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P. Bahadur ¹, J. J. Saimbi ¹, N. V. Sastry ²

Affiliations
1 Department of Chemistry, South Gujarat University, Surat 395007, IN
2 Department of Chemistry, S.P. University, Vallabh Vidyanagar, 388120, IN

Abstract

The aggregation behaviour of several styrene-ethylene oxide block copolymers has been studied in pure and mixed selective solvents. The copolymers are characterized by photon correlation spectroscopy, viscosity and turbidity methods. Various factors that affect micelle formation, viz., molecular characteristics of copolymers, solvent nature, temperature and inorganic and organic additives, are examined and their influence is explained. Compact polymolecular micelles formed are dissociated or destabilized with an increase in temperature, and in the presence of a second solvent or salt or an alcohol.

Keywords

Homopolymers, Copolymers, Photon Correlation Spectroscopy, Micelle, Viscosity, Turbidity.

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P. Bahadur ¹, Simmi Tyagi ¹

Affiliations
1 Department of Chemistry, D.A.V. (P.G.) College, Muzaffarnagar (U.P.), IN

Abstract

Metal carboxylates-higher carboxylates of alkali (Soaps) and other metals (metallic soaps)-are used in many areas of daily life and industry. While the basic colloidal and other physicochemical properties of these derivatives have already been extensively studied, there has recently been a revival of interest in the various modes of bonding exhibited by metal carboxylates. Many metal carboxylates have been known from ancient times. The oldest organic derivatives of metals are the alkali metal carboxylates, commonly known as soaps. These soaps are soluble in water, with which they readily produce foam, commonly used for washing or cleansing purposes. Carboxylates of metal other than alkali metals (with the exception of lithium) are generally insoluble in water and are called Metallic soaps. The first use of such soaps in the form of lead linoleates appears to have been made quite early in paints for mummification. Metallic soaps are, therefore, simple carboxylates of alkaline earths or other polyvalent metals with the general formula, M(O₂CR)n, where 'M' is a metal in oxidation state 'n' and 'R' is an organic radical containing at least 6-7-carbon atoms. The term metallic soaps is restricted by some of the salts of fatty acids (i.e. those in which R is an aliphatic radical) although in the broad sense the term also includes salts of certain cyclic acids.

Keywords

Heavy Metal Soaps, Tensides, Surfactants, Metal Carboxylates.

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P. Bahadur ¹, Simmi Tyagi ¹

Affiliations
1 Department of Chemistry, D.A.V. (P.G.) College, Muzaffarnagar (U.P.), IN

Abstract

Operation and effects of surfactants can be understood as follows; Surfactants reduce the surface tension of water by adsorbing at the liquid-gas interface. They also reduce the interfacial tension between oil and water by adsorbing at the liquid-liquid interface. Many surfactants can also assemble in the bulk solution into aggregates. Some of these aggregates are known as micelles. The concentration at which surfactants begin to form micelles in known as the critical micelle concentration or cmc. When micelles form in water, their tails form a core that can encapsulate an oil droplet, and their (ionic/ polar) heads form an outer shell that maintains favourable contact with water. When surfactants assemble in oil, the aggregate is referred to as a reverse micelle. In a reverse micelle, the heads are in the core and the tails maintain favourable contact with oil. Surfactants are also often classified into four primary groups; anionic, cationic, non-ionic and zwt terionic (dual charge). Thermodynamics of the surfactant systems are of great importance, theoretically and practically. This is because surfactant systems represent systems between ordered and disordered states of matter. Surfactant solutions may contain an ordered phase (micelles) and a disordered phase (free surfactant molecules and / or ions in the solution). Ordinary washing up (dishwashing) detergent, for example, will promote water penetration in soil, but the effect would only last a few days (although many standard laundry detergent powders contains levels of chemicals such as sodium and boron, which can be damaging to plants, so these should not be applied to soils). Commercial soil wetting agents will continue to work for a considerable period, but they will eventually be degraded by soil micro-organisms. Some can however, interfere with the life-cycles of some aquatic organism, so care should be taken to prevent run- off of these products into streams, and excess product should not be washed down gutters. When a water droplet is in the air, surface tension, a force to reduce the surface area acts on the surface of the water, resulting in spherical water droplets. When water and oil are present in a container, they do not mix together even after stirring and separate in two layers (Fig. 1).

Keywords

Interfacial Chemistry, Interface, Food Emulsifiieres.

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