ELECTROCHEMICALLY DEBONDABLE ADHESIVE COMPOSITION

Abstract

The present invention is directed to a curable and electrochemically debondable adhesive composition comprising, based on the weight of the composition: from 40 to 99 wt. % of a) at least one ethylenically unsaturated non-ionic monomer; from 0.9 to 50 wt. % of b) at least one polymerizable ionic compound, wherein said polymerizable ionic compound comprises: b1) at least one compound in accordance with general formula IV; and/or b2) at least one compound in accordance with general formula V; and, from 0.1 to 10 wt. % of c) at least one free radical initiator.

##STR00001##

Claims

1. A curable and electrochemically debondable adhesive composition comprising, based on the weight of the composition: from 40 to 99 wt. % of a) at least one ethylenically unsaturated non-ionic monomer; from 0.9 to 50 wt. % of b) at least one polymerizable ionic compound, wherein said polymerizable ionic compound comprises: b1) at least one compound in accordance with general formula IV: ##STR00010## and/or b2) at least one compound in accordance with general formula V: ##STR00011## wherein: R.sup.7 is selected from: C.sub.1-C.sub.30 alkyl; C.sub.2-C.sub.8 alkenyl; C.sub.1-C.sub.30 heteroalkyl; C.sub.3-C.sub.30 cycloalkyl; C.sub.6-C.sub.18 aryl; C.sub.1-C.sub.9 heteroaryl; C.sub.7-C.sub.18 alkylaryl; C.sub.2-C.sub.5 heterocycloalkyl; or, —R.sup.a—C(═O)—R.sup.b where R.sup.a is a C.sub.1-C.sub.6 alkylene group and R.sup.b is a C.sub.1-C.sub.6 alkyl group; each R.sup.a is independently selected from H, C.sub.1-C.sub.18 alkyl, C.sub.1-C.sub.18 heteroalkyl; C.sub.3-C.sub.18 cycloalkyl, C.sub.6-C.sub.18 aryl, C.sub.1-C.sub.9 heteroaryl, C.sub.7-C.sub.18 alkylaryl; or, C.sub.2-C.sub.5 heterocycloalkyl; R.sup.9 is H or C.sub.1-C.sub.4 alkyl; each R.sup.10 is independently selected from: C.sub.1-C.sub.30 alkyl; C.sub.1-C.sub.30 heteroalkyl; C.sub.3-C.sub.30 cycloalkyl; C.sub.6-C.sub.18 aryl; C.sub.1-C.sub.9 heteroaryl; C.sub.7-C.sub.18 alkylaryl; C.sub.2-C.sub.5 heterocycloalkyl; or, —R.sup.a—C(═O)—R.sup.b where R.sup.a is a C.sub.1-C.sub.6 alkylene group and R.sup.b is a C.sub.1-C.sub.6 alkyl group; A is a non-polymerizable anion; T is an ethylenically unsaturated anion; d and m are each integers having a value of at least 1; e and n have a numeric value such that the compound is electrically neutral; and, is a covalent bond, C.sub.1-C.sub.2 alkylene, —CH.sub.2OC(═O)—, —CH.sub.2CH.sub.2OC(═O)—, p-benzyl or p-tolyl; and, from 0.1 to 10 wt. % of c) at least one free radical initiator.

2. The adhesive composition according to claim 1 comprising: from 45 to 95 wt. % of a) said at least one ethylenically unsaturated non-ionic monomer; from 5 to 30 wt. % of b) said at least one polymerizable ionic compound; from 0.1 to 5 wt. % of c) said at least one free radical initiator; and, from 0 to 10 wt. % of d) solubilizer.

