Supporting Information Healable shape-memory (thio)urethane ...

Electronic Supplementary Material (ESI) for Polymer Chemistry. This journal is © The Royal Society of Chemistry 2015

Supporting Information Healable shape-memory (thio)urethane thermosets Le-Thu T. Nguyen,*,† Thuy Thu Truong,† Ha Tran Nguyen,†,‡ Lam Le,†, ‡ Viet Quoc Nguyen,§ Thang Van Le,†,‡ Anh Tuan Luu† †Faculty

of Materials Technology, Ho Chi Minh City University of Technology (HCMUT), Vietnam National University, 268 Ly Thuong Kiet, District 10, Ho Chi Minh City, Vietnam.

‡Materials

Technology Key Laboratory (Mtlab), Ho Chi Minh City University of Technology, Vietnam National University, 268 Ly Thuong Kiet, District 10, Ho Chi Minh City, Vietnam.

§National

Key Laboratory of Polymer and Composite Materials- Ho Chi Minh City University of Technology,

Vietnam National University, 268 Ly Thuong Kiet, District 10, Ho Chi Minh City, Vietnam. * Corresponding author. E-mail address: [email protected]

1. Methods 1H

NMR spectra were recorded in deuterated chloroform (CDCl3) with TMS as an internal reference, on a Bruker

Avance 300 at 300 MHz. Transmission Fourier transform infrared (FT-IR) spectra, collected as the average of 128 scans with a resolution of 4 cm−1, were recorded from KBr disk on the FT-IR Bruker Tensor 27. Attenuated total reflectance (ATR) FT-IR spectra were collected as the average of 128 scans with a resolution of 4 cm−1 on a FT-IR Tensor 27 spectrometer equipped with a Pike MIRacle ATR accessory with a diamond/ZnSe element. Size exclusion chromatography (SEC) measurements were performed on a Polymer PL-GPC 50 gel permeation chromatograph system equipped with an RI detector, with either tetrahydrofuran or chloroform as the eluent at a flow rate of 1.0 mL/min. Molecular weight and molecular weight distribution were calculated with reference to polyethylene glycol standards. Differential scanning calorimetry (DSC) measurements were carried out with a DSC Q20 V24.4 Build 116 calorimeter under nitrogen flow, at a heating rate of 10 °C/min, from -40 to 170 oC. The samples were quenched rapidly from 170

oC

using liquid nitrogen before each DSC heating scan.

Thermogravimetric analysis (TGA) measurements were performed under nitrogen flow using a NETZSCH STA 409 PC Instruments with a heating rate of 10 °C/min from ambient temperature to 900 °C. Hardness measurements were performed on Teclock Durometer GS-709N (Shore A) ASTM D2240A. Tensile tests were measured using a Tensilon RTC-1210A tensile testing machine, making use of a 1000 N load cell. The rectangular specimens met the

1

requirements of ASTM D882 but the dimensions were scaled down. The specimens were rectangular strips of film with a thickness of approximately 0.1 mm, a length of 40 mm and width of 3 mm. The tensile tests were run at a speed of 0.05 mm/min. At least three specimens were tested for each material. Controlled macro-scratches (>2 cm) were performed by sliding a razor or scalpel blade oriented at 45° to the sample surface, with a motorized constant rate and an applied normal force of 1 N. Optical microscopic images were recorded on an Olympus GX51F microscope.

2. Materials All materials were used as received, without further purification. Solvents for the synthesis were dried according to standard laboratory procedures prior to use. 1,1′-(Methylenedi-4,1-phenylene)bismaleimide (bismaleimide, 95%), were purchased from Sigma-Aldrich. 3Amino-1-propanol (99%), 2-furfurylthiol (97%), triethylamine (99%), tetrahydrofuran (99.5+%), methanol (99.9%) and poly(caprolactone) diol (average Mn 2000, Mn

1H NMR

= 2112 g/mol) were purchased from Acros. n-Heptane

(99+%), chloroform (99+%), dichloromethane (99.5%), diethyl ether (99+%) and toluene (99+%) were purchased from Fisher Chemicals. Exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride (98+%) was purchased from TCI Chemicals (Japan). Zirconium(IV) acetylacetonate was purchased from Merck. Poly(caprolactone) diol (Capa™ 2201A Mn

1NMR

= 2100g/mol) was kindly provided by Perstorp Chemicals Asia Pte Ltd. Hexamethylene

diisocyanate isocyanurate trimer (HDI-trimer, tradename Desmodur® N 3390 BA, 90 % in n-butyl acetate, NCO content by 1H NMR = 0.00366 mol/g) was kindly provided by Bayer Vietnam Ltd.

