Chemistry Reference
In-Depth Information
Matyjaszewski and Gao synthesized functional polymers by combining ATRP and the “click
reactions.” They also prepared telechelic polymers, star polymers and brush polymers [
282
]. Forma-
tion of telechelic polymers was illustrated as follows:
Br
Br
Br
N
3
Br
N
3
O
O
O
O
n
n
NaN
3
DMF
CuBr, toluene,80
o
C
CuBr
DMF
OH
N
N
N
N
N
N
HO
HO
OH
N
N
N
N
3
OH
n
n
CuBr,DMF
Also, a synthesis of an iniferter that consists of a trithiocarbonate moiety and two bromine chains
ends was reported [
282
]. This iniferter was used to conduct either independently or concurrently both
ATRP and reversible addition-fragmentation chain transfer polymerizations. The iniferter was
illustrated as follows:
S
R
R
'
R
'
R
Br
S
S
Br
M
w
/
M
n
equal to 1.15 and 1.16 respectively. Polymerization of methyl methacrylate, however, yielded a
polymer with a broad
RAFT polymerizations with this iniferter of
N
-butyl acrylate and styrene yielded polymers with
M
n
ratio. On the other hand, polymerization in the presence of CuBr/TMPA by
ATRP exclusively through the bromine chain ends yielded a polymer with narrow
M
w
/
M
w
/
M
n
ratio [
282
].
3.14.5 Special Types of Controlled/“Living” Polymerizations
It was reported that it is possible to employ persistent phosphorus-based radicals in controlled/living
free-radical polymerization [
283
,
284
]. Also, in cases of low stability of the hyper coordinated
radicals, the ligand exchanges become facile and some organoaluminum, organoboron, and other
compounds have been used successfully as transfer agents in polymerization of styrene, acrylics, and
vinyl acetate [
283
,
284
].
Chung and coworkers [
286
] described a “living” radical initiator that is based on oxidation
adducts of alkyl-9-borabicyclononanes, such as hexyl-9-borabicyclononane. The “living” radical
polymerizations take place at room temperature. The initiators form in situ by reactions with oxygen:
O
2
RCH
2
B
B
RCH
2
O-O
R-CH
2
-O
O
B
+
