Surfactant Activity & Application

A value that indicates the balance between the hydrophilic (water-loving) and lipophilic (oil-loving) parts of a surfactant molecule.

The process of dissolving a substance (solute) into a solvent, often using surfactants to enhance solubility.

A type of emulsion where the oil droplets are dispersed in a continuous water phase.

The amount of HLB required by a particular oil phase to form a stable emulsion. It's specific to each type of oil.

Mixing different surfactants with varying HLB values to achieve a specific HLB value as needed for a particular formulation.

The minimum concentration of a surfactant at which micelles begin to form in solution.

Aggregates of surfactant molecules in solution, formed above the CMC, consisting of a hydrophobic core and hydrophilic exterior.

The relationship between surface tension (γ) and bulk concentration (Cb) of a surfactant solution, often displayed as a graph.

The process of surfactants accumulating at the interface between two immiscible phases, such as air-water or oil-water.

The process of small droplets coalescing into larger ones, often due to the concentration of surfactant molecules at the surface.

A type of emulsion where tiny droplets of water are dispersed throughout a continuous oil phase. Think mayonnaise.

A molecule that contains both hydrophilic (water-loving) and lipophilic (oil-loving) parts.

An emulsion where the droplets are evenly distributed, forming a smooth and stable product.

Surfactant molecules self-assemble into spherical structures called micelles when their concentration surpasses a critical threshold, known as the critical micelle concentration (CMC). This occurs due to the minimization of free energy within the system.

The tendency of water molecules to surround hydrophobic groups, like the tails of surfactant molecules, results in an unfavorable energy state, as water molecules become more ordered, leading to a decrease in entropy.

The formation of micelles is a dynamic process, constantly breaking and reforming, with an equilibrium established between monomers (individual surfactant molecules) and micelles.

Non-ionic surfactants tend to form micelles at significantly lower concentrations compared to ionic surfactants, due to the absence of repulsive forces between charged head groups.

Ionic micelles are typically spherical and contain a large number of counter ions (oppositely charged ions) bound to the micelle surface.

Non-ionic micelles are generally larger in size than ionic micelles and are often asymmetrically shaped, like ellipsoids. This is due to the entrapment of water molecules within the oxyethylene chains of non-ionic surfactants.

The CMC (critical micelle concentration) is the concentration at which micelle formation begins. The aggregation number is the number of surfactant molecules in each micelle. These parameters can be influenced by several factors including the structure of the hydrophobic and hydrophilic portions of the surfactant molecule.

Non-ionic surfactants generally have a lower CMC (critical micelle concentration) and a higher aggregation number (number of molecules per micelle) compared to ionic surfactants with similar hydrocarbon chains.

The number of surfactant molecules that come together to form a single micelle. It indicates the size and stability of micelles.

The effect of increasing the length of the polyoxyethylene chain in non-ionic surfactants. This results in greater hydrophilicity, leading to a higher CMC.

The influence of the counterion on micelle formation. A less hydrated counterion (larger mass) can interact with the micelle surface, reducing the repulsive forces between head groups, leading to smaller micelle size and a lower CMC.

The effect of adding electrolytes to ionic micelles. Electrolytes decrease repulsive forces between surfactant head groups, resulting in smaller micelle size and a lower CMC.

The temperature at which aqueous solutions of non-ionic surfactants become cloudy due to a decrease in solubility. This is a reversible phenomenon.

The temperature above which the solubility of ionic surfactants increases significantly. This is a critical factor for the use of ionic surfactants in various applications.

The process by which surfactants solubilize substances, including those that are not normally soluble in water, by incorporating them into the micelles. This allows for the formation of stable dispersions.

As you add more surfactant to a solution, the number of micelles increases. This happens because the surfactant molecules start forming these structures to minimize their contact with water.

The ability of a substance to conduct electricity. In the case of ionic micelles, their electrical conductivity is influenced by the movement of ions within the micelle.

The movement of ions within a solution is hindered by the viscosity of the solvent. Micelles can actually reduce the viscosity, because one micelle experiences less drag than 100 individual molecules.

The counter-ions surrounding a micelle exert attractive forces and hold water molecules, creating an 'atmosphere' around it. This creates a fluid flow that opposes the movement of the actual micelle, leading to a decrease in conductance.

Most counter-ions stick to the micelle (bound), reducing its overall charge. These bound counter-ions move in the opposite direction of the micelle, creating a retarding force and further decreasing conductance.

Higher concentrations of electrolytes (salts) in a solution can 'pull' some counter-ions away from the micelle. This can impact the balance of forces and ultimately affect both the size and stability of the micelles.