3. Monomer synthesis 3.1. Thiourethane-trisfuran (TUF3) A triethylamine-catalyzed thiol-isocyanate reaction took place between HDI-trimer and 2-furfurylthiol in tetrahydrofuran (THF), under ambient conditions. 42.513 g (155.6 mmol of NCO groups) of Desmodur N3390 BA was mixed with 20 mL (198.3 mmol) of 2-furfurylthiol in 110 mL of THF. Triethylamine (277 µL) was then added and the reaction was stirred at room temperature overnight. The product was precipitated into n-heptane, filtered and dried under vacuum to give a brown solid. Yield: 92%.

2

O C N

O

HN

N N

O

C

+3

N O

N

O

12

O

N

O C

S

HN C

S O

N N

1

O N

O 14

16 15

N H 17

O

O

O C

19 S 18

O

20 21

7

5 O

4

O

11

3 2

solvent:

10 9 SH

13 O

O C

6

8

1 2, 6, 7 3

4 8

5

CHCl3

10 13

12 11

9

18 15 21

14

20 19 17

1.0

1.0 0.9

7

1.0

6

2.1

16 2.3

5 4 Chemical Shift (ppm)

3

2

1

Fig. S1. Synthetic scheme of TUF3 by the thiol-isocyanate reaction between hexamethylene diisocyanate isocyanurate trimer with 2-furfurylthiol and the corresponding 1H NMR spectra.

3

1.0

Transmittance %

0.8 0.6

3339 cm-1 NH-C(O)S 1013 cm-1 furan

0.4 0.2 HDI-trimer TUF3

0.0 -0.2

3500

3000

2271 cm-1 NCO

2500

2000

1500

1000

Wavenumber (cm-1) Fig. S2. Overlay of the transmission FT-IR spectra of hexamethylene diisocyanate isocyanurate trimer and TUF3.

3.2. 3-Maleimido-1-propanol 3-Maleimido-1-propanol was prepared according the previously reported procedure.1 3-Amino-1-propanol (2.04 g, 27.1 mmol) in 20 mL of methanol was added dropwise to a suspension of exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride (8) (4.5 g, 27.1 mmol) in methanol (180 mL) at 0 oC. The mixture was stirred at 0 oC for another 5 min and at room temperature for 30 min. The mixture was then refluxed at at 62 °C for 3 days and concentrated to give a clear oil. This oil was purified by column chromatography using methanol/dichloromethane (1: 15) as eluent to give an intermediate product (DA adduct of furan and 3-maleimido-1-propanol). This intermediate product was refluxed in toluene at 110 oC for 8 h to yield 3-maleimido-1-propanol as a yellowish oil. Yield: 63%.

4

O

O

H 2N

OH

O N

O

O

O a

OH

O

O

d

b

N

c

e OH

O

a

b d CHCl3

c e

2.0

2.0 2.0

7

6

5 4 Chemical Shift (ppm)

1.0

3

2.1

2

1

Fig. S3. Synthetic scheme and the 1H NMR spectrum of 3-maleimido-1-propanol.

Transmittance

1.00

0.75

0.50 3456 cm -OH

-1

-1

0.25 -1

1701 cm C=O stretch

3500

3000

2500 2000 Wavenumber (cm-1)

1150 cm maleimide ring -1 828 cm -1 696 cm maleimide double bond

1500

1000

500

Fig. S4. Transmission FT-IR spectrum of 3-maleimido-1-propanol.

