物理药剂学文稿演示

Invisible in electron microscope Pass through ultrafilter and semipermeable membrane undergo rapid diffusion
Oxygen molecules, ordinary ions, glucose
Colloidal dispersion
Colloidal silver sols, natural and synthetic polymers, cheese, butter, jelly, milk, etc.
Coarse dispersion
Greater than o.5 μm
Visible under microscope Do not passthough normal filter paper Do not dialyze though semipermeable menmbrane Do not diffusion
From 1 nm to o.5 μm
Not resolved by ordinary microscope (although may be detected under ultramicroscope) Visible in electron microscope Pass though filter paper Do not pass semipermeable membrane Diffusion very slowly
Type of micelle
•Cylindrical micelle •Bilayer •Bilayer vesicle •Inverted micelle •Microtubule
Classification and typical examples of association colloids
ultrafiltration
• Electro ultrafiltration
Association colloids
CMC
the critical micelle concentration (CMC) is defined as the concentration of surfactants above which micelles form and all additional surfactants added to the system go to micelles.
Brownian Motion—the random movement of colloidal partocles
The first satisfactory theoretical treatment of Brownian motion was made by Albert Einstein in 1905.
The Faraday-Tyndall Effect
• When a strong beam of light is passed through a colloidal sol, a visible cone, resulting from the scattering of light by the colloidal particles, is formed. This is the Faraday-tyndall effect.
Kinetic properties of colloids
1,Thermally induced: Brownian movement, diffusion, osmosis. 2,gravitationally induced: sedimentation 3,applied externally: viscosity
Lyophilic colloids
Systems containing colloidal particles that interact to an appreiable extent with the dispersion medium are referred to as lyophilic(solventloving)colloids. hydrophilic sols: gelatin, acacia, insulin, albumin Lipophilic colloids: rubber, polystyrene. A material that forms a lyophilic colloidal system in one liquid(e.g. water) may not do so in another liquid(e.g. benzene).
Lyophobic colloids
Lyophobic colloids is composed of materials that have little attraction. e.g. gold, silver, sulfur, arsenous sulfide, and silver iodide.
The methods to prepare lyophobic colloids
• Dispersion methods 1,grinding method 2,sonication dispersion method 3,arc discharge method
• Condensation methods 1,physical methods 2,chemical methods
—
Dimenthyldodecy
Ampholytic
lammonio-propane
CH3(CH2)11N+(CH3)2(CH2)3OSO2-
—
sulfonate
Properties of surface-active agents showing changes that occur sharply at the CMC
Grains of sand,most pharmaceutical emulsions and suspension, red blood cells
Types of Colloidal dispersion
Lyophilic colloids Lyophobic colloids Association colloids
Predict the CMC of the mixture
•
To determine the minimum amount of surfactant
Optical properties of colloids
scattering of light
Light scattering is a form of scattering in which light is the form of propagating energy which is scattered. Light scattering can be thought of as the deflection of a ray from a straight path, for example by irregularities in the propagation medium, particles, or in the interface between two media.
Diffusion
Deduced by Einstein and Strokes
• Where NA is Avogadro's number, R is the gas constant, η is the coefficient of viscosity of the surrounding medium, r is the radius of the spherical particle, T is the absolute temperature
物理药剂学文稿演示
Classification of dispersed system based on particle
size
பைடு நூலகம்
class
Particle size
Characteristics of system
example
Molecular dispersion
Less than 1 nm
+3HCl • 2H2S(w）+ SO2(g) → 2H2O +3S (sol） • Na2S2O3 +2HCl → 2NaCl +H2O +SO2 +S (sol) • 2HAuCl4+ 3HCHO +11KOH → 2Au(sol）
+3HCOOK + 8KCl + 8H2O
Sol purification
Example
Type
Compound
Amphiphile
Gegenions
Anionic
Sodium lauryl sulfate
CH3(CH2)11OSO3-
Na+
Cationic
Cetyl trimethyl-ammonium bromide
CH3(CH2)15N+(CH3)3
Br-
Nonionic Polyoxyethylene laury ether CH3(CH2)10CH2O(CH2OCH2)23H
grinding method
sonication dispersion method
arc discharge method
• Owing to the intense heat generated by the arc, some of the metal of the electrodes is dispersed as vapor, which condenses to form colloidal particles.
Ultramicroscope
Electron microscope
Electron microscope ,capable of yielding pictures of the actual particles, even those approaching molecular dimensions, is now widely used to observe the size, shape, and structure of colloidal particles.
Ultramicroscope
• An ultramicroscope is a microscope with a system of illumination that allows viewing of tiny particles. When the diameter of a particle is below or near the wavelength of visible light (around 500 nanometers), the particle cannot be seen in a light microscope with the usual method of illumination. The ultramicroscope system is based on light scattering, not light reflection.
Physical condensation methods
1,replacement of solvent
Physical condensation methods
2, Steam quench method
chemical condensation methods
• 2H3AsO3（w）+ 3H2S →As2S3（sol）+6H2O • FeCl3 （w）+3H2O （H）→ Fe(OH)3 （sol）
• 1,dialysis method
• 2,ultrafiltration
dialysis method
• Semipermeable membrane
dialysis method
• Electrodialysis
ultrafiltration
• Semipermeable membrane