Anti-corrosion adhesive device

Abstract

The present invention relates to a device comprising an electro-responsive adhesive whose adhesive properties can be modified from a bonded state to a debonded state by a first electric stimulus, and which can be modified from a debonded state to a bonded state by a second electric stimulus, the first and second electric stimulus being different from each other, and an electrically conductive substrate or backing to which the adhesive is adhered, wherein the device satisfies one, two, or all of the following: i) the open circuit potential between the adhesive and the backing and / or the substrate is 100 mV or less; ii) the device comprises an anti-corrosion agent that can undergo a reversible electrochemical reaction, which is present within the adhesive and / or between the adhesive and the substrate and / or the backing; iii) the adhesive comprises one or more selected from the group consisting of an anti-corrosion agent, a drying agent and oxygen scavenger. The device offers enhanced electrochemical stability, improved conductivity, and superior corrosion resistance through the strategic selection of suitable materials, enabling efficient and reversible adhesion control in electrically triggered applications.

Description

[0001] tesa SE Norderstedt

[0002] ANTI-CORROSION ADHESIVE DEVICE

[0003] TECHNICAL FIELD

[0004] The present invention relates to a device comprising an electro-responsive adhesive and an electrically conductive substrate or backing to which the adhesive is adhered, and which is capable or reducing, or fully avoiding, corrosion of the electrically conductive substrate or backing.

[0005] BACKGROUND ART

[0006] Electrically debondable adhesive devices have gained attention for their ability to enable on-demand, removal of adhesive layers through the application of an electrical stimulus. These devices typically comprise a conductive backing, an electro-responsive adhesive layer, and in some cases, a conductive or redox active interlayer. In use, such devices are adhered to an electrically conductive substrate, often a metal substrate, by the adhesive action of the electro-responsive adhesive. Upon application of an electric stimulus, e.g. a direct current (DC) voltage, the adhesive's bond strength decreases significantly ("debonding"), allowing for easy separation of the adhesive from the substrate. This technology is particularly useful in applications requiring reworkability, recyclability, and demounting assemblies. A further advantage is that due to the low adhesive strength in the debonded state, the risk of damaging the substrate surface upon removal of the adhesive from the substrate is limited.

[0007] Several prior art disclosures describe adhesive devices wherein the electro-responsive adhesive comprises ionic liquids and polyacrylates, and the device comprises an electrically conductive backing on which the electro-responsive adhesive is provided. For example, WO2023 / 165966 Al and US2023 / 303894 Al disclose devices wherein the electro- responsive adhesive is a pressure-sensitive adhesives (PSAs) that comprises ionic components and crosslinkers, where debonding occurs preferentially at the anode or cathode side depending on the system configuration. The adhesive compositions used in such devices typically cause or even rely on electrochemical reactions at the substrate interface, which may lead to irreversible changes in the substrate's surface, including corrosion and loss of conductivity. WO2024 / 204367 Al discloses electrically debondable adhesive tapes relying on a PSA (pressure-sensitive adhesive) as electro-responsive adhesive and which are said to exhibit improved weathering stability. The disclosed tape comprises polyacrylates, ionic liquids, crosslinking agents and a backing film. The backing film is produced by applying either organic or inorganic coatings onto a polyethylene terephthalate (PET) film having a thickness of 100 pm. The resulting backing films exhibit a surface resistivity in the range of 75-200 / sqr at a total light transmission of 70-93% and a coating thickness of 350-550 nm. The tapes prepared using these backing films are intended for debonding from conductive surfaces at the cathode side under conditions of high humidity. While these systems demonstrate improved environmental durability, they continue to exhibit limitations with respect to corrosion protection and reversibility.

[0008] CN104910752B shows a nanocomposite material comprising polyaniline and graphene dispersed within a thermally cured epoxy adhesive matrix. While such composites offer potential for corrosion protection, they exhibit poor dispersibility and limited compatibility within highly crosslinked polymer networks. Furthermore, the use of polyaniline as a corrosion inhibitor under prolonged or severe environmental conditions is not recommended, as its degradation products are known to be carcinogenic.

[0009] JP5700572B2 describes an anti-corrosion coating layer that is free of chromium-based metals. In this disclosure, thermally cured epoxy coatings are formulated with magnesium oxide particles having a particle size of less than 100 microns. The patent further proposes the use of primers based on organic polymers as a means to enhance corrosion resistance. In summary, as exemplified with the aforementioned existing solutions still face challenges and leave metal substrates result in corrosion particularly under harsh environmental and electrochemical conditions. There is a need for easily applicable examples that prevent the metal substrates under oxidizing conditions.

[0010] TECHNICAL PROBLEM

[0011] Corrosion and oxidation of surfaces, e.g. corrosion of metallic surfaces, presents a persistent challenge across various industrial domains, particularly where materials are exposed to environmental stressors such as pH, ionic strength, humidity and temperature. To name a few of these; in automotive applications, metal substrates such as those found in chassis components and battery enclosures are vulnerable to degradation due to moisture and electrolyte exposure. Especially battery systems, including those used in electric vehicles and stationary energy storage, are subject to corrosion risks due to electrolyte leakage and thermal cycling. In aerospace environments, the use of lightweight alloys introduces susceptibility to galvanic corrosion, especially in areas exposed to humidity or altitude-induced condensation.

[0012] Another common daily life example is the railway systems which operate under fluctuating thermal and mechanical loads, often in humid or polluted conditions that accelerate corrosion. Additionally, a highly corrosive environment is frequently encountered in marine applications where continuous exposure to saltwater and atmospheric moisture leads to rapid corrosion of metal surfaces. Stationary surfaces of ships such as hulls, superstructures, and submerged elements are the very first areas corroded in time.

[0013] In electronic assemblies, particularly in printed circuit boards (PCBs), corrosion at metal traces and contact points can lead to signal degradation and device failure. These contact points need corrosion protection from moisture and contaminants so that these components are shielded during manufacturing or rework processes.

[0014] In renewable energy systems, such as photovoltaic panels and wind turbines, metal frames and connectors are continuously exposed to outdoor conditions that promote corrosion. These devices undergo cycles of humidity and thermal change during the year, and protective layers or functional elements are applied onto these structures, offering environmental sealing. In the construction sector, facade panels, cladding systems, and architectural metal elements are often subject to weathering, condensation, and pollution- induced corrosion. These metal elements are coated with corrosion protecting primer layers before the application of paint providing a corrosion-inhibiting interface that also accommodates reversible installation.

[0015] Electrically controllable adhesive devices may be employed to enable reversible adhesion while simultaneously forming a barrier that inhibits corrosion. Electrically controllable adhesive devices offer the dual functionality of enabling reversible adhesion and providing a protective barrier against corrosion. In electronic assemblies, electrically controllable adhesives can serve as sealing and joining layers that can be electrically debonded and subsequently rebonded on demand. This capability supports non-destructive disassembly for repair and component replacement, as well as end-of-life separation for recycling and material recovery— all while maintaining corrosion protection during service. Electrically controllable adhesives are particularly valuable for assembling batteries, displays, camera and sensor modules, and connectors in electronic devices, where controlled debonding and rebonding enhance repairability, refurbishment, and circularity.

[0016] However, current electrically controllable adhesive formulations still exhibit corrosion issues, either on the backing or on the substrate, which remains a critical barrier to broader adoption. Despite this limitation, these devices significantly facilitate maintenance operations and reapplication without compromising surface integrity and are especially relevant in electronic systems, where internal contact points require robust protection against electrochemical degradation.

[0017] To this end, as a first example application, temporary sensor mounts and surveillance devices require secure yet reversible adhesion to metallic structures in outdoor or industrial settings. An adhesive device may be used to affix such equipment to surfaces exposed to moisture, temperature variation, or chemical contaminants, while simultaneously protecting the underlying metal from corrosion. This enables rapid deployment and retrieval of instrumentation without leaving residues or causing surface damage. The device's dual function supports both operational flexibility and long-term preservation of host structures.

[0018] Furthermore, while an adhesive device (such as an adhesive tape) may protect an underlying substrate surface against environmental factors that cause or facilitate corrosion, such as moisture and oxygen, often the adhesive itself may be a cause of oxidation or degradation of the substrate surface. That is, in addition to the technical nature of the corrosion problem in the aforementioned applications, corrosion is regularly observed with the current electrically debondable adhesive systems — particularly their irreversible degradation of conductive substrates due to electrochemical corrosion.

[0019] OBJECT OF THE INVENTION

[0020] The present inventors have developed an adhesive device capable of mitigating or solving one or more of the above problems. This adhesive device can operate by reversible adhesion and debonding while simultaneously protecting the substrate from corrosion, while also mitigating the problems that may occur due to interaction of the substrate surface with the adhesive.

[0021] SUMMARY OF INVENTION

[0022] The present invention is based on the finding that by carefully designing the adhesive device and selecting appropriate materials— specifically a redox-active interfacial layer composed of conjugated polymers such as PEDOT with optimized counterions— it is possible to solve or mitigate the dual challenges of substrate corrosion and irreversible debonding in electrically controllable adhesive systems. The adhesive properties of the device can be modulated between at least one first adhesive state and one second adhesive state through the application of an electrical stimulus. The invention enables reversible adhesion through redox transitions in a PEDOT layer, maintaining the electrochemical oxidation state of the conductive substrate unchanged during activation, thereby delivering a corrosion-inhibiting, reworkable adhesive solution for long-term substrate preservation in industrial applications.

[0023] In order to achieve one or more of the above objects, the present invention provides the following:

[0024] 1. A device comprising: an electro-responsive adhesive whose adhesive properties can be modified from a bonded state to a debonded state by a first electric stimulus, and which can be modified from a debonded state to a bonded state by a second electric stimulus, the first and second electric stimulus being different from each other, and an electrically conductive substrate or backing to which the adhesive is adhered, wherein the device satisfies one, two, or all of the following: i) the open circuit potential between the adhesive and the backing and / or the substrate is 100 mV or less; ii) thedevice comprises an anti-corrosion agent that can undergo a reversible electrochemical reaction, which is present within the adhesive and / or between the adhesive and the substrate and / or the backing; iii) the adhesive comprises one or more selected from the group consisting of an anti-corrosion agent, a drying agent and oxygen scavenger.

[0025] 2. The device according to embodiment 1, wherein the anti-corrosion agent comprises one or both an oxygen scavenger and a corrosion inhibitor.

[0026] 3. The device according to embodiment 1 or 2, wherein the difference in open circuit potential is achieved by providing a conducting layer between the adhesive and the substrate and / or the adhesive and the backing, and or by including an additive for modifying the open circuit potential of the adhesive, preferably in an amount of 10% by weight or less, relative to the total weight of the adhesive.

[0027] 4. The device according to embodiment 1, 2 or 3, wherein the anti-corrosion agent that can undergo reversible electrochemical reaction is present in the form of a corrosion- protective layer on the substrate and / or the backing. 5. The device according to any one of embodiments 1 to 4, wherein the anti-corrosion agent has a lower standard reduction potential than the material forming the electrically conductive substrate or the backing, the absolute difference in standard reduction potentials preferably being 100 mV or more, such as 300 mV or more or 500 mV or more.

[0028] 6. The device according to any one of embodiments 1 to 5, wherein a corrosion protective layer is formed on the substrate and / or the backing, which is made from a metal oxide, which may be a spontaneously formed oxide layer or an oxide layer formed by anodic oxidation, from a metal having a standard reduction potential of 0V or less, such as -0.2 V or less or -0.5 V or less, for example zinc or magnesium, or from an alkali metal or earth alkali metal halide, such as CaFz.

[0029] 7. The device according to any one of the preceding embodiments, wherein the anticorrosion agent that can undergo a reversible electrochemical reaction is present in the form of a coating on the backing and / or the substrate, the coating preferably being a polymer coating, the polymer coating preferably being electrically conductive.

[0030] 8. The device according to any of the preceding embodiments, which exhibits an adhesive strength in the bonded state of 0.5 N / cm to 15 N / cm or higher, such as 25 N / cm or higher or 40 N / cm, and an adhesive strength in the debonded state of 0.1 to 0.4 N / cm.

[0031] 9. The device according to any one of the preceding embodiments, wherein the electric stimulus is selected from the group consisting of an alternating current (AC), an alternating voltage, a direct current (DC), a direct voltage, or a pulsed current or voltage, which preferably is a DC or AC current or voltage in the range of 0.5 - 230 V, preferably a DC voltage in the range of 5 to 100 V or 5 to 20 V.

[0032] 10. The device according to any one of the preceding embodiments, which is in the form of an adhesive tape comprising a backing and an adhesive layer comprising the adhesive, and wherein preferably the backing is an electrically conductive backing, such as for example a metal foil, an electrically conductive polymer, or on insulating polymer that has been treated to impart electrical conductivity, e.g. by providing a metallic film on a polymer foil. The device according to any one of the preceding embodiments, wherein the pressure sensitive adhesive has ionic conductivity, preferably, in the range of 1010S / cm to 10-3S / cm, and / or comprises one or more ionic liquids and / or one or more salts that are no ionic liquids, preferably a lithium salt. The device according to any one of the preceding embodiments, wherein the pressure sensitive adhesive is prepared by polymerizing a mixture comprising at least the following components: a) 35 to 70 wt % of acrylate monomer (al) from the group of (meth)acrylic esters containing at least one oxygen atom; and b) 20 to 40 wt % of acrylate monomer (a 2) from the group of (meth)acrylic esters and / or amides containing at least one nitrogen atom; and c) 0.1 wt % to 15 wt % of one or more electro-responsive compounds from the group of polymerizable zwitterionic monomers and / or non-polymerizable zwitterionic compounds, preferably one or more zwitterionic monomers; and d) 0.005 to 10 wt % of at least one initiator; and e) 0 wt % to 20 wt % of one or more ionic liquids; and f) 0.1 wt % to 20 wt % of one or more salts that are no ionic liquids; and g) Optionally 1 wt % to 20 wt % by weight of one or more acrylate monomers (a 3), wherein the one or more acrylate monomers (a3) are different from acrylate monomers (al) and (a2); and h) optionally additives, wherein the weight fractions of the components are based on the total weight of the mixture. The device according to any one of the preceding embodiments, wherein the adhesive is selected from the group consisting of acrylic-based adhesives, urethane- based adhesives, rubber-based adhesives, vinyl-based adhesives, epoxy-based adhesives, silicone-based adhesives, and mixtures thereof, and which is preferably a pressure-sensitive adhesive. Use of the device as set out in any of the preceding embodiments in an assembly process of electric or electronic devices, the electric or electronic devices preferably being selected from the group consisting of computers, chips, smartphones, displays, touch panels, sensors, light sources such as LEDs or OLEDs, power supply units, or other electronic devices. Further aspects and features of the present invention will become apparent from the following description.

[0033] DEFINITIONS

[0034] The "comprising" is used open-endedly and requires the presence of the recited components of features, while additional components of features are not excluded. The term however also encompasses the more restrictive meanings "consisting of" and "consisting essentially of", unless the context dictates otherwise. The term "consisting essentially of" requires the presence of other features or components and allows for the presence of other features or components as long as the objects of the present invention are not impaired.

