silicone elastomers with covalently incorporated aromatic ... · 1 electronic supplementary...

1

Electronic Supplementary information

Silicone elastomers with covalently incorporated aromatic voltage

stabilizers

Aliff Hisyam A Razaka,b and Anne Ladegaard Skova

a Danish Polymer Center, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Building

227, 2800 Kgs. Lyngby, Denmark.

b Faculty of Engineering Technology, University of Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor, Malaysia.

1) Number of PDMS-PPMS repeating units and stoichiometric ratio of cross-linked PDMS-

PPMS copolymers

The targeted number of PDMS-PPMS repeating units in the copolymer (X) was calculated such

that the targeted Mn,T results in a telechelic hydride terminated PDMS-PPMS copolymer as

shown below:

� =��,� − ��,��

��,�� + ��,��

Equation 1

where ��,�� and ��,�� are the molecular weight of PDMS and PPMS, respectively.

The stoichiometric ratio for preparing telechelic hydride-functional PDMS-PPMS

copolymers (r1) was calculated as:

�� =[ℎ��]

[��]=

(� + 1)��

��

=� + 1

�

Equation 2

where �� and �� are the functionality of PDMS (�� = 2) and PPMS (�� = 2),

respectively.

2) Stoichiometric ratio of crosslinking

The stoichiometric ratio for the cross-linking (r2) was 1.5 and was calculated below:

�� =[��]

[ℎ��]=

� !["#]$

� �["%]$

=� !

� �

∙' ! � !⁄

' � � �⁄

Equation 3

Electronic Supplementary Material (ESI) for RSC Advances.This journal is © The Royal Society of Chemistry 2016

2

where � ! and � � are average numbers of functional group on the crosslinker (15-functional)

and the PDMS-PPMS copolymer (2-functional), respectively, while […]0, mx, and Mx are the

initial concentration, the mass and the molecular weight, respectively, (x = CL, CP).

3) Calculation of molar concentration of phenyl groups in PDMS-PPMS elastomers from 1H-NMR

Figure S1 The illustration of NMR spectrum with peaks of phenyl and methyl of PDMS-PPMS

elastomer.

a) Relative number of moles of phenylmethylsiloxane (X1):

Note: The proton signal at δ = 7.2 – 7.6 ppm representing the phenyl (C6H5) protons

(5H’s).

�� =)�

*�

Equation 4

where A1 and H1 are the area of integration and the number of protons for phenyl

group, respectively.

b) Relative number of moles of dimethylsiloxane (X2):

Note: The proton signal at δ = 0.02 – 0.4 ppm representing the dimethyl [(CH3)2]

protons (6H’s).

�� )� �� %�+�

*��

)� � 12�� 3' . ��

*�

Equation 5

where A2 and H2 are the area of integration and the number of protons for methyl,

respectively, while �� and ��%�+� are methyl groups for telechelic hydride end-

groups and phenylmethylsiloxane unit (m), respectively.

c) Actual mole percentage of phenyl groups of PDMS-PPMS elastomer (� /0/ in mol):

A1 = Area of Ph-H

A2 = Area of Si-CH3

ẟ = 7.2 – 7.6 ppm ẟ = 0.02 – 0.4 ppm

5 H’s 6 H’s

3

� /0/ =��

�� + ��

Equation 6

d) True molar concentration of phenyl groups of PDMS-PPMS elastomer (" /0/ in

mol/g):

" /0/ =� /0/

'�� + '��

Equation 7

where '�� and '�� are masses of PPMS and PDMS, respectively.

4) Calculation of engineering stress and strain

The engineering stress (12) was calculated from the force (F) and the cross-sectional area of

the strip (A):

12 =�

)=

�

3 × 5=

6 ∙ �

3 ∙ 5

Equation 8

where A = film thickness (3) ∙ constant width (5 = 6 mm) and F = torque (6) ∙ drum diameter

(d = 10.3 mm).

The engineering strain (72) was calculated as a ratio of a stretched strain (L – L0) to an

initial strain (L0) as:

72 =# − #$

#$

Equation 9

where a final strain after stretching (L) was determined from Hencky strain (70) as follows:

70 = ��#

#$

Equation 10

# = #$�89 = #$�(:9);< Equation 11

where 70 is a product of Hencky rate (rH = 1×10-3 rotation/s) and step time (ts).

