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The self-assembly of the cationic surfactant cetylpyridiniumchloride (CPC) in cyclohexane was studied using polarizing-microscopy (POM), small angle X-ray scattering (SAXS), and rheology measurements. Homogeneous solutions of CPC/aromatic salts were produced using aromatic salts, specifically, NaBzs, NaNphs, or NaSal. The majority of the samples showed highly viscous gel-like appearances. SAXS measurements together with POM observations indicate hexagonal liquid crystals in both the CPC/NaNphs and CPC/NaSal, while multiple types of aggregates were shown to co-exist in the CPC/NaBzs. These were attributed to the interactions of aromatic counterions with the pyridinium head-group of CPC, resulting in increased size of the CPC head to different extents depending on the aromatic counterions. The formation of core-shell aggregates consequently caused further packing into liquid crystals. The specific role of NaSal that carried an ortho-hydroxyl in its benzene ring is discussed, and the mechanism of trace water molecules bridging neighboring NaSal molecules was revealed according to Fourier transform infrared (FT-IR) measurements. The samples had high viscoelasticity, for example, the steady-state low-shear viscosity at a shear rate of 0.001, (L), of the samples at W-0=32 was 3.3x10(5), 2.0x10(4), and 6.8x10(2)Pas for CPC/NaBzs, CPC/NaNphs, and CPC/NaSal, respectively, at 25 degrees C. The corresponding elastic plateau moduli, G(P), were 1.9x10(3), 1.1x10(3), and 1.1x10(2)Pa, respectively. The temperature effect was examined for samples at W-0=32, which were found to retain high viscosity at higher temperatures, for example, the relative viscosity to solvent cyclohexane, (r), reached 10(7) and 10(5) for CPC/NaBzs and CPC/NaNphs, respectively, at 70 degrees C.
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COLLOID AND POLYMER SCIENCE
ISSN: 0303-402X
Year: 2019
Issue: 2
Volume: 297
Page: 271-283
1 . 5 3 6
JCR@2019
2 . 2 0 0
JCR@2023
ESI Discipline: CHEMISTRY;
ESI HC Threshold:184
JCR Journal Grade:3
CAS Journal Grade:3
Cited Count:
WoS CC Cited Count: 0
SCOPUS Cited Count: 1
ESI Highly Cited Papers on the List: 0 Unfold All
WanFang Cited Count:
Chinese Cited Count:
30 Days PV: 0
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