3. The adhesive composition according to claim 1, wherein part a) comprises from 40 to 95 wt. %, based on the weight of the composition, of a1) at least one (meth)acrylate monomer represented by Formula I:
H.sub.2C=CGCO.sub.2R.sup.1  (I) wherein: G is hydrogen, halogen or a C.sub.1-C.sub.4 alkyl group; and, R.sup.1 is selected from: C.sub.1-C.sub.30 alkyl; C.sub.2-C.sub.30 heteroalkyl; C.sub.3-C.sub.30 cycloalkyl; C.sub.2-C.sub.8 heterocycloalkyl; C.sub.2-C.sub.20 alkenyl; and, C.sub.2-C.sub.12 alkynyl.

4. The adhesive composition according to claim 1, wherein part a) comprises comprises up to 50 wt. % based on the weight of the composition, of a3) at least one (meth)acrylate-functionalized oligomer.

5. The adhesive composition according to claim 1, wherein part a) comprises at least one α,β-ethylenically unsaturated monocarboxylic acid having from 3 to 5 carbon atoms.

6. The adhesive composition according to claim 1, wherein in part b): R.sup.7 is selected from C.sub.1-C.sub.8 alkyl; C.sub.2-C.sub.4 alkenyl; C.sub.1-C.sub.8 heteroalkyl; C.sub.3-C.sub.12 cycloalkyl; C.sub.6-C.sub.18 aryl; C.sub.1-C.sub.9 heteroaryl; C.sub.7-C.sub.18 alkylaryl; C.sub.2-C.sub.5 heterocycloalkyl; or, —R.sup.a—C(═O)—R.sup.b where R.sup.a is a C.sub.1-C.sub.4 alkylene group and R.sup.b is a C.sub.1-C.sub.4 alkyl group; each R.sup.8 is independently selected from H or C.sub.1-C.sub.2 alkyl; R.sup.9 is H or methyl; and, R.sup.10 is selected from C.sub.1-C.sub.8 alkyl; C.sub.1-C.sub.8 heteroalkyl; C.sub.3-C.sub.12 cycloalkyl; C.sub.6-C.sub.18 aryl; C.sub.1-C.sub.9 heteroaryl; C.sub.7-C.sub.18 alkylaryl; C.sub.2-C.sub.5 heterocycloalkyl; or, —R.sup.a—C(═O)—R.sup.b where R.sup.a is a C.sub.1-C.sub.4 alkylene group and R.sup.b is a C.sub.1-C.sub.4 alkyl group.

