Polymeric surfactants, based on grafted polyethyleneglycol (PEG) with different chain lengths on polymethylmetacrylate (PMMA), have been prepared and studied. The `'stabilizing moiety'', PEG, was grafted by a transesterification reaction on the -OCOCH3 groups of the `'anchoring moiety'' PMMA, obtaining comb type substituted PMMA. The amphiphilic polymers reduce only slightly the water/air surface However, interfacial tension of certain `'oil phases'' such as toluene were significantly reduced. The best polymeric surfactant, reducing interfacial tension practically to zero, was PMMA of MW 130000 grafted with 6.5 wt% PEG consisting of 22 ethylene oxide (EO) units. Spontaneous emulsification was achieved with very low polymer concentration (\textless1.0%). Flocculation was observed in emulsion in which excess emulsifier was used or in systems containing free ungrafted PEG.

Hydraulic fluids based on water-in-oil microemulsions and non-ionic emulsifiers were prepd. Phase diagrams of the microemulsions were constructed with the intention of using the most suitable of them for formulation of hydraulic fluid with and without additives. Up to 22 wt.% water could be solubilized when a carefully designed mixt. of nonionic ethoxylated alcs. was used as the surfactant; up to nearly 35 wt.% water could be solubilized when a mixt. of paraffinic oil and pentanol was used as the oil phase and the same mixt. of nonionic ethoxylated alcs. was used as the surfactant. Droplet size, stability, and other phys. characteristics were evaluated. [on SciFinder(R)]

A review with 45 refs. Gum arabic is compared to colloidal microcryst.-cellulose (MCC) and galactomannans in view of their ability to reduce surface tension, interfacial tension and to stabilize oil-in-water emulsions via the steric and mech. stabilization mechanisms. While gum arabic adsorbs strongly and effectively onto the oil droplets via its proteinaceous moieties, guar gum and locust bean gum (LBG) adsorb weakly and for the most part only "ppt." on the oil surface, and form birefringent layers of the polymer oriented with its hydrophobic mannose backbone facing the oil. The stabilization with MCC is claimed to be achieved via adsorption of solid particles on the oil droplets (mech. stabilization). [on SciFinder(R)]

The influence of octaethylene glycol mono-n-hexadecyl ether (I) and SDS on the crystn. of Ca oxalate from 0.3 mol dm-3 NaCl solns. was investigated. The crit. micellar concn. (CMC) of I in H2O and 0.3 mol dm-3 NaCl was detd. by surface tension measurements (CMCH2O:CMCNaCl = 7.2.10-6 mol·dm-3). The kinetics of pptn. of Ca oxalate was followed by Coulter counter, and solid phases were characterized by polarized microscopy, thermal anal., and x-ray powder diffraction patterns. Under the pptn. conditions employed, the thermodynamically stable monohydrate, CaC2O4·H2O was the predominant cryst. form. In the presence of micellar solns. of I, pptn. of this phase was facilitated as evidenced by higher initial pptn. rates and higher ppt. vol. and no. of particles, as compared to the controls. Micellar solns. of SDS retarded pptn. but induced crystn. of Ca oxalate dihydrate, CaC2O4·(2+x)H2O (COD, x ≤ 0.5). Thus at c(SDS)\textgreaterCMC, the ppts. contained ≥85 mass % COD. The results were discussed in relation to previously reported data on the pptn. of Ca oxalate in the presence of dodecyl ammonium chloride. [on SciFinder(R)]

The influence of octaethylene glycol mono-n-hexadecyl ether (C16EO8) and sodium dodecyl sulphate (SDS) on the crystallization of calcium oxalate from 0.3 mol dm-3 sodium chloride solutions has been investigated. The critical micellar concentration (CMC) of C16EO8 in water and 0.3 mol dm-3 NaCl was determined by surface tension measurements (CMCH2O=CMCNaCl = 7.2.10(-6) mol dm-3). The kinetics of precipitation of calcium oxalate was followed by Coulter counter, and solid phases were characterized by polarized microscopy, thermal analysis and X-ray powder diffraction patterns. Under the precipitation conditions employed, the thermodynamically stable monohydrate, CaC2O4.H2O (COM) was the predominant crystalline form. In the presence of micellar solutions of C16EO8 precipitation of this phase was facilitated as evidenced by higher initial precipitation rates and higher precipitate volume and number of particles, as compared to the controls. Micellar solutions of SDS retarded precipitation but induced crystallization of calcium oxalate dihydrate, CaC2O4.(2+x)H2O (COD, x less-than-or-equal-to 0.5). Thus at c(SDS)\textgreaterCMC the precipitates contained greater-than-or-equal-to 85 mass % COD. The results are discussed in relation to previously reported data on the precipitation of calcium oxalate in the presence of dodecyl ammonium chloride.