[0035] The present invention embraces all the features which are subjects of any dependent claims. Further, the present invention embraces combinations of individual features with one another, including at different preference levels. The present invention thus embraces, for example, the combination of a first feature identified as being "preferred" with a second feature identified as being, e.g., "particularly preferred". In this context, subjects identified as part of "embodiments", likewise at different preference levels, are also embraced. In other words, where the present description refers to different levels of preferences, combinations of these preferred embodiments and / or features shall also be deemed as disclosed if this combination is technically meaningful.

[0036] Whenever ranges are specified below, the upper and lower limit are included, as is any value in between.

[0037] Physical properties referred to below are generally determined at 25 °C and 1 atm pressure, unless a specific test method is indicated or the circumstances require otherwise. Properties can be determined by methods known in the art or by specific test methods indicated below. In case of discrepancy, the specific test methods below prevail.

[0038] The terms "first", "second", "third", etc. are used in the present invention to distinguish between different elements, states or properties. These terms are not to be understood as implying any particular order of elements, magnitude of a physical state or property or sequence of steps. In the present invention, a "second" element or state could be named "first" element or state, and vice versa, without changing the subject matter.

[0039] A "device" in the context of the present application is characterized in that it comprises an electro-responsive adhesive whose adhesive properties can be modified from a bonded state to a debonded state by a first electric stimulus, and which can be modified from a debonded state to a bonded state by a second electric stimulus, the first and second electric stimulus being different from each other, and an electrically conductive substrate or backing to which the adhesive is adhered. The device may comprise either one of the backing or substrate, but may also include both a backing and a substrate. The device may take the form of an adhesive tape, where the backing is formed from any material, including plastic films that inherently have of which have been treated to have electrical conductivity. The substrate is typically part of an adherent to which the adhesive is adhered (e.g. a member to be protected against corrosion), and may be made from metal or steel, or may possess a metal or steel surface.

[0040] The device may take any form or shape, and it may also contain additional components.

[0041] In one embodiment, the device is a tape, i.e. an adhesive tape. In the embodiment of an adhesive tape, the device contains at least a backing, which preferably is transparent or translucent. The backing may be coated with a primer. The primer or the electrochromic backing may be electrically conductive.

[0042] The adhesive tape may take any desired converted form, with adhesive tape rolls being preferred. The adhesive tape, more particularly in web form, may be produced either in the form of a roll, i.e., in the form of an Archimedean spiral rolled up onto itself, or as an adhesive strip, of the kind obtained in the form of die-cuts, for example.

[0043] The device may be a capacitive-like device, for example wherein an adhesive layer is disposed on an electrically conductive backing and / or an electrically conductive substrate / adherend, or two electrically conductive substrates sandwiching the adhesive (which may be a PSA), with or without interposing elements such as additional layers.

[0044] The adhesive tape according to one embodiment of the present invention is present more particularly in web form. A web refers to an object whose length (extent in x direction) is greater by a multiple than its width (extent in y direction), e.g., by a x:y ratio of at least 10:1, and the width is approximately, preferably exactly, the same along the entire length.

[0045] The general expression "adhesive tape" synonymously also called "adhesive strip", in the sense of the present invention encompasses all sheetlike structures, such as two- dimensionally extended films or film portions, tapes with extended length and limited width, tape portions and the like, lastly also die cuts or labels. As well as the lengthwise extent (x direction) and widthwise extent (y direction), the adhesive tape also has a thickness (z direction), extending perpendicularly to both extents, with the widthwise extent and lengthwise extent being greater by a multiple than the thickness. The thickness is extremely similar, preferably exactly the same, over the entire two-dimensional extent of the adhesive tapes as defined by length and width. The statements apply analogously to the carrier, which as an integral constituent of the adhesive tape forms a layer in x and y directions. It will be appreciated that the individual layers are disposed one atop another along the z direction.

[0046] A pressure sensitive adhesive or adhesive composition is understood in the invention, as is customary in the general usage, as a material which at least at room temperature is permanently tacky and also adhesive. A characteristic of a pressure sensitive adhesive is that it can be applied by pressure to a substrate and remains adhering there, with no further definition of the pressure to be applied or the period of exposure to this pressure. In general, though in principle dependent on the precise nature of the pressure sensitive adhesive and also on the substrate, the temperature and the atmospheric humidity, the influence of a minimal pressure of short duration, which does not go beyond gentle contact for a brief moment, is enough to achieve the adhesion effect, while in other cases a longer- term period of exposure to a higher pressure may also be necessary.

[0047] Pressure sensitive adhesives have particular, characteristic viscoelastic properties which result in the permanent tack and adhesiveness. A feature of these adhesives is that when they are mechanically deformed, there are processes of viscous flow and there is also development of elastic forces of recovery. The two processes have a certain relationship to one another in terms of their respective proportion, in dependence not only on the precise composition, the structure and the degree of crosslinking of the pressure sensitive adhesive, but also on the rate and duration of the deformation, and on the temperature.

[0048] The proportional viscous flow is necessary for the achievement of adhesion. Only the viscous components, frequently brought about by macromolecules with relatively high mobility, permit effective wetting and effective flow onto the substrate where bonding is to take place. A high viscous flow component results in high pressure sensitive adhesiveness (also referred to as tack or surface stickiness) and hence often also in high adhesion. Highly crosslinked systems, crystalline polymers, or polymers with glasslike solidification lack flowable components and are in general devoid of tack or possess only little tack at least.

[0049] The proportional elastic forces of recovery are necessary for the achievement of cohesion. They are brought about, for example, by very long-chain macromolecules with a high degree of coiling, and also by physically or chemically crosslinked macromolecules, and they allow the transmission of the forces that act on an adhesive bond. As a result of these forces of recovery, an adhesive bond

[0050] The term "initial bonding or "initially bonded" or "initial adhesive strength" refers to the adhesion strength of the adhesive measured by Test A (Peel Adhesion) outlined below without and prior to applying any electric stimulus.

[0051] The term "bonding" refers to the application of an electric stimulus that leads to an increase in adhesion strength of the adhesive, as measured by Test A (described below), compared to its initial bonding state. A "bonded adhesion strength" refers to the adhesion strength that is observed after the stimulus has been applied.

[0052] The term "debonding" refers to the application of an electric stimulus that reduces adhesion strength as compared to the "bonded" adhesion strength, as measured by Test A (described below). A "debonded adhesion strength" denotes the adhesion strength that is observed after an electric stimulus (e.g. voltage) for debonding (i.e. for reducing adhesive strength) has been applied. The adhesive strength of a debonded adhesive is lower than the initial adhesive strength. The term also encompasses a reduction of the bond strength after it has been increased by an electric stimulus (bonding), back to its initially bonded adhesive strength or lower to allow for easy removal.

[0053] The term "rebonding" or "rebonded" refers to the adhesive strength of the adhesive as measured by Test A when or after a debonded adhesive is subjected to a (second) electric stimulus (e.g. voltage) that changes / modifies the adhesive properties such as to increase adhesive strength as compared to the adhesive strength before the electric stimulus is applied. The rebonded adhesive strength is higher than the debonded adhesion strength, and may be lower, higher or the same as the initial adhesive strength, and is typically higher than the initial adhesive strength.

[0054] The term "rebonding" thus refers to the third step in a sequence including subsequently initial bonding, debonding and rebonding, but also encompasses any further rebonding performed subsequently thereafter, e.g. in subsequent debonding-rebonding cycles, such as bonding-debonding-(first) rebonding-debonding- (second) rebonding, etc. The term "cycle" is defined as including at least the sequence: bonding-debonding, and a device of the present application may be suitable for 2, 3, 4, 5 or more of such cycles without a loss of adhesive strength in the second, third, or fourth rebonded state as compared to the adhesive strength in the first debonding, or with a loss of adhesive strength that is less than 20%, preferably less than 10% in the second and third rebonding as compared to the first rebonding, each based on the same electric stimulus (voltage, duration, polarity) for each rebonding step.

[0055] The term "ionic conductivity" refers to the conductivity that is caused by the movement of ions, e.g. in an adhesive layer, under an electromotive force (e.g., DC voltage), where the cations and anions are the charge carriers. In the present invention, the ionic conductivity may be determined by methods known in the art or by Test B: Ionic Conductivity set out below. In case of discrepancy, the result obtained by Test B prevails.

[0056] The term "adhesive property" denotes any property of an adhesive that is of relevance in practice to exert the adhesive function. The adhesive property may in particular refer to the adhesive strength, determined in N / cm as determined by Test A below.

[0057] The term "adhesive state" denotes the state of the adhesive, such as a PSA, in particular in relation to its adhesive properties. The adhesive state may be characterized by the adhesive strength as determined by the below Test A (Peel adhesion). In this meaning, a "first" and "second" adhesive state denote different adhesive strengths of the adhesive, and a "first" adhesive strength may be lower or higher than a "second" adhesive strength. In order to qualify as different adhesive states, e.g., as "first" and "second" adhesive states, the absolute difference in adhesive strength between the states may be 0.1 N / cm or more, such as 0.3 N / cm or more, 0.5 N / cm or more, 1.0 N / cm or more orl.5 N / cm or more, e.g. 3 N / cm or more, 4 N / cm or more, or 5 N / cm or more.

[0058] The term "electric stimulus" refers to any electric stimulus, and may thus include any current, voltage, polarity, duration, or frequency. The term may denote an alternating current (AC) or a direct current (DC) or a pulsed current and also alternating voltage (AC voltage), direct voltage (DC voltage), or pulsed voltage

[0059] The alternating current may have a sinusoidal waveform or may have a rectangular wave form, and the shape of the waveform is not particularly limited. In one embodiment, the electric stimulus has a voltage of 1 to 100 V, such as 5 to 50 V, 5 to 20 V, or 10 to 50 V, and may be a AC or DC voltage, and preferably is a DC voltage. The duration of the electric stimulus is not particularly limited and may be from 0.1 to 10,000 seconds, such as from 30 to 1000 seconds or from 30 to 300 seconds. For testing whether an adhesive has adhesive properties that can be modified from a bonded state to a debonded state by a first electric stimulus, and which can be modified from a debonded state to a bonded state by a second electric stimulus, an electric stimulus as a direct current of 50 V for 1000 seconds may be employed. Of course, also lower voltages for a shorter period of time can be employed if thereby a corresponding modification of the adhesive properties can be caused and observed. The polarity of the electric stimulus, e.g. in DC form, is not particularly limited. Amongst others, the polarity may be the decisive factor for an electric stimulus to increase or decrease bonding strength of the electro-responsive adhesive.

[0060] The term "electrically conductive" is well understood by a skilled person. A possible threshold may be defined at a conductivity of 10 S / cm or higher, e.g. 102S / cm or higher or 103S / cm or higher.

[0061] ADHESIVE STATES AND MODIFICATION THEREOF BY AN ELECTRIC STIMULUS

[0062] The device of the present invention comprises an adhesive having at least one first (bonded) and at least one second (debonded) adhesive state. By applying an electric stimulus, the adhesive state can be modified, e.g. can be changed from a first state to a second state, or from a second state to a first state, at least at the side where a substrate or adherend is, or is to be, provided.

[0063] The bonded state may by the initial adhesive state, or a rebonded adhesive state. The initial adhesive state corresponds to the adhesive strength of the adhesive, such as a PSA, prior to any application of an electric stimulus, as tested by Test A described below. The first state may also be a rebonded state, obtained by applying a corresponding electric stimulus to the adhesive in the debonded state. The debonded state is obtained after applying a corresponding electric stimulus to the adhesive in the initial adhesive state of a rebonded adhesive state.

[0064] A rebonded state is generally characterized in that it has an adhesive strength that is equal to or higher than the adhesive strength of the initial adhesive state. A debonded state is generally characterized in that it has an adhesive strength that is lower than the adhesive strength in the initial adhesive state. A rebonded state refers to the adhesive strength of an adhesive that has previously been bonded and debonded, and is then re-bonded, and is characterized by an adhesive strength that is higher than the debonded state and which may be equal to or, preferably, higher than the adhesive strength of the initial adhesive state, and lower, equal to or higher than the bonded state.

[0065] The rebonded state exhibits an adhesive strength that is higher than the debonded state, and lower, equal to, or higher than the bonded state, preferably equal to or higher than the bonded state. The debonded state may exhibit an adhesive strength that is lower than the initial state. The adhesive strength in each bonded state (initial state or rebonded state) may be 0.5 N / cm or higher, e.g. in the range from 0.5 N / cm to 15 N / cm higher, such as 25 N / cm or higher or 40 N / cm or higher. The lower limit may be 0.5 N / cm, but may also be 1.0 N / cm or higher, 1.5 N / cm or higher, or 2.0 N / cm or higher, such as 2.5 N / cm or higher. The adhesive strength in the debonded state is lower than in the bonded state, and may thus be in the range of 0.4 N / cm or less, such as 0.1 to 0.4 N / cm.

[0066] The adhesive state (adhesive strength) of the device of the present invention can be controlled by means of an electric stimulus. As well known to a skilled person, the voltage and in particular the polarity of an applied stimulus determines whether the adhesive strength is increased or decreased, e.g. whether a modification from a bonded to a debonded or from a debonded to a rebonded state occurs. The electric stimulus is typically obtained by providing the device of the present invention on an electrically conductive substrate to which it may be (re)bonded or from which it may be debonded, and / or by using a backing that is electrically conductive.

[0067] An electric stimulus can be obtained and controlled by simple methods, i.e., control of electromotive force (electrochemical stimuli, e.g., application of DC voltage and resulting in movements of charged species within the adhesive), without resorting to certain special conditions such as the use of UV-C radiation, high heat, or high pressure. That allows providing an adhesive device that can not only be debondable from the conductive substrate by electrical stimuli but also can be rebondable, in certain embodiments even with higher bonding strength than initially, just simply by controlling the electromotive force at different (DC) voltages, at different time scales, and polarities.

[0068] While the adhesive used in the present invention is not particularly limited and may e.g. be selected from the group consisting of acrylic adhesives, rubber-based adhesives, silicone adhesives, epoxy adhesives, polyurethane adhesives, cyanoacrylate adhesives, and UV- curable adhesives, in one embodiment, the adhesive used in the device of the present in invention is a pressure-sensitive adhesive (PSA), in particular an acrylic pressure-sensitive adhesive. The PSA preferably contains one or more ionic liquids and optionally one or more salts that are not ionic liquids, in particular lithium salts, in order to increase ionic conductivity. A PSA is particular preferred when the device of the present invention is in the form of an adhesive tape.