7. The adhesive composition according to claim 1, wherein part b) comprises: b1) at least one compound selected from the group consisting of: 1H-Imidazolium, 3-ethenyl-1-methyl-, iodide; 1H-Imidazolium, 3-ethenyl-1-methyl-, chloride; 1H-Imidazolium, 3-ethenyl-1-methyl-, bromide; 1H-Imidazolium, 3-ethenyl-1-methyl-, methanesulfonate; 1H-Imidazolium, 3-ethenyl-1-methyl-, 1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide; 1H-Imidazolium, 3-ethenyl-1-ethyl-, 1,1, 1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide; 1H-Imidazolium, 3-ethenyl-1-methyl-, hexafluorophosphate; 1H-Imidazolium, 3-ethenyl-1-methyl-, 4-methylbenzenesulfonate; 1H-Imidazolium, 3-ethenyl-1-methyl-, tetrafluoroborate; 1H-Imidazolium, 3-ethenyl-1-ethyl-, iodide; 1H-Imidazolium, 3-ethenyl-1-ethyl-, bromide; 1H-Imidazolium, 3-ethenyl-1-ethyl-, 1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide; 1H-Imidazolium, 3-ethenyl-1-ethyl-, hexafluorophosphate; 1H-Imidazolium, 3-ethenyl-1-ethyl-, tetrafluoroborate; 1H-Imidazolium, 3-ethenyl-1-(1-methylethyl)-, bromide; 1H-Imidazolium, 3-(1,1-dimethylethyl)-1-ethenyl-, bromide; 1H-Imidazolium, 3-ethenyl-1-propyl-, bromide; 1H-Imidazolium, 3-ethenyl-1-(phenylmethyl)-, bromide; 1H-Imidazolium, 1-ethenyl-3-(4-methylphenyl)-, chloride; 1H-Imidazolium, 3-ethenyl-1-(1-methylpropyl)-, chloride; 1H-Imidazolium, 1-butyl-3-ethenyl-, bromide; 3-[(4-ethenylphenyl)methyl]-1-methyl-, iodide; 1H-Imidazolium, 3-[(4-ethenylphenyl) methyl]-1-methyl-, chloride; 1H-Imidazolium, 3-[(4-ethenylphenyl)methyl]-1-methyl-, 1,1, 1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide; 1H-Imidazolium, 3-[(4-ethenylphenyl)methyl]-1-methyl-, hexafluorophosphate; 1H-Imidazolium, 3-[(4-ethenylphenyl)methyl]-1-methyl-, tetrafluoroborate; 1H-Imidazolium, 3-[(4-ethenylphenyl)methyl]-1-ethyl-, chloride; 1H-Imidazolium, 1-[(4-ethenylphenyl)methyl]-3-ethyl-, salt with 1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide; 1H-Imidazolium, 1-(3-aminopropyl)-3-[(4-ethenylphenyl)methyl]-, chloride; 1H-Imidazolium, 1-butyl-3-[(4-ethenylphenyl)methyl]-, chloride; and/or b2) at least one compound selected from the group consisting of: 1H-Imidazolium, 1-methyl-3-hexyl-, 4-ethenylbenzenesulfonate; 1H-Imidazolium, 1-dodecyl-3-ethenyl-, 4-ethenylbenzenesulfonate; 1H-Imidazolium, 1-methyl-3-propyl-, 4-ethenylbenzenesulfonate; and, 1H-Imidazolium, 3-ethyl-1-methyl-, 4-(1-methylethenyl) benzenesulfonate.

8. The adhesive composition according to claim 1, wherein part b) comprises at least one compound selected from the group consisting of: 1H-Imidazolium, 3-methyl-1-hexyl-4-ethenylbenzenesulfonate; 1H-Imidazolium, 3-ethenyl-1-ethyl-1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide; and, 1H-Imidazolium, 3-methyl-1-butyl-1,1,1-trifluoro-N-[(trifluoromethyl)sulfonyl]methanesulfonamide.

9. The adhesive composition according to claim 1, wherein part c) comprises at least one azo free radical initiator selected from the group consisting of: azo nitriles; azo esters; azo amides; azo amidines; azo imidazoline; and, macro azo initiators.

10. The adhesive composition according to claim 1, wherein said composition comprises d) solubilizer in an amount up to 10 wt. %, based on the weight of the composition, and said solubilizer is selected from the group consisting of: polyoxyalkylene glycols; silicone surfactants; polyhydric alcohols; and, sugars.

11. The adhesive composition according to claim 1, wherein said composition comprises electrically conductive particles in an amount up to 10 wt. %, based on weight of the composition.

12. The adhesive composition according to claim 11, wherein said electrically conductive particles are selected from the group consisting of silver, carbon black and mixtures thereof.

13. A bonded structure comprising a first material layer having an electrically conductive surface; and, a second material layer having an electrically conductive surface; wherein the curable and electrochemically debondable adhesive composition according to claim 1 is disposed between the first and second material layers.

14. A method of debonding said bonded structure according to claim 13, the method comprising the steps of: 1) applying a voltage across both surfaces to form an anodic interface and a cathodic interface; and 2) debonding the surfaces.

15. A method according to the claim 14, wherein the voltage applied in step 1 is from 0.5 to 200 V and it is applied for a duration of from 1 second to 30 minutes.

Description

[0182] The present invention will be described with reference to the appended drawings in which:

[0183] FIG. 1a depicts a bonded structure in accordance with a first embodiment of the present invention.

