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| Home > JCE Print > Journal of Chemical Education > Issues >
2006
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March
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In the Laboratory
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Advanced Chemistry Classroom and Laboratory
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Microwave-Induced Chain Transfer Polymerization of a Stimuli-Responsive Polymer and Determination of Its Critical Solution Temperature
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F. Fischer
Institute of Chemical and Biological Process Science, Chemistry Section, Faculty
of Basic Science, Swiss Federal Institute of Technology, Lausanne, Switzerland;
Hochschule Wallis, Life Technologies Institute, Biotechnology Unit, Sion 2, Switzerland
R. Freitag
Institute of Chemical and Biological Process Science, Chemistry Section, Faculty
of Basic Science, Swiss Federal Institute of Technology, Lausanne, Switzerland
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March 2006
Vol. 83 No. 3
p. 447
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| Abstract |
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This experiment provides an introduction for undergraduate students to the concepts
of living radical polymerization (oligomerization) and to stimuli-responsive
materials, namely, those showing a critical solution temperature in aqueous
solution. Students learn to polymerize and examine an intelligent polymer in
a 8-hour, one-day laboratory period. The poly-N-isopropylacrylamide
(PNIPAM) is a thermo-responsive polymer with a critical solution temperature
(CST) of approximately 32 °C in pure water. Oligomeric PNIPAM (2000 g/mol)
is telomerized with AIBN as initiator and 3-mercaptopropionic acid as chain
transfer agent. The reactants are heated by microwave irradiation in a solvent-free
process, employing a domestic microwave oven with 2.45 GHz magnetron frequency.
The isolated telomer contains a single carboxylic function at one end of the
polymer chain, allowing precise determination of the average molar mass by
titration with NaOH solution and phenolphthalein as indicator. The CST phenomenon
is easily detected by direct observation in daylight or by a temperature-programmed
UV–vis spectrometer.
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| Supplement |
Instructions for the students and notes for the instructor are available.
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 Contents |
JCE2006p0447W.doc (Microsoft Word)
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| Download |
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| More Information |
Citation |
Fischer, F.; Freitag, R. J. Chem. Educ. 2006 83 447.
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Keywords |
Addition Reactions; Free Radicals; Hands-On Learning / Manipulatives; Laboratory Instruction; Mass Spectrometry; Materials Science; NMR Spectroscopy; Polymer Chemistry; Polymerization; Upper-Division Undergraduate; UV-Vis Spectroscopy
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History |
Created:
Last Updated: |
1/31/2006
2/9/2006
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| Home > JCE Print > Journal of Chemical Education > Issues >
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447
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