5

3.3. Bismaleimidic terminated PCL (PCLM2) HDI (2.0 mL, 12.4 mmol), freshly azeotropically dried PCL (Acros product, Mn 1H NMR = 2112 g/mol), 13.15 g, 6.2 mmol) and zirconium(IV) acetylacetonate (121 mg, 1 mol% per OH group) were dissolved in 160 mL of dry chloroform under nitrogen atmosphere. The reaction was refluxed for 6 h. After the mixture was cooled down, 3maleimido-1-propanol (1.93 g, 12.4 mmol) was added and the mixture was again refluxed. After 2 h, the reaction was kept at room temperature overnight under nitrogen atmosphere to assure that all –NCO groups were consumed. After the reaction, chloroform was removed. The product was re-dissolved in THF and precipitated into distilled water. The precipitate was washed with diethyl ether and dried under vacuum. Yield: 80%. Mn (estimated by 1H NMR) = 2942 g/mol. SEC (THF as eluent): Mn = 3750 g/mol; Ð = 1.33.

O a

N

O

d

b c

O

H N

N H

k

O i

O

O

O

k

O

l

m

x/2

u H N

O

n

O

O

O

o

x/2

O

H1

O

O

H2

O

N H

H3

N O

y

m

i

k,l, H2,H3

a

n

o,b,d

H1 c

u 0.22

7.5

7.0

6.5

0.24

6.0

5.5

5.0

0.252.33

0.63

4.5 4.0 3.5 Chemical Shift (ppm)

0.53

3.0

2.20

2.5

0.26

2.0

1.5

1.0

0.5

Fig. S5. 1H NMR spectrum of PCLM2.

6

Transmittance

0.75

-1

837 cm -1 697 cm maleimide double bond

-1

0.50

3335 cm NHC(O)O stretch

-1

1531 cm amide II (urethane)

0.25

-1

1689 cm -1 1732 cm C=O stretch

3500

3000

2500 2000 Wavenumber (cm-1)

1500

1000

500

Fig. S6. Transmission FT-IR spectrum of PCLM2.

3.4. Bisfuranic terminated PCL (PCLF2) HDI (15.0 mL, 93.4 mmol), freshly azeotropically dried PCL (Capa™ 2201A, 98.05 g, 46.7 mmol) and zirconium(IV) acetylacetonate (0.91 g, 1 mol% per OH group) were dissolved in 600 mL of dry chloroform under nitrogen atmosphere. The reaction was refluxed at 65 oC under nitrogen for 2 h. After the mixture was cooled down, 2-furfurylthiol (11.3 mL, 112.1 mmol) and triethylamine (26 µL) were added and the mixture was stirred at room temperature under nitrogen atmosphere overnight. After the reaction, the solution was concentrated and the product was precipitated from chloroform to n-heptane for 3 times. The precipitate was dried under vacuum. Yield: 85%. Mn (estimated by 1H NMR) = 2846 g/mol. SEC (chloroform as eluent): Mn = 5025 g/mol; Ð = 1.52.

7

O

a

S

b

u H N

O

d

N H w

c

k

O O

i

O

k

q O

l

m

O

O

x/2

u H N

O

q

x/2

O

H1'

O S

N H

H3

H1

O

o

o

H2

y m

i

k

l H2

H3

CHCl3 q d

a

b c w

0.98

7.5

7.0

o

1.99

6.5

6.0

H1'

u

0.95

1.15

5.5

5.0

1.97

2.15

4.5 4.0 3.5 Chemical Shift (ppm)

H1

4.15

19.01

3.0

2.5

2.0

2.96

1.5

1.0

0.5

0

Fig. S7. 1H NMR spectrum of PCLF2.

Transmittance

1.00

0.75

-1

3352 cm NHC(O) stretch

1011 cm

0.50

1688 cm

-1

-1

737 cm furan

-1

0.25 -1

1734 cm C=O stretch

3500

3000

2500 2000 Wavenumber (cm-1)

1500

1000

Fig. S8. Transmission FT-IR spectrum of PCLF2.

