Talks about various types of polymerization and majorly about ATRP

2. Living Radical
polymerizations
Stable Free-Radical
Polymerization
(SFRP)
Atom transfer
Radical
Polymerization
(ATRP)
Reversible
Addition-
Fragmentation
Transfer (RAFT)

3. 1
Introduction
2
Comparision
3
Requirements
4
Block copolymers
Atom Transfer Radical Polymerization

4. • ATRP, SFRP, and RAFT differ in the method of radical
generation.
• Atom-transfer radical polymerization involves an organic
halide undergoing a reversible redox process catalyzed by
a transition metal compound such as Cuprous halide
Atom Transfer Radical Polymerization
Br CuBr(L)
RR. CuBr(L)

5. ATRP proceeds as described
L -ligand that complexes with the
cuprous salt and helps to solubilize it
in the organic reaction system
Ka -rate constant for activation
kd -rate constant for deactivation of the
halide initiator
ka
𝐾 =
𝑘 𝑎
𝑘 𝑑

6. • CuBr metal center undergoing an
Electron transfer with simultaneous halogen
atom abstraction and
Expansion of its coordination sphere.
• R is the reactive radical that initiates polymerization.
Activation of the initiator involves…
R.
-Activator
-Deactivator
R.
.Br CuBr(L)

7. ATRP vs conventional radical polymerization
Conventional
Radical
polymerizationATRP
• The effects of the following are same in ATRP and
conventional radical polymerization
Inhibitors and retarders
Solvents
Chain-transfer agents
Regioselectivity
Stereoselectivity

8. • The concentration of propagating radicals in ATRP is
obtained as
R. =
𝑲 𝑰 [𝑪𝒖
+
]
[𝑪𝒖 𝟐+]
ka
Rp =
𝒌 𝒑
𝑲[𝐌] 𝑰 [𝑪𝒖
+
]
[𝑪𝒖 𝟐+]
• Combination with the above expression for
propagation gives the polymerization rate as
I-Initiator (RBr)

9. • Fast and quantitative initiation (activation of RBr)
so that all propagating species begin growth at the same
time, which results in a narrow molecular weight distribution
• Rapid reversible deactivation of propagating radicals
Needed to maintain low radical concentrations and minimize normal
termination of living polymers. This further ensures a narrow molecular
weight distribution because all propagating chainsgrow at the same rate
and for the same length of time.
• The number-average degree of polymerization for a living
polymerization under these conditions is given by
Requirements for ATRP to be successful
x̅n =
𝐌 𝟎
−[𝐌]
𝐈 𝟎
=
𝒑 𝐌 𝟎
𝐈 𝟎
𝐌 𝟎 – Initial conc. Of Monomer
𝐈 𝟎 -- Initial conc. Of Initiator

10. Fig shows the decrease in monomer concentration to be first-order in monomer

11. Block Copolymers
Statistical (random) copolymers
Gradient copolymers
Block copolymers
Graft copolymers
A number of different types of copolymers
are possible with ATRP—
Other polymer architectures are also possible -
Hyperbranched polymers
Functionalized polymers
Brush polymers
Star polymers

12. All Blocks via ATRP
• Block copolymers are synthesized via ATRP by two methods:
One-pot sequential method and
Isolated macroinitiator method
• In the one-pot sequential method AB diblock copolymer is produced
by polymerizing monomer A. Monomer B is then added when most
of A has reacted
• In the isolated macroinitiator method, the halogen-terminated polyA
(RAnX) is isolated and then used as an initiator (the macroinitiator)
together with CuX to polymerize monomer B.

13. Requirements
• Both methods require that the polymerization of the first
monomer not be carried to completion, usually 90%
conversion is the maximum conversion (due to bimolecular termination).
• The one-pot sequential method has the disadvantage that
the propagation of the second monomer involves a
mixture of the second monomer plus unreacted first
monomer. The second block is actually a random
copolymer. The isolated macroinitiator method is the
method of choice to avoid this ‘‘contamination’’ of the
second block.

14. Tri- and higher block copolymers
• Copolymers such as ABA, ABC, ABCB, can be synthesized
by a continuation of the processes with the successive
additions of the appropriate monomers.
• A symmetric block copolymer such as ABA or CABAC can
be made efficiently by using a difunctional initiator, such
as, 2,6-dibromoheptanedioate.
• For the ABA block copolymer only two, instead of three,
monomer charges are needed:

15. Producing the desired block copolymer
• How does one add A first or B first to produce an AB block
copolymer?
• The answer depends on the reactivity of an AX chain end toward
monomer B compared to the reactivity of a BX chain end toward
monomer A:

16. Other Polymer Architectures
• A star polymer:
• contains polymer chains as arms emanating from a branch point.
Star polymers can be synthesized via ATRP by using an initiator
containing three or more halogens

17. Other Polymer Architectures
• A graft copolymer:
• Branched polymer containing a polymer chain derived from one
monomer to which are attached one or more polymer side
chains of another monomer.

18. Other Polymer Architectures
• Hyperbranched polymers
• These are monomers that contain both a polymerizable double
bond and an initiating function, such as p-(chloromethyl) styrene.

19. References

20. THANK
YOU