[0184] FIG. 1b depicts a bonded structure in accordance with a second embodiment of the present invention.

[0185] FIG. 2a depicts the initial debonding of the structure of the first embodiment upon application of a voltage across that structure.

[0186] FIG. 2b depicts the initial debonding of the structure of the second embodiment upon application of a voltage across that structure.

[0187] As shown in FIG. 1a appended hereto, a bonded structure is provided in which a layer of cured adhesive (10) is disposed between two conductive substrates (11). A layer of non-conductive material (12) may be disposed on the conductive substrates (11) to form the more complex bonded structure as depicted in FIG. 1b. Each layer of conductive substrate (11) is in electrical contact with an electrical power source (13) which may be a battery or an AC-driven source of direct current (DC). The positive and negative terminals of that power source (13) are shown in one fixed position but the skilled artisan will of course recognize that the polarity of the system can be reversed.

[0188] The two conductive substrates (11) are shown in the form of a layer which may be constituted by inter alia: a metallic film; a metallic mesh or grid; deposited metal particles; a resinous material which is rendered conductive by virtue of conductive elements disposed therein; or, a conducting oxide layer. As exemplary conductive elements there may be mentioned silver filaments, single-walled carbon nanotubes and multi-walled carbon nanotubes. As exemplary conducting oxides there may be mentioned: doped indium oxides, such as indium tin oxide (ITO); doped zinc oxide; antimony tin oxide; cadmium stannate; and, zinc stannate. The selection of the conductive material aside, the skilled artisan will recognize that the efficacy of the debonding operation may be diminished where the conductive substrates (11) are in the form of a grid or mesh which offers limited contact with the layer of cured adhesive (10).

[0189] When an electrical voltage is applied between each conductive substrate (11), current is supplied to the adhesive composition (10) disposed there between. This induces electrochemical reactions at the interface of the substrates (11) and the adhesive composition, which electrochemical reactions are understood as oxidative at the positively charged or anodic interface and reductive at the negatively charged or cathodic interface. The reactions are considered to weaken the adhesive bond between the substrates allowing the easy removal of the debondable composition from the substrate.

[0190] As depicted in FIGS. 2a and 2b for illustrative purposes only, the debonding occurs at the positive interface, that interface between the adhesive composition (10) and the electrically conductive surface (11) that is in electrical contact with the positive electrode. By reversing current direction prior to separation of the substrates, the adhesive bond may be weakened at both substrate interfaces.

[0191] It is however noted that the composition of the adhesive layer (10) may be moderated so that debonding occurs at either the positive or negative interface or simultaneously from both. For some embodiments, a voltage applied across both surfaces so as to form an anodic interface and a cathodic interface will cause debonding to occur simultaneously at both the anodic and cathodic adhesive/substrate interfaces. In an alternative embodiment, reversed polarity may be used to simultaneously disbond both substrate/adhesive interfaces if the composition does not respond at both interfaces to direct current. The current can be applied with any suitable waveform, provided that sufficient total time at each polarity is allowed for debonding to occur. Sinusoidal, rectangular and triangular waveforms might be appropriate in this regard and may be applied from a controlled voltage or a controlled current source.

[0192] Without intention to limit the present invention, it is considered that the debonding operation may be performed effectively where at least one and preferably both of the following conditions are instigated: a) an applied voltage of from 1 to 100 V, for example from 20 to 50 V; and, b) the voltage being applied for a duration of from 1 second to 180 minutes, for example from 1 second to 30 minutes. Where the release of the conductive substrate from the cured adhesive is to be facilitated by the application of a force—exerted via a weight or a spring, for instance—the potential might only need to be applied in the order of seconds.

[0193] The following examples are illustrative of the present invention and are not intended to limit the scope of the invention in any way.

