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Micellization in aqueous solution of an ethylene oxide-propylene oxide triblock copolymer, investigated with H-1 NMR spectroscopy, pulsed-field gradient NMR, and NMR relaxation
Alternative TitleJ. Colloid Interface Sci.
Ma, Junhe; Guo, Chen; Tang, Yalin; Xiang, Junfeng; Chen, Shu; Wang, Jing; Liu, Huizhou
2007-08-15
Source PublicationJOURNAL OF COLLOID AND INTERFACE SCIENCE
ISSN0021-9797
Volume312Issue:2Pages:390-396
AbstractH-1 nuclear magnetic resonance (NMR) spectroscopy has been applied to study the temperature and concentration-induced micellization of a poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) triblock copolymer, Pluronic P105, in D2O solutions in the temperature range from 5 to 45 degrees C and the concentration range from 0.01 to 15% (w/v). The intrinsic probes, the chemical shift, and the half-height width of the PO -CH3 signal are very sensitive to the local environment and can be used to characterize the temperature and concentration-dependent aggregation process. When the temperature approaches the critical micellization temperature or the polymer concentration reaches the critical micellization concentration, the chemical shift of the PO -CH3 signal moves toward lower ppm values and the half-height width of the PO -CH3 signal shows a sudden increase. It indicates that the methyl groups are experiencing a progressively less polar environment and transferring from water to the hydrophobic micellar core. The hydrodynamic radius of the unimers and the micelles are determined as be 1.8 and 5.0 nm by means of pulsed-field gradient spin-echo (PGSE) NMR. They were independent of temperature and concentration. The drastic shortening of spin-lattice relaxation time T-1 for the PO -CH3/-CH2- protons in the transition region suggested that the PPO blocks are located in a "liquid-like" micellar core, whereas the exponential increase of T-1 for the PEO -CH2- protons implied that the PEO blocks are still keeping in contact with surrounding water. Thermodynamics analysis according to a closed association model shows that the micellization process is entropy-driven and has an endothermic micellization enthalpy. (c) 2007 Elsevier Inc. All rights reserved.; H-1 nuclear magnetic resonance (NMR) spectroscopy has been applied to study the temperature and concentration-induced micellization of a poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) triblock copolymer, Pluronic P105, in D2O solutions in the temperature range from 5 to 45 degrees C and the concentration range from 0.01 to 15% (w/v). The intrinsic probes, the chemical shift, and the half-height width of the PO -CH3 signal are very sensitive to the local environment and can be used to characterize the temperature and concentration-dependent aggregation process. When the temperature approaches the critical micellization temperature or the polymer concentration reaches the critical micellization concentration, the chemical shift of the PO -CH3 signal moves toward lower ppm values and the half-height width of the PO -CH3 signal shows a sudden increase. It indicates that the methyl groups are experiencing a progressively less polar environment and transferring from water to the hydrophobic micellar core. The hydrodynamic radius of the unimers and the micelles are determined as be 1.8 and 5.0 nm by means of pulsed-field gradient spin-echo (PGSE) NMR. They were independent of temperature and concentration. The drastic shortening of spin-lattice relaxation time T-1 for the PO -CH3/-CH2- protons in the transition region suggested that the PPO blocks are located in a "liquid-like" micellar core, whereas the exponential increase of T-1 for the PEO -CH2- protons implied that the PEO blocks are still keeping in contact with surrounding water. Thermodynamics analysis according to a closed association model shows that the micellization process is entropy-driven and has an endothermic micellization enthalpy. (c) 2007 Elsevier Inc. All rights reserved.
KeywordPeo-ppo-peo Triblock Copolymer Micellization H-1 Nmr Diffusion Nmr Nmr Relaxation
SubtypeArticle
WOS HeadingsScience & Technology ; Physical Sciences
DOI10.1016/j.jcis.2007.03.013
URL查看原文
Indexed BySCI
Language英语
WOS KeywordPEO BLOCK-COPOLYMER ; LIGHT-SCATTERING ; AGGREGATION BEHAVIOR ; ASSOCIATION BEHAVIOR ; MICELLE FORMATION ; WATER ; SURFACTANT ; DIFFUSION ; TEMPERATURE ; SYSTEMS
WOS Research AreaChemistry
WOS SubjectChemistry, Physical
WOS IDWOS:000247838300024
Citation statistics
Document Type期刊论文
Version出版稿
Identifierhttp://ir.ipe.ac.cn/handle/122111/3409
Collection研究所(批量导入)
Affiliation1.Chinese Acad Sci, Grad Sch, Lab Separat Sci & Engn, State Key Lab Biochem Engn,Inst Proc Engn, Beijing 100080, Peoples R China
2.Chinese Acad Sci, Inst Chem, Beijing 100080, Peoples R China
Recommended Citation
GB/T 7714
Ma, Junhe,Guo, Chen,Tang, Yalin,et al. Micellization in aqueous solution of an ethylene oxide-propylene oxide triblock copolymer, investigated with H-1 NMR spectroscopy, pulsed-field gradient NMR, and NMR relaxation[J]. JOURNAL OF COLLOID AND INTERFACE SCIENCE,2007,312(2):390-396.
APA Ma, Junhe.,Guo, Chen.,Tang, Yalin.,Xiang, Junfeng.,Chen, Shu.,...&Liu, Huizhou.(2007).Micellization in aqueous solution of an ethylene oxide-propylene oxide triblock copolymer, investigated with H-1 NMR spectroscopy, pulsed-field gradient NMR, and NMR relaxation.JOURNAL OF COLLOID AND INTERFACE SCIENCE,312(2),390-396.
MLA Ma, Junhe,et al."Micellization in aqueous solution of an ethylene oxide-propylene oxide triblock copolymer, investigated with H-1 NMR spectroscopy, pulsed-field gradient NMR, and NMR relaxation".JOURNAL OF COLLOID AND INTERFACE SCIENCE 312.2(2007):390-396.
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