By putting equation (11) in (9), the final expression of engineering strain (72) was

obtained as below:

72 = �89 − 1 Equation 12

Young’s moduli were determined from slopes in the linear regime of stress-strain plots

at 5 % strain.

4

5) NMR spectra of PDMS-PPMS copolymers

The NMR spectra for PDMS-PPMS copolymers with different true molar concentrations of

phenyl groups (" /0/ ) are shown in Figures S2– S9.

a) PDMS-PPMS copolymer (377DMS_2PMS, " /0/ = 5.0 × 10-4 mol g-1)

1H-NMR (CDCl3, 300 MHz): = -0.02 - = 0.6 (m, 6 H’s, -SiO(CH3)2-), = 4.70 (m, 1 H, -SiH-), = 7.10

- = 7.60 (m, 5 H’s, -SiC6H5-).

Figure S2 The NMR for 377DMS_2PMS.

b) PDMS-PPMS copolymer (231DMS_2PMS, " /0/ = 6.9 × 10-4 mol g-1)


- = 7.60 (m, 5 H’s, -SiC6H5-).


ppm (t1)0.01.02.03.04.05.06.07.0

7.5

747

.553

7.2

60

4.7

654

.756

4.7

46

1.0

0

66.

13

PDMS-PPMS copolymer (V31 and H03)

Si-H (4.7 ppm)Si-Phenyl-H (~7.1 - 7.6 ppm)

Si-CH3 (~0 - 0.4 ppm)

Mn_SEC = 32098 g/mol

m

X

n

S iS i

O

C H 3

S i

C H 3

O

C H 3CH 3C H 3

CH 3

C H 3

C H 3

S i

O S i

C H 3

O

C H 3

S i

C H 3

CH 3

O S iS i O

CH 3

CH 3

H S i

CH 3

CH 3

C H 3 m

ppm (t1)0.01.02.03.04.05.06.07.0

7.548

7.343

7.318

7.260

0.095

0.072

0.038

0.024

0.015

1.0

0

51.

54

PDMS-PPMS copolymer (V25 & H03)Mn_SEC = 36032 g/mol

Si- Phenyl-H (7.1 - 7.6 ppm)

Si-H (4.7 ppm)

Si-CH3 (~0 - 0.4 ppm)

m

X

n

S iS i

O

C H 3

S i

C H 3

O

C H 3CH 3C H 3

CH 3

C H 3

C H 3

S i

O S i

C H 3

O

C H 3

S i

C H 3

CH 3

O S iS i O

CH 3

CH 3

H S i

CH 3

CH 3

C H 3 m

5

c) PDMS-PPMS copolymer (126DMS_2PMS, " /0/ = 7.8 × 10-4 mol g-1)


- = 7.60 (m, 5 H’s, -SiC6H5-).


d) PDMS-PPMS copolymer (80DMS_2PMS, " /0/ = 8.4 × 10-4 mol g-1)


- = 7.60 (m, 5 H’s, -SiC6H5-).


ppm (t1)0.01.02.03.04.05.06.07.0

7.3

44

7.3

19

7.2

60

0.1

40

0.0

74

0.0

38

0.0

35

0.0

26

0.0

16

0.0

06

0.0

03

-0.1

25

1.0

0

44

.69

PDMS-PPMS copolymer (V22 H03)Mn_SEC = 73889 g/mol

Si-Phenyl-H (7.1 - 7.6 ppm) Si-H (4.7 ppm)

Si-CH3 (~0 - 0.4 ppm)

m

X

n

S iS i

O

C H 3

S i

C H 3

O

C H 3CH 3C H 3

CH 3

C H 3

C H 3

S i

O S i

C H 3

O

C H 3

S i

C H 3

CH 3

O S iS i O

CH 3

CH 3

H S i

CH 3

CH 3

C H 3 m

ppm (t1)0.01.02.03.04.05.06.07.0

7.536

7.331

7.305

7.247

0.060

1.00

32.2

9

PDMS-PPMS copolymer (V21 H03) Mn_SEC = 47274 g/mol

Si-Phenyl-H (7.1 - 7.6 ppm) Si-H (4.7 ppm)

Si-CH3 (~0 - 0.40 ppm)

m

X

n

SiSi

O

CH3

Si

CH3

O

CH3CH3CH3

CH3

CH3

CH3

Si

O Si

CH3

O

CH3

Si

CH3

CH3

O SiSi O

CH3

CH3

H Si

CH3

CH3

CH3 m

6

e) PDMS-PPMS copolymer (377DMS_6PMS, " /0/ = 8.7 × 10-4 mol g-1)


– = 7.60 (m, 5 H’s, -SiC6H5-).


f) PDMS-PPMS copolymer (231DMS_6PMS, " /0/ = 9.8 × 10-4 mol g-1)


- = 7.60 (m, 5 H’s, -SiC6H5-).


ppm (t1)0.01.02.03.04.05.06.07.0

7.4

87

7.4

73

7.4

61

7.2

60

4.7

28

4.7

21

4.7

12

4.7

05

0.0

76

1.0

0

30.

