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Free ion diffusivity and charge concentration on cross-linked Polymeric Ionic Liquid films doped with sulfonated zwitterion salts and Lithium ions David Valverde,a Abel Garcia-Bernabé,b Andreu Andrio,a Eduardo García-Verdugo,a* Santiago V. Luis,a Vicente Compañ*b

1. General Information

All reagents were purchased from Sigma-Aldrich and used without further purification. 1H and 13C NMR experiments were carried out using a Varian INOVA 500 (1H, 500 MHz

and 13C, 125 MHz) spectrometer. The chemical shifts are given in delta (δ) values and the

coupling constants (J) in Hertzs (Hz).

Impedance measurements

Impedance measurements were carried out on samples at several temperatures lying in

the range 393 K (20ºC) to 453 K (180ºC) and frequency window 10-1 < f < 107 Hz. The

temperature was firstly and gradually raised and lowered from 20ºC to 180ºC in steps of

20ºC. To ensure the measurements reproducibility the values considered in this work were

obtained from the third cycle of temperature scan. The experiments were performed with

100 mV amplitude, using a Novocontrol broadband dielectric spectrometer (Hundsangen,

Germany) integrated by a SR 830 lock-in amplifier with an Alpha dielectric interface.

The amplitude of 100 mV was chosen in order to get a linear regime. The membranes

were placed between two gold electrodes of 20 mm of diameter coupled to the impedance

spectrometer acting as blocking electrodes in a liquid parallel plate cell coupled to the

spectrometer and deionized water was incorporated to ensure a fully hydrated state of the

samples below 100 °C and in equilibrium with its vapor above 100 °C. The membranes

thickness was measured afterwards using a digital micrometer, taking the average of ten

measurements at different parts of the surface. During the conductivity measurements,

the temperature was kept constant or changed stepwise in all the range of temperatures

controlled by a nitrogen jet (QUATRO from Novocontrol) with a temperature error of 0.1

ºC, during every single sweep in frequency.

Differential scanning calorimetry: Glass-transition temperatures and melting points

were measured by using a Mettler–Toledo differential scanning calorimeter (DSC),

model DSC822e. The instrument was calibrated for temperature and heat flow with zinc

and indium reference samples provided by Mettler-Toledo. The samples were placed in

a 40-µL hermetically sealed aluminum pan with a pinhole in the top. An empty aluminum

Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics.This journal is © the Owner Societies 2019

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pan was used as the reference. Samples were exposed to a flowing N2 atmosphere. Before

the DSC test, each sample was dried at 90–100 oC and 10-2-10-3 mbar for 4 h, and further

in situ dried in the differential scanning calorimeter by holding the sample at 130 oC for

120 min as the presence of volatiles, especially water, can affect the glass transition and

melting temperatures. Melting transition temperatures were determined by multiple

cycles (typically three) involving heating the sample from -50 to 250 oC, followed by

cooling from 250 to -50 oC, both at a rate of 5 oC min-1. The melting temperatures were

determined at the onset of the transition.

Spectroscopic studies: FTIR spectra were acquired with a MIRacle single-reflection

ATR diamond/ZnSe accessory in a JASCO FT/IR-6200 instrument. Raman spectra were

obtained in a NRS-3100 equipment (Jasco) with optic microscope and a CCD detector.

Samples were exposed to a flowing N2 atmosphere. Before the spectra were recorded,

each sample was dried at 90–100 oC and 10-2-10-3 mbar for 4 h to remove traces of residual

solvent and water.

Thermogravimetric analysis (TGA): the data were recorder in a TG-STDA Mettler Toledo model TGA/SDTA851e/LF/1600 using the following heating program: 1. Heating

from 25 oC to a 120 ºC at 10 ºC/min under N2 and holding the sample at this temperature

for 25 min. 2. Cooling from 120ºC to 25º, at 10 ºC/min. 3. Measuring the weight loss from

25ºC a 700ºC at 10 ºC/min under N2.

