Supporting Information. Light-Induced Bonding and Debonding with Supramolecular Adhesives

Transcription

1 Supporting Information Light-Induced Bonding and Debonding with Supramolecular Adhesives Christian Heinzmann, Souleymane Coulibaly, Anita Roulin, Gina L. Fiore,* and Christoph Weder* Adolphe Merkle Institute, University of Fribourg, CH-1700 Fribourg, Switzerland *To whom correspondence should be addressed, and 1

2 Characterization of UPy-PEB-UPy. 1 H-NMR (360 MHz, CDCl 3 ): δ = (s), (s), (s), 5.86 (s), 4.84 (s), 4.06 (s), 3.20 (m), 2.23 (s), (m), (m). 13 C-NMR (91 MHz, CDCl 3 ): δ = , , , , , 39.27, 38.81, 38.27, 36.50, 33.89, 33.64, 31.08, 30.62, 30.16, 27.18, 26.99, 26.83, 26.44, 26.27, 11.28, 11.05, 10.95, 10.78, 10.67, IR (cm -1 ): 2959, 2921, 2872, 2852, 2270, 1700, 1666, 1589, 1527, 1460, 1379, 1304, 1254, 1139, 1041, 942, 843, 761, 744, 721, 621, 612, 602, 593, 586. GPC: M n = 3900 g/mol, M w = 5400 g/mol, PDI = 1.41 Characterization of Mebip-PEB-Mebip. 1 H-NMR (360 MHz, CDCl 3 ): δ = 8.05 (s), 7.94 (s), (m), (m), (m), (m). 13 C-NMR (91 MHz, CDCl 3 ): δ = , , , , , , , , , , 39.02, 38.52, 38.04, 36.26, 33.39, 30.81, 30.36, 29.90, 26.93, 26.74, 26.26, 26.19, 26.02, 11.03, 10.82, GPC: M n = 3700 g/mol, M w = 4700 g/mol, PDI =

3 Table S1. Mechanical data obtained from DMTA (Figure S3) and stress-strain measurements (Figure S4) for and UPy-PEB-UPy. Mebip-PEB- UPy-PEB-UPy Mebip](NTf 2 Storage -70 C (MPa) a 2230 ± ± 140 Storage 25 C (MPa) a 100 ± ± 1.8 Strain at break (%) b 35 ± 2 71 ± 11 Stress at break (MPa) b 5.3 ± ± 0.1 Young s modulus (MPa) b 88 ± ± 1 Maximum stress (MPa) b 5.6 ± ± 0.1 Experiments were repeated 5 times and errors are standard deviations. a DMTA experiments were conducted at a heating rate of 5 C/min and a frequency of 1 Hz under N 2. b Stress-strain experiments were conducted at 25 ºC with a strain rate of 10 mm/min and a preload force of 0.1 N with dog-bone shaped samples. 3

4 Table S2. Shear test results of lap joints with different substrates thermally bonded or rebonded with UPy-PEB-UPy. UPy-PEB-UPy Substrate Shear stress (MPa) Bonded a glass 1.2 ± 0.1 Rebonded b glass 1.3 ± 0.2 Bonded a stainless steel 1.0 ± 0.2 Rebonded b stainless steel 1.4 ± 0.2 Bonded (+ 0.25% w/w Tinuvin 326) a quartz 0.7 ± 0.1 Rebonded (+ 0.25% w/w Tinuvin 326) b quartz 1.0 ± 0.1 Experiments were repeated 5 times and errors are standard deviations. a Bonding was achieved by exposure to heat (5 min, 80 C). b For rebonding experiments, samples were first thermally bonded, subjected to a shear-test experiment until the bond failed, and the lap joint was rebonded using the original bonding conditions, but without applying additional adhesive. 4

5 Table S3. Quantitative data for debonding on demand experiments. Heat a UV light b c t fail F d c t fail F d Sample (s) (% F max ) (s) (% F max ) UPy-PEB-UPy + Tinuvin 326 (0.25% w/w) UPy-PEB-UPy Experiments were repeated 3 times and data shows representatives. Thermally bonded quartz glass lap joints (for preparation see caption to Figure S1 in the manuscript) were held under constant stress (53 N for and 31 N for UPy-PEB-UPy + Tinuvin 326 (0.25% w/w)), then the debonding stimulus was applied until debonding occurred. To prove that in UPy-PEB-UPy UV light debonding is enabled by the addition of a light-heat converter (Tinuvin 326), the experiment was also conducted with neat UPy-PEB- UPy, which did not fail upon irradiation with UV light. a Heat was applied with a heatgun set to 300 C. b UV light was applied with a UV light source (λ = nm, 950 mw/cm 2 ). c t fail is the time in s for the sample to debond. d F max is the average force necessary for debonding while shear testing without a debond stimulus (see Table 1), and [% F max ] is calculated by dividing the constant force applied during the debonding on demand experiment (53 N or 31 N) by their respective F max. 5