EXAMPLES

[0194] The following materials and abbreviations for said materials were employed in the Examples: [0195] MMA: Methyl methacrylate [0196] MAA: Methacrylic acid [0197] EGDMA: Ethylene glycol dimethylacrylate [0198] PEG-MEA: Polyethylene glycol methyl ether acrylate [0199] BENZYL MA: Benzyl methacrylate [0200] HEMA: (Hydroxyethyl)methacrylate [0201] IBOA: Isobornyl acrylate [0202] AIBN: Azobisisobutyronitrile, available from Sigma Aldrich [0203] BPO: Benzoyl peroxide, available from PanReac AppliChem [0204] HEXMIM StSO3: 1H-Imidazolium, 3-methyl-1-hexyl-4-ethenylbenzenesulfonate [0205] EMIM Acrylate: 1H-Imidazolium, 1-ethyl-3-methyl-acrylate [0206] ViEIM NTf2: 1H-Imidazolium, 3-ethenyl-1-ethyl-1,1,1-trifluoro-N-[(trifluoromethyl) sulfonyl]methanesulfonamide [0207] BMIM NTf2: 1H-Imidazolium, 3-methyl-1-butyl-1,1,1-trifluoro-N-[(trifluoromethyl) sulfonyl]methanesulfonamide [0208] PEG400: Polyethylene glycol, available from Sigma Aldrich. [0209] CN966H90: An aliphatic polyester based urethane diacrylate oligomer blended with 10% 2(2-ethoxyethoxy) ethyl acrylate, available from Sartomer [0210] SR9054: An acid acrylate adhesion promoter, available from Sartomer

[0211] Preparation of a first set of Formulations: The formulations EDA1 to EDA14 plus the Controls 1, 2 and 3 are described in Table 1a & 1b herein below were formed under mixing.

TABLE-US-00001 TABLE 1a Control 1 EDA1 EDA2 EDA3 EDA4 EDA5 EDA6 EDA7 EDA8 Ingredient (g) (g) (g) (g) (g) (g) (g) (g) (g) MMA 0.780 0.780 0.780 0.780 0.780 0.780 0.780 0.780 0.780 MAA 0.100 0.100 0.100 0.100 0.100 0.100 0.100 0.100 0.100 EGDMA 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 PEG-MEA 0.100 0.100 0.100 0.100 0.100 0.100 0.100 0.100 0.100 AIBN 0.061 0.073 0.073 0.077 0.069 0.065 0.069 0.069 0.061 HEXMIM StSO3 0.623 0.208 0.104 0.052 0.208 0.312 (1.78 (0.59 (0.30 (0.15 (0.59 (0.89 mmol) mmol) mmol) mmol) mmol) mmol) ViEIM NTf2 0.717 0.717 0.359 0.180 0.240 0.120 (1.78 (1.78 (0.89 (0.44 (0.59 (0.30 mmol) mmol) mmol) mmol) mmol) mmol) Copolymer PE 0.463 (1.16 mmol)

TABLE-US-00002 TABLE 1b EDA9 EDA10 EDA11 EDA12 Control 2 EDA13 Control 3 EDA14 Ingredient (g) (g) (g) (g) (g) (g) (g) (g) MMA 0.780 0.780 0.780 0.780 0.630 0.630 MAA 0.100 0.100 0.100 0.100 0.100 0.100 0.100 0.100 EGDMA 0.020 0.020 0.020 0.020 0.020 0.020 0.020 0.020 PEG-MEA 0.100 0.100 0.100 0.100 0.100 0.100 0.100 0.100 BENZYL MA 0.780 0.780 0.150 0.150 AIBN 0.061 0.061 0.061 0.073 0.039 0.047 0.057 0.065 HEXMIM StSO3 0.052 0.052 0.052 0.105 0.105 (0.15 (0.15 (0.15 mmol) mmol) mmol) ViEIM NTf2 0.179 0.179 0.179 0.359 0.359 (0.44 (0.44 (0.44 mmol) mmol) mmol) BMIM NTf2 0.012 0.20 Carbon Black 0.012 PEG-400 0.012

[0212] The bracketed amounts given in Table 1a & 1b for the polymerizable electrolyte are in millimoles (mmol).