Viscosity: It was determined with a rotating viscometer (Brookfield R/S-CPS+

Rheometer, USA). Before data were recorded, each sample was dried at 90–100 oC and

10-2-10-3 mbar for 4 h to remove traces of residual solvent and water.

Preparation of ZIs:LiNTF2 mixtures (melting protocol): Mixtures of ZIs and LiNTF2 were prepared the ratios indicated in Table 1. For this purpose, LiNTF2 and ZIs-1 were

mixed together in a mortar till forming a homogeneous solid paste. The resulting mixture

was introduced into a glass vial and heated-up to 150 - 160 ºC to obtain a melted mixture.

Nitrogen was bubbled for 10 min to eliminate dissolved oxygen. The samples were then

heated in vacuum at 130-140 ºC under high vacuum to eliminate any residual water

present.

General procedure for film fabrication: The cross-linked films used in this study were

prepared by thermal copolymerisation of the monomeric mixture containing the ZIs-1-

LiNTf2 mixtures following the composition indicated in Table 2. A typical procedure for

the preparation of the samples is described as follows: AIBN was added to a solution

formed by the monomeric mixture and the ZIs-1-LiNTf2 mixture. Nitrogen was bubbled

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for 10 min to eliminate dissolved oxygen. A small part of this solution was pipetted into

the narrow space formed between two glass microscopy plates separated by means of two

thin lamellas at the ends. The system was introduced into an oven at 65 oC for 24 hours.

After polymerization, the two glasses were separated and the film removed and stored in

a desiccator. The measured film thickness was very homogeneous even in different points

of large samples and from sample to sample.

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Figure S1. DSC of the zwitterionic salt (3-(1-butyl-1H-imidazol-3-ium-3-yl)propane-1-sulfonate ZIs-1. Insert: DSC of LiNTf2. Conditions: 10 K/min under a nitrogen atmosphere.

5

Figure S2. a) Pictures for the different mixtures obtained by mixing ZIs-1 and LiNTf2 at different molar ratios (see Table 1 in the main text for composition). b) 1H-NMR (CD3SOCD3) of the some of these mixtures in comparison with pure ZIs-1.

0.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.59.09.5f1 (ppm)

1

2

3

4

5

6

M-1a M-1b M-1c M-1d M-1e M-1f

ZIs-1

M-1b

M-1a

M-1c

M-1d

M-1g

a)

b)

(ppm)

6

-40 0 40 80 120 160 200 240 280-8

-7

-6

-5

-4

-3

-2

-1

0

1

2

Ts(°C)

dV42.g (1:1)

C (J

/g K

)

dV42.a (1:2)

dV42.b (1:3)

dV42.c (1:5)

dV42.d (2:1)M1-a (1:2)

M1-c (1:5) M1-b (1:3) M1-d (2:1)

M1-g (1:1)

-50 0 50 100 150 200 250

-6

-3

0

C

(J/g

K)

Ts (°C)

LiNTf2 dV42 dV42.a dV42.b dV42.c dV42.d dV42.e dV42.f

M1-aM1-f

M1-c

M1-b

M1-d

M1-e

Figure S3. Top: DSC of the different r.t. liquid mixtures obtained by mixing ZIs-1 and LiNTf2 at different molar ratios (see Table 1 in the main text for composition). Bottom: DSC of all the mixtures obtained by mixing ZIs-1 and LiNTf2 at different molar ratios (see Table 1 in the main text for composition) after being heated to >200 oC. Curves correspond to the second cycle. Obtained at 10 K/min under a nitrogen atmosphere.

7

100 200 300 400 500 600 7000

20

40

60

80

100

Temperature (°C)

% M

olar

Wei

ght

ZILs-1 M-1a M-1b M-1c M-1d M-1g

Figure S4. TGA of the mixtures obtained by mixing ZIs-1 and LiNTf2 at different molar ratios (see Table 1 in the main text for composition).

