definition
emulsion
a system of 2 immiscible liquids in which one is dispersed as droplets
* dispersed phase = droplets
* continuous phase = base
Applications of Emulsion
Oral
* ___ to mask the taste of an oil
* O/W to enhance ___ of an oil (Vit A and D, fish oil)
- O/W
- adsorption
Applications of Emulsion
External
* ___: water-washable; vanishing cream
* ___: for cleansing skin; cold cream
- O/W
- W/O
Applications of Emulsion
Intravenous lipid emulsion (___)
* for parenteral ____
* 100 mL of 20% lipid emulsion provides ___ kcal, while 100 mL of 5% dextrose only provides ___ kcal.
* smallest capillaries are 5 mcm. It is critical that droplet size is less than ___ mcm to avoid embolisms
- O/W
- nutrition
- 200 kcal, 20 kcal
- 1 mcm
Interfacial phenomena
- In the bulk portion of each phase, molecules are attracted
to each other ___ in all directions. - At the boundary between phases, molecules are acted
upon ____ because they are in contact with other molecules exhibiting different forces of ___. - water: H bond, mineral oil: ___
- molecules situated at the interface experience different than the ones in the bulk phase
- equally
- unequally, attraction
- london dispersion forces
Interfacial phenomena
In liquid systems such ___ leads to ___ movement of molecules from the interface into the bulk phase. This leaves ___ molecules per unit area at the interface
- imbalance
- spontaneous
- fewer
Interfacial tension or surface tension
When you try to reverse the spontaneous movement of molecules at the interface (by ___ the area of contact between phase) the interface resists expansion and behaves as though it is under a ___ everywhere in a tangential direction.
- increasing
- tension
definition
interfacial tension
the force of tension per unit length of interface
* liquid-liquid interface
* example: oleic acid-water = 15.6 dynes/cm
definition
surface tension
- liquid-air interface
- example: water-air=72.8 dynes/cm, oleic acid-air=32.5 dynes/cm
Interfacial tension or surface tension
The stronger the intermolecular force in a bulk phase, the ___ the
interfacial tension.
higher
Interfacial tension or surface tension
the greater the tendency to interact, the ___ the interfacial tension
less
Interfacial tension or surface tension
the higher the temperature, the __ interfacial tension
lower
intermolecular forces are reduced at high temp
emulsifying agents (emulsifiers)
types of emulsifying agents
- surface active agents (surfactants)
- hydrophilic colloids (polymers)
- finely divided solid particles
T or F: emulsifying agents are added to stabilize the emulsion
True
What type of emulsifier is this?
surfactant
amphiphilic (interacts with both water and oil), think soap
What type of emulsifier is this?
hydrophilic colloid
What type of emulsifier is this?
fine particles
Surface active agents (Surfactants)
- molecules that contain both a ___ and ___ region
- orient at the liquid-liquid or liquid-air interface and ___ interfacial or surface tension
- hydrophilic and hydrophobic
- lower
Classification of surfactants
What type of surfactant is this?
anionic - alkyl sulfate
Classification of surfactants
What type of surfactant is this?
cationic - alkyltrimethylammonium bromide
Classification of surfactants
What type of surfactant is this?
zwitterionic - alkyl betaine
neutral net charge
Classification of surfactants
What type of surfactant is this?
non-ionic - alcohol ethoxylate
Hydrophile-lipophile balance (HLB)
- low HLBs indicate ___ lipid solubility
- ranges 0-20 for ____ surfactants
- calculated according to an empirical formula (picture)
- in practice, a mixture of emulsifying agents are used to get a desired HLB
- greater
- non-ionic
definition
hydrophile-lipophile balance (HLB)
A measure of the relative contributions of the hydrophilic and lipophilic regions of a surfactant.
