Supporting Information Supramolecular Cross-Links in Poly(Alkyl Methacrylate) Copolymers and Their Impact on the Mechanical and Reversible Adhesive Properties Christian Heinzmann, 1 Ulrich Salz, 2 Norbert Moszner, 2 Gina L. Fiore, 1 and Christoph Weder 1, * 1 Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg, Switzerland 2 Ivoclar Vivadent AG, Bendererstrasse 2, FL-9494 Schaan, Liechtenstein * To whom correspondence should be addressed, Email: christoph.weder@unifr.ch 1
Table of contents Synthesis of UPy-HMDI-HEMA 3 Figure S1. DSC and TGA traces of UPy-HMDI-HEMA 4 Figure S2. 1 H-NMR spectrum of poly(hexyl methacrylate) 5 Figure S3. 1 H-NMR spectrum of 2.5 mol % UPy poly(upy-hmdi-hema-co-hexyl-ma) 5 Figure S4. 1 H-NMR spectrum of 5 mol % UPy poly(upy-hmdi-hema-co-hexyl-ma) 6 Figure S5. 1 H-NMR spectrum of 10 mol % UPy poly(upy-hmdi-hema-co-hexyl-ma) 6 Figure S6. 1 H-NMR spectrum of poly(butyl methacrylate) 7 Figure S7. 1 H-NMR spectrum of 2.5 mol % UPy poly(upy-hmdi-hema-co-butyl-ma) 7 Figure S8. 1 H-NMR spectrum of 5 mol % UPy poly(upy-hmdi-hema-co-butyl-ma) 8 Figure S9. 1 H-NMR spectrum of 10 mol % UPy poly(upy-hmdi-hema-co-butyl-ma) 8 Figure S10. Representative DSC and TGA traces of (co)polymers 9 Figure S11. FT-IR spectra of (co)polymers 10 Figure S12. Pictures of poly(upy-hmdi-hema-co-hexyl-ma) after shear test 11 Figure S13. Pictures of poly(upy-hmdi-hema-co-butyl-ma) after shear test 12 Figure S14. Pictures of poly(upy-hmdi-hema-co-hexyl-ma) after heat-dod 13 Figure S15. Pictures of poly(hexyl-ma) after DoD experiment with heat 14 Figure S16. UV-Vis absorbance spectra 15 Figure S17. Temperature-time-diagram of poly(upy-hmdi-hema-co-hexyl-ma) 16 Figure S18. Pictures of lap joints with quartz glass 17 Figure S19. Pictures after debond on demand experiment with UV light 18 Table S1. Additional data from DSC and DMA measurements 19 Table S2. Additional SEC data in DMF/LiBr solution 20 References 21 2
Synthesis of UPy-HMDI-HEMA The original procedure of UPy-HMDI-HEMA 1 was modified as follows: UPy-HMDI 2 (20 g, 68.2 mmol) was dispersed in anhydrous CHCl 3 (200 ml), before hydroxyethyl methacrylate (1.5 equiv., 12.3 ml, 102 mmol) was added under nitrogen atmosphere. After stirring the mixture for 5 min, 4 drops of dibutyltin dilaurate were added and the reaction mixture was heated to reflux overnight. The cloudy suspension was cooled to room temperature and poured into cold hexane. The white product was filtered off, washed with hexane and the solvent was removed under vacuum at 40 C. The product was dried for 1 d under these conditions and obtained as a white powder (27.90 g; 97%). 1 H-NMR (300 MHz, CDCl 3 ): δ = 13.12 (bs, 1H), 11.87 (bs, 1H), 10.02 (bs, 1H), 6.15 6.10 (m, 1H), 5.85 (s, 1H), 5.60 5.56 (m, 1H), 4.98 (s, 1H), 4.31 (bs, 4 H), 3.21 (dq, J = 25.8, 6.6 Hz, 4H), 2.23 (s, 3H), 1.96 1.92 (m, 3H), 1.55 (dt, J = 26.0, 6.4 Hz, 4H), 1.40 1.33 (m, 4H). MS (ESI): m/z = 424.2 (+ H + ; calc. = 423.21). T m = 161 C (Supporting Information Figure S1a). 3
Mass (%) exo (mw) (a) 5 0 134 C -5-10 -15 heating cooling 161 C -20 0 20 40 60 80 100 120 140 160 180 200 Temperature ( C) (b) 100 80 60 40 20 0 50 100 150 200 250 300 350 400 450 500 Temperature ( C) Figure S1. Differential scanning calorimetry (DSC) traces (a), and thermogravimetric analysis (TGA) trace (b) of UPy-HMDI-HEMA. 4
