| A rheo-optical apparatus for real time kinetic studies on shear-induced alignment of self-assembled soft matter with small sample volumes. | |
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MedLine Citation:
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PMID: 17503948 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In soft materials, self-assembled nanoscale structures can allow new functionalities but a general problem is to align such local structures aiming at monodomain overall order. In order to achieve shear alignment in a controlled manner, a novel type of rheo-optical apparatus has here been developed that allows small sample volumes and in situ monitoring of the alignment process during the shear. Both the amplitude and orientation angles of low level linear birefringence and dichroism are measured while the sample is subjected to large amplitude oscillatory shear flow. The apparatus is based on a commercial rheometer where we have constructed a flow cell that consists of two quartz teeth. The lower tooth can be set in oscillatory motion whereas the upper one is connected to the force transducers of the rheometer. A custom made cylindrical oven allows the operation of the flow cell at elevated temperatures up to 200 degrees C. Only a small sample volume is needed (from 9 to 25 mm(3)), which makes the apparatus suitable especially for studying new materials which are usually obtainable only in small quantities. Using this apparatus the flow alignment kinetics of a lamellar polystyrene-b-polyisoprene diblock copolymer is studied during shear under two different conditions which lead to parallel and perpendicular alignment of the lamellae. The open device geometry allows even combined optical/x-ray in situ characterization of the alignment process by combining small-angle x-ray scattering using concepts shown by Polushkin et al. [Macromolecules 36, 1421 (2003)]. |
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Authors:
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Ari Laiho; Olli Ikkala |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Review of scientific instruments Volume: 78 ISSN: 0034-6748 ISO Abbreviation: Rev Sci Instrum Publication Date: 2007 Jan |
Date Detail:
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Created Date: 2007-05-16 Completed Date: 2007-06-22 Revised Date: 2008-11-21 |
Medline Journal Info:
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Nlm Unique ID: 0405571 Medline TA: Rev Sci Instrum Country: United States |
Other Details:
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Languages: eng Pagination: 015109 Citation Subset: IM |
Affiliation:
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Department of Engineering Physics and Mathematics and Center for New Materials, Helsinki University of Technology, FI-02015 HUT, Espoo, Finland. ari.laiho@hut.fi |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Elasticity Kinetics Microfluidic Analytical Techniques* / instrumentation Optics and Photonics Reproducibility of Results Shear Strength |
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