6 Figure S1. Schematic representation of bonding and debonding lap joints with supramolecular polymers). a) Two substrates were first bonded by placing a film of either Mebip- PEB-Mebip](NTf 2 or UPy-PEB-UPy between them, fixating this lap joint with the help of two clips, which provide a force orthogonal to the lap joint, cutting off overhang film, and subsequently applying either heat (2 min, 200 C for ; 5 min, 80 C for UPy-PEB-UPy) or UV light (2 60 s, λ = nm, 900 mw/cm 2 ). b) Shear tests were subsequently performed with a Zwick Z010 tensile tester by gripping the ends of the substrates and applying a force with a strain rate of 10 mm/min. c) Alternatively, debonding experiments were performed in a similar setup, but the lap joints were placed under a constant load, which they could bear without debonding or creeping. Upon exposure to heat (airflow with 300 C heatgun) or light (λ = nm, 900 mw/cm 2 ), the lap joint eventually debonded and the time to failure was measured. d) After failure (b) the lap joint was rebonded using the original bonding conditions, but without applying additional adhesive. 6

7 Absorbance Mebip-PEB-Mebip 90 µm drop-cast Tinuvin mg/ml UPy-PEB-UPy 90 µm UPy-PEB-UPy + Tinuvin 326 (0.25 % w/w) 90 µm Wavelength (nm) Figure S2. UV-Vis absorbance spectra of solutions of neat Mebip-PEB-Mebip (λ max = 314 nm) and 2-(5-chloro-2H-benzotriazole-2-yl)-6-(1,1-dimethylethyl)-4-methyl-phenol (Tinuvin 326, λ max = 311 and 348 nm) and films of the metallosupramolecular polymer Mebip- PEB-Mebip](NTf 2 (λ max = 344 nm), the hydrogen-bonded supramolecular polymer UPy- PEB-UPy (λ max < 300 nm), and of a blend of UPy-PEB-UPy with 0.25% w/w Tinuvin

8 Storage Modulus (MPa) Storage Modulus Tan Delta UPy-PEB-UPy Storage Modulus UPy-PEB-UPy Tan Delta Tan Delta Temperature ( C) Figure S3. Representative dynamic mechanical thermal analysis (DMTA) traces of the metallosupramolecular polymer (, ) and the hydrogenbonded supramolecular polymer UPy-PEB-UPy (, ). Shown are storage moduli (, ) and mechanical loss factor (tan delta;, ). The experiments were conducted at a heating rate of 5 C/min and a frequency of 1 Hz under N 2 and were repeated 5 times. 8

9 8 7 6 UPy-PEB-UPy Stress (MPa) Strain (%) Figure S4. Representative stress-strain curves of dog bone-shaped samples of Mebip- PEB-Mebip](NTf 2 (red) and UPy-PEB-UPy (black). Data were collected at a strain rate of 10 mm/min with a preload force of 0.1 N at room temperature. 9

10 Mass (%) UPy-PEB-UPy UPy-PEB-UPy + Tinuvin 326 (0.25 % w/w) Temperature ( C) Figure S5. Thermogravimetric analysis traces of ( ), UPy-PEB-UPy ( ), and UPy-PEB-Upy % w/w Tinuvin 326 ( ). Data were collected at a heating rate at 10 C/min under N 2 atmosphere. 10

11 Temperature ( C) film melted UPy-PEB-UPy + Tinuvin 326 (0.25 % w/w) Lamp switched off neat film between quartz slides 20 Lamp switched on Time (s) Figure S6. Surface temperature of UPy-PEB-UPy % w/w Tinuvin 326 neat film blend (solid line) and bonded quartz slides (dashed line) upon irradiation with UV light (λ = nm; 950 mw/cm 2 ). Surface temperatures were recorded using an IR camera. 11