Figure S2. 1 H-NMR spectrum of poly(hexyl methacrylate) in CDCl 3. Figure S3. 1 H-NMR spectrum of 2.5 mol % UPy poly(upy-hmdi-hema-co-hexyl-ma) in CDCl 3. 5
Figure S4. 1 H-NMR spectrum of 5 mol % UPy poly(upy-hmdi-hema-co-hexyl-ma) in CDCl 3. Figure S5. 1 H-NMR spectrum of 10 mol % UPy poly(upy-hmdi-hema-co-hexyl-ma) in CDCl 3. 6
Figure S6. 1 H-NMR spectrum of poly(butyl methacrylate) in CDCl 3. Figure S7. 1 H-NMR spectrum of 2.5 mol % UPy poly(upy-hmdi-hema-co-butyl-ma) in CDCl 3. 7
Figure S8. 1 H-NMR spectrum of 5 mol % UPy poly(upy-hmdi-hema-co-butyl-ma) in CDCl 3. Figure S9. 1 H-NMR spectrum of 10 mol % UPy poly(upy-hmdi-hema-co-butyl-ma) in CDCl 3. 8
Mass (%) exo Mass (%) exo (a) 100 (b) 80 60 40 20 0 50 100 150 200 250 300 350 400 450 500 Temperature ( C) -40-20 0 20 40 60 80 100 Temperature ( C) (c) 100 (d) 80 60 40 20 0 50 100 150 200 250 300 350 400 450 Temperature ( C) -40-20 0 20 40 60 80 100 120 140 Temperature ( C) Figure S10. Representative TGA (a, c) and DSC (b, d) traces of poly(upy-hmdi-hema-co-hexyl- MA) (a, b) and poly(upy-hmdi-hema-co-butyl-ma) (c, d). The UPy-HMDI-HEMA content in the (co)polymers was 0 mol % (black), 2.5 mol % (red), 5 mol % (blue), 10 mol % (green). For better visualization in the DSC experiments, only the curves from the first heating cycle are displayed. The values of the glass transition temperatures are given in Table 2. 9
Transmittance (%) Transmittance (%) (a) 100 poly(upy-hmdi-hema-co-butyl-ma) 80 60 40 20 0 1750 1700 1650 1600 1550 1500 Wavenumber (cm -1 ) (b) 100 poly(upy-hmdi-hema-co-hexyl-ma) 80 60 40 20 0 1750 1700 1650 1600 1550 1500 Wavenumber (cm -1 ) Figure S11. FT-IR spectra of poly(upy-hmdi-hema-co-butyl-ma) (a) and poly(upy-hmdi- HEMA-co-hexyl-MA) (b) (co)polymers, normalized to the peak at 1725 cm -1. The UPy-HMDI- HEMA content in the (co)polymers was 0 mol % (black), 2.5 mol % (red), 5 mol % (blue), 10 mol % (green). The signals at 1697, 1660, 1583, and 1526 cm -1 are indicative of the hydrogen bond array. 3 10
UPy (mol %) poly(upy-hmdi-hema-co-hexyl-ma) 24 C 24 C (rebond) 40 C 60 C 0 2.5 5 10 Figure S12. Pictures of lap joints bonded with poly(upy-hmdi-hema-co-hexyl-ma) after shear testing bonded samples at 24, 40, and 60 C and rebonded samples at 24 C. The UPy content in the polymer is indicated in the figure. 11
UPy (mol %) poly(upy-hmdi-hema-co-butyl-ma) 24 C 24 C (rebond) 40 C 60 C 0 2.5 5 10 Figure S13. Pictures of lap joints bonded with poly(upy-hmdi-hema-co-butyl-ma) after shear testing bonded samples at 24, 40, and 60 C and rebonded samples at 24 C. The UPy content in the polymer is indicated in the figure. 12
50 N 100 N 200 N 300 N 400 N Figure S14. Pictures of lap joints with stainless steel bonded with 10 mol % UPy poly(upy-hmdi- HEMA-co-hexyl-MA) after the debond on demand experiment of Figure 6a. The corresponding force is indicated in the figure. 13
10 N 20 N 25 N 30 N Figure S15. Pictures of lap joints with stainless steel bonded with poly(hexyl-ma) after the debond on demand experiment of Figure 6c. The corresponding force is indicated in the figure. 14
