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Extraction and Characterization of Surfactants from Atmospheric Aerosols
Published on: April 21, 2017
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Phase Behavior and Aggregation in a Catanionic System Dominated by an Anionic Surfactant Containing a Large Rigid
Zhaolan Zhai1, Xinyan Yan1, Ji Xu1
1Institute of Chemical Industry of Forest Products, CAF, National Engineering Lab. for Biomass Chemical Utilization, Key and Open Lab. of Forest Chemical Engineering, SFA, Key Lab. of Biomass Energy and Material, Jiangsu Province, 16 SuojinWucun, XuanWu District, Nanjing, China.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|April 20, 2018
Summary
This study explores catanionic surfactant systems, revealing how varying concentrations of sodium N-alkylmaleimidepimaric carboxylate (Cn-MPA-Na) with cetyltrimethylammonium bromide (CTAB) influence phase behavior and aggregate structures, including novel sponge-like micelles.
Area of Science:
- Colloid and Surface Science
- Materials Science
- Supramolecular Chemistry
Background:
- Catanionic surfactant systems, formed by mixing anionic and cationic surfactants, exhibit complex phase behaviors.
- Sodium N-alkylmaleimidepimaric carboxylates (Cn-MPA-Na) possess unique structures derived from rosin, featuring rigid skeletons and flexible chains.
- Cetyltrimethylammonium bromide (CTAB) is a common cationic surfactant used in various applications.
Purpose of the Study:
- To investigate the phase behavior of catanionic systems composed of Cn-MPA-Na (n=12, 14, 16) and CTAB.
- To characterize the aggregate structures formed in different phases using rheology and Cryo-TEM.
- To understand the influence of alkyl chain length on phase transitions and microstructure.
Main Methods:
- Preparation of anionic surfactants: sodium N-alkylmaleimidepimaric carboxylates (Cn-MPA-Na).
- Systematic variation of Cn-MPA-Na concentration in mixtures with CTAB.
- Rheological measurements to assess viscoelastic properties.
- Cryogenic transmission electron microscopy (Cryo-TEM) for microstructure visualization.
Main Results:
- The C14-MPA-Na/CTAB system exhibited sequential phase transitions: viscoelastic solution, aqueous surfactant two-phase system (ASTP), aqueous surfactant three-phase system (AS3P), and anisotropic homogeneous phase.
- The C16-MPA-Na/CTAB system showed similar behavior, but the C12-MPA-Na/CTAB system did not form the AS3P.
- Identified aggregates included thread-like, annular, worm-like, rod-like, spherical, and novel sponge-like micelles in different phases.
Conclusions:
- The alkyl chain length of the anionic surfactant significantly impacts the phase behavior and aggregate formation in catanionic systems.
- Sponge-like micelles were observed in the AS3P middle phase and anisotropic homogeneous phase, visualized clearly by Cryo-TEM.
- These findings contribute to understanding the self-assembly of complex surfactant systems and their potential applications.
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