[0069] In one embodiment the PSA, e.g. as present in an adhesive tape of the present invention, can be debonded from at least one substrate without remnants upon application of an electric stimulus. Especially, the adhesive strength may be decreased by up to 95% from its initial adhesive strength in less than 60 seconds after the application of an electric stimulus. ADHESIVE

[0070] The adhesive is responsible for binding the device, e.g. in the form of a tape, to a target substrate. The adhesive formulation typically consists of a polymeric matrix that provides structural integrity, combined with a tackifier to enhance initial stickiness (tack), and various additives to modify properties such as flexibility, durability, conductivity, or resistance to environmental conditions. Examples of some adhesive chemistries are acrylic adhesives, rubber-based adhesives, silicone adhesives, epoxy adhesives, polyurethane adhesives, cyanoacrylate adhesives, UV-curable adhesives.

[0071] The present invention is not limited to any adhesive chemistries until some properties are fulfilled as long as the adhesive properties can be modified from at least one first adhesive state to at least one second adhesive state by an electric stimulus. One way to achieve this is to provide for ionic conductivity to improve the electro-responsive properties, better adhesion and cohesion. Here, the ionic conductivity is preferably in the range of 1010S / cm to 10-3S / cm at 25 °C. One way to achieve ionic conductivity is to include an ionic liquid in the adhesive formulation, optionally in combination with a salt that is not ionic liquid, in particular a lithium salt or other salt that is soluble in the formulation.

[0072] Accordingly, in one embodiment, the adhesive used in the device of the present invention comprises one or more selected from acrylic adhesives, rubber-based adhesives, silicone adhesives, epoxy adhesives, polyurethane adhesives, cyanoacrylate adhesives, UV-curable adhesives; an ionic liquid, and optionally a salt that is not ionic liquid. In one embodiment, the adhesive is a PSA that comprises an acrylic adhesive, an ionic liquid, and a salt that is not ionic liquid, which is preferably a lithium salt.

[0073] An ionic liquid is a salt that is in the liquid state at or near room temperature (25 °C). It is made up entirely of ions— typically a bulky, asymmetric organic cation and a weaker coordinating anion. When ionic liquids are incorporated into the adhesive an electrolyte adhesive is formed. This provides ionic conductivity as well as adhesive properties.

[0074] Common cations of ionic liquids are imidazolium, pyridinium, pyrrolidinium, ammonium, phosphonium, cholinium, morpholinium, piperidinium, guanidinium, thiazolium based, and common anions are tetrafluoroborate, hexafluorophosphate, bis(trifluoromethanesulfonyl)imide, trifluoromethanesulfonate, dicyanamide, nitrate, chloride, acetate, hydrogen sulfate, and methanesulfonate. The ionic liquid is preferably selected from the group comprising l-ethyl-3- methylimidazolium bis(fluorosulfonyl) imide (EMIM FSI), l-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (EMIM TFSI), l-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (BMIM TFSI), l-ethyl-3-methylimidazolium thiocyanate (EMIM SCN), l-ethyl-3-methylimidazolium dicyanamide (EMIM DCA), l-ethyl-3- methylimidazolium tetrafluoroborate (EMIM BF4), l-butyl-3-methylimidazolium tetrafluoroborate (BMIM BF4), l-allyl-3-methylimidazolium dicyanamide (AllylMIM DCA), l-allyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (AllylMIM TFSI), l-ethyl-3- vinylimidazolium bis(trifluoromethylsulfonyl) imide (EVIM TFSI), N-methyl-N- propylpyrrolidinium bis(trifluoromethanesulfonyl) imide (Pyrl3 TFSI), N-methyl-N- propylpyrrolidinium bis(fluorosulfonyl) imide (Pyrl3 FSI), N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl) imide (Pyrl4 FSI), l-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide, 1-butyl-l-methylpyrrolidinium dicyanamide (Pyrl4 DCA), 1-butyl-l-methylpyrrolidinium triflate (Pyrl4 OTf), l-Ethyl-3-methylimidazolium triflate (EMIM OTf), l-butyl-3-methylimidazolium triflate (BMIM OTf), 1,3- dimethylimidazolium bis(trifluoromethylsulfonyl) imide (DiMIM BTA), l-butyl-3- methylimidazolium tricyanomethanide (BMIM TCM), l-butyl-3-methylimidazolium methyl sulfate (BMIM MeSO4), 1,3-diethylimidazolium bis(trifluoromethylsulfonyl) imide (DiEIM TFSI), N-butyl-N-methylpyrrolidinium tricyanomethanide (Pyrl4 TCM), diethylmethylsulfonium bis(trifluoromethylsulfonyl) imide (S122 TFSI), l-propyl-4- methylpyridinium bis(trifluoromethylsulfonyl)imide (Pro4Pic TFSI), l-ethyl-3- methylimidazolium ethyl sulfate (EMIM EtS04), triethylsulfonium bis(trifluoromethylsulfonyl) imide (S222 TFSI), l-(2-methoxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (MeOEMIM TFSI), l-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl) imide (PMIM TFSI), 1-butyl-l-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (Pyrl4 TFSI), l-butyl-4-methylpyridinium bis(trifluoromethylsulfonyl) imide, 1,3-dimethylimidazolium methyl sulfate (DiMIM MeSO4), 1-ethylimidazolium bis(trifluoromethylsulfonyl) imide (EIM TFSI), l-ethyl-3- methylimidazolium methanesulfonate (EMIM OMs), l-ethyl-4-methylpyridinium bis(trifluoromethylsulfonyl) imide (Et4Pic TFSI), l-ethyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl) imide (EDiMIM TFSI), 2-methyl-l-propylpyridinium bis(trifluoromethylsulfonyl) imide (Pro2Pic TFSI), l-ethyl-3-methylimidazolium acetate (EMIM OAc), l-ethyl-3-methylimidazolium hexafluorophosphate (EMIM PFe), l-butyl-3- methylimidazolium hexafluorophosphate (BMIM PFe), 1-hexylpyridinium bis(trifluoromethylsulfonyl)imide (HexPy TFSI), l-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide (VEImn TFSI), l-allyl-3-methylimidazolium chloride (AllylMIM Cl), and l-(2-methacryloyloxyethyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (MOEMIm TFSI), l-butyl-3-methylimidazolium thiocyanate (BMIM SCN) and l-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide (BDiMIM TFSI).

[0075] Ionic liquids or conducting salts may be used to give ionic conductivity. To enhance ionic conductivity, one or more plasticizers may be added to the adhesive formulation. Common plasticizers are various PEG, different carbonates and water.

[0076] In one embodiment, the adhesive is a PSA that is prepared by polymerizing a mixture comprising at least the following components: a) 35 wt % to 70 wt % of acrylate monomer (al) from the group of (meth)acrylic esters containing at least one oxygen atom; and b) 20 wt % to 40 wt % of acrylate monomer (a 2) from the group of (meth)acrylic esters and / or amides containing at least one nitrogen atom; and c) 0.1 wt % to 15 wt % of one or more electro-responsive compounds from the group of polymerizable zwitterionic monomers and / or non-polymerizable zwitterionic compounds, preferably one or more zwitterionic monomers; and d) 0.005 wt % to 10 wt % of at least one initiator; and e) 0.0 wt % to 20 wt %, preferably 0.1 to 20 wt%, of one or more ionic liquids; and f) 0.0 wt % to 20 wt %, preferably 0.1 to 20 wt%, of one or more salts that are no ionic liquids; and g) 0.0 to 20 wt%, optionally 0.1 wt % to 20 wt % of one or more acrylate monomers (a3), wherein the one or more acrylate monomers (a3) are different from acrylate monomers (al) and (a2); and h) optionally additives, wherein the weight fractions of the components are based on the total weight of the mixture. All weight ratios of components present in the mixture are chosen to add up to 100 wt %. However, if a solvent is present in the mixture for polymerization in the present invention, which forms the basis forthe adhesive composition of the present invention, the solvent is disregarded when stating the weight fractions of the components.

[0077] The use of such a PSA allows obtaining a surprisingly high adhesive strength upon rebonding and facilitates the ability for repeated debonding-rebonding. The PSA may be prepared a two-step process (also described in further detail below), including: (i) the provision of a mixture, including UV syrup preparation and liquid electrolyte formulation, followed by (ii) polymerization, including curing by UV web polymerization or UV polymerization to obtain the adhesive composition that is employed in one embodiment of the present invention.

[0078] In one such embodiment, the PSA employed in the present invention is a pressure-sensitive adhesive polymer (random / statistical copolymer) electrolyte composition. The copolymer structure is prepared by polymerizing monomers (al) and (a 2) and therefore contains units derived from these monomers also containing both oxygen and nitrogen atoms. The ratio of the unit containing at least one oxygen atom and the unit containing at least one nitrogen atom corresponds to the weight ratio of monomer (al) to monomer (a2) as defined in further detail below and which is adjusted to achieve several properties such as: high polarity to dissolve enough conducting salts and electro-responsive compounds (preferably zwitterionic monomers), controlling the glass transition temperature (Tg) of the copolymer, and making the adhesive effectively debondable. The latter cause can be explained as follows.

[0079] Without wishing to be bound by theory, it is assumed that debonding occurs by reactive dissolution of the PSA, in particular when an ionic liquid is present. This means that when the DC voltage is applied, the cation of the ionic liquid is expected to form an N-heterocyclic carbene or similar reactive species by abstracting a proton from the cations, specifically the cation of the ionic liquid containing a proton at the C2 position. This carbene species then modifies or reacts with the bonding side of the adhesive, facilitating debonding. A similar mechanism has been experimentally demonstrated for the solubilization of cellulose, proteins and polymers. It is also possible that debonding occurs by physical dissolution (no reaction) or similar processes. The latter is more likely if the C2 carbon of the cation of the ionic liquid does not have a proton. In this scenario, migration of the ionic liquid to the adhesive-adherend interface causes physical solubilization of the adhesive, resulting in debonding. Of course, both processes can occur during debonding along with another process as gas evaluation, most probably H2 gas. The gas release facilitates the debonding by mechanical stress and this makes the adhesive surface porous. But whatever the reasons for the debonding mechanism, the polymer structure preferably provides sufficient polar groups (containing oxygen and nitrogen or similar) together with polar plasticizers such as water (as described below) or PEG or similar for better migration of the ionic liquid to the substrate-adhesive interface and facilitating effecting debonding.

[0080] According to further embodiments, the adhesive composition may contain one or more electro-responsive compounds from the group of polymerizable zwitterionic monomers or non-polymerizable zwitterionic compounds, preferably one or more zwitterionic monomers. The one or more electro-responsive compounds are ionic species having both cation and anion in their structure, which enable the adhesive tape comprising the adhesive composition of the present invention responsive to electric fields. More preferably, the electro-responsive compounds are zwitterionic compounds. In particular, zwitterionic compounds are molecules that contain both positive and negative charges but are overall neutral.

[0081] As outlined above, in one embodiment the adhesive contains salts that are no ionic liquid (e.g., different Na and Li salts), facilitating the adhesive composition to be ionically conductive. The salts aids in the solubilization of electro-responsive compounds, preferably zwitterionic monomers, and contribute to the entire adhesive becoming more electro- responsive (i.e. can be modified from a first adhesive state to a second adhesive state by an electric stimulus). Electro-responsive properties of the adhesive may not originate solely from the electro-responsive compounds. Rather, it may be a combined property of the electro-responsive compounds, including zwitterionic monomers, and the conducting salt.

[0082] After the preparation of adhesive mass with bulk or solution or UV prepolymer methods, the adhesive is mixed with ionic liquids / plasticizers / curing agents (e.g., initiators or crosslinkers) or other additives (tackifier) to formulate the ion-conductive liquid adhesive. The next step is to coat the adhesive on the electrochromic carrier layer and cure it.

[0083] In preferred embodiments, the initial peel adhesion, i.e. the initial adhesive strength, as measured with Test A described hereinafter (cf. experimental section) before the application of a DC voltage source ranges from 2.5 N / cm to 7 N / cm. After voltage application, the peel adhesion may increase to values higher than 5 N / cm, such as 6 N / cm or or higher, or from to 8 N / cm to 16 N / cm.

[0084] In an embodiment, a UV syrup-based acrylic adhesive is mixed with one or more ionic liquids and then applied to an electrochromic layer that is present on a backing, and the mixture is then UV cured to obtain an adhesive tape. This is preferable over a solvent cast method, as the curing here is polymerization that increases the anchorage of the adhesive to the electrochromic layer as well as increasing the anchorage to the electrochromic and backing film. The backing may be inherently electrically conductive or may be rendered electrically conductive by inclusion of suitable additives or by appropriate treatment. Further, the backing may be primed before application of an electrochromic layer, as described below.

[0085] Below a more detailed description of the monomers and other components that may be used in the preparation of the PSA present in the device of the present is given. As to the ionic liquids, those mentioned above can also be used in this specific embodiment. Monomer (a

[0086] In one embodiment, the PSA is prepared by polymerizing a mixture comprising monomer (al) as component a) of the mixture. The monomer (al) is an acrylate monomer from the group of the (meth)acrylic esters, preferably containing at least one oxygen atom in the alcohol moiety. In the mixture, the one monomer (al) may be contained or two or more thereof may be contained in combination. The one or more monomer(s) (al) according to the invention are present in an amount of 35 wt % to 70 wt %, preferably 45 wt % to 68 wt %, more preferably 50 wt % to 66 wt %, based on the total weight of the mixture.

[0087] The monomer (al) contains preferably at least two oxygen atoms, even more preferably 2 to 20 oxygen atoms. To the skilled person it is clear that the at least one oxygen atom (or the at least two oxygen atoms) in the acrylate monomer is (are) present in addition to the two O atoms (oxygen atoms) of the ester functionality, i.e. (C=O)O. In other words, monomer (al) in total contains at least three oxygen atoms, namely the two oxygen atoms of the ester functionality and an additional oxygen atom. Preferably, monomer (al) in total contains at least four oxygen atoms, namely the two oxygen atoms of the ester functionality and two additional oxygen atoms. The at least one oxygen atom (or the at least two oxygen atoms) is (are) typically present in the hydrocarbon part of the alcohol component of the (meth)acrylic ester. The expression "hydrocarbon part" as used herein is the part of the ester which is introduced by an alcohol upon reaction with the carboxylic functional group of acrylic acid to form the ester.

[0088] In a preferred embodiment, the monomer (al) is from the group of (meth)acrylic esters having 4 to 44 carbon atoms, preferably 7 to 44 carbon atoms, or the monomer (al) and at least one oxygen atom or at least two oxygen atoms as described above. More preferably monomer (al) is from the group of (meth)acrylic esters having 4 to 30 carbon atoms and comprising at least one oxygen atom, more preferred 8 to 30 carbon atoms and at least 2 oxygen atoms.

[0089] Preferred (meth)acrylic esters contain the at least one oxygen atom (or the at least two oxygen atoms in the hydrocarbon part of the alcohol component of the ester, wherein at least one non-adjacent CH2 group is replaced by O. The hydrocarbon part of the alcohol component may be branched, unbranched or cyclic, saturated, or unsaturated, aliphatic or aromatic, substituted or unsubstituted, preferably it is branched or unbranched, saturated or unsaturated, and aliphatic since aromatic groups may cause color.

