Early Transition Metal Catalyzed Living Radical and Ring Opening Polymerizations for Complex Copolymer Architectures Alexandru D. Asandei, University of Connecticut, Department of Chemistry, Storrs CT, 06269
The Cp2TiCl mediated radical ring opening of epoxides, SET reduction of aldehydes, halide activation and redox reaction with peroxides were demonstrated as novel initiating methodologies for the living radical polymerization (LRP) of styrene, living ring opening polymerization of lactones and for the synthesis of complex polymer architectures.
O
H B
R5
Cl
Styrene Ti(III) LRP
O
N
N
N N
N
N
Ti
n
Cl
Ti Cl
Cl
~Pn
+ Ti Cp2Cl
kp, M
Cl Ti
X
R
Cl
O
KDC
TiCp2Cl
H+ X
HO-Pn-H
16000
2
12000
1.75
X = H, Cl, tBu, MeO
Cp2Cl Ti O CH2 CH2 R O O R-X H R' R
PDI
X Ti
CH2 CH
Mn
R
Cp2Cl Ti O CH2 CH R
8000
1.5
4000
1.25
0
1 0
0.5
1
Conversion (%)
Cl
e-CL ROP
10
12
14 16 elution time, min
18
20
O O O
ClCp2Ti O
O CH2 C O CH2 CH Ti ClCp2 5 n R
St, Lact PGMA
O O
Styrene O
GMA O
O
O
O
O
O O
CH2 CH R
O
O
O
O
O
H2C
O
O
O
O Cl Ti
H2C
CH O
O
CH2
n-1
Cl
Ti
O
O
CH3
C H2C
C H2C C C O
C O
O
O
O
CH2
CH2
CH2
C
O
m-1
CH3
CH3 O
HC
CH3 C C O
OH HC CH2 C CH2
CH2 CH2 O
CH3
CH2 OH
C O
O