[0213] The Controls 1, 2 and 3 are constituted by the non-ionic matrix monomers that form the adhesive without any ionic species. Formulations EDA1 to EDA7, EDA9 to EDA11 and EDA13 to EDA14 are based on the copolymerization of the non-ionic matrix monomers with polymerizable ionic compounds.

[0214] EDA8 is a blend of the non-ionic matrix monomers and a cured polymerizable electrolyte (PE) copolymer and was obtained in the following way: first, ViEIM NTf2 (0.359 g) and HexMIM StSO3 (0.104 g) were speed-mixed with azobisisobutyronitrile (0.008 g) at 3600 rpm for one minute; the mixture was then cured for 15 minutes at 80° C. followed by 2 hours at 120° C.; and, finally, the cured material was mixed with the non-ionic matrix monomers and azobisisobutyronitrile.

[0215] EDA12 forms a reference and is based on a mixture of the non-ionic matrix monomers with a non-polymerizable ionic compound (BMIM NTf2).

[0216] The application substrate for the following Formulations EDA1 to EDA14 and the Controls was aluminium (AA6016) having a thickness of 1.25 mm and application of the coating composition was performed using glass beads having a diameter of from 100 to 200 microns as spacers. The substrate was cut into samples of 2.5 cm×10 cm in size for tensile testing. Tensile lap shear (TLS) test was performed at room temperature based upon ISO 4587 Adhesives—Determination of tensile lap-shear strength of rigid-to-rigid bonded assemblies (International Organization for Standardization, 2003). The bond overlapping area for each stated substrate was 2.5 cm×1.0 cm with a bond thickness of 0.1 cm (40 mil). An INSTRON 3366 with a 10 kN cell was employed.

[0217] The applied adhesive compositions were cured in the overlapping region by the application of a temperature of 80° C. for 15 minutes and 120° C. for 120 minutes. The bonded structures were then stored at room temperature for 24 hours prior to initial tensile testing.

Example 1

[0218] Tensile lap shear strength was investigated after said 24 hour storage period both prior and subsequent to the application of a constant potential of 50 V across the adhesive layer for a duration of 30 minutes. The results are documented in Table 2 herein below.

TABLE-US-00003 TABLE 2 Initial Bond Strength Bond Strength after Adhesive (MPa) 50 V, 30 minutes (MPa) Control 1 2.03 (±0.59) 2.11 (±0.28) EDA1 3.67 (±0.56) 3.15 (±0.06) EDA2 2.18 (±0.36) 1.48 (±0.20) EDA3 3.44 (±0.31) 0 EDA4 3.07 (±0.58) 0.71 (±0.62) EDA5 2.63 (±0.51) 1.10 (±0.23) EDA6 2.66 (±0.34) 1.71 (±0.12) EDA7 3.85 (±0.71) 2.80 (±0.63) EDA8 2.09 (±0.13) 2.08 (±0.33) EDA9 2.61 (±0.09) 0.97 (±0.09) EDA10 1.98 (±0.41) 0 EDA11 2.35 (±0.11) 0 EDA12 1.60 (±0.60) 0 (Reference) Control 2 1.76 (+0.77) 1.17 (±0.61) EDA13 2.60 (±0.54) 1.54 (±0.12) Control 3 1.53 (±0.63) 2.32 (±0.45) EDA14 2.67 (±0.86) 0

[0219] Formulations containing polymerizable ionic compounds increase the initial adhesive strength. The bond strength of formulations based on the copolymerization of polymerizable ionic compounds and the non-ionic matrix monomers decreases after applying a voltage.

Example 2

[0220] This example investigates the electro-delamination behavior of the afore-described adhesive formulation EDA5 by measurement of tensile lap shear strength after said 24 hour storage period both prior to and subsequent to the application of different constant potentials across the adhesive layer for a duration of 30 minutes. The results are documented in Table 3 herein below.