8

3.5. Urethane-trismaleimide (UM3) Under nitrogen atmosphere, the mixture of Desmodur N3390 BA (2.35 g, 8.6 mmol of NCO groups), 3-maleimido1-propanol (2 g, 12.9 mmol) and zirconium(IV) acetylacetonate (41.9 mg) in 150 mL of dry chloroform was refluxed at 65 oC for 5 h, and was then stirred at room temperature overnight. After the reaction, the solution was concentrated and the product was precipitated from chloroform to n-heptane. The product was further purified to remove excess 3-maleimido-1-propanol by thorough washing with distilled water for many times until a pure product was obtained as indicated by thin layer chromatography. Yield: 82%. O C N

HN

O C O

O N O

O O

N N

O

C

+3

N O

N

O

O 4

12 13 11

O

OH

N

O C

N N

1 O

O N

O 14

HN C

16 15

O

N

O

N H 17

O C

O 21

20

O

19 N

O

7

5 O

10

N O

3 2

solvent:

9

O

18

8

6

1 2, 6, 7 3

4 8

5

CHCl3 9

10 12 11 13 18

19 17 2.00

7.5

7.0

6.5

1.08

6.0

5.5

5.0

21 14

2.08 2.16 2.16

4.5 4.0 3.5 Chemical Shift (ppm)

15 16

20

2.23

3.0

2.5

2.0

1.5

1.0

0.5

Fig. S9. Synthetic scheme of UM3 and the corresponding 1H NMR spectra.

9

1.0

Transmittance

0.9 0.8

-1

3383 cm NHC(O)O stretch

0.7

829 cm

-1

696 cm

0.6

-1

maleimide -1

1531 cm amide II (urethane)

0.5 0.4

-1

1686 cm -1 1706 cm C=O stretch

0.3 3500

3000

2500 2000 Wavenumber (cm-1)

1500

1000

Fig. S10. Transmission FT-IR spectrum of UM3.

4. Synthesis of DA cross-linked networks To prepare DA cross-linked thio(urethane) networks, a mixture of multi-maleimide and multi-furan compounds in a 1:1 furan to maleimide equivalent ratio in tetrahydrofuran was cast in a glass petri disk at 40 oC for 48 h, followed by vacuum dried at 60 oC for 24 h. Fig. S11-14 compare the ATR FT-IR spectra of the maleimide and furan monomers and corresponding (thio)urethane networks 1-4, respectively. The occurrence of the DA crosslinking reaction was proven by the nearly complete disappearance of the furan (1011 cm-1, as a shoulder) and maleimide (696 and 828 cm-1) bands in the resulting materials.

10

1011 cm-1

828 cm-1

696 cm-1

Absorbance (a.u.)

TUF3

PCLM2

Network 1 2000

1800

1600 1400 1200 Wavenumber (cm-1)

1000

800

Fig. S11 . ATR FT-IR spectra of PCLM2, TUF3 and Network 1 (TUF3-PCLM2).

1011 cm-1

829 693 -1 cm-1 cm

Absorbance (a.u.)

TUF3

M2

Network 2 2000

1800

1600 1400 1200 1000 -1 Wavenumber (cm )

800

Fig. S12. ATR FT-IR spectra of TUF3, M2 and Network 2 (TUF3-M2).

11

1011 cm-1

828 696 -1 cm-1 cm

Absorbance (a.u.)

TUF3

UM3

Network 3

2000

1800

1600 1400 1200 1000 -1 Wavenumber (cm )

800

Absorbance (a.u.)

Fig. S13. ATR FT-IR spectra of TUF3, UM3 and Network 3 (TUF3-UM3).

1011 cm-1

828 696 cm-1 cm-1

PCLF2 UM3

Network 4 2000

1800

1600 1400 1200 1000 -1 Wavenumber (cm )

800

Fig. S14. ATR FT-IR spectra of PCLF2, UM3 and Network 4 (UM3-PCLF2).

12

5. TGA analysis of (thio)urethane networks

Fig. S15. Comparative TGA thermograms under N2 of (thio)urethane networks of different structures.

6. Shape memory behavior

Fig. S16. Photographs showing the sequential recovery from the temporary shape (spiral) to the permanent shape (strip) of Network 1 at 60 oC.

13

Fig. S17. Photographs showing the sequential recovery from the temporary shape (spiral) to the permanent shape (strip) of Network 4 at 60 oC.