32

PDMS-PPMS copolymer (V31 and H11)Mn_SEC = 42041 g/mol

Si-Phenyl-H (7.0 - 7.6 ppm)

Si-H (4.7 ppm)

Si-CH3 (~ 0 - 0.4 ppm)

m

X

n

S iS i

O

C H 3

S i

C H 3

O

C H 3CH 3C H 3

CH 3

C H 3

C H 3

S i

O S i

C H 3

O

C H 3

S i

C H 3

CH 3

O S iS i O

CH 3

CH 3

H S i

CH 3

CH 3

C H 3 m

ppm (t1)0.01.02.03.04.05.06.07.0

7.4

85

7.4

59

7.2

60

7.1

66

4.7

18

4.7

14

4.7

09

4.7

03

4.7

00

0.0

98

0.0

75

0.0

63

1.0

0

26.9

9

PDMS-PPMS copolymer (V25 H11) Mn _SEC = 37321 g/mol


Si-H (4.7 ppm)

Si-CH3 (~0 - 0.4 ppm)

m

X

n

S iS i

O

C H 3

Si

C H 3

O

C H 3CH 3C H 3

CH 3

C H 3

CH 3

Si

O Si

C H 3

O

C H 3

Si

C H 3

CH 3

O SiS i O

CH 3

CH 3

H S i

CH 3

CH 3

C H 3 m

7

g) PDMS-PPMS copolymer (126DMS_6PMS, " /0/ = 1.5 × 10-3 mol g-1)


- = 7.60 (m, 5 H’s, -SiC6H5-).


h) PDMS-PPMS copolymer (80DMS_6PMS, " /0/ = 2.0 × 10-3 mol g-1)


- = 7.60 (m, 5 H’s, -SiC6H5-).


ppm (t1)0.01.02.03.04.05.06.07.0

7.458

7.434

7.321

7.317

7.234

7.212

7.164

0.063

0.051

0.029

0.018

-0.00

8-0

.019

-0.02

5

1.0

0

18.

61

PDMS-PPMS copolymer (V22 H11)Mn_SEC = 51820 g/mol


Si-H (4.7 ppm)

Si-CH3 (~0 - 0.4 ppm)

m

X

n

S iS i

O

C H 3

S i

C H 3

O

C H 3CH 3C H 3

CH 3

C H 3

C H 3

S i

O S i

C H 3

O

C H 3

S i

C H 3

CH 3

O S iS i O

CH 3

CH 3

H S i

CH 3

CH 3

C H 3 m

ppm (t1)0.01.02.03.04.05.06.07.0

7.4627.459

7.435

7.233

4.7034.6944.6874.6834.680

4.6524.6484.6434.6404.6384.6344.6294.6234.6144.602

0.0640.0520.030

-0.007

1.0

0

13.

18

PDMS-PPMS copolymer (V21 H11) Mn_SEC = 31676 g/mol


Si-H (4.7 ppm)

Si-CH3 (~0 - 0.4 ppm)

m

X

n

SiSi

O

CH3

Si

CH3

O

CH3CH3CH3

CH3

CH3

CH 3

Si

O Si

CH3

O

CH3

Si

CH3

CH3

O SiSi O

CH3

CH3

H Si

CH3

CH3

CH3 m

8

6) Scanning electron microscopy (SEM) images for the cross-linked copolymers and the

reference

a b

c d

e f

9

Figure S10 SEM images of: a) DMS-H31 (C=0), b) 377DMS_2PMS (C=5.0), c) 231DMS_2PMS

(C=6.9), d) 126DMS_2PMS (C=7.8), e) 80DMS_2PMS (C=8.4), f) 377DMS_6PMS (C=8.7), g)

231DMS_6PMS (C=9.8), h) 126DMS_6PMS (C=15), and i) 80DMS_6PMS (C=20), C is in 10-4

g/mol.

g

i

h

10

7) Electrical breakdown strengths as function of Young’s moduli for the cross-linked

PDMS-PPMS copolymers and the reference elastomer

0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.5045

50

55

60

65

70

75E

lect

rical

bre

akdo

wn

stre

ngth

(V

µm

-1)

Young's modulus (MPa)

Figure S11 A plot of electrical breakdown strengths versus Young’s moduli.

