Polymer particles

Applications

-cosmetics - beauty

-DDS

-building materials - paints

-toothpastes - grinder

-composites

Synthesis methods

-Emulsion polymerization

-Precipitation polymerization

-Suspension polymerization

Suspension polymerization

-Particle forming occurs while agitating.

-Initiator is added after particle forming

d is the average particle size, k includes parameters related to the reaction vessel design, D_v is the reaction vessel diameter, D_s is the diameter of the stirrer, R is the volume ratio of the monomer to the liquid matrix, N is the stirring speed, ν_m and ν_l are the viscosity of the monomer phase and liquid matrix respectively, ε is the interfacial tension of the two phases, and C_s is the concentration of stabilizer.

Precipitation polymerization

-Continuous phase -> separation while precipitation -> swelling of monomer and initiator -> particle growth

-Typically trying at low concentration of monomer

Emulsion polymerization

-Surfactants are used for encapsulation of monomer

-Polymerization occurs inside

-Three types of surfactants

Ionic surfactants (cationic, anionic)

non-ionic surfactants (block-copolymer)

-Two types of initiators (hydrophobic, hydrophilic)

thermo-,opto-

Monodisperse particles

Particle growth

-Nucleation (seed)

-Condensation

-Agglomeration

Which steps we should control for monodispersity?

t

t^(1/3)

2 particles: 2^(1/3)=1.26

3 particles: 3^(1/3)=1.44

4 particles: 4^(1/3)=1.59

…

Ordered particles-color

Knudsen effect – super insulation (~50nm)