1. No category

Sample Name: Poly(styrene-b-1,2-butadiene)
Sample #: P2848-SBd
1H-NMR
CH
p2848-SBd
1,2 and 3,4Isoprene
vinylic protons
5.0-5.4 ppm
Structure:
CH2
Spectrum of the block copolymer:
b
n
CH2
Styrene
6.3-7.2 ppm
CH
m
CH
CH2
Composition:
Mn × 103
S-b-Bd
63.5-b-33.0
Tg for PBd block: -17oC
PDI
SEC of the block copolymer:
1.09
P 2 8 4 8 -S B d
Tg for PS block: 105oC
Synthesis Procedure:
Poly(styrene-b-butadiene)
rich
in
1,2
addition
polybutadiene is prepared by living anionic polymerization
with sequence addition of styrene followed by butadiene
(Bd) in THF or a mixture of THF and cyclohexane.
16
20
22
24
26
28
V e (m l)
Characterization:
An aliquot of the anionic polystyrene block was
terminated before addition of butadiene and analyzed by
size exclusion chromatography (SEC) to obtain the
molecular weight and polydispersity index (PDI).
18
S iz e e x c lu s io n c h r o m a t o g r a p h y o f p o ly s t y r e n e - b - p o ly b u t a d ie n e
( 1 , 2 a d d it i o n )
P o ly s t y r e n e , M n = 6 3 5 0 0 , M
w
= 6 8 5 0 0 , P I= 1 .0 8
B lo c k C o p o ly m e r P S ( 6 3 5 0 0 )- b - P B d ( 3 3 0 0 0 ) , P I = 1 . 0 9
H
M o le c u l a r C o m p o s it i o n o f d i b lo c k f r o m
NMR
DSC thermogram for PS block:
-0.38
Note: The 1H-NMR of 1,2-polybutadiene is composed of
1 proton signal at 5.4 ppm and 2 proton signals at 5.0
ppm. Copolymer PDI is determined by SEC.
-0.40
Heat Flow (W/g)
The final block copolymer composition was calculated
from 1H-NMR spectroscopy by comparing the peak area
of the polybutadiene protons (double bond 4.9 - 5.6 ppm)
with the aromatic protons of polystyrene at 6.3-7.2 ppm.
100.87°C
-0.42
104.86°C(T)
-0.44
107.87°C
-0.46
Thermal analysis:
-0.48
Thermal analysis of the samples was carried out on a TA
Q100 differential scanning calorimeter at a heating rate of
10oC/min.The midpoint of the slope change of the heat
flow plot of the second heating scan was considered as
the glass transition temperature (Tg).
95
100
105
110
115
120
Universal V4.2E TA Instruments
Temperature (°C)
DSC thermogram for Bd block:
-0.22
-0.24
-20.66°C
Solubility:
-0.26
Heat Flow (W/g)
Poly(styrene-b-butadiene) is soluble in toluene,
cyclohexane, benzene,THF, dioxane and CHCl3 . This
polymer readily precipitates from methanol, ethanol,and
water.
90
Exo Up
-17.19°C(T)
-0.28
-13.70°C
-0.30
-0.32
-0.34
-40
Exo Up
-30
-20
-10
Temperature (°C)
0
10
20
Universal V4.2E TA Instruments