11

8) Weibull parameters η and β as function of Young’s moduli for the cross-linked PDMS-

PPMS copolymers and the reference elastomer

The curves of Weibull parameters η and β versus determined Young’s moduli for the cross-

linked copolymers and the reference are shown in Figure S12. Figure S12 (a) shows an

optimum of β-parameter (60) occurring at Young’s modulus of 0.33 MPa. For η-parameter,

the optimum occurs at the highest Young’s modulus of 0.43 MPa (see Figure S12 (b)).

0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.5015

20

25

30

35

40

45

50

55

60

65 xDMS_2PMS xDMS_6PMS

Wei

bull

β−pa

ram

eter


0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50

52

54

56

58

60

62

64

66

68

70

72

74

76 xDMS_2PMS xDMS_6PMS

Wei

bull

η−pa

ram

eter


Figure S12 Weibull parameters versus Young’s moduli: a) β-parameter, b) η-parameter.

a

b

12

9) Theoretical molar concentration of phenyl group

The numbers of phenyl groups in PPMS with ��,�� of 400 and 1000 g mol-1, respectively,

are given by:

'∗ ��,�� 2�?�@

��

Equation 13

where �� and �?�@ are molecular weights of phenylmethylsiloxane unit (�� = 136 g

mol-1) and telechelic hydride groups, Si(CH3)2-H, (�?�@ = 56 g mol-1), respectively. Thus a

cross-linked PDMS-PPMS copolymer containing short- and long-chain PPMS are defined as

m* = 2 and 6, respectively.

The theoretical molar concentration of phenyl groups in cross-linked PDMS-PPMS

copolymers ";, /0/ in mol g-1 was determined as:

";, /0/ ='∗ ∙ ��

'�� + '��

='∗ ∙ ��

�� ∙ ��,�� + �� ∙ ��,��

Equation 14

where '�� and '�� are masses of PPMS and PDMS, respectively, while �� and

�� are molar amounts.

The molar amount of PPMS is expressed as �� = (� + 1)�� and Equation 14

can be simplified as follows:

";, /0/ ='∗ ∙ (� + 1)

(� + 1)��,�� + ��,��

Equation 15

The simplified theoretical molar concentrations of phenyl group in PDMS-PPMS can be

calculated below:

";, /0/ ='∗

��,�� + (� + 1)A��,��

Equation 16

Samples with different theoretical molar concentrations of phenyl groups in PDMS-

PPMS copolymer are listed in Table S1:

13

Table S1 Theoretical phenyl concentrations of cross-linked PDMS-PPMS copolymers.

PDMS-PPMS copolymer

(nDMS_mPMS)

Theoretical molar concentration of phenyl groups

";, /0/

[10-4 mol g-1]

377DMS_2PMS 1.3

231DMS_2PMS 1.6

126DMS_2PMS 2.3

80DMS_2PMS 3.5

377DMS_6PMS 3.7

231DMS_6PMS 5.6

126DMS_6PMS 7.3

80DMS_6PMS 11

14

10) UV/Vis spectra of the cross-linked copolymers and the reference elastomer

The absorption spectra of energy from UV/Vis light absorbed by different concentrations of

phenyl group are shown in Figure S13. The phenyl group of the cross-linked copolymers

absorbs UV/Vis light in the energy band of 4.5 – 5.5 eV as seen from the absorbance peaks.

3.5 4.0 4.5 5.0 5.5 6.00.0

0.5

1.0

1.5

2.0

2.5 DMS-H31 C=5.0, 377DMS_2PMS C=6.9, 231DMS_2PMS C=7.8, 126DMS_2PMS C=8.4, 80DMS_2PMS C=8.7, 377DMS_6PMS C=9.8, 231DMS_6PMS C=15, 126DMS_6PMS C=20, 80DMS_6PMS

Abs

orba

nce

(OD

)

Energy (eV)

Figure S13 Spectra of UV/Vis absorption of PDMS elastomer and cross-linked PDMS-PPMS

copolymers; C is in 10-4 mol g-1.

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