Journal of Colloid and Interface Science 332 (2009) 91–95 Contents lists available at ScienceDirect Journal of Colloid and Interface Science www.elsevier.com/locate/jcis Surface micellization of poly(2-oxazoline)s based copolymers containing a crystallizable block Charles-André Fustin a , Nathalie Lefèvre a , Richard Hoogenboom b,c , Ulrich S. Schubert b,c,d , Jean-François Gohy a,b,∗ a Unité de Chimie des Matériaux Inorganiques et Organiques (CMAT), Université catholique de Louvain, Place L. Pasteur 1, 1348 Louvain-la-Neuve, Belgium b Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology, Den Dolech 2, 5600 MB Eindhoven, The Netherlands c Dutch Polymer Institute (DPI), John F. Kennedylaan 2, 5612AB Eindhoven, The Netherlands d Laboratory of Organic and Macromolecular Chemistry, Friedrich-Schiller-Universität Jena, Humboldtstrasse 10, 07743 Jena, Germany article info abstract Article history: Received 30 October 2008 Accepted 8 December 2008 Available online 13 December 2008 Keywords: Micelles Morphology Spin-coating Surfaces Block copolymers The micellization on surfaces of copoly(2-oxazoline) diblock copolymers consisting of a crystallizable poly(2-nonyl-2-oxazoline) (pNonOx) block linked to a poly(2-ethyl-2-oxazoline) (pEtOx) block is investi- gated. Those micelles are not pre-existing in the initial ethanol solution but are formed during the spin- coating process by the evaporation of the solvent inducing the precipitation of the less soluble pNonOx block. The morphology and size of the surface micelles vary according to the pNonOx molar fraction in the copolymers. Reorganization of the micelles and evolution of the surface energies after a thermal annealing are also studied.  2008 Elsevier Inc. All rights reserved. 1. Introduction Block copolymers are well known for their ability to self- assemble into well defined nanostructures exploitable in many dif- ferent fields and providing thus a large number of possible applica- tions [1]. This self-assembly can occur in the solid state (thin films, or bulk), or in solution (formation of micelles). Block copolymer micelles are generally formed by dissolving directly the copolymer in a selective solvent for one of the blocks, or by starting from a non-selective solvent and adding a selective solvent afterwards to induce the precipitation of one block [2]. Micelle-like structures can also be prepared with the help of surfaces. This is achieved by depositing the copolymer from a non-selective solvent on a sur- face, the formation of the micelles being due to preferential inter- actions between one of the blocks and the substrate surface [3–6]. A typical illustration of this strategy is found in the deposition of poly(styrene)-block-poly(4-vinyl pyridine) copolymers (PS-b-P4VP) onto mica where the P4VP block is spread on the substrate be- cause of strong interactions with the mica, and the PS block is forming clusters on the surface of the samples [3,5]. Another strat- egy consists in depositing a copolymer solution at the water/air interface instead of on a solid substrate. The Langmuir–Blodgett micellar film thus formed can then be transferred onto a solid * Corresponding author at: Unité de Chimie des Matériaux Inorganiques et Or- ganiques (CMAT), Université catholique de Louvain, Place L. Pasteur 1, 1348 Louvain- la-Neuve, Belgium. Fax: +32 10 479269. E-mail addresses: jean-francois.gohy@uclouvain.be, j.f.gohy@tue.nl (J.-F. Gohy). substrate. This method has been implemented in the early 90’s by Eisenberg and coworkers [7]. The morphologies (starfish, rod, and planar) adopted by these (quasi)-2D micellar aggregates were crit- ically dependent on the ratio of the hydrophobic and hydrophilic block sizes. All these approaches can be used for the preparation of structured surfaces exhibiting chemical and/or topographical fea- tures at the nanoscale. Such nanostructured surfaces can of course also be prepared by depositing micelles pre-existing in a selective solvent [8–10]. Recently, we reported on an alternative strategy to prepare mi- celles on a surface [11]. This method is simply based on spin- coating a dilute solution of a block copolymer in a non-selective solvent on a substrate, the process itself inducing the precipita- tion of one of the blocks. As the solvent evaporates during the spin-coating process, the solubility limit of the less soluble block is crossed, inducing its precipitation, and hence the formation of micelles since the other block is still soluble. Diblocks, triblocks, tetrablocks and two series of quasi-diblock copolymers made from poly(2-oxazolines) were previously used as starting materials [11]. The different blocks were made of 2-phenyl-2-oxazoline (PhOx), 2-methyl-2-oxazoline (MeOx) and 2-ethyl-2-oxazoline (EtOx). The PhOx block was responsible for the formation of micelles dur- ing spin-coating, being the less soluble block in the used solvent (ethanol). It was shown that the morphology and size of the mi- celles vary according to the molar fraction of the PhOx block but are not dependent on the block order in the copolymer. The poly(2-oxazoline) family is highly interesting because of the large number of differently substituted monomers that can be 0021-9797/$ – see front matter  2008 Elsevier Inc. All rights reserved. doi:10.1016/j.jcis.2008.12.026