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4704769 
Journal Article 
Toward an equilibrium structure in lamellar diblock copolymer thin films using solvent vapor annealing - An in-situ time-resolved GISAXS study 
Sepe, A; Zhang, J; Perlich, Jan; Smilgies, DM; Posselt, D; Papadakis, CM 
2016 
Yes 
European Polymer Journal
ISSN: 0014-3057 
PERGAMON-ELSEVIER SCIENCE LTD 
OXFORD 
81 
607-620 
WOS:000381329300048 
Solvent vapor annealing (SVA) is frequently used to improve the ordering in diblock copolymer thin films. An important question is which SVA protocol should be chosen to ensure thermodynamic equilibrium. Here, we investigate two thin films from a low molar-mass, lamellae-forming polystyrene-block-polybutadiene (PS-b-PB) diblock copolymer (28.0 kg/mol). The films are prepared by spin-coating Si wafers from toluene solutions and have film thicknesses of 215 nm and 332 nm. The as-prepared films have mainly the parallel lamellar orientation with a lamellar thickness D-lam,D-par significantly lower than in the bulk. SVA cycles were carried out with cyclohexane, and the structural changes were followed in-situ using time-resolved grazing-incidence small-angle X-ray scattering (GISAXS). Before and after SVA, D-lam,D-par is significantly lower than in the bulk, i.e. the equilibrium value of D-lam,D-par in thin film geometry is different from the bulk value. Whereas the behavior of D-lam,D-par is different for the two films in the early stages of the first swelling, it is very similar in the late stages of swelling and during drying. During the first drying, the lamellae deswell, initially slowly and later, when PS becomes glassy again, affinely. During the second SVA cycle on the thin film, the scaling behavior of the lamellar thickness is identical to the one during the first drying and to the drying behavior of the thicker film. We conclude that one cycle of solvent vapor treatment with a degree of swelling of ca. 1.5 is sufficient to bring the PS-b-PB thin films studied into equilibrium and to create a nearly defect-free lamellar structure. (C) 2015 Elsevier. Ltd. All rights reserved. 
Nanostructured thin films; Solvent vapor annealing; Block copolymers; Grazing-incidence small-angle X-ray scattering 
6th Conference on the Synchrotron Radiation in Polymer Science (SRPS) 
Madrid, SPAIN