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PHOTOLUMINESCENT PROPERTIES OF OCTADECYLRHODAMINE B IN MICELLES OF LOW‐MOLECULAR‐WEIGHT DETERGENTS AND WATER‐SOLUBLE TRIBLOCK COPOLYMERS
Author(s) -
Nakashima Kenichi,
Fujimoto Yoshinori,
Anzai Takayuki
Publication year - 1995
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1995.tb09874.x
Subject(s) - micelle , copolymer , ethylene oxide , chemistry , fluorescence , propylene oxide , critical micelle concentration , polymer chemistry , materials science , organic chemistry , polymer , aqueous solution , optics , physics
The fluorescence intensity, lifetime and degree of polarization of octadecylrhodamine B (ORB) have been measured in order to examine the usefulness of this molecule as a probe of micelle properties for low‐molecular‐weight detergents and water‐soluble triblock copolymers. The surfactants examined are hexadecyltrimethylammonium chloride (HTAC), Triton X‐100 (TX‐100), sodium dode‐cylsulfate (SDS), sodium tetradecylsulfate (STS), and Pluronic L64 (ethylene oxide [EO] 13 propylene oxide 30 EO 13 , L64). The fluorescence intensity and degree of polarization of ORB show drastic increases at the critical micelle concentrations (CMC) of HTAC, TX‐100 and L64, indicating that ORB is cooperatively incorporated into the micelles upon micellization. This feature demonstrates the validity of ORB as a probe for detecting micelle formation of these surfactants. However, in the case of SDS and STS, the fluorescence intensity starts to rise at concentrations far below the CMC, and the degree of polarization does not show significant changes at the CMC. The details of the interactions between ORB and the anionic surfactants have been unclear. These facts imply that some caution is needed for the applications of ORB to the systems containing anionic surfactants. The local viscosity of L64 micelles has been determined by polarization and lifetime measurements. The structure of the block copolymer micelles and the locations of the probe in the micelles are discussed in terms of the viscosity data.