. E. 2002, 7, 345-352.

Covalent stabilization of nanostructures: robust block copolymer templates from novel thermoreactive systems. E. Drockenmuller, L. Y. T. Li, D. Y. Ryu, E. Harth, T. P. Russell, H-C. Kim, C. J. Hawker J. Pol. Sci.: Part A 2005, 43, 1028-1037.

Living/controlled radical polymerization of acrylates at 90°C mediated by b-sulfinyl nitroxides: influence of the persistent radical stereochemistry. E. Drockenmuller, J.-P. Lamps, J.-M. Catala Macromolecules 2004, 37, 2076-2083.