[0090] In a more preferred embodiment, the hydrocarbon part of the alcohol component is based on polyethylene oxide (PEO). The PEO can be linear or branched, and preferably is linear. In an even more preferred embodiment, the monomer (al) is based on the following formula (1). formula (1)

[0091] In present formula (1), R1is H or CH3, R2is H, -C(=O)CH2C(=O)CH3, CH3 or CH2CH3, preferably CH3 or CH2CH3, and n is an integer between 0 and 18, preferably 1 and 15, more preferably 2 and 11. In a preferred embodiment at least one monomer (al) used has a value n between 1 and 5, preferably 2 and 4. Preferred are monomers, which are liquid at 25 °C.

[0092] R2is a hydrocarbon group, optionally substituted, and may be selected from linear, branched, or cyclic alkyl groups, arylalkyl groups such as benzyl, hydroxyalkyl groups, or polyether chains.

[0093] Examples of the (meth)acrylic esters include 2-(2-ethoxyethoxy)ethyl acrylate) (EEEA, also designated as EDGA, n=2, R1=H, R2=CH2CH3), 2-[2-(2-methoxyethoxy)ethoxy]ethyl acrylate (n=3, R1=H, R2=CH3), diethylene glycol monomethyl ether methacrylate (n=2, R1=CH3, R2=CH3), 2-ethoxyethyl methacrylate (n=l, R1=CH3, R2=CH2CH3), 2-methoxyethyl methacrylate (n=l, R1=CH3, R2=CH3) and ethylene glycol monoacetoacetate monomethacrylate (n=l, R1=CH3, R2=-C(=O)CH2C(=O)CH3), methyl acrylate (n= 0, R1=H, R2= CH3), methyl methacrylate (n=0, R1=CH3, R2=CH3), n-butyl acrylate (n=0, R1=H, R2=CH2CH2CH2CH3), 2-ethylhexyl acrylate (n=0, R1=H, R2=CH2CH(C2H5)CH2CH3), 2-octyl acrylate (n=0, R1=H, R2=CH2CH(C6HI3)), n-heptyl acrylate (n=0, R1=H, R2=CH2(CH2)5CH3), Isobornyl acrylate (n=0, R1=H, R2=isobornyl group), 2-hydroxyethyl methacrylate (HEMA) (n=0, R1=CH3, R2=CH2CH2OH), 4-hydroxybutyl acrylate (n=0, R1=H, R2=CH2CH2CH2CH2OH), 2- ethylhexyl diglycol acrylate (n=2, R1=H, R2=CH2CH(C2H5)CH2CH3).

[0094] Monomer (a

[0095] In one embodiment, the PSA may be prepared by polymerizing a mixture comprising monomer (a2) as component b) of the mixture. The monomer (a2) is an acrylate monomer from the group of the (meth)acrylic esters or amides containing at least one nitrogen atom. In the mixture, one monomer (a2) may be contained or two or more thereof may be contained in combination. The one or more monomer(s) (a2) according to the invention are present in an amount of 20 to 40 wt %, preferably 20 wt % to 35 wt %, more preferably 24 wt % to 32 wt % based on the total weight of the mixture.

[0096] In a preferred embodiment, the monomer (a 2) is from the group of (meth)acrylic esters or amides having 4 to 25 carbon atoms, more preferably 5 to 15 carbon atoms, and even more preferably 5 to 9 carbon atoms. Those ranges refer to the (meth)acrylic esters and (meth)acrylic esters amides. This achieves particularly good characteristics with regard to the object to be achieved.

[0097] The monomer (a2) is from the group of (meth)acrylic esters or amides having at least one nitrogen atom within the molecule and may have one nitrogen atom or two or more nitrogen atoms. Moreover, because the monomer (a2) has an (meth)acrylic functionality within the molecule, the monomer (a2) is a monofunctional monomer. The monomer (a2) is a component copolymerizable with the monomer (al). This achieves particularly good characteristics with regard to the object to be achieved.

[0098] If monomer (a 2) is a (meth)acrylic ester, the at least one nitrogen atom (or the at least two nitrogen atoms) is (are) typically present in the hydrocarbon part of the alcohol component of the (meth)acrylic ester, wherein at least one non-adjacent CH2 group is replaced by N. The hydrocarbon part of the alcohol component may be branched, unbranched or cyclic, saturated, or unsaturated, aliphatic or aromatic, substituted or unsubstituted, preferably it is branched or unbranched, saturated or unsaturated, and aliphatic since aromatic groups may cause color.

[0099] In the present invention, by use of the monomer (a2), a proper degree of polarity can be given to the acrylic copolymer. This can provide a pressure-sensitive adhesive sheet that keeps a high adhesive force and adhesion reliability (particularly, repulsion resistance and holding power) when the sheet is bonded and can be easily peeled off from an adherend when the sheet is peeled. This achieves particularly good characteristics with regard to the object to be achieved.

[0100] In particular, with the use of the monomer (a2), a proper degree of polarity can be given to the acrylic copolymer and Tgcan be controlled.

[0101] In a preferred embodiment, the monomer (a2) is based on the following formula (2). formula (2)

[0102] In present formula (2), R1is H or CH3, R2or R3is H, CH3, CH2OH, CH2CH2OH, CH3or CH2CH3, preferably CH3or CH2CH3.

[0103] More generally, R2and R3are each independently selected from H, straight-chain or branched Ci-C8alkyl groups, hydroxyalkyl groups having 1 to 4 carbon atoms, or aminoalkyl groups, preferably methyl, ethyl, propyl, butyl, isopropyl, or 2-hydroxyethyl.

[0104] In a preferred embodiment the monomer (a2) is liquid at 25 °C.

[0105] Examples of the (meth)acrylamides include (meth)acrylamide, N-alkyl (meth)acrylamide, and N,N-dialkyl (meth)acrylamide. Examples of the N-alkyl (meth)acrylamide include N- methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-n-butyl (meth)acrylamide, and N- octyl acrylamide. Further, examples thereof include amino group-containing (meth)acrylamides such as dimethylaminoethyl (meth)acrylamide and diethylaminoethyl (meth)acrylamide. Next, examples of the N,N-dialkyl (meth)acrylamide include N,N- dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N,N-dipropyl (meth)acrylamide, N,N-diisopropyl (meth)acrylamide, N,N-di(n-butyl) (meth)acrylamide, N,N-di(t-butyl) (meth)acrylamide, N,N-dimethyl acrylamide (R1=H, R2=CH3, R3=CH3) and N,N-dimethyl methacrylamide (R1=CH3, R2=CH3, R3=CH3).

[0106] Further, examples of the (meth)acrylamides also include cyclic (meth)acrylamides having an N-acryloyl group such as (meth)acryloyl morpholine (like 4-acryloylmorpholine), (meth)acryloyl pyrrolidone, and (meth)acryloyl pyrrolidine. This achieves particularly good characteristics with regard to the object to be achieved.

[0107] Further, examples of the (meth)acrylamides also include N-dialkylaminoalkyl (meth)acrylamide monomers having an N-dialkylaminoalkyl group such as N-[3- (dimethylamino)propyl]acrylamide, N-[2-(dimethylamino)ethyl]acrylamide, N-[2- (diethylamino)ethyl] acrylamide. This achieves particularly good characteristics with regard to the object to be achieved.

[0108] Further, examples of the (meth)acrylamides include N-hydroxylalkyl (meth)acrylamide monomers having a hydroxyalkyl group having 1 to 4 carbon atoms. Examples of the N- hydroxylalkyl (meth)acrylamide monomers having a hydroxyalkyl group having 1 to 4 carbon atoms include N-methylol (meth)acrylamide, N-(2-hydroxyethyl)acrylamide,

[0109] N-(2-hydroxyethyl)methacrylamide, N-(2-hydroxypropyl)acrylamide,

[0110] N-(2-hydroxypropyl)methacrylamide, N-(l-hydroxypropyl)acrylamide,

[0111] N-(l-hydroxypropyl)methacrylamide, N-(3-hydroxypropyl)acrylamide,

[0112] N-(3-hydroxypropyl)methacrylamide, N-(2-hydroxybutyl)acrylamide,

[0113] N-(2-hydroxybutyl)methacrylamide, N-(3-hydroxybutyl)acrylamide,

[0114] N-(3-hydroxybutyl)methacrylamide, N-(4-hydroxybutyl)acrylamide,

[0115] Monomer

[0116] The optionally present one or more monomers (a3) may be selected from the group consisting of (meth)acrylic acid and vinyl-based monomers, such as vinyl esters & ethers, vinyl aromatics, vinyl nitriles, vinyl pyrrolidone.

[0117] Additionally, monomer (a3) may comprise reactive or polymeric components based on other chemistries, including polyurethane prepolymers, rubber-based components such as natural rubber, styrene-butadiene rubber (SBR), styrene-isoprene-styrene (SIS), and ethylene-vinyl acetate (EVA) copolymers, as well as silicone-based oligomers or macromers. These monomers or components can be used to tailor properties such as softness, cohesion, elasticity, water resistance, or thermal stability of the adhesive.

[0118] Optionally, the adhesive may be prepared by polymerizing a mixture comprising one or more acrylate monomers (a3), wherein the one or more acrylate monomers (a3) are different from acrylate monomers (al) and (a 2). If the mixture comprises monomer (a 3) it may be present in an amount of 0.1 wt % to 20 wt %, such as from 0.1 wt % to 15 wt %, preferably 5 wt % to 10 wt %, based on the total weight of the mixture.

[0119] According to particularly preferred embodiments, the one or more monomers (a 3) may be selected from the group consisting of vinyl acetate, N-vinylpyrrolidone, vinyl versatate, vinyl caprolactam, vinyl propionate, styrene, acrylonitrile, methacrylonitrile, and combinations thereof. Electro-responsive compounds

[0120] The mixture may comprise 0.0 wt % to 20 wt % of one or more electro-responsive compounds from the group of polymerizable zwitterionic monomers and / or non- polymerizable zwitterionic compounds, preferably one or more zwitterionic monomers. The one or more electro-responsive compounds are ionic species having both cation and anion in their structure, which enable the adhesive tape comprising the adhesive composition responsive to electric fields. More preferably, the electro-responsive compounds are zwitterionic compounds. In particular, zwitterionic compounds are molecules that contain both positive and negative charges but are overall neutral.

[0121] The one or more electro-responsive compounds are optional, and may present in an amount of 0.1 wt % to 20 wt %, preferably 0.5 wt % to 10 wt %, more preferably 1 wt % to 5 wt %, based on the total weight of the mixture.

[0122] The mixture may in principle comprise any type of electro-responsive compounds from the group of polymerizable zwitterionic monomers or non-polymerizable zwitterionic compounds, preferably zwitterionic monomers, known to the skilled person.

[0123] According to preferred embodiments, the mixture of the present invention may comprise one or more zwitterionic monomers. Exemplary zwitterionic monomers may include but are not limited to monomers based on phosphobetaine, carboxybetaine, sulfobetaine, or combinations thereof. Preferably the one or more zwitterionic monomers comprise phosphobetaine monomers, carboxybetaine monomers, sulfobetaine monomers, or combinations thereof. Mixtures of different types of zwitterionic monomers may be used. The one or more zwitterionic monomers may contain acrylic functional groups. More preferably, one or more zwitterionic acrylic monomers are used in the mixture of the present invention.

[0124] According to more preferred embodiments, the one or more polymerizable electro- responsive monomers, preferably zwitterionic monomers, that may be contained in the mixture of the present invention include but not limited to:

[0125] 2-methacryloyloxyethyl phosphorylcholine;

[0126] 2-[[2-(methacryloyloxy)ethyl]dimethylammonio]acetate;

[0127] 3-[[2-(methacryloyloxy)ethyl]dimethylammonio]propionate;

[0128] 3-[(3-acrylamidopropyl)dimethylammonio]propanoate;

[0129] 3-[[2-(methacryloyloxy)ethyl]dimethylammonio]propane-l-sulfonate;

[0130] 4-[[2-(methacryloyloxy)ethyl]dimethylammonio]butane-l-sulfonate; 3-[[2-(acryloyloxy)ethyl]dimethylammonio]propane-l-sulfonate;

[0131] 3-[bis[2-(methacryloyloxy)ethyl](methyl)ammonio]propane-l-sulfonate;

[0132] 3-[(3-methacrylamidopropyl)dimethylammonio]propane-l-sulfonate;

[0133] 4-[(3-methacrylamidopropyl)dimethylammonio]butane-l-sulfonate.

[0134] Alternatively, the mixture of the present invention may comprise one or more non- polymerizable zwitterionic compounds. Compared to zwitterionic monomers which are polymerizable, the non-polymerizable zwitterionic compounds according to the embodiment of the present invention do not have any polymerizable group. In the present invention, the use of a polymerizable zwitterionic monomer is preferred since its distribution in the adhesive composition, obtained by polymerizing the mixture, is generally easier to achieve. However, the use of a non-polymerizable zwitterionic compound is also possible provided that it can be dissolved in the mixture of the other components prior to preparation of the adhesive composition by polymerizing this mixture. In this case, no zwitterionic monomer is necessary but the effects of the present invention may also be achieved by the non-polymerizable zwitterionic compound.

[0135] The non-polymerizable zwitterionic compounds may in principle be any type known to the skilled person. Exemplary non-polymerizable zwitterionic compounds may include but are not limited to phosphatidylcholine and non-polymerizable zwitterionic compounds based on phosphobetaine, carboxybetaine, sulfobetaine, or combinations thereof. Preferably the one or more non-polymerizable zwitterionic compounds are selected from the group comprising a zwitterionic polymer, obtained by polymerizing phosphobetaine monomers, carboxybetaine monomers, sulfobetaine monomers, or combinations thereof; phosphatidylcholine; and betaine, such as sulfobetaine, phosphobetaine and carboxybetaine. Mixtures of different types of non-polymerizable zwitterionic compounds may be used.

[0136] Initiator

[0137] The mixture for polymerization in the present invention, which forms the basis for the adhesive composition of this embodiment of the present invention, comprises 0.005 to 10 wt %, preferably 0.005 to 5 wt %, more particularly 0.01 to 3 wt %, based on the total weight of the mixture, of at least one initiator as component d) of the mixture. If a mixture of two or more initiators is used, the above weight fractions are based typically on the total amount of the initiators.

[0138] The term "initiator" as used in the present disclosure refers to a compound that generate radicals or cations upon exposure to UV light and heat. The initiator used in the present invention is preferably an initiator which initiates a radical polymerization. Accordingly, the polymerization taking place in accordance with the present invention is preferably a radical polymerization.

[0139] Preferably, the initiator is a thermal initiator and / or photoinitiator, more preferably the initiator is a photoinitiator. According to a preferred embodiment, the adhesive composition is prepared by polymerizing a mixture comprising at least one, more preferably comprising at least two photoinitiators.

