Free Radical Polymerization

A. Type of polymerization.

 6. 1 Introduction

Free-radical polymerization
Ionic polymerization
Complex coordination

B. Commercialized free-radical polymerization.

6.2 Free Radical Initiators.

 6.2.1 Peroxides and Hydroperoxides
A. Benzoly

d. Other peroxides.

Diacetyl peroxide      Di-t-butyl peroxide
  Diacetyl peroxide      Di-t-butyl

e. Promoters : Inducing initiation at lower temperature.

(6.9)

(6.10)

+

+

+

-

 6.2.1 Peroxides and

B. Hydroperoxide
a. Thermal decomposition hydroperoxide

 b. Cumyl hydroperoxide.

 6.2.1 Peroxides

A. α,α'-Azobis(isobutyronitrile) (AIBN).
a. Decomposition of AIBN.

b. Half-life of isobutyronitrile

B. Side reaction : Cage effect.
a. Tetramethylsuccinonitrile

b. Ketenimine                

6.2.2

  A. One electron transfer reaction.
a. Making free radical by

B. Photolabile initiator.

A. Polymerization without initiators.
a. Dimer formation by Diels-Alder reation.

11

12

·

b.

6.2.6 Electrochemical Polymerization.

A. Polymerization of electrolysis.

  a. Cathode reaction

 6.3 Techniques of Free Radical Polymerization.

 6.3 Techniques of Free Radical Polymerization.

 6.3.1 Bulk
A. Reactor charges.

 6.3.2 Suspension.

A. Reactor charges.
 a. Monomer.
b. Initiator (soluble in

6.3.3 Solution.

A. Reactor charges.
a. Monomer (soluble in solvent).
b.

 6.3.4 Emulsion.

A. Reactor charges.
a. Monomer.
 b. Redox initiator
 c.

 6.3.4 Emulsion.

TABLE 6.3. Typical Emulsion Polymerization Recipesa

Ingredients, Conditions
Ingredients (parts by

6.4 Kinetic and Mechanism of polymerization.

A. Mechanism of free-radical polymerization.

b. Propagation.

(6.26)

 1) Head-to-tail orientation : predominant reaction.
      Steric and electronic

 c. Termination.
1) Combination.

(6.27)

Polystyrene radical.

(6.29)

6.4 Kinetic and Mechanism of

 2) Disproportionation.

Poly(methyl methacrylate) radical.

① Repulsion of ester group.

B. Kinetic of free radical polymerization.
a. Assumption.
1) The

 c. Termination rate ( Rt )
d. Propagation rate ( Rp

e. Average kinetic chain length ( )

ν

B. Kinetic of free

 f. Gel effect : Trommsdorff effect, Norris-smith effect.
1) Difficult termination

   by hydrogen abstracting.
   Lowering average kinetic chain length.
a. Growing radicals

 c. Moving to initiators or monomers.

 d. Moving to solvent.

(6.34)

(6.35)

(6.36)

(6.37)

C.

e. Moving to chain transfer agent.

  
  Ct : Chain

 
a. Copper(I) bypyridyl(bpy) complex: 

 b. TEMPO (18) : 2,2,6,6-tetramethylpiperidinyl-1-oxy.

(6.42)

(6.43)

(6.44)

(6.45)

D. Leaving

 c. Synthesis of block copolymers like anionic polymerization.
 d. Monodisperse polymerization

6.5 Stereochemistry of polymerization.
A. General consideration.
a. Stereoregular polymerization :

B. Factors influencing stereochemistry in free-radical polymerization.
 a. Interaction between the

 c. Terminal carbon : sp2( planar )
    Penultimate repeating unit :

  6.6.1 Isolated Dienes
A. Crosslinked or cyclopolymerization.

6.6 Polymerization of

A. Structure of conjugated Diene monoer.

Isoprene

B. a. 1,2-Addition :

C. 1,4-Addition : Delocalized double bond
a.

D. 3,4-Addition

E. Polymerization

TABLE 6.6 Structure of Free Radical-Initiated Diene Polymersa

polymerization
Temperature (oC)
-20
20
100
233
-20
-5

F. s-cis and s-trans

6.6.2 Conjugated Dienes.

6.7 Monomer Reactivity

B. Factors of monomer reactivity in free radical polymerization.
a. The

C. The inverse relationship between monomer stability and
   polymerization rate.
 a.

D. Ceiling temperature (Tc)
a.

 b. Definition of ceiling temperature.

A. Mechanism of copolymerization.

6.8 Copolymerization.

 a. 
b. 
c. let, (reactivity ratio)
steady state assumption.
d. solving

a. r1 = r2 = ∞ : Homopolymer.
b.

D. Alfrey-price Q-e scheme.

E. Charge transfer complex polymerization(alternating copolymer).
a. Styrene and maleic anhydride(D-A