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a)

b)

Figure S5. Selected region of the ATR-FT-IR of LiNTf2, ZIs-1 and M-1g (equimolecular mixture of LiNTf2 and ZIs-1).

820 800 780 760 740 720

Wavelength (nm)

Abs

(a.u

)

Wavenumber (cm-1)

780 cm-1

749 cm-1

747 cm-1

740 cm-1

790 cm-1

800 cm-1

755 cm-1

LiNTf2

ZIs-1

M-1a (1:1)

1250 1200 1150 1100 1050 1000 9500,0

0,2

0,4

0,6

Wavelength (nm)

Abs

(a.u

)

LiNTf2

ZIs-1

M-1g (1:1)

10611052

1032

Wavenumber (cm-1)

9

a)

0,3 0,4 0,5 0,6 0,7 0,8 0,9

1E-6

1E-5

1E-4

1E-3

0,01

Cond

uctiv

ity (S

/cm

)

XLiNTf2

20 (oC) 40 (oC) 100 (oC)

b) T=25

0,3 0,4 0,5 0,6 0,7 0,8 0,9

1x10-6

1x10-5

1x10-4

1x10-3

XLiNTf2

Cond

uctiv

ity (S

/cm

)

0

500

1000

1500

2000

2500

3000

Viscosity (Pa·s)

T= 100

0,3 0,4 0,5 0,6 0,7 0,8 0,9

1x10-4

1x10-3

1x10-2

XLiNTf2

Cond

uctiv

ity (S

/cm

)

0

1

2

3

4

5

6

7

Viscosity (Pa·s)

Figure S6. a) Effect of the mole fraction of LiNTf2 on the ionic conductivity at 20, 40 and 100 °C for the different molar mixtures ZIs-1:LiNTf2. b) Comparison of conductivity and viscosity at 25 and 100 °C for the different molar mixtures ZIs-1:LiNTf2.

10

770 760 750 740 730 720 710 7000

6000

12000

Raman Shift / cm-1

LiNTf2

Int.

(a.u

.)

dV42.A

dV42.B

dV42.C

dV42.D

LiNTf2M-1a (1:2)M-1b (1:3)M-1c (1:5)M-1d (2:1)

746 cm-1LINTf2

745 cm-1

744 cm-1

743 cm-1

742 cm-1

753 cm-1

Figure S7. Selected region of the Raman spectra of the different ZIs-1:LiNTf2 molar mixtures in comparison with LiNTf2.

11

1500 1450 1400 12504000

6000

8000

10000

Raman Shift / cm-1

Int.

LiNTf2 dV42 dV42.A dV42.B dV42.C

LiNTf2Zis-1M-1a (1:2)M-1b (1:3)M-1c (1:5)

1425 cm-1

1242 cm-1

1239 cm-1

1241 cm-1

1240 cm-11456 cm-1

1447 cm-1

1446 cm-1

1445 cm-1

1419 cm-1

1419 cm-1

1419 cm-1

Figure S8. Selected region of the Raman spectra of the different ZIs-1:LiNTf2 molar mixtures in comparison with LiNTf2 and ZIs-1.

12

-100 -50 0 50 100 150 200 250 300-4

-3

-2

-1

0

1

2

3

Temperature (oC)

dv44a

C (J

/gK)

dv44B dv44c dv44d dv44e

F-1a F-1b F-1c F-1d F-1e

F-1g’ F-1gF-1aF-1bF-1c

Figure S9. DSC for the films prepared (see Table 2 in the main text for composition). Cycle 2. Obtained at 10 K/min under a nitrogen atmosphere.

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0 100 200 300 400 500 600 7000

20

40

60

80

100

% w

eigh

t los

s

Temp (oC)

dV42 dV44.a dV44.b dV44.c dV44.d dV44.e

ZIs-1F-1a F-1b F-1c F-1d F-1e

ZIs-1F-1g’ F-1gF-1aF-1bF-1c

Figure S10. TGA of all films prepared in comparison with ZIs-1 (see Table 2 in the main text for composition).

