Effect of DPG On Silinization
Effect of DPG On Silinization
Effect of DPG On Silinization
1,3-diphenylguanidine (DPG)
2
1. Introduction
Crosslinking reaction
Sy
Polymer Sz
Silanization Silica
1. Silanization kinetics
2. Crosslinking reaction between model olefins
3. Change of sulfur distribution in TESPT
4. TESPT-model olefin reaction
5. DPG-TESPT reaction
4
2. Experimental
Materials
n-decane 2,3-dimethyl-2-butene
(TME)
Intensity
Internal diameter 4.6 mm S3
Mobile phase Acetonitrile : water = 97 : 3 S2 S5
Flow rate 0.3 ml/min S6 S7
Temperature 23 C
Detector UV (DAD)
Retention time
Wavelength 254 nm (200 to 700 nm)
Injection volume 0.5 ml Chromatogram of TESPT (Mixture 1 or 2)
x105
Intensity [mAU]
Flow rate 20 ml/min 1.5 266.9
294.9
Nebliser gas pressure 25 psi 1.0
Dry gas flow 3 L/min
0.5 238.9
Dry gas Temp. 320 C
Vaporise Temp. 425 C 0
C ( t 0 ) − C ( t1 )
S6 S7
x=
C( t0 ) Summed peak = amount of un-reacted TESPT
ln( 1 − x t1 ) − ln( 1 − x t0 )
k1 = [min −1 ]
t1 − t 0
x is conversion of TESPT, C(t0) and C(t1) are the amounts of un-reacted TESPT
at time t0 and t1, respectively, k1 is the rate constant of silanization.
Arrhenius equation Ea
ln k1
Ea
ln k1 = ln( k 0 ) −
RT
Ea is the activation energy, R is the gas constant, 1/T
T is the absolute temperature.
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3.1 Influence of DPG on Silanization Kinetics
Conversion of TESPT
OC2H5 OC2H5
OH O Si (CH2)3
H5C2O Si (CH2)3 S2
+ S2
OH OC2H5
OC2H5
2 OH
Silica TESPT
0.0 0.0 0.0
without DPG without DPG without DPG
-1.0 -1.0 -1.0
ln(1-x)
ln(1-x)
ln(1-x)
-2.0 -2.0 -2.0
with DPG with DPG with DPG
-3.0 -3.0 -3.0 with
-4.0 (a) 120 C -4.0 (b) 140 C -4.0 (c) 160 C
-5.0 -5.0 -5.0
0 2 4 6 8 10 0 2 4 6 8 10 0 2 4 6 8 10
Time (min) Time (min) Time (min)
Mixture 1 Mixture 2
without DPG with DPG
6.0 ** TESPT
S3* S4* S5**
4.0 S2**
2.0 S2* S5* S6*S6** S7**
0
18 20 22 24 26 28 Time [min]
11
3.2 Influence of DPG on crosslinking reaction
between model olefins
300000
250000
with DPG
150000
0.6 0.6
S3
0.4 S3 0.4
0.2 0.2
0.0 0.0
0 10 20 30 40 0 10 20 30 40
Reaction time (min) Reaction time (min)
( ) : S2 ; ( ) : S3 ; ( ) : S4 ; ( ) : S5 ; ( ) : S6 ; ( ) : S7
5 34
3
4 2
( x 104)
55
Ion intensity x 104 ( mAU)
32 2
44 1
55 2 00 (d)
33 1 0 12 14 16 18 TME+TESPT+DPG (Mixture 4)
44 1 0 12 14 16 18
22
33 00 (c)
(b) TME+TESPT (Mixture 3)
1 1 00 12
12 14
14 16
16 18
18 Tim e [min]
22
0 (b) TME+DPG
11 00 12
12 14
14 16
16 18
18
00
0 12 14 16 18
(a) TME Reaction Temperature:140 ºC
0 12 14 16 18
Retention time (min)
Time: 30 minutes
14
3.4 Influence of DPG on reaction between
TESPT and model olefins
Fragmentation of 323 m/z using the MS
x105
2.0
[M + H+] 323.0
Intensity [mAU]
1.5
266.9
294.9
1.0
0.5
238.9
0
Masses of 295 m/z, 267 m/z and 239 m/z coming from
the TESPT-TME complex are obtained.
This decrease with each time 28 m/z can be related to progressive
hydrolysis of the ethoxy groups of the TESPT moiety.
15
3.4 Influence of DPG on reaction between
TESPT and model olefins
Possible structures of TESPT-Model Olefin Complex
H5C2O
Si
OC2H5 H5C2O Si OH H5C2O Si OH HO Si OH
OC2H5 OC2H5 OH OH
16
3.4 Influence of DPG on reaction between
TESPT and model olefins
Amount of TESPT-Model Olefin Complex
12000000
10000000
Peak area [mAU]
with DPG
8000000
6000000
4000000
without DPG
2000000
0
0 10 20 30 40
Reaction time (min)
5
4
x 105 [mAU]
Reaction Temperature:140 ºC
4 3 Time: 30 minutes
3 2
2 1
Intensity
18
16
12
10
8
6
4
Mw=530 g/mol
2
0
0 10 20 30 40
Reaction time (min)
The total peak area of the DPG-TESPT complex slowly increases at the
beginning of the reaction and then increases very fast.
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4. Conclusions
Due to the presence of DPG in reaction mixture…
22