Investigation of self-assembly and micelle polarity for a wide range of ethylene oxide propylene oxide ethylene oxide block copolymers in water

被引:136
作者
Lopes, JR [1 ]
Loh, W [1 ]
机构
[1] Univ Estadual Campinas, Inst Quim, BR-13083970 Campinas, SP, Brazil
关键词
D O I
10.1021/la9709655
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Critical micelle concentrations (cmc) were determined far aqueous solutions of 15 EO-PO-EO (EO = ethylene oxide, PO = propylene oxide) block copolymers by using three different techniques: spectral changes of an iodine/iodide mixture, methyl yellow solubilization, and surface tension measurements. Two polymers showed no sign of micelle formation up to phase separation: one reverse (PO-EO-PO) and the other with low EO/PO ratio, The obtained cmc's were consistent for the different techniques employed and allowed the determination of the Delta G values associated with the micellization. These values were analyzed in terms of the EO and PO contributions, confirming the leading role of the hydrophobic PO units and revealing a small, but favorable, contribution of the hydrophilic EO chains, in contrast to the usual behavior of small nonionic surfactants, The polarity of the micelle solubilization sites was determined using the solvatochromic dye E(T)30, revealing environments similar to those observed for micelles of hydrocarbon surfactants. These findings, allied to the thermodynamic similarity between the micellization and the phase separation processes for the copolymers and PPO, support the view that the micellization is accompanied by a large dehydration of the PO units.
引用
收藏
页码:750 / 756
页数:7
相关论文
共 37 条
[1]   SURFACE-ACTIVITY OF POLY(ETHYLENE OXIDE)-BLOCK-POLY(PROPYLENE OXIDE)-BLOCK-POLY(ETHYLENE OXIDE) COPOLYMERS [J].
ALEXANDRIDIS, P ;
ATHANASSIOU, V ;
FUKUDA, S ;
HATTON, TA .
LANGMUIR, 1994, 10 (08) :2604-2612
[2]   A CORRELATION FOR THE ESTIMATION OF CRITICAL MICELLIZATION CONCENTRATIONS AND TEMPERATURES OF POLYOLS IN AQUEOUS-SOLUTIONS [J].
ALEXANDRIDIS, P ;
HOLZWARTH, JF ;
HATTON, TA .
JOURNAL OF THE AMERICAN OIL CHEMISTS SOCIETY, 1995, 72 (07) :823-826
[3]   MICELLIZATION OF POLY(ETHYLENE OXIDE)-POLY(PROPYLENE OXIDE)-POLY(ETHYLENE OXIDE) TRIBLOCK COPOLYMERS IN AQUEOUS-SOLUTIONS - THERMODYNAMICS OF COPOLYMER ASSOCIATION [J].
ALEXANDRIDIS, P ;
HOLZWARTH, JF ;
HATTON, TA .
MACROMOLECULES, 1994, 27 (09) :2414-2425
[4]   POLY(ETHYLENE OXIDE)-POLY(PROPYLENE OXIDE)-POLY(ETHYLENE OXIDE) BLOCK-COPOLYMER SURFACTANTS IN AQUEOUS-SOLUTIONS AND AT INTERFACES - THERMODYNAMICS, STRUCTURE, DYNAMICS, AND MODELING [J].
ALEXANDRIDIS, P ;
HATTON, TA .
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 1995, 96 (1-2) :1-46
[5]   Lyotropic liquid crystallinity in amphiphilic block copolymers: Temperature effects on phase behavior and structure for poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymers of different composition [J].
Alexandridis, P ;
Zhou, DL ;
Khan, A .
LANGMUIR, 1996, 12 (11) :2690-2700
[6]   SCANNING MICROCALORIMETRIC INVESTIGATIONS OF PHASE-TRANSITIONS IN DILUTE AQUEOUS-SOLUTIONS OF POLY(OXYPROPYLENE) [J].
ARMSTRONG, J ;
CHOWDHRY, B ;
OBRIEN, R ;
BEEZER, A ;
MITCHELL, J ;
LEHARNE, S .
JOURNAL OF PHYSICAL CHEMISTRY, 1995, 99 (13) :4590-4598
[7]  
ATWOOD D, 1983, SURFACTANTS SYSTEMS, pCH3
[8]   AN INVESTIGATION OF DILUTE AQUEOUS-SOLUTION BEHAVIOR OF POLY(OXYETHYLENE) PLUS POLY(OXYPROPYLENE) PLUS POLY(OXYETHYLENE) BLOCK-COPOLYMERS [J].
BEEZER, AE ;
LOH, W ;
MITCHELL, JC ;
ROYALL, PG ;
SMITH, DO ;
TUTE, MS ;
ARMSTRONG, JK ;
CHOWDHRY, BZ ;
LEHARNE, SA ;
EAGLAND, D ;
CROWTHER, NJ .
LANGMUIR, 1994, 10 (11) :4001-4005
[9]   STRUCTURE AND DYNAMICS OF BLOCK-COPOLYMER COLLOIDS [J].
CHU, B .
LANGMUIR, 1995, 11 (02) :414-421
[10]   A SINGLE SPECTROSCOPIC PROBE FOR THE DETERMINATION OF BOTH THE INTERFACIAL SOLVENT PROPERTIES AND ELECTROSTATIC SURFACE-POTENTIAL OF MODEL LIPID-MEMBRANES [J].
DRUMMOND, CJ ;
GRIESER, F ;
HEALY, TW .
FARADAY DISCUSSIONS, 1986, 81 :95-106