88.5 Surfactants, their properties and Applications (active learning)
§8.5 Surfactants, their properties and Applications （active learning）
88.5 Surfactants and their properties and Applications 8.5.1 Surfactants The surface tension declines steeply Definition: The substances that even at c<×10-3 mol dm3 drastically lower the surface tension of water even at low concentrations. 1)Structure of surfactants The Amphiphilicity is the basic characters of surfactants: They have both polar and nonpolar moieties Hydrophilic group, hydrophobic/lipophilic group
Definition: The substances that drastically lower the surface tension of water even at low concentrations. 8.5.1 Surfactants The Amphiphilicity is the basic characters of surfactants: They have both polar and nonpolar moieties: Hydrophilic group, hydrophobic/lipophilic group. The surface tension declines steeply even at c < 10-3 mol dm-3 . 1) Structure of surfactants c §8.5 Surfactants and their properties and Applications
88.5 Surfactants and their properties and Applications 8.5.1 Surfactants (1)Classification by structure/active moiety hydrophilic group CooH carboxyl anon I-OSO3H, sulphate IonIc cationic SO3 H, sulphonic acid NR4, ammonium amphoteric -CH2-CH2-O, poly-ethylene oxide etc. ester ether I hydrophobic group nonionIc I(CH2) (CF2) amide I(SiR2-O-) 4(CH2-CH2-CH2-0-)n nonionic-cationic nonionIc-anionIc branched linear or aromatic
8.5.1 Surfactants (1) Classification by structure/active moiety branched, linear, or aromatic §8.5 Surfactants and their properties and Applications
88.5 Surfactants and their properties and Applications 8.5.1 Surfactants (4)Classification on composition (2)Classification on functions Siloxane surfactants fluorosurfactants Emulsifier; deemulsifier, wetting agent, Organometallic surfactant: Zn soap, Mg soap anti-wetting agent, dispersant, vesicant, SO,H O F FFFF FFF (3)Classification on molecular weight (5) Classification on solubility M>10000, polymeric surfactant water-soluble surfactant oil-soluble surfactant OH ignIn
(2) Classification on functions Emulsifier; deemulsifier, wetting agent, anti-wetting agent, dispersant, vesicant, (3) Classification on molecular weight M > 10000, polymeric surfactant. (4) Classification on composition Siloxane surfactants, Fluorosurfactants Organometallic surfactant: Zn soap, Mg soap water-soluble surfactant oil-soluble surfactant (5) Classification on solubility 8.5.1 Surfactants §8.5 Surfactants and their properties and Applications
88.5 Surfactants and their properties and Applications 8.5.2 Critical micelle concentration and micelle When concentration(c) below ca. 10-3 mol-dm23 most ionic surfactants in aqueous solution display similar conductance as other strong electrolytes detergence Concentration-dependence of some physical properties of sodium dodecyl Surface tension sulfate between 1-2 x 10-3 mol-dm-3 Molar conductivity sharp breaks occur interface tension 0.2 0
8.5.2 Critical micelle concentration and micelle When concentration (c) below ca. 10-3 moldm-3 , most ionic surfactants in aqueous solution display similar conductance as other strong electrolytes. Concentration-dependence of some physical properties of sodium dodecyl sulfate: between 1~2 10-3 moldm-3 , sharp breaks occur. NaCl C12 C14 c 0 0.2 0.4 0.6 detergence Osmotic pressure Surface tension Molar conductivity interface tension §8.5 Surfactants and their properties and Applications