New ethoxylated monofatty acid esters are obtained by esterification of 10-undecenoic acid chloride with several well defined polyethylene glycol mono-Me ethers. The monomeric surfactants show interesting surface properties, and they are characterized and compared to other known ethoxylated alcs. (Brijs) and acids (Mirjs). The crit. micelle concn. and area per mol. at the air-water interface are much higher than the similar com. Brijs, due to the special structure of the new surfactant allowing preferred orientation at the interface. [on SciFinder(R)]

10-undecenoic acid chloride was esterified with several well-defined polyethyleneglycolmonomethylethers to obtain new ethoxylated monofatty acid esters. The new surfactants will, at a later stage, be grafted into a silicone backbone to obtain polymeric surfactants. The monomeric surfactants have shown interesting surface properties, and here we report their characterization compared to other known ethoxylated alcohols (Brijs) and acids (Mirjs). It was observed that the CMC (critical micelle concentration), and area per molecule (a), at the air-water interface were much higher than the similar commercial Brijs, due to the special structure of the new surfactant allowing preferred orientation at the interface.

Dielec. investigation of myoglobin aq. soln. over a wide temp. range -80°C - +30°C was accomplished with the help of Time Domain Dielec. Spectroscopy. Three relaxation processes ($\beta$, $δ$1,$δ$2, with characteristic times ≈10-8 s, ≈10-9S and ≈10-10s resp.) were obsd. in the overlapped time window 10-5-10-10 s. The nature of this processes are discussed in this article. [on SciFinder(R)]

Several food proteins, together with some naturally occurring water-soluble gums (viscosity builders) and lecithin, are evaluated as clouding agents for formulated orange drinks. The use of these three types of natural products represents a significant advantage over the present formulations in which synthetic emulsifiers and weighting agents are used. The effects of concentration of each of the above ingredients, pH, temperature and mode of preparation are explored and related to cloud stability, droplet size distribution and the opacity of the emulsion both in concentrated and diluted formulations. A mechanism for protein adsorption onto the droplets is suggested.

Solvent extn. and sepn. of polar components from kerosine was based on the formation of an emulsion liq. membrane; such extns. were successful if a facilitating agent (e.g., N-methylpyrrolidone, I) was used in conjunction with a high HLB surfactant (e.g., Tween 20). Phase sepn. of an oil-in-water emulsion of kerosine and I dispersed in n-hexane was achieved in a mixer-settler (at 300-350 rpm) for 10 min.; mass transfer was estd. quant. Surfactants with low HLB inhibited sepn. of polar components but participated in the sepn. of apolar components. The emulsion system behaved like a regular liq.-liq. extn. process with increasing addns. of I in the presence of Tween 20; however, a lower yield of non-polar components was obsd. with increasing polarity of the permeate stream. [on SciFinder(R)]

Carob or guar gum was used as the only emulsifier in the prepn. of nonviscous oil-in-water food model emulsions, and the structure and properties of the emulsions were studied. Microscopy under polarized light showed liq. crystals of the gums arranged in Maltese cross shapes around the oil droplets. The gums adsorbed on oil droplets, formed layers of lamellar liq. crystals, and enhanced emulsion stability to coalescence and flocculation. [on SciFinder(R)]

The solubilization of hydrocortisone (HC) in lamellar liq. crystals (LC) contg. monoglyceride laurate (MGL) and water was studied. The max. capacity of the 70:30 (wt./wt.) MGL/water system to solubilize HC is larger than any other reported solubilization system (such as microemulsions and micelles), and exceeded 1.0 wt.%. The systems were tested by polarized light microscopy, small angle x-ray diffraction, DSC, and deuterium NMR. The addn. of HC caused no change in the interplanar spacing of the system, and had no effect on the gel-to-LC transition temp. However, the solubilization enlarged the quadrupole splitting of the water deuteron. These results suggest that the HC mols. are positioned in the vicinity of, or within, the polar head groups of the monoglyceride. [on SciFinder(R)]