TABLE-US-00004 TABLE 3 Initial Bond Bond Strength after Bond Strength after Bond Strength after Strength 20 V, 30 minutes 50 V, 30 minutes 80 V, 30 minutes Adhesive (MPa) (MPa) (MPa) (MPa) Control 2.03 (±0.59) 2.11 (±0.28) EDA5 2.63 (±0.51) 1.59 (±0.22) 1.10 (±0.23) 0

Example 3

[0221] This example investigates the electro-delamination behaviour of certain of the afore-described adhesives by measurement of tensile lap shear strength after said 24 hour storage period and after a 2 month storage period both prior and subsequent to the application of a constant potential of 50 V across the adhesive layer for a duration of 30 minutes. The results are documented in Table 4 herein below.

TABLE-US-00005 TABLE 4 Bond Strength after Initial Bond Bond Strength after Bond Strength after 2 Months Aging Strength 50 V, 30 minutes 2 Months Aging 50 V, 30 minutes Adhesive (MPa) (MPa) (MPa) (MPa) Control 2.03 (±0.59) 2.11 (±0.28) EDA5 2.63 (±0.51) 1.10 (±0.23) 2.34 (±0.03) 0.97 (±0.42) EDA11 2.35 (±0.11) 0 2.30 (±0.26) 0 EDA12 1.60 (±0.60) 0 0 0 (Reference)

[0222] Formulations based on the copolymerization of the non-ionic matrix monomers with polymerizable ionic compounds maintain the initial bond strength after two months and still show a decrease of the bond strength after applying a voltage.

[0223] Preparation of a second set of Formulations: The formulations EDA15 to EDA19 plus the Control 4 are described in Table 5 herein below were formed under mixing.

TABLE-US-00006 TABLE 5 Control 4 EDA15 EDA16 EDA17 EDA18 Reference EDA19 Ingredient (g) (g) (g) (g) (g) (g) CN966H90 0.600 0.600 0.600 0.600 0.600 0.600 HEMA 0.340 0.340 0.340 0.340 0.340 IBOA 0.340 SR9054 0.060 0.060 0.060 0.060 0.060 0.060 BPO 0.040 0.040 0.040 0.040 0.040 0.040 HEXMIM StSO3 0.208 0.208 0.312 EMIM Acrylate 0.108 ViEIM NTf2 0.717 0.717 0.717 ViEIM MMS 0.760 BMIM NTf2 0.231

[0224] The Control 4 is constituted by the non-ionic matrix monomers that form the adhesive without any ionic species. Formulations EDA15 to EDA18 are based on the copolymerization of the non-ionic matrix monomers with polymerizable ionic compounds.

[0225] EDA19 forms a reference and is based on a mixture of the non-ionic matrix monomers with a non-polymerizable ionic compound (BMIM NTf2).

[0226] The application substrate for the following Formulations EDA15 to EDA19 and Control 4 was aluminium (AA6016) having a thickness of 1.25 mm and stainless steel (1.4301) having a thickness of 1.5 mm and application of the coating composition was performed using glass beads having a diameter of from 100 to 200 microns as spacers. The substrate was cut into samples of 2.5 cm×10 cm (1″×4″) in size for tensile testing. Tensile lap shear (TLS) test was performed at room temperature based upon ISO 4587 Adhesives—Determination of tensile lap-shear strength of rigid-to-rigid bonded assemblies (International Organization for Standardization, 2003). The bond overlapping area for each stated substrate was 2.5 cm×1.0 cm with a bond thickness of 0.1 cm (40 mil). A Zwick Z020 with a 20 kN cell was employed.

[0227] The applied adhesive compositions were cured in the overlapping region by the application of a temperature of 80° C. for 15 minutes and 120° C. for 30 minutes. The bonded structures were then stored at room temperature for 24 hours prior to initial tensile testing.