[0140] A thermal initiator is a compound that generates reactive species (free radicals, cations, or anions) upon exposure to heat. In the context of the present invention, the thermal initiator is not particularly limited. A photoinitiator is a compound that generates reactive species (free radicals, cations, or anions) when exposed to radiation (UV or visible). The photoinitiator typically comprises a UV initiator. Accordingly, the polymerization taking place in accordance with the present invention is preferably a UV polymerization.

[0141] The UV polymerization for syrup preparation and / or on the coated-out web may take place, for example, with the following photoinitiators, i.e. light-active initiators: 2,2-dimethoxy-2- phenylacetophenone (DMPA, 340 nm, 250 nm, Irgacure 651), 1-Hydroxy-cyclohexyl- phenyl-ketone (Irgacure 184), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (BAPO, 295 nm, 370 nm), iodonium (4-methylphenyl)[4-(2- methylpropyl)phenyl]hexafluorophosphate (242 nm), 2,2'-bithiophen-5-yl 4-N,N'- diethylaminophenyl ketone (THBP), 6,6'-(((lE,l'E)-(2,5-bis(octyloxy)-l,4- phenylene)bis(ethene-2,l-diyl))bis(4,l-phenylene))bis(l,3,5-triamine-2,4-diamine)) (400 nm). As well as the stated initiators it is possible to use other known initiators from the following classes: alpha-amino ketones, metallocenes, iodonium salts, alpha-hydroxy ketones, or phosphines. Thermal stability exists preferably up to at least 50°C.

[0142] Depending on the energy of the radicals formed on initiator scission, they may be limited to initiating the acrylate polymerization or may additionally produce crosslinking reactions as well, such as, for example, 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-l,3,5-triazine (MTT). Crosslinking of the chain is unwanted during the polymerization or syrup preparation, in order to keep the viscosities low for the coating. In the second polymerization step in the case of UV polymerization, crosslinking, photoactive crosslinkers may be added. They may also be polymerized electively into the chains. When using 2-oxo- 1,2-diphenylethyl acrylate (benzoin acrylate) or analogues thereof, polymerization in a UV tunnel at a wavelength between 300 and 400 nm produces polymers which, after the end of the polymerization in the UV tunnel, can be crosslinked briefly and intensely with UV radiation at 250 nm by activation of the benzoin acrylate units incorporated by polymerization. These crosslinkers may equally be incorporated by polymerization during a thermally initiated solution polymerization, and activated later, after drying, with UV radiation.

[0143] Benzophenone methacrylate (Visiomer 6976, 300 nm) and analogues thereof can also be used, with their known benefits and disadvantages. These initiators reduce the contamination with small molecules but require a greater time for reaction because of the biomolecular reaction. Crosslinking must take place under inert conditions.

[0144] According to preferred embodiments, a mixture of more than one initiator or multiple different initiators is used for different polymerization steps, for example, preparation of the UV syrup and final curing preferably done by UV polymerization or UV web polymerization. Preferably, a mixture of multiple initiators with different molar absorption coefficients is being used.

[0145] According to more preferred embodiments, 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651) and 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184) are used.

[0146] Ionic liquid

[0147] An ionic liquid is a salt that is in the liquid state at or near room temperature (25 °C). It is made up entirely of ions— typically a bulky, asymmetric organic cation and a weaker coordinating anion. When ionic liquids are incorporated into the adhesive an electrolyte adhesive is formed. This provides ionic conductivity as well as adhesive properties.

[0148] An ionic liquid is preferably present. If present, it may be be present in an amount of preferably 0.1 to 20 wt%, such as from 0.5 to 15 wt% or from 1.0 to 10 wt%.

[0149] Common cations of ionic liquids are imidazolium, pyridinium, pyrrolidinium, ammonium, phosphonium, cholinium, morpholinium, piperidinium, guanidinium, thiazolium based, and common anions are tetrafluoroborate, hexafluorophosphate, bis(trifluoromethanesulfonyl)imide, trifluoromethanesulfonate, dicyanamide, nitrate, chloride, acetate, hydrogen sulfate, and methanesulfonate.

[0150] The ionic liquid is preferably selected from the group comprising l-ethyl-3- methylimidazolium bis(fluorosulfonyl) imide (EMIM FSI), l-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide (EMIM TFSI), l-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (BMIM TFSI), l-ethyl-3-methylimidazolium thiocyanate (EMIM SCN), l-ethyl-3-methylimidazolium dicyanamide (EMIM DCA), l-ethyl-3- methylimidazolium tetrafluoroborate (EMIM BF4), l-butyl-3-methylimidazolium tetrafluoroborate (BMIM BF4), l-allyl-3-methylimidazolium dicyanamide (AllylMIM DCA), l-allyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (AllylMIM TFSI), l-ethyl-3- vinylimidazolium bis(trifluoromethylsulfonyl) imide (EVIM TFSI), N-methyl-N- propylpyrrolidinium bis(trifluoromethanesulfonyl) imide (Pyrl3 TFSI), N-methyl-N- propylpyrrolidinium bis(fluorosulfonyl) imide (Pyrl3 FSI), N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl) imide (Pyrl4 FSI), l-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide, 1-butyl-l-methylpyrrolidinium dicyanamide (Pyrl4 DCA), 1-butyl-l-methylpyrrolidinium triflate (Pyrl4 OTf), l-Ethyl-3-methylimidazolium triflate (EMIM OTf), l-butyl-3-methylimidazolium triflate (BMIM OTf), 1,3- dimethylimidazolium bis(trifluoromethylsulfonyl) imide (DiMIM BTA), l-butyl-3- methylimidazolium tricyanomethanide (BMIM TCM), l-butyl-3-methylimidazolium methyl sulfate (BMIM MeSO4), 1,3-diethylimidazolium bis(trifluoromethylsulfonyl) imide (DiEIM TFSI), N-butyl-N-methylpyrrolidinium tricyanomethanide (Pyrl4 TCM), diethylmethylsulfonium bis(trifluoromethylsulfonyl) imide (S122 TFSI), l-propyl-4- methylpyridinium bis(trifluoromethylsulfonyl)imide (Pro4Pic TFSI), l-ethyl-3- methylimidazolium ethyl sulfate (EMIM EtS04), triethylsulfonium bis(trifluoromethylsulfonyl) imide (S222 TFSI), l-(2-methoxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (MeOEMIM TFSI), l-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl) imide (PMIM TFSI), 1-butyl-l-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (Pyrl4 TFSI), l-butyl-4-methylpyridinium bis(trifluoromethylsulfonyl) imide, 1,3-dimethylimidazolium methyl sulfate (DiMIM MeSO4), 1-ethylimidazolium bis(trifluoromethylsulfonyl) imide (EIM TFSI), l-ethyl-3- methylimidazolium methanesulfonate (EMIM OMs), l-ethyl-4-methylpyridinium bis(trifluoromethylsulfonyl) imide (Et4Pic TFSI), l-ethyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl) imide (EDiMIM TFSI), 2-methyl-l-propylpyridinium bis(trifluoromethylsulfonyl) imide (Pro2Pic TFSI), l-ethyl-3-methylimidazolium acetate (EMIM OAc), l-ethyl-3-methylimidazolium hexafluorophosphate (EMIM PF6), l-butyl-3- methylimidazolium hexafluorophosphate (BMIM PF6), 1-hexylpyridinium bis(trifluoromethylsulfonyl)imide (HexPy TFSI), l-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide (VEImn TFSI), l-allyl-3-methylimidazolium chloride (AllylMIM Cl), and l-(2-methacryloyloxyethyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (MOEMIm TFSI), l-butyl-3-methylimidazolium thiocyanate (BMIM SCN) and l-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide (BDiMIM TFSI).

[0151] Ionic liquids or conducting salts may be used to give ionic conductivity. To enhance ionic conductivity, one or more plasticizers may be added to the adhesive formulation. Common plasticizers are various PEG, different carbonates and water. Salt that is no ionic li

[0152] The conducting salt may be selected based on its solubility in the mixture, cost, safety handling and long-term stability. For example, lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) is considered to demonstrate improved moisture resistance. Lithium bis(fluorosulfonyl)imide (LiFSI) or ILithiumtriflate (LiOTf), lithium difluoro(oxalato)borate (LiDFOB), or lithium bis(oxalato)borate (LiBOB) can also be used.

[0153] It is also possible to use other cations, such as Na+, K+, Cs+, Rb+, Ag+, Cu+, Cu2+, Mg2+, NH4+and other anions, such as Cl’, Br, I’, CIO4’, OH’, SCN’, AsFe’, [(CF3SO2)2N]’, [(FSO2)2N]’, CF3SO3’ , CH3CO2’, [B(C2O4)2]’, [BF2(C2O4)2]’, PF6’, BF4’, [PF3(CF2CF3)3]’ (FAP), C2O42’, and C(CF3SO2)3’, in pure form or in a mixture. An anion such as PFe’ is not preferred since they form toxic and corrosive gases such as HF on reaction with moisture.

[0154] The salt can also be a mixture of two or more salts, which may be beneficial for preventing corrosion of the conductive substrate or backing.

[0155] While the presence of the salt that is no ionic liquid is optional, in certain embodiments the salt is present in an amount of 0.1 wt % to 20 wt %, preferably 1 wt % to 10 wt %, more particularly 3 wt % to 8 wt %, based on the total weight of the mixture forming the basis for the adhesive composition.

[0156] Further additives

[0157] Optionally, the adhesive composition may be prepared by polymerizing a mixture further comprising additives as crosslinker (examples of include TMPTA, PETA, DPEPA (or DPHA), HDDA, and EO-TMPTA), salt of acrylate, plasticizer, antioxidant, tackifier, corrosion inhibitor, oxygen scavenger, water, and a combination thereof, preferably in an amount of 0.01 wt % to 10 wt %, based on the total weight of the mixture.

[0158] In a further embodiment of the invention, the adhesive composition may be prepared by polymerizing a mixture further comprising water as an optional additive. The presence of small amounts of water may be beneficial to activate the debonding function as described in the present disclosure. Generally, the compounds (e.g. Li salt, monomers, etc.) used for preparing the mixture forming the basis for the adhesive composition already contain traces of water. In addition, water is also taken up into the mixture upon its preparation and to the adhesive composition upon its use. In other words, the mixture and the adhesive composition always contain a certain amount of water. However, adjusting the amount of water to 0.01 wt % to 10 wt %, preferably 0.5 to 5 wt % may further improve the debonding properties. The amount of water in the mixture may be varied depending on the type of ionic liquid used. That is, when a low conductive ionic liquid is used, a larger amount of water may be required than when a high conductive ionic liquid is used. On the other hand, the amount of water in the mixture and the adhesive composition is preferably 10 wt % or less, more preferably 5 wt % or less to avoid hydrolysis of the conducting salts (e.g. Li salts) and the ionic liquid. The mixture and the adhesive composition are therefore preferably stored under dry conditions.

[0159] Water can activate the debonding function since it generally makes the adhesive softer by providing a certain flexibility to the polymer chains and allows ionic liquid to move faster by improving polymer chain dynamics, resulting in debonding. Similar effects are achieved by the addition of plasticizers (as described in detail below) to the mixture. Accordingly, in the present disclosure, when water is added to the mixture forming the basis for the adhesive composition, it may also be referred to as plasticizer. Water also contributes to debonding by enabling hydrogen gas generation.

[0160] In a further embodiment of the invention, the adhesive composition may be prepared by polymerizing a mixture further comprising 0.01 wt % to 10 wt %, preferably 0.5 to 5 wt % of plasticizer, as an optional additive. When the mixture forming the basis for the adhesive composition comprises a conventional plasticizer within above ranges, the presence of water can be avoided while debonding properties can still be achieved. As explained above with respect to the presence of water, the amount of plasticizer in the mixture may be varied depending on the type of ionic liquid used. That is, when a low conductive ionic liquid is used, a larger amount of plasticizer may be required than when a high conductive ionic liquid is used.

[0161] Conventional plasticizers that may be used in the present invention include, for example, cyclic carbonates such as ethylene carbonate (EC), vinylene carbonate (VC), propylene carbonate (PC), butylene carbonate (BC) or fluoroethylene carbonate (FEC), linear carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC) or ethyl methyl carbonate (EMC), mixed carbonates, dimethylacetamide, ethyl methanesulfonate (EMS), gamma-butyrolactone, dimethyl sulfoxide, polyethylene oxide (PEO, also referred to as polyethylene glycol) i.e. PEG), "glymes" such as diglyme, triglyme, tetraglyme, ethylene glycol diacetate, ketones, or various ethers or polyethers, polypropylene oxides or block copolymer thereof, trimethylolpropane ethoxylate, or mixtures thereof. Particular preference in the present invention is given to the use of plasticizers that are based on polyethylene oxides, polypropylene oxides or block copolymers thereof, trimethylolpropane ethoxylate, or glymes. The polyethylene oxides preferably have hydroxyl, (meth)acrylate, methoxy or ethoxy groups as chain ends. In the case of (meth)acrylate, polyethylene oxides with only one (meth)acrylate chain end are preferred. It is also possible to use mixtures of PEOs with and without (meth)acrylate chain ends. The chain end or chain ends with no (meth)acrylate groups are preferably hydroxy groups. Methoxy groups may further improve conductivity, and hydroxy groups may further improve adhesion strength to the substrates.

[0162] PEOs with (meth)acrylate groups function as monomers and will be copolymerized with monomers (al) and (a2). This introduces long PEO chains as side groups into the polymer. In preferred embodiments, the chain length of the PEOs used is between 5 to 20 preferably 5 to 12 which corresponds to the number of consecutive ethylene oxide (-O-CH2-CH2-) repeat units in the polymer chain. An example of polymerizable PEOs is PEGMA480 and unpolymerizable is PEG200.

[0163] In preferred embodiments, the plasticizer can be selected from cyclic carbonates such as ethylene carbonate (EC), vinylene carbonate (VC), propylene carbonate (PC), butylene carbonate (BC) or fluoroethylene carbonate (FEC), linear carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC) or ethyl methyl carbonate (EMC), mixed carbonates, dimethylacetamide, ethyl methanesulfonate (EMS), gamma-butyrolactone, dimethyl sulfoxide. Especially EC or DEC are flammable (low flash point), volatile and also sensitive to moisture.

[0164] All the stated plasticizers may typically improve the solubility during the polymerization and, at the same time, act as an integral constituent of the final electrolyte. Adding plasticizer may increase softness of the adhesive, which reduced peel adhesion.

[0165] The mixture may comprise further ingredients like heteroaromatic substances like triazine. Such substances may help to improve the conductivity.

[0166] The salt of acrylate may in principle be any type of salt of acrylate known to the skilled person. Exemplary salts of acrylate described herein may include but are not limited to sodium acrylate, potassium acrylate, lithium acrylate and ammonium acrylate.