Orange oil cloudy emulsions based on naturally occurring oil-soluble gum elemi and naturally occurring water-soluble gum arabic have been prepared and evaluated. Cloud and emulsion stability, as well as the opacity of each emulsion, were recorded and compared. It was demonstrated that the emulsion stability is determined by the gum elemi/orange oil ratio, the orange oil content, and the gum arabic/orange oil ratio. The opacity is a function of the orange oil content and to a lesser extent also depends on the gum elemi/orange oil ratio. Since the gum elemi/orange oil ratio is a critical parameter affecting both opacity and stability it should be carefully chosen and controlled. Gum arabic is not the sole emulsifier, as gum elemi also adsorbs on the oil droplets and plays a role in emulsion stability.

A review, with 42 refs., on (1) adsorption at fluid-fluid interfaces, (2) surface activity response to factors, (3) adsorption at solid-liq. interfaces, (4) proteins at interfaces of biol. interest, and other topics. Proteins at surfaces in pharmaceutical and food industries as well as in natural processes are discussed. [on SciFinder(R)]

The role of emulsifiers in polymorphic transformations of fats and fatty acids is treated in this paper. Their effect as crystal modifiers in soln.-mediated transformations (in fatty acids) is compared to that of a dynamic controller of polymorphic transformations in triglycerides. The importance of chem. structure both in the hydrophilic and in the hydrophobic moieties of the emulsifier for an inhibitory effect on phase transitions has been emphasized. The emulsifier soly. and crystn. behavior in different solvents are probably the main factors affecting its ability to interfere with the kinetics of soln.-mediated transformations. On the other hand, certain requirements for a specific chem. structure of the emulsifier which provides good structure compatibility must be met to affect the kinetics and mechanism of solid-solid or melt-mediated transformations. A mechanism of emulsifier incorporation in the fat and its effect in delaying the polymorphic transformation of tristearin is proposed. It has been concluded that the presence of the emulsifier does not dictate the formation of any preferred polymorph but rather controls the mobility of the mols. and their facility to undergo polymorphic transformations. The relationship between polymorphism in fats and presence of additives plays a major role in the food industry, because of the serious quality implications involved in phase transitions. [on SciFinder(R)]

In the present work, surface tensions of LBG (locust bean) and guar gum have been studied. It has been demonstrated that galactomannans, although highly hydrophilic in nature, can adsorb at interfaces, reducing surface tension to levels whereby they can be categorized as surfactants. Surface tensions of LBG solns. with ethoxylated sorbitan trioleate indicate the formation of a new species (complexes) with improved surface properties. The viscosities of aq. solns. of guar gum, LBG and their mixts. with ethoxylated mono- and trioleates (Tween 80 and 85) were measured at different shear rates. At high emulsifier concns. (5.0 gr/dL) a significant increase in viscosity is shown with Tween 85 in comparison to a sharp decrease with Tween 80. Both LBG and guar gum exhibited similar performance. The results are discussed in relation to the mol. structure of the galactomannan-emulsifier complex and the hydrophobicity of the constituents. [on SciFinder(R)]

The parameters affecting simple coacervation and the ability to encapsulate oleic acid using this technique were investigated. Coacervation was achieved using different types of gelatin (bloom no., charge) and various electrolytes. The electrolytes used for the coacervation can be divided into 3 groups: (1) inert salts; (2) phase sepn. inducers, (a) pptn. inducing agents (PIA), and (b) coacervation inducing agents (CIA); and (3) coacervation inhibiting agents. The encapsulation of oleic acid was evaluated with two types of gelatin and various emulsifiers (anionic, cationic, and nonionic). For pos. charged gelatin, the encapsulation is incomplete in presence of cationic emulsifiers. For neg. charged gelatin no general trend was obsd. The stirring rate for each step of the prepn. of the microcapsules was evaluated. High stirring is essential only in the cooling stage. The study was carried out in view of encapsulation of particular bacteria dispersed in the oil phase. [on SciFinder(R)]