Example 4

[0228] Tensile lap shear strength was investigated after said 24 hour storage period both prior and subsequent to the application of a constant potential of 50 V across the adhesive layer for a duration of 30 minutes. The results are documented in Table 6 herein below.

TABLE-US-00007 TABLE 6 Aluminium Stainless Steel Initial Bond Bond Strength after Initial Bond Bond Strength after Strength 50 V, 30 minutes Strength 50 V, 30 minutes Adhesive (MPa) (MPa) (MPa) (MPa) Control 4 11.02 (±0.39) 11.19 (±0.46)  11.05 (±0.54)  10.58 (±0.10) EDA15 12.38 (±0.64) 0 9.19 (±1.03) 0 EDA16 9.76 (±0.17) 4.39 (±0.12) Not tested Not tested EDA17 5.82 (±0.14) 0 Not tested Not tested EDA18 10.54 (±0.04) 2.86 (±0.03) Not tested Not tested EDA19 6.03 (±0.39) 0 6.46 (±0.62) 0

[0229] Formulations EDA15 and EDA18 containing polymerizable ionic compounds maintains the initial adhesive strength, while formulation EDA17 saw a drop in initial strength. Formulation EDA19 containing a non-polymerizable ionic liquid sees a drop in initial strength by 50%. The bond strength of formulations based on the copolymerization of polymerizable ionic compounds and the non-ionic matrix monomers decreases after applying a voltage.

Example 5

[0230] This example investigates the electro-delamination behavior of certain of the afore-described adhesives (EDA15 in comparison with EDA19) by measurement of tensile lap shear strength after said 24 hour storage period and after 1 week, 1 month, 2 months and 3 months storage period both prior and subsequent to the application of a constant potential of 50 V across the adhesive layer for a duration of 30 minutes. A climatized chamber was used set to 23° C. and 50% relative humidity. The results are documented in Tables 7 and 8 herein below.

TABLE-US-00008 TABLE 7 Aluminium EDA19 EDA15 Bond Strength after Initial Bond Bond Strength after Bond Strength after 2 Months Aging Strength 50 V, 30 minutes 2 Months Aging 50 V, 30 minutes Storage Time (MPa) (MPa) (MPa) (MPa) Initial 12.38 (±0.64) 0 6.03 (±0.39) 0 1 week 12.45 (±0.56) 0 5.83 (±0.38) 0 1 month 10.00 (±0.88) 0 4.48 (±0.95) 0 2 months 10.94 (±0.20) 0 4.18 (±0.16) 0 3 months 11.03 (±1.43) 0 Not tested Not tested

TABLE-US-00009 TABLE 8 Stainless Steel EDA19 EDA15 Bond Strength after Initial Bond Bond Strength after Bond Strength after 2 Months Aging Strength 50 V, 30 minutes 2 Months Aging 50 V, 30 minutes Storage Time (MPa) (MPa) (MPa) (MPa) Initial 9.19 (±1.03) 0 6.46 (±0.62) 0 1 week 9.38 (±0.69) 0 5.46 (±0.33) 0 1 month 9.09 (±1.75) 0 4.25 (±0.30) 0 2 months 8.51 (±0.51) 0 4.58 (±0.21) 0 3 months 8.13 (±0.28) 0 Not tested Not tested

[0231] Formulation EDA15 based on the copolymerization of the non-ionic matrix monomers with polymerizable ionic compounds show a slight decrease in bond strength after three months (12%). Formulation based on the mixture of a non-polymerizable ionic liquid and non-ionic matrix monomers show a higher decrease in bond strength after two months of 30% for both aluminium and stainless steel. All formulations show a decrease of the bond strength after applying a voltage.

[0232] In view of the foregoing description and examples, it will be apparent to those skilled in the art that equivalent modifications thereof can be made without departing from the scope of the claims.