Association and phase behavior of hydrophobically modified photoresponsive poly(acrylamide)s in the presence of ionic surfactant |
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Authors: | C Howley D G Marangoni J C T Kwak |
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Institution: | (1) Department of Chemistry Dalhousie University Halifax, Nova Scotia, Canada B3H 4J3, CA;(2) Department of Chemistry Saint Francis Xavier University Antigonish, Nova Scotia, Canada B2G 2W5, CA |
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Abstract: | The extent of association between the cationic surfactant TTAB and a series of hydrophobically modified polyacrylamides (HPAMs)
containing an N-n-alkyl and substituted azobenzene hydrophobic sidegroup has been studied utilizing a cationic surfactant-selective membrane
electrode. Binding of TTAB to the polymer hydrophobes is found to increase with increasing hydrophobicity of the hydrophobe.
In the presence of electrolyte, aqueous solutions of HPAMs and ionic surfactant exhibit an associative phase separation. The
temperature or clearing point (CP) at which the system goes from a one phase to two-phase system are reported. The area of
the two-phase region is found to increase with increasing electrolyte concentration, hydrophobicity of the hydrophobe for
the high molecular weight HPAMs, and decreasing hydrophobicity for low molecular weight HPAMs. Exposure of HPAMs containing
an azobenzene hydrophobe to UV light results in a decrease in interaction between the hydrophobe and surfactant and a corresponding
decrease in the CP due to conversion of azobenzene from the more hydrophobic trans form to the less hydrophobic cis isomer.
Received: 23 September 1996 Accepted: 11 March 1997 |
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Keywords: | Hydrophobically modified polymers azobenzene photoresponsive polymer polymer/surfactant complexes associative phase separation |
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