[0167] In order to optimize the technical adhesive properties, it is furthermore possible to admix the adhesive composition with resins. Resins are considered for the purposes of this present invention typically to be small molecule compounds to oligomeric and polymeric compounds having number-average molecular weights Mnof not more than 10 000 g / mol; they are not included in the polymer component. Tackifying resins for addition (peel adhesion-enhancing resins, i.e. tackifier) that can be used include all existing tackifier resins and those described in the literature. Representatives include the pinene resins, indene resins and rosins, their disproportionated, hydrogenated, polymerized, and esterified derivatives and salts, the aliphatic and aromatic hydrocarbon resins, terpene resins and terpene-phenolic resins, and also Cs to C9 and other hydrocarbon resins. Any desired combinations of these and further resins may be used in order to adjust the properties of the resultant adhesive in line with requirements. Generally speaking, it is possible to use any resins or rosins which are compatible with (soluble in) the corresponding base polymer; reference may be made more particularly to all aliphatic, aromatic and alkylaromatic hydrocarbon resins, hydrocarbon resins based on pure monomers, hydrogenated hydrocarbon resins, functional hydrocarbon resins, and natural resins or hydrogenated rosins like methyl ester of hydrogenated rosin.

[0168] With the acrylate-based, adhesive composition, there is no need for the presence of tackifier resins, and so one outstanding variant constitutes the adhesive composition of the present invention wherein no resins have been added to the PSA. Such additions frequently possess adverse effects in the context of application for optical bonds. The resins used in the prior art as tackifier resins for acrylate PSAs are usually polar in nature, in order to achieve compatibility with the polyacrylate matrix. This usually leads to the use of aromatic tackifier resins, which on prolonged storage or on light exposure are subject to a yellowish discoloration.

[0169] Depending on the application, e.g. if no optical clarity is needed, tackifier resins may be used, preferably in a low range, preferably 0 to 5 wt %, more preferably 0.1 to 2 wt %.

[0170] Means to Prevent Corrosion

[0171] While specific aspects of the adhesive and the device of the present invention have been described above, it is a key finding of the present invention that additionally certain means need to be adapted in order to avoid or reduce the risk of corrosion of the substrate (the surface of member to which the adhesive adheres) and / or the backing on which the adhesive is present. These means apply to all devices of the present invention, yet of course can be combined with specific aspects of e.g. the composition of the electro-responsive adhesive as described above.

[0172] The device of the present invention therefore satisfies one or more of the following: i) the open-circuit potential between the conductive layers (backing and substrate), separated by the adhesive / electrolyte layer, is 100 mV or less; ii) the device comprises an anti-corrosion agent that can undergo a reversible electrochemical reaction, which is present within the adhesive and / or between the adhesive and the substrate and / or the backing; iii) the adhesive comprises one or more selected from the group consisting of an anti-corrosion agent, a drying agent and oxygen scavenger. i) Open Circuit Potential

[0173] The open circuit potential (OCP or OCV) is defined as the voltage difference between a working electrode and a reference electrode in an electrochemical cell when no external current or potential is applied to the cell.

[0174] In one embodiment, the open circuit potential between the backing and / or the substrate, both being in contact with the electro-responsive adhesive, is 100 mV or less. It is sufficient if the OCP between the adhesive and the backing or the substrate is 100 mV is or less, but preferably the OCP between the adhesive and both of the backing and the substrate is 100 mV or less.

[0175] Here, the value of 100 mV refers to the absolute difference in potential, independent of the polarity of the voltage.

[0176] By limiting the OCP in this manner, the electrochemical driving force for corrosion is limited. While it is sufficient if the OCP is 100 mV or less, it may be 80 mV or less, 60 mV or less, 50 mV or less, 40 mV or less, 30 mV or less, 20 mV or less, or 10 mV or less, or even 5 mV or less, such as 0 mV. A lower value is generally preferable, as it corresponds to the electrochemical driving force of the unwanted oxidation reaction.

[0177] An OCP within this range can be achieved by a suitable choice of materials for the backing, the substrate and the adhesive. While the substrate surface if often a fixed material for a given application, the backing and in particular the adhesive composition can be adjusted to reduce or minimize the OCP by employing substrate and backing that are from similar materials e.g. both from stainless steel or coated with similar materials e.g. PEDOT or suitable substances in the adhesive and / or the backing, such as reducing agents such as metals in elementary form (e.g. zinc powder) or organic substances, such as ascorbic acid.

[0178] In one embodiment, a conducting layer is provided between the adhesive and the substrate and / or the adhesive and the backing, and an additive for modifying the open circuit potential of the adhesive, preferably in an amount of 10% by weight or less, relative to the total weight of the adhesive, is included, in order to adjust the OCP to fall within the ranges indicated above. ii) Anti-Corrosion Agent that can undergo a reversible electrochemical reaction

[0179] In one embodiment, the device of the present invention comprises an anti-corrosion agent that can undergo a reversible electrochemical reaction, which is present within the adhesive and / or between the adhesive and the substrate and / or the backing.

[0180] The presence of such an anti-corrosion agent facilitates maintaining the electrochemical oxidation state of the conductive substrate during transitions between adhesive states. The compound is able of undergoing reversible redox transitions, e.g upon application of an electric stimulus or a change in environmental conditions such as presence of oxygen and moisture, thereby enabling modulation of adhesive strength while avoiding or preventing corrosive reactions at the metal interface.

[0181] The anti-corrosion agent may be present in layer form, e.g. on the surface of the backing (i.e., intermediate the backing and the adhesive). The layer may exhibit changes in its electrochemical properties— such as conductivity, oxidation state, or ion mobility— that correlate with the adhesive's transition from bonded to debonded states. These changes are not necessarily visible but are functionally significant in preserving the substrate's integrity.

[0182] The anti-corrosion agents that can undergo a reversible electrochemical reaction are not particularly limited, and examples include poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT :PSS), poly(3,4-ethylenedioxythiophene):p-toluenesulfonate (PEDOT:Tos), poly(3,4-propylenedioxythiophene) (ProDOT), poly(dioxythiophenes), poly(3,4-dialkylthiophenes), polyaniline (PANI), polypyrrole (PPy), poly(2,5- thienylenevinylene) (PTV), polythiophene (PTh), polythiophene derivatives, metallo- supramolecular polymers, polyacetylene (PAc), poly(p-phenylene vinylene) (PPV), polyfluorene (PF), polycarbazole (PCz), polybithiophene (PBTh), tungsten trioxide (WO3), nickel oxide (NiO), Prussian Blue (PB), Viologens (V), molybdenum trioxide (MoO3), titanium dioxide (TiO2). Further examples include inorganic materials, e.g. salts or complexes of transition metals that can stably exist in two or more oxidation states, such as iron^ / m, cobalt H / "L manganese" / IV / VI, Cer^l / IV, etc. As mentioned above, the anti-corrosion materials may be comprised in, or may be provided as, a layer present e.g. on a backing, optionally with a primer layer in between (see also the Figures), but may also be present in the adhesive.

[0183] In one embodiment, the redox-active layer is formed by or comprises a conjugated polymer, e.g. PEDOT (poly(3,4-ethylenedioxythiophene)). For example, during bonding or rebonding, a PEDOT-based layer facilitates electron transfer while shielding the substrate from ionic species that could otherwise trigger corrosion. During debonding, the same layer maintains its redox stability, ensuring that no irreversible electrochemical degradation occurs.

[0184] Correlation between the redox state of the layer that comprises or is formed of the anticorrosion agent and the adhesive state can be achieved by suitable selection of conjugated polymers and counterions forming the anti-corrosion agent. Materials such as PEDOT doped with tosylate (TOS“) or chloride (Cl-) exhibit high conductivity and redox reversibility, which may facilitate maintaining substrate protection during electrical activation. These counterions promote tighter packing and higher crystallinity in the polymer matrix, enhancing charge transport and environmental stability.

[0185] The anti-corrosion agent may be formed as, or present in, a separate layer adjacent to the adhesive, or it may be integrated within the adhesive matrix itself. In one embodiment, a PEDOT layer is coated onto a conductive backing, such as metal foil or a treated polymer film, and an electro-responsive pressure-sensitive adhesive (PSA) is polymerized directly onto this layer. This architecture ensures optimal interfacial contact and electrical continuity, while spatially separating the redox-active layer from the substrate to prevent direct exposure to ionic liquids or salts that may be present in the adhesive.

[0186] In another embodiment, a layer based on conjugated polymers and counterions, e.g. a PEDOT layer, may be formed via in situ electrochemical polymerization, photo-induced polymerization, or gas-phase deposition. Preferred methods include direct coating from aqueous or solvent-based dispersions, which simplify processing and eliminate the need for post-polymerization rinsing. Regardless of the method, the layer based on conjugated polymers and counterions, e.g. PEDOT, layer should exhibit sufficient electrical conductivity and redox stability to support corrosion protection and adhesive modulation.

[0187] The device may also be configured such that the redox transitions of the anti-corrosion agent that can undergo a reversible electrochemical reaction are triggered by the same electric stimulus that modulates the adhesive state. This unified response reduces complexity and ensures that corrosion protection is active precisely when adhesion is being altered. In this way, the anti-corrosion agent that can undergo a reversible electrochemical reaction (e.g. in the form of a PEDOT layer) serves a dual function: enabling reversible adhesion and acting as a corrosion-inhibiting barrier.

[0188] Preferred anti-corrosion agent that can undergo a reversible electrochemical reaction are conductive polymers, including those selected from the group consisting of PEDOT, PANI, ProDOT and their derivatives e.g. obtained from modified monomer structures including alkyl-substituted EDOT, EDOT-OH, Br-EDOT, EDOT-NH2, EDOT-COOH. As the PEDOT is a composite material and needs counter anion which is not limited but could be PSS" (poly(styrenesulfonate)), Tos" (p-toluenesulfonate), CI04“ (perchlorate), BF4“ (tetrafluoroborate), PF6“ (hexafluorophosphate), OTf" (triflate), DBSA" (dodecyl benzenesulfonate), CSA" (camphorsulfonate), NO3“ (nitrate), SO42-(sulfate), HS04“ (hydrogen sulfate), TFSI" (bis(trifluoromethanesulfonyl)imide), Cl" (chloride), Br“ (bromide), I" (iodide), F" (fluoride), CF3SO3“ (trifluoromethanesulfonate), CH3SO3“ (methanesulfonate), acetate (CH3COO“), citrate, phosphate. Whatever anti-corrosion materials are used, they should have sufficient electrical conductivity. The choice of counter-ion may be significant, as it influences the polymer's conductivity, crystallinity, and resistance to degradation under electrochemical stress.

[0189] In one embodiment, the adhesive device comprises an electro-responsive PSA sandwiched between two electrically conductive substrates or between a conductive backing and a substrate. An anti-corrosion layer based on a conjugated polymer, e.g. a PEDOT layer, may be present on the backing or substrate, providing corrosion protection and electrical functionality. The layer ensures that ions generated during electrical activation do not reach the substrate, thereby preventing corrosion and enabling multiple bonding- debonding cycles without loss of performance.

[0190] Thus, the anti-corrosion layer of the present invention that comprises an anti-corrosion agent that can undergo a reversible electrochemical reaction may provide a chemically and electrically responsive interface that preserves substrate integrity, supports reversible adhesion, and enhances the long-term reliability of the adhesive system.

[0191] In a particular embodiment, the anti-corrosion agent has a lower standard reduction potential than the material forming the electrically conductive substrate or the backing, the absolute difference in standard reduction potentials preferably being 100 mV or more, such as 300 mV or more or 500 mV or more. This allows achieving a highly oxidationpreventing effect. iii) Anti-Corrosion Agent, Drying Agent or Oxygen Scavenger

[0192] While in the above embodiment ii) the anti-corrosion agent that can undergo a reversible electrochemical reaction may be present within the adhesive and / or between the adhesive and the substrate and / or the backing, in a further embodiment, the adhesive itself comprises one or more selected from the group consisting of an anti-corrosion agent, a drying agent and oxygen scavenger.

[0193] Here, the description of the anti-corrosion agent that can undergo a reversible electrochemical reaction as given above also applies, except that its position is confined to the adhesive itself.

[0194] However, also other anti-corrosion agents may be used, e.g. sacrificial compounds such as anti-oxidants, e.g. synthetic antioxidants such as butylated hydroxyanisole (BHA), butylated hydroytoluene (BHT), tert-butyl hydroquinone (TBHQ), thiols, certain polyols such as ascorbic acid, phenols, polyphenols, resinols, aldehydes, alcohols, etc.

[0195] If an anti-corrosion agent is present in the adhesive, the corrosive action of the adhesive itself or from the environment may be mitigated. The amount of the anti-corrosion agent in the adhesive is preferably 10 wt% or less, such as 5 wt% or less, but typically 0.01 wt% or more, such as 0.1 wt% or more, relative to the total mass of the adhesive.

[0196] In addition, or alternatively, a drying agent may be included in the adhesive. Drying agents known to a skilled person can be used without limitation as far as the object of the present invention are not impaired. Examples include molecular sieves, silica, zeolites, desiccants, for example based on alkali metal or earth alkali metal oxides, chlorides, carbonates and sulfates (e.g. CaCIz, MgClz, MgSC , CaSC , NazSC , CaO, K2CO3). Since moisture is a key factor driving oxidation and corrosion, limiting the amount of moisture originating from the adhesive or taken up from the environment provides an effective means to avoid or delay corrosion of the substrate and / or the backing. Here, the amount of the drying agent is preferably 10 wt% or less, such as 5 wt% or less, but typically 0.01 wt% or more, such as 0.1 wt% or more, relative to the total mass of the adhesive.

[0197] In addition, or alternatively, an oxygen scavenger may be included in the adhesive. Examples include metal powder (e.g. zinc or iron powder), ascorbic acid, sulfites, bisulfites, metabisulfites, and phosphites of the earth alkali and alkali metals, e.g. sodium sulfite, sodium bisulfite, pyrogallol, thiols, dithionites (e.g. sodium dithionite), as well as certain types of enzymes. Here, again the amount of the oxygen scavenger is preferably 10 wt% or less, such as 5 wt% or less, but typically 0.01 wt% or more, such as 0.1 wt% or more, relative to the total mass of the adhesive.

[0198] If two or more selected from the group consisting of an anti-corrosion agent, a drying agent and oxygen scavenger are present, the total amount of the anti-corrosion agent, drying agent and oxygen scavenger is preferably 10 wt% or less, such as 5 wt% or less, but typically 0.01 wt% or more, such as 0.1 wt% or more, relative to the total mass of the adhesive.

[0199] DEVICE CONFIGURATIONS

[0200] The device of the present invention satisfies the requirements i), ii) and / or iii), and comprises at least the adhesive and the electrically conductive backing and / or substrate, and preferably includes both the backing and the substrate, but is otherwise not limited. The device may comprise additional components, e.g. a layer formed of, or comprising, an anti-corrosion agent that can undergo a reversible electrochemical reaction, the layer being present between the adhesive and the substrate and / or the backing. The device may additionally or alternatively comprise a corrosion protective layer that is formed on the substrate and / or the backing, but which is formed from a material other than an anticorrosion agent. The corrosion protective layer may be formed from a metal oxide, which may be a spontaneously formed oxide layer or an oxide layer formed by anodic oxidation, from a metal having a standard reduction potential of 0 V or less, such as -0.2 V or less or - 0.5 V or less, for example zinc or magnesium, or from an alkali metal or earth alkali metal halide, such as CaFz.

