Phase behaviors and self-assembled properties of ion-pairing amphiphile molecules formed by medium-chain fatty acids andl -arginine triggered by external conditions
| Autor: | Ling Jiang, Hongman Zhang, Yuxian Wang, Ce Wei |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Phase transition
Vesicle 02 engineering and technology General Chemistry Decanoic acid 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Lauric acid Krafft temperature Micelle Catalysis 0104 chemical sciences chemistry.chemical_compound chemistry Phase (matter) Polymer chemistry Amphiphile Materials Chemistry Organic chemistry 0210 nano-technology |
| Zdroj: | New Journal of Chemistry. 41:14486-14497 |
| ISSN: | 1369-9261 1144-0546 |
| Popis: | Fatty acids, composed of an amphiphilic carbon chain and a carboxyl group, are a simple class of anion surfactants when they are protonated in the presence of an alkali. They can form ion-pairing amphiphile molecules and self-assemble into different nanostructures, which can be widely applied. However, the phase transition of these nanostructures can be easily triggered by external conditions, such as pH, temperature, the addition of salts and so on. In this work, medium-chain fatty acids (MCFAs) containing 8–12 carbons were chosen as the objects for self-assembly with organic amino counter-ions, L-arginine. We investigated the effects of chain length, pH, temperature and solvent on the phase transition based on diagrams, which could be determined by freeze fracture transmission electron microscopy (FF-TEM) and polarizing microscopy observations (PMO) combined with rheological properties. The results showed that rich phase behavior was observed in the octanoic acid (C8:0) system. However, it was insensitive to changes in pH because of the lower hydrophobicity. In contrast, for decanoic acid (C10:0) and lauric acid (C12:0) systems, phase transition from the L1 phase (micelles) to the Lα phase (vesicles) was observed and they showed stimulus-response to the change of pH. At the same time, lauric acid was sensitive to temperature, which was ascribed to the higher Krafft point. Besides, when the solvent was replaced by glycerin, phase transitions occurred from vesicles to micelles in these three systems. We hope that this phase transition observed in the MCFA system will provide a good insight into drug delivery, material science, and other related areas. |
| Databáze: | OpenAIRE |
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