Absorbance 2 without UV sensitizer with UV sensitizer 1 0 250 300 350 400 450 500 550 600 Wavelength (nm) Figure S16. UV-Vis absorbance spectra of 100 µm thick films of 10 mol % UPy poly(upy-hmdi- HEMA-co-hexyl-MA) with (red) and without (black), 0.25 wt % of the UV sensitizer 2-(5-chloro-2Hbenzotriazole-2-yl)-6-(1,1-dimethylethyl)-4-methyl-phenol (Tinuvin 326). 15
Temperature ( C) 300 250 258 C free-standing on quartz lap joint 200 186 C 150 100 85 C 50 0 0 30 60 90 120 Time (s) Figure S17. Temperature-time-diagram for 10 mol % UPy poly(upy-hmdi-hema-co-hexyl-ma) comprising 0.25 wt % Tinuvin 326. Surface temperatures were measured with an IR camera. A 100 µm thick film was either free-standing (black), placed on quartz glass (red), or was placed inbetween two quartz slides to form a lap joint (blue). The UV lamp (λ = 320-500 nm; 2500 mw/cm 2 ) was switched on after 5 s, and was switched off after the sample degraded (free-standing sample), or after 30 s (quartz sample), or 40 s (lap joint). As quartz glass has a low thermal conductivity and the infrared camera measures surface temperatures only, the sample temperature in the lap joint is suggested to be higher. 16
Non-bond UV bond heat bond Figure S18. Pictures of lap joints with quartz glass and of 100 µm thick films of 10 mol % UPy poly(upy-hmdi-hema-co-hexyl-ma) comprising 0.25 wt % of the UV sensitizer. The slightly opaque, non-bonded lap joint is a sandwich of the polymer film inbetween two quartz slides. In the bonded state, both bonding procedures (UV light and heat) yield clear, colorless films. 17
50 N 100 N 150 N Figure S19. Pictures of lap joints with quartz glass bonded with 10 mol % UPy poly(upy-hmdi- HEMA-co-hexyl-MA) comprising 0.25 wt % of the UV sensitizer after the debond on demand experiment of Figure 6b. The corresponding force is indicated in the figure. 18
Table S1. Additional data from DSC and DMA measurements. UPy DSC DMA a onset midpoint b E tan δ c (mol %) 1 st 2 nd 1 st 2 nd onset d max Poly(UPy-HMDI-HEMA-co-hexyl-MA) 0-7 -6 3 3 7 ± 2 32 ± 1 2.5-3 -5 7 6 4 ± 4 29 ± 3 5-1 -2 12 10 7 ± 1 33 ± 2 10 15 13 24 24 27 ± 2 49 ± 1 Poly(UPy-HMDI-HEMA-co-butyl-MA) 0 27 24 38 31 19 ± 2 53 ± 2 2.5 42 37 48 34 38 ± 1 64 ± 2 5 44 44 50 44 51 ± 3 76 ± 3 10 50 42 57 58 60 ± 2 84 ± 1 a Standard deviations determined from 3-5 measurements. b Determinded by the minimum of the first derivative. c Maximum value of tan δ (phase angle: loss modulus (E ) divided by storage modulus (E )) from the transition of the glassy to the rubbery state. d Softening point (not a T g ). 19
Table S2. Additional SEC data in DMF/LiBr solution UPy (mol %) M n M w Ð Poly(UPy-HMDI-HEMA-co-butyl-MA) 0 34,000 50,100 1,47 2.5 41,500 116,900 2,82 5 30,900 53,800 1,74 10 15,400 34,500 2,24 Poly(UPy-HMDI-HEMA-co-butyl-MA) 0 n.m. a n.m. a n.m. a 2.5 9,900 11,800 1,19 5 11,000 13,000 1,19 10 5,620 10,800 1,92 Instrument/Experimental description: SEC measurements were performed with an Agilent Technologies 1260 Infinity System in a dimethylformamide solution with 0.05 M LiBr at 45 C and 1 ml/min, calibrated with PMMA standards. a Insoluble in DMF/LiBr solution. 20
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