[0201] The device of the present invention may take the form of a double-sided adhesive tape, as illustrated for example in Fig. 2 A and B.

[0202] In one embodiment of the present invention, a capacitor-like configuration— comprising an anti-corrosion agent coated backing, an ionically conductive adhesive layer, and an electrically conductive substrate— enables the anti-corrosion agent layer to actively protect the surface of the substrate. Corrosion-inhibiting materials such as poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) or poly(3,4-ethylenedioxy- thiophene):p-toluenesulfonate (PEDOT:Tos) may be used as the corrosion-inhibiting layer and coated onto a flexible backing, such as a transparent PET film. On top of this layer, an electro-responsive adhesive can be applied, for example via polymerization, to form an adhesive tape. When this tape is laminated onto an electrically conductive substrate— such as a steel plate— the resulting assembly forms a capacitor-like device of the present invention in which the PEDOT-based layer mediates charge redistribution and stabilizes interfacial potential, thereby minimizing electrochemical side reactions. When a positive DC voltage is applied to the steel plate (substrate) relative to the corrosioninhibiting layer on the carrier, the redox-active layer undergoes an electrochemical transition that enhances its protective function. Simultaneously, the bonding strength of the adhesive tape to the substrate increases, e.g. transitioning from a lower (initial) adhesive state to a higher (bonded) adhesive state. During this process, the corrosioninhibiting layer acts as a barrier that prevents ionic species within the adhesive from reaching the substrate surface, thereby maintaining the substrate's electrochemical oxidation state and protecting it from corrosion. Note that this step is optional if the initial adhesive strength is sufficient for the intended application.

[0203] Upon reversing the polarity— applying a negative DC voltage to the steel plate and a positive voltage to the corrosion-inhibiting layer— the bonding strength of the tape relative to steel plate decreases, transitioning the adhesive from a bonded to a debonded state. This allows for easy removal of the tape from the substrate with minimal force. During this process, the redox-active corrosion-inhibiting layer, maintains its protective function by minimizing ionic species from reaching the substrate surface. The electrochemical stability of the layer ensures that the substrate's oxidation state remains unchanged, thereby avoiding corrosion even during repeated bonding-debonding cycles.

[0204] In certain embodiments, a priming is provided that increases the anchorage strength between a corrosion-inhibiting layer and the backing. This can be achieved by physical priming (e.g., flame treatment or corona / plasma treatment) or chemical priming (e.g., curing a very thin adhesive layer or several layers on the backing film by UV light or temperature) or depositing transparent conductive oxides [e.g., Indium tin oxide (ITO)] or carbon nanotubes. Curing means here polymerization or crosslinking.

[0205] In preferred embodiments, the corrosion-inhibiting layer comprises materials that exhibit adequate electrical conductivity and hydrophobicity. The layer should be resistant to corrosion in ionic or electrolyte-rich environments, should offer good weatherability, and form a strong bond with the backing film. This corrosion-inhibiting layer may be applied to a surface of the backing that is optionally primed, either through in situ polymerization of corrosion-inhibiting monomers (with or without primer) or by direct coating of corrosioninhibiting conductive polymers onto the primed surface of the backing. To ensure efficient corrosion inhibition, the coating thickness may be optimized. In some cases, an indium tin oxide (ITO) layer of backing can be employed as a primer to enhance electrical conductivity. Additionally, a more porous structure may be achieved in the corrosion-inhibiting coating to facilitate ion penetration from the electrolyte as well as strong anchorage to the adhesive and the corrosion-inhibiting layer. The adhesive is not limited to particular chemistries, but the preferred system is preparation by in a two-step process (also described in further detail below), including: (i) the provision of a mixture, including UV syrup preparation and liquid electrolyte formulation with ionic liquids, followed by (ii) polymerization, including curing by UV web polymerization or UV polymerization to directly form the adhesive on a corrosion-inhibiting layer that is provided on an optionally primed backing (see also the Figures). The UV syrup may be the mixture described above, including the monomers al) and a2) and optionally other components.

[0206] According to further embodiments, the adhesive device of the present invention comprises a conductive substrate to which the adhesive is / will be applied. The substrate surface is preferably smooth and electrically conductive in order to increase adhesive strength and to allow easy application of an electric stimulus.

[0207] BACKING

[0208] A backing may not just be a film to support the adhesive (layer), but may form an integral part of a tape. A backing can be made from plastic, metal, textiles, and so on. A PSA adhesive layer is often thin, sticky, and, overall, not a free-standing material, so that often a backing is beneficial to provide support, dimensional stability, strength, flexibility, and handling ease. It may act as the carrier for the adhesive (layer), protects the adhesive before application, and may have an impact on the mechanical, thermal, and electrical properties of the tape. The backing can also influence the tape's resistance to moisture, heat, chemicals, and environmental exposure.

[0209] Common backing films are polyethylene terephthalate (PET), polypropylene (PP), Polyethylene (PE), polyvinyl chloride (PVC), Polyimide (PI), cellulose acetate, kraft paper, crepe paper, nonwoven fabric, aluminum foil, copper foil, polyester fabric, glass cloth, rayon fabric, foam (e.g. polyethylene foam, polyurethane foam), PTFE (polytetrafluoroethylene), silicone-coated paper or film, fluoropolymer films, polycarbonate (PC), and nylon. Also, a backing can be made of natural fabric (cotton, linen, wool, silk, hemp, or ramie) or synthetic fabric (acrylic or spandex) or from a composite fabric (poly-cotton, cotton-spandex, or wool-acrylic).

[0210] The backing is not limited to the materials mentioned above. Its main purpose is to provide sufficient mechanical strength. In a preferred embodiment, backing films are selected from the group of polyethylene terephthalate) (PET), cloth and poly(propylene) (PP) films with different thicknesses. A backing can also be transparent or translucent colored film to have a complementary color in combination with e.g. a corrosion-inhibition layer (see also the Figures).

[0211] PRIMER

[0212] A priming / primer is a surface treatment or intermediary layerthat may be used to promote adhesion between a substrate or backing material to the adhesive or other layer, e.g. a corrosion-inhibitor layer. It functions as a compatibility bridge, increasing bonding strength and longevity.

[0213] The inventive device in the form of a tape may include multiple layers, such as a backing layer followed by a corrosion-inhibitor layer. Due to the differing chemistries and surface polarities of these materials, the use of a primer may be beneficial to achieve a stable, uniform coating of the corrosion-inhibitor layer and to ensure strong adhesion to the backing film. This may also allow to improve the anchorage of the corrosion-inhibitor layer to the backing film instead of the substrate and adhesive, as may otherwise be observed.

[0214] Priming could be done by physical treatment like flame / corona / plasma to increase polar groups to the backing surface that can hold the corrosion-inhibitor coating better as well as increase compatibility to achieve uniform coating. This is beneficial when the corrosioninhibitor material is applied from polar aqueous dispersion.

[0215] Another physical priming is chemical etching, which increases the roughness of the backing to make more surface area. This process induces a slightly opaque appearance due to the rough surface structure. This is sometimes beneficial if the compatibility of the primer and substrates is low. For example, coating a fluorinated chemical in solution due to its low surface energy seems to be very difficult; however, making the surface rough can solve the issue. Mechanical surface treatment (e.g., sandblasting or abrasion) can increase the roughness of the backing and enhance the anchorage of the adjacent layer, which may be an anti-corrosion layer. The application of a thin adhesive layer or adhesion promoter onto the backing substrate is a non-reactive chemical priming method, serving as a bridging layer between the backing and the anti-corrosion layer. Typically, single or several thin layers of adhesive are coated on the backing and then UV or thermally cured. As the adhesive layer is sticky and has polar or unipolar groups that help to bind the anti-corrosion layer to the backing. If the anti-corrosion layer is coated with press, then even the anti-corrosion layer is adsorbed, which further increases the anchorage. Chemical priming can also be reactive, where the primer forms a bond through a chemical reaction with the backing surface. Examples include silane-based, isocyanate, epoxy, acrylate, or UV-activated azide / diazirine primers that form covalent bonds with various backing surfaces.

[0216] Sometimes different inorganic coatings also act as primers. For example, TCO coating on PET film also increases the binding of the anti-corrosion layer, as well as giving it better electrical conductivity.

[0217] A preferred priming for the invention may involve both physical and chemical priming. Chemical priming includes creating a very thin adhesive layer on the backing film and then UV curing or crosslinking. The adhesive could be from any chemistry, such as acrylic, synthetic rubber, or PU-based. Preferably, several criteria are fulfilled, such as it should be weather-resistant (e.g., not weaken in a high relative humidity environment), allow the corrosion-inhibitor material to be coated uniformly, sufficiently optically clear and finally, strong anchorage to the backing. Examples include acrylic adhesives from EDGA, DMAA, BA, MA, benzyl acrylate, AA monomer, Irgacure photo initiators 184 / 651, and crosslinkers like PEGDA, glycerol triacrylate, and crosslinkers with epoxy groups.

[0218] Another preferred primed backing is transparent conductive coating (TCO), e.g. ITO / FTO- coated film, as it shows faster color change due to higher electrical conductivity of the transparent oxides. Also, it suffers a bit weaker anchorage with the anti-corrosion layer than the adhesive-coated backing.

[0219] In a further embodiment, the present invention uses priming / primer to the backing to increase anchorage strength with adhesive and backing. It can also be used without priming if the anchorage of the anti-corrosion layer is enough to do the (re) bonding and debonding operation to the adhesive device. Priming types should not limit the scope of the present invention.

[0220] One embodiment of the present invention provides an electrically debondable adhesive device comprising an electro-responsive PSA that preferably has ionic conductivity and which is sandwiched by two electrically conductive substates or one substates and one backing and operated by voltage application, with optional layers between the adhesive and the substrate and / or the backing. In one embodiment, it is possible to use anticorrosion materials to visualize the adhesive states. These materials can either be used in the electro-responsive adhesive as dispersed form or as a thin layer coated on backing to get the color changing effect. In the examples this is used as a layer coated on backing film. This was possible because the anti-corrosion layer used had sufficient electrical conductivity. So, in the examples the anti-corrosion layer served as both an electrical conductivity layer and as an anti-corrosion layer. ELECTRICALLY CONDUCTIVE SUBSTRATES OR ADHEREND

[0221] The adherend is the target substrate where the device (e.g. as a tape) is applied. Not every adherend may be suitable, as typically electrical conductivity may be required. Examples of adherends include copper foil, stainless steel plates, aluminum foil, gold-coated surfaces, silver-coated substrates, nickel plating, titanium, ITO-coated glass, carbon-coated films, graphene films, metal-coated plastics, chromium-coated substrates, zinc-plated surfaces, tin-plated surfaces, silicon wafers with conductive coatings, and conductive carbon fiber composite substrates. From the examples, it is also clear that nonconductive substrates can also be used once coated with an electrically conductive layer with a higher conductive and smooth surface. Preferred adherends of the present invention include stainless steel plates or copper or aluminum surfaces or silver-coated plastic substrates.

[0222] BRIEF DESCRIPTION OF FIGURES

[0223] Figure 1 schematically illustrates embodiments of an adhesive tape of the present invention, namely a single-sided adhesive tape comprising a layer (D) of electro-response adhesive and carrier (T) (Fig. 1A). Here, the carrier comprises an anti-corrosion layer (Cl) that present on a primer (P) that is formed on a backing film F, all of these layers constitute the carrier (T).

[0224] Another embodiment is shown in Figure IB, which shows a double-sided adhesive tape comprising carrier (T) disposed between layer (D) of electro-response adhesive and layer (2S) of another adhesive (Fig. IB). This embodiment is identical to the one of Fig. 1A, except that a conventional double-sided adhesive tape (2S) is provided on the side where no electro-responsive adhesive is provided.

[0225] Figure 1C shows another embodiment of a double-sided adhesive tape comprising a carrier (T) disposed between two layers (D) of electro-responsive adhesive. Carrier (T) can be defined as a combination of a backing film (F), primer layers (P) and anti-corrosion layers (Cl). The electro-responsive adhesive layers (D) are present on both sides.

[0226] Figure 2 schematically illustrates embodiments of an adhesive device of the present invention, namely a single-sided adhesive tape comprising a carrier (T) and a layer (D) of electro-responsive adhesive, laminated on an electrically conductive substrate S. The carrier possesses an anti-corrosion layer (Cl), primer layer (P) and backing film (F).

[0227] Between the adhesive and the electrically conductive substrate is a protected noncorroded smaller metal substrate (NCS). Harsh conditions cannot alter the smaller metal substrate. Conversely, the smaller metal substrate corrodes (CS) when exposed to harsh conditions and left unprotected.

[0228] ADHESIVE TAPE DESIGN

[0229] In one embodiment, the device of the present invention may take the form of an adhesive tape. The following further illustrates possible configurations of the adhesive tape of this embodiment of the present invention. However, they are in no way a limitation of the teachings or disclosure of the present invention as set forth herein.

[0230] As described above, the adhesive tape of the present invention may adopt various structures. Fig. 1A depicts a single-sided adhesive tape of the present invention. The adhesive tape may preferably comprise a carrier (T) constituted by a backing film (F) with a primer (P) and an anti-corrosion layer (Cl) on top. The anti-corrosion layer is followed by an electro-responsive PSA layer (D). The layer (D) is coated on the anti-corrosion layer side of carrier (T) and in contact with the anti-corrosion layer.

[0231] According to a further preferred embodiment, the adhesive tape of the present invention may be configured as a double-sided adhesive tape. In the configuration shown in Fig. IB, the carrier (T) has an anti-corrosion layer and electro-responsive PSA on one side, while the opposite side is laminated with a commercially available double-sided adhesive tape, such as tesa tape.

[0232] The adhesive tape of the present invention may preferably be a double-sided tape with both sides of the backing (F) coated with an anti-corrosion and primer layer, which is then coated with a electro-responsive PSA layer (D) of adhesives (A) on both sides of the anticorrosion layers, Fig. 1C.

[0233] The anti-corrosion layer of carrier (T) and adhesive (D) can be slightly protruding outside of the adhered surfaces (e.g. conductive substrates) if the view of the NCS is restricted as well as to facilitate space for the voltage connection. For example, when voltage is to be applied to the anti-corrosion layer of the carrier (T) that comprises only one side coated, sufficient connection of the voltage source to such a carrier may be ensured if the backing layer protrudes.