Fig. S18. Photographs of Network 2 film: a) permanent shape, b) temporary shape after deforming at 85 oC and fixing at room temperature, c) shape recovery after heating at 85 oC for 60 sec. St=40% St=20%-cycle 1 St=20%-cycle 2 St=20%-cycle 3

Shape recovery ratio (%)

100 95 90 85 80

Network 1

Network 3

Network 4

Fig. S19. Shape recovery rate at 60 oC of (thio)urethane networks.

14

Table S1. Strain fixity (Rf) and recovery (Rr) ratesa cycle I (exp. 1)

I (exp. 2)

II (exp. 2)

III (exp. 2)

aThe

Network 1

Network 3

Network 4

St (%)

40

25

40

Rf_4 (%)

99.5

96.6

100

Rf_30 (%)

99.5

75.9

91.0

Rr (%)

100

98.9

89.4

St (%)

20

15

20

Rf_4 (%)

100

100

100

Rf_30 (%)

100

96.3

91.9

Rr (%)

100

100

98.4

St (%)

20

15

20

Rf_4 (%)

100

100

100

Rf_30 (%)

100

95.5

89.2

Rr (%)

100

98.9

89.5

St (%)

20

15

20

Rf_4 (%)

100

100

100

Rf_30 (%)

100

92.8

89.1

Rr (%)

100

97.2

86.8

cast films were stretched with a strain of St% by external stress at 60 oC, and the stretched films were kept at

either 4 oC for 10 min or at room temperature (30 oC) for 15 min (corresponding to the Rf-4 and Rf-30 parameters, respectively).

7. Study of the reversibility of the DA crosslinking reaction by ATR FT-IR The networks were heated up to 100 °C for 1 h, and the rDA reaction was checked by the fast recovery of typical maleimide (696 and 828 cm-1) absorption bands in the ATR FT-IR spectra. Then, a mild heating at 60 °C for 3 days reformed the DA cross-linkers. These results were evidenced in Fig. S20-22 for Network 1-4, respectively.

15

696 cm-1

Absorbance (a.u.)

60 oC-3 days

110 oC-1 h

Original Network 1

1100

1000 900 800 Wavenumber (cm-1)

700

Fig. S20. ATR FT-IR spectra of Network 1 (TUF3-PCLM2) showing the evolution of the 696 cm-1 maleimide band upon the rDA reaction at 110 oC and the DA reaction at 60 oC.

Absorbance (a.u.)

60 oC-3 days

829 cm-1

693 cm-1

110 oC-1 h

Original Network 2

1200

1100

1000 900 Wavenumber (cm-1)

800

700

Fig. S21. ATR FT-IR spectra of Network 2 (TUF3-M2) showing the evolution of the 696 and 829 cm-1 maleimide bands upon the rDA reaction at 110 oC and the DA reaction at 60 oC.

16

o

Absorbance (a.u.)

60 C-3 days

828 cm-1

696 cm-1

110 oC-1 h

Original Network 4

1100

1000 900 800 Wavenumber (cm-1)

700

Fig. S22. ATR FT-IR spectra of Network 4 (UM3-PCLF2) showing the evolution of the 696 and 829 cm-1 maleimide bands upon the rDA reaction at 110 oC and the DA reaction at 60 oC.

8. Scratch healing

Fig. S23. Optical micrographs of a scratches of the Network 1 sample before (i) and after (ii) healing at 60 °C for 5 min.

17

Initial Healing at 60 oC- 2 h Healing at 60 oC-24 h Healing at 50 oC-48 h

2.0

Stress (MPa)

1.5

1.0

0.5

0.0

0

10

20 30 Strain (%)

40

50

Fig. S24. Stress-strain curve of the initial and damaged Network 1 sample after healing. Initial Healing at 60 oC-24 h Healing at 60 oC-72 h

30 25

Stress (MPa)

20 15 10 5 0

0

10 Strain (%)

20

Fig. S25. Stress-strain curve of the initial and damaged Network 3 sample after healing.

18

Reference

1

M. Narita, T. Teramoto and M. Okawara, Bull. Chem. Soc. Jpn., 1971, 44, 1084-1089.

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