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0,28 0,32 0,36 0,40 0,44 0,48 0,52

19

20

21

22

23

E a (K

J/m

ol)

XLiNTf2

F-1a (M-1g)

F-1b (M-1g)

F-1c (M-1a)F-1d (M-1b)

F-1e (M-1c)

F-1g’ (M-1g)

F-1g (M-1g)

F-1a (M-1a)F-1b (M-1b)

F-1c (M-1c)

Figure S11. Activation Energy vs composition of the mixture used (see Table 2 in the main text for composition).

15

2,6 2,8 3,0 3,2 3,41E-10

1E-9

1E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0,01

0,1

L3 F5 F6 DV44a DV44e

Cond

uctiv

ity (S

/cm

)

1000/T (K-1)

F-2 (without IL)F-3 ([BMIM][NTf2])F-4 ([BMIM][Cl])F-1a (M-1g)F-1e (M-1c)

F-3 (with [BMIM][NTf2])F-4 (with [BMIM][Cl])F-1g’F-1c

F-2 (without IL)

Figure S12. A comparative study of conductivity versus temperature for different PILs with similar crosslinking and doped with either [BMIM][Cl] or [BMIM][NTf2] (B. Altava, V. Compañ, A. Andrio, L. F. del Castillo, S. Mollá, M. I. Burguete, E. García-Verdugo and S. V. Luis, Polymer, 2015, 72, 69 and A. Garcia-Bernabé, A. Rivera, A. Granados, S. V. Luis and V. Compañ, Electrochim. Acta, 2016, 213, 887) and “ion gels” F-1g’ and F-1c from this work. F-2: ca. 90 % wt of IL-1 and 10 % wt TMPTMA in the monomeric mixture (without IL). F-3: ca. 90 % wt of IL-1, 10 % wt TMPTMA in the monomeric mixture, ca. 50 % [BMIM][NTf2] in the film; F-4: ca. 90 % wt of IL-1 and 10 wt % TMPTMA in the monomeric mixture, ca. 50 % [BMIM][NTf2] in the film.

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Figure S13. Selected region of the ATR-FT-IR of the some of the films doped with different ZIs-1:LiNTf2 mixtures (see Table 2 in the main text for composition) in comparison with F-2 (film without doping).

1300 1250 1200 1150 1100 1050 1000

0,0

0,4

0,8

Wavelength (nm)

Abs.

(a.u

) dV44.B dV44.C dV44.D dV44.E AGM34-95:5

F-1b (M-1g)F-1c (M-1a)F-1d (M-1b)F-1e (M-1c)F2

1185 cm-1

1185 cm-1

1183 cm-1

1181 cm-1

1198 cm-1LINTf2

1178 cm-1

1060 cm-1LINTf2

1055 cm-1

1052 cm-1

1052 cm-1

1052 cm-1

1051 cm-1

Wavenumber (cm-1)

17

Figure S14. Selected region of the Raman spectra of the some of the films doped with different ZIs-1:LiNTf2 mixtures (see Table 2 in the main text for composition).

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Figure S15. Comparison of ATR-FT-IR spectra of the different ZIs-1:LiNTf2 molar mixtures as prepared using the melting protocol.

Wavenumber (cm-1)

%T

M-1g (1:1)M-1a (1:2)M-1b (1:3)M-1c (1:5)M-1d (2:1)

19

Figure S16. Comparison of ATR-FT-IR spectra of ZIs-1:LiNTf2 1:2 molar mixtures as prepared using the dissolution protocol (black line) and the melting protocol (red line) as well as a sample after thorough vacuum drying (> 120 ºC) (blue line).

Wavenumber (cm-1)

%T

M-1a (dissolution protocol)M-1a (melting protocol)M-1a (vacuum drying (> 120 ºC))