Cetylpyridinium chloride, structure

Fig. 10.8 Quaternary ammonium compounds (QACs) A, general structure ofQACs B, benzalkonium chloride (n - S - 18) C, cetrimide (n - 12 - 14 or 16) D, cetylpyridinium chloride.

The present report describes new results for benzene at temperatures in the range 15 to 45°C, solubilized in aqueous solutions of sodium dodecylsulfate (SDS) and 1-hexadecylpyridinium chloride (referred to as cetylpyridinium chloride or CPC). The solute activity vs. concentration data provide insight into the nature of chemical and structural effects responsible for the solubilization of benzene by aqueous micellar systems in addition, the results find direct use in predicting the performance of MEUF in removing dissolved benzene from aqueous streams. 

The degree of retardation is dependent on the micellar structure of the system. Hoefner and Fogler (75) described one such microemulsion system containing cetylpyridinium chloride and butanol as the surfactant-cosurfactant in a 35 65 weight ratio. In this system, dodecane was used as the... 

Most polysaccharides used today are of plant origin. However, also bacteria produce polysaccharides. Especially extracellular polysaccharides (eps s) produced by lactic acid bacteria may find application in foods. Lactic acid bacteria are food-grade organisms and the eps s produced offer a wide variety of structures. The presence of eps is considered to contribute greatly to texture and structure of fermented milk products. An exopolysaccharide produced by Lactococcus lactis ssp. cremoris B40 was chosen as a subject of study. The eps was a gift from the Dutch Institute of Dairy Research (NIZO), Ede, the Netherlands. The eps had no gelling properties, could not be precipitated in plates by ethanol or cetylpyridinium chloride and did not show interaction with Congo red. 

It was suggested [284] that the perforated lamellar phase may form via the growth of branched and multiconnected threadlike micelles. Interconnection of threadlike micelles reduces the overall curvature of the monolayer making up the micelles and thereby reflects a preference for microstructures of decreasing curvature [119]. The suggested morphological sequence for the system cetylpyridinium chloride-hexanol-brine is spheres, small disks, long capped cylinders, branched cylinders, perforated bilayers, smooth bilayers, loose network of connected bilayers (foamlike structure), and multiphasic domain [284]. 

As just stated, the L3 phase resembles structurally a bicontinuous microemulsion, which makes it interesting to compare their rheological properties. Viscosity measurements on an L3 phase [in the system cetylpyridinium chloride-hexanol-brine (0.2 M NaCl)] showed Newtonian flow behavior for the range of shear rates of 0.1-100 s" [113]. The viscosity of this highly interconnected, spongelike system is always very low and close to the solvent viscosity, even for a volume fraction of 0.2 it is less than 10 mPa s. (Similar viscosity values have been observed in the L3 phase of the system tetradecyldimethylamine oxide-hexanol-water [114].) It increases linearly with the volume fraction of the amphiphilic material, where it is interesting to note that extrapolation to zero concentration does not yield the solvent viscosity but a value about three times as high. A similar value for the extrapolated viscosity was also reported more recently for another L3 phase (in the system SDS pentanol-dodecane-water [115]), and it seems that this enhanced viscosity is a universal property connected to the structure of the L3 phase. 

PPy-coated ceramic nanomaterial (zeohte and titanium sihcate) has been fabricated with microscopic structural homogeneity [216]. The core-shell nanoparticle was synthesized via a self-assembled array of cetylpyridinium chloride on the surface of core material. Cetylpyridinium chloride played a critical role for sustaining the colloidal stability of resulting product and providing a nanoscopically confined environment for the growth of ordered PPy film. An ultrathin PPy layer (thickness 10-30 nm) was successfully deposited on the ceramic nanoparticle (diameter 100 nm). Even with a fairly low amount of PPy in the core-shell nanoparticle (8%), a high conductivity (5 S cm ) was obtained. The result was attributed to the enhanced molecular order of PPy chains compared with conventional PPy. 

In the present study, hydrophobic interaction between hydroxypropylcellulose (HPC) and an ionic surfactant in an aqueous phase was discussed. HPC, as well as EHEC, is a nonionic cellulose ether which contains hydrophobic groups in its molecular structure. Therefore, it might be interesting to compare the complex-formation properties of HPC with that of EHEC. The surfactants used here were an anionic surfactant SDS and a cationic one cetylpyridinium chloride (CPC). HPC formed a complex with these surfactants, of which cloud point changed with the surfactant concentration in the same manner as that observed in the EHEC-surfactant systems [4]. Effects of the complex on stability of dilute and concentrated kaoiinite suspensions were also studied, taking physicochemical properties of the complex into account. 

The effect of shear on the L3 phase in the cetylpyridinium chloride/hexanol/(water+NaCl) system with a significant amount of added dextrose has been examined. Additions of of dextrose slow down the diffusional process discussed above. At low shear rate, the sponge phase structure is retained but starting at a shear rate above 500 s, shear thinning reveals the occurrence of a transition to a lamellar phase. Unfortu-... 

A second method for the formation of nanostructured surfiice-functionalized ionosilicas consists in the cocondensation reaction involving ionic precursor displaying surfactant-like behavior (Scheme 16.8) [108]. Template-directed syntheses of long chain-substituted silylated imidazolium or ammoniiun precursors in the presence of cationic surfactant such as CTAB or cetylpyridinium chloride yield highly structured ionosilica materials with surface-tethered ionic groups. 

In addition, Yei and co-workers also reported the preparation of two types of PS/clay nanocomposites formed from clays treated with either cetylpyridinium chloride (CPC) or the CPC/a-CD inclusion complex. Structures of these two intercalation agents were shown in Fig. 5.6. We found that CPC, a linear aliphatic surfactant, is able to form a crystalline complex with cyclodextrin. Including CPC within CD channels improves the thermal stability of die virgin... 

Two-phase titration is usually less sensitive to interference from other foreign (nonsurfactant) species. When applied to anionic surfactant systems, two-phase titration is primarily used for the analysis of alkyl sulfates and sulfonates. Typical titrants in these applications are solutions of cetylpyridinium bromide, cetyltrimethylammonium bromide, and benzyldimethylalkyl (C12 or C14) ammonium chloride. The most accurate results are, however, obtained with p-tert-octyl-phenoxy-ethoxy-ethyl-dimethyl-benzylammonium chloride, also known under the commercial name of Hyamine 1622. The structure of Hyamine 1622 is shown in Fig. 11-32,a. 

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