[0234] PREPARATION OF DEVICE AND METHOD OF MODIFYING THE ADHESIVE STRENGTH

[0235] When a device (e.g. tape) is disposed on electrically conductive substrates, an embodiment of an adhesive device of the present invention is constructed. According to preferred embodiments, the device (tape) of the present invention could be a single-sided adhesive tape and preferably has only one layer of an adhesive containing one or more ionic liquids, e.g., layer (D) of the electro-responsive adhesive on a carrier (T) shown in Fig. 1A. In this configuration, when an electrically conductive substrate (S) is disposed onto the first face of the layer (D) of electro-responsive adhesive (Fig. 2), is connected to the positive terminal of a DC voltage source, and the an anti-corrosion layer of the carrier (T), being on the opposite, i.e., the second, face of the layer (D) of adhesive, is connected to the negative terminal of the DC voltage source, and when a DC voltage, preferably a DC voltage of 5 to 50 V for 15 s to 1000 s, is applied, the peel adhesion between the layer (D) of electro- responsive adhesive and the electrically conductive substrate is increased, thereby achieving bonding between the layer (D) and the conductive substrate (S) and changing the adhesive state from an initial state to a bonded state. This step is optional if the initial bonding strength is sufficient for the intended application.

[0236] If the connection is reversed, e.g., the negative terminal of the DC voltage source is connected to the electrically conductive substrate (S) and the positive terminal is connected to the carrier (T), and a higher DC voltage, preferably a DC voltage above 10 V, more preferably of (5 to 50) V for 15 s to 1000 s, is applied, the debonding of the layer (D) of adhesive from the substrate (S) can be achieved.

[0237] For both cases, the peel adhesion increases with the positive DC voltage to the conductive substrate (S) relative to carrier (T) and decreases with the negative DC voltage to the conductive substrate (S) relative to carrier (T).

[0238] The present invention relates to the use of the corrosion-inhibiting adhesive device defined in the claims in applications where protection of metallic surfaces or conductive substrates is critical. These include: (i) different metal surfaces or substrates coated with conductive materials; (ii) robotics, preferably in the manufacturing of robotic gripping arm; (iii) sealing applications; (iv) applications where high bonding strength or debonding is needed without application of heat, light or pressure; (v) consumer electronics; (vi) electronic packaging; (vii) microelectronics; (viii) battery mounting for EVs or cell phones with reusable functions; (ix) cell phone back cover mounting; (x) biomedical applications; (xi) recycling applications (e.g., disassembly and reassembly of products); (xii) microfabrication (e.g., transfer and positioning of small components); (xiii) environmental and structural adaptability (adaptability to surface conditions or structural changes); (xiv) printing plate mounting on printing sleeves in flexoprint processes; (xv) cleanroom handling; (xvi) micro-assembly; (xvii) optical component placement; (xviii) temporary fixturing during machining; (xix) adaptive handling of soft or fragile items; (xx) non-mechanical holding in sterile environments; and (xxi) gentle release systems for automated packaging. Further examples include the use in an assembly process of electric or electronic devices, the electric or electronic devices preferably being selected from the group consisting of computers, chips, smartphones, displays, touch panels, sensors, light sources such as LEDs or OLEDs, power supply units, or other electronic devices.

[0239] EXAMPLES

[0240] The present invention is illustrated below by a number of examples. The examples described below illustrate particularly advantageous versions of the present invention, without wishing thereby to subject the present invention to any unnecessary limitation.

[0241] RAW MATERIALS

[0242] (a) Backing films:

[0243] PET / etched PET film of different thicknesses

[0244] - PP film

[0245] Fabric

[0246] ITO coated PET film with different thickness from Sigma Aldrich

[0247] (b) Redox Active Layer

[0248] PEDOT:PSS aqueous dispersion from Ossila

[0249] PEDOT:PSS ink from Sigma Aldrich

[0250] PEDOT:PSS nano particles aqueous dispersion from Sigma Aldrich

[0251] EDOT monomer with different derivatives from TCI

[0252] (c) Acrylate monomers:

[0253] 2-(2-Ethoxyethoxy)ethyl acrylate (EEEA or EDGA)

[0254] N,N-Dimethylacrylamide (DMAA)

[0255] Butyl acrylate (BA)

[0256] Benzyl acrylate

[0257] 2-Hydroxyethyl acrylate (HEA)

[0258] Methyl acrylate (MA)

[0259] Acrylic acid (AA)

[0260] (d) Initiators:

[0261] 2,2-Dimethoxy-2-phenylacetophenone (Irgacure 651) from Sigma-Aldrich 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184) from Sigma-Aldrich (e) Ionic liquids l-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM FSI) from Proinic 1-Butyl-l-methylpiperidinium bis(trifluoromethylsulfonyl)imide (BMPip TFSI) from lolitec 1,3-Dimethylimidazolium bis(trifluoromethylsulfonyl)imide (DiMIM TFSI) from lolitec Triethylsulfonium bis(trifluoromethylsulfonyl)imide (S222 TFSI) from lolitec 1-Methyl-l-propylpyrrolidinium bis(fluorosulfonyl)imide (Pyrl3 FSI) from TCI l-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM TFSI) from Proionic l-Ethyl-3-methylimidazolium hexafluorophosphate (EMIM PFe) from Sigma- Aldrich l-Butyl-3-methylimidazolium hexafluorophosphate (BMIM PFe) from Sigma- Aldrich l-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIM TFSI) from lolitec l-Butyl-3-methylimidazoliumtetrafluoroborat (BMIM BF4) from Sigma-Aldrich

[0262] (f) Electrically conductive substrate / adherend:

[0263] ASTM steel plate

[0264] (h) Other materials):

[0265] Water as plasticizer

[0266] Crosslinkers: Erisys 240, Polyethylene glycol) diacrylate (PEGDA)

[0267] Oxidant: Iron(lll) p-toluenesulfonate hexahydrate from Sigma Aldrich Butanol from Sigma Aldrich

[0268] Different types of PEGs (PEG 200, PEG 400 and similar kinds)

[0269] Different types of carbonates as ethylene carbonate (EC), vinylene carbonate (VC)

[0270] EXPERIMENTAL EXAMPLE 1:

[0271] Electrically debonding PSA tapes often suffer from corrosion problems such as pitting, crevice corrosion, or even galvanic corrosion, either on the metallic backing or on the adhered substrate. The issue becomes even more pronounced at elevated temperature and humidity. Below is the description of corrosion prevention studies of backing. For that, the typical metallic backing used in electrical debondable adhesive has been replaced by an electrically conductive anti-corrosion polymer layer, for example PEDOT:PSS, which eliminates the corrosion induced by ion-conductive PSA tapes.

[0272] The electrically debondable adhesive was prepared according to WO 2025 / 068404 Al. The formulation contains 91.85 wt % of UV-curable syrup [prepared from 60:40 EDGA and DMAA, with 0.0065 wt % Irgacure 651] as described in WO 2025 / 068404 Al, mixed with 8 wt % of the ionic liquid EMIM FSI and 0.15 wt % of the photoinitiator Irgacure 185. The mixture was homogenized using a roll bench until completely mixed. This liquid electrolyte was then directly coated onto a backing to the side of pre-coated with PEDOT:PSS conductive ink and cured with a UV dose of 3000 mW-s / cm2.

[0273] For comparison, the same adhesive was coated on metalized PET films (AI-PET and Sn-PET). All samples were cut to 20 x 100 mm strips and applied on ASTM steel plates for corrosion studies. Two approaches were used: (A) visual inspection under accelerated weather conditions, and (B) electrochemical measurements.

[0274] (A) Visual inspection

[0275] Corrosion behavior was first assessed visually using the following rating system:

[0276] Excellent: no visible stain, no corrosion, unchanged surface

[0277] Good: almost clean, only faint traces visible at certain angles, especially edges, no residue Fair / Average: noticeable staining, partial loss of backing

[0278] Poor: clear residue or strong corrosion staining requiring cleaning

[0279] Very poor: heavy residue, visible discoloration, backing completely degraded

[0280] At 25 °C and 50 RH% condition, all samples were rated as excellent, showing no signs of corrosion.

[0281] However, after exposure to harsh conditions (85 °C and 85% RH for 3-7 days), clear differences were observed. The Sn-PET and AI-PET backings corroded completely and were rated as very poor. By contrast, the PEDOT:PSS-coated samples only showed slight color change of the backing, but the coating itself remained intact. These were rated as good in terms of corrosion resistance. The ASTM steel plate for all samples also shows no sign of corrosion except some adhesive residues. Table 1 summarizes these results. (B) Electrochemical measurements

[0282] To gain a deeper understanding of how the backing corrodes in the ion-conductive PSA system, electrochemical methods were applied.

[0283] Linear Polarization Resistance (LPR):

[0284] LPR measurements were carried out following ASTM G59-97. First, the open-circuit potential (OCP) of the samples [table 1] were recorded at 5 and 55 minutes to ensure that the system reached a stable state. The samples were then polarized at -30 mV vs. OCP for 1 minute, after which the potential was scanned from -30 mV to +30 mV relative to OCP at a scan rate of 10 mV / min. From the slope of the current-potential curve, the polarization resistance (Rp) was determined using an Rp fit analysis tool. Based on Rp, the corrosion current density (icorr) and the corresponding corrosion rate were calculated.

[0285] Electrochemical Impedance Spectroscopy (EIS):

[0286] In addition, impedance spectroscopy was used to obtain qualitative and comparative information. Measurements were performed with a Biologic VMP-300 in the frequency range of 1 MHz to 100 mHz, using a 10 mV AC perturbation at room temperature and 50% RH. In the Bode plots, the absolute impedance | Z | at the plateau (frequency-independent region) was compared across different backings. Higher impedance values were interpreted as lower corrosion tendency, while lower impedance values indicated faster corrosion.

[0287] The results showed that metalized PET backings exhibited low impedance, confirming their high susceptibility to corrosion. In contrast, the PEDOT:PSS-coated samples displayed much higher impedance, indicating significantly improved corrosion resistance.

[0288] TEST METHODS

[0289] Unless otherwise indicated, all measurements were conducted at 23 °C and 50 % relative humidity. Unless indicated otherwise, moreover, the measurements of the adhesive tape were carried out with an adhesive layer with a thickness of 50 pm to 150 pm.

[0290] Test A: Peel Adhesion

[0291] A single-sided adhesive tape was cut with a width of 20 mm and a length of 150 mm. The adhesive tape was then laminated on a cleaned (using acetone after removing the protective film) ASTM steel plate upon removal of the siliconized PET liner. The other side of the adhesive tape was provided with [PEDOT:PSS or PEDOT:Tos - primer - PET] backing. The primer could be less than a 10-micron acrylic adhesive layer. Then the whole setup (adhesive device) was pressed by rolling back and forth over five times using a 4 kg roller.

[0292] The adhesive device was then vertically hooked to the bottom holder of a tensile testing instrument (ZwickRoell Z020), and the [PEDOT:PSS or PEDOT:Tos - primer - PET] backing was attached to the upper holder of the instrument.

[0293] For peel adhesion measurement, the [PEDOT:PSS or PEDOT:Tos - primer - PET] backing was pulled off at an angle of 180° with a velocity of 300 mm / min. The maximum force was recorded in N / cm for a complete peel of the adhesive tape from the steel substrate. The values reported here are the average of two individual measurements.

[0294] Test B: Ionic

[0295] The ionic conductivity, more specifically DC conductivity was measured by EIS (Electrochemical Impedance Spectroscopy) and extracted from the log-log plot of real part of the AC conductivity over an angular frequency by extrapolating the plateau region to the zero-frequency using the Dyre fit function. Measurements were done by a BioLogic VMP- 300 in the mode of PEIS (potentio EIS) with a constant voltage amplitude of 10 mV and a frequency range from 7 MHz to 50 mHz. A transfer tape of the adhesive (no carrier layer) of circular dimension with a diameter of 18 mm was applied between two circular steel plate electrodes. The tape thickness was 50 pm to 150 pm. The measuring temperature was 25 °C.

[0296] Test C: Surface Resistance

[0297] A NAGY SD-510 Sheet Resistivity Meter from INNOVENT e. V. Technologieentwicklung Jena was used to measure surface resistance of PEDOT:PSS or PEDOT:Tos layers on primed PET backing.

[0298] Test D: Corrosion Testing:

[0299] To evaluate the corrosion protection performance of the adhesive device of the present invention, a comparative test was conducted using a reference substrate and test substrates coated with the adhesive system. The reference substrate was left uncoated to serve as a control, while the test substrates were laminated with the adhesive device comprising an electrochemically polymerized PEDOT layer (anti-corrosion layer) with varying counterions (e.g., tosylate, chloride). All substrates were subjected to accelerated environmental aging conditions in a controlled climate chamber at 80 °C and 80% relative humidity (RH) for a defined exposure period (e.g., 72 hours). This harsh environment simulates corrosive stress and enables evaluation of the protective capabilities of the adhesive system.

[0300] After exposure, the substrates were analyzed by two complementary methods:

[0301] Visual Inspection:

[0302] Each substrate was visually compared against reference control. Corrosion was assessed based on the presence of discoloration, pitting, or surface degradation. The degree of corrosion was qualitatively ranked (e.g., none, mild, moderate, severe) and documented photographically under standardized lighting conditions.

[0303] Gravimetric Analysis:

[0304] Substrates were weighed before and after environmental exposure using a precision analytical balance (±0.1 mg accuracy). The mass loss (Am) was calculated as an indicator of material degradation due to corrosion. Lower mass loss values correlate with higher corrosion protection efficiency. TTI ^initial ^-filial where: niinitiai = mass before exposure nifinai = mass before exposure

[0305] The performance of the adhesive device was correlated with the type of counterion used in the PEDOT layer. Smaller counterions (e.g., Cl", Tos") were found to enhance corrosion resistance, as evidenced by reduced visual degradation and lower mass loss compared to larger or less mobile counterions.

[0306] This test method demonstrates the protective function of the adhesive device and highlights the critical role of counterion selection in optimizing corrosion resistance under electrochemical and environmental stress.

Claims

Claims1. A device comprising: an electro-responsive adhesive whose adhesive properties can be modified from a bonded state to a debonded state by a first electric stimulus, and which can be modified from a debonded state to a bonded state by a second electric stimulus, the first and second electric stimulus being different from each other, and an electrically conductive substrate and / or backing to which the adhesive is adhered, wherein the device satisfies one, two, or all of the following: i) the open circuit potential between the adhesive and the backing and / or the substrate is 100 mV or less; ii) the device comprises an anti-corrosion agent that can undergo a reversible electrochemical reaction, which is present within the adhesive and / or between the adhesive and the substrate and / or the backing; iii) the adhesive comprises one or more selected from the group consisting of an anti-corrosion agent, a drying agent and oxygen scavenger.

2. The device according to Claim 1, wherein the anti-corrosion agent comprises one or both an oxygen scavenger and a corrosion inhibitor.

3. The device according to Claim 1 or 2, wherein the difference in open circuit potential is achieved by providing a conducting layer between the adhesive and the substrate and / or the adhesive and the backing, and or by including an additive for modifying the open circuit potential of the adhesive, preferably in an amount of 10% by weight or less, relative to the total weight of the adhesive.

4. The device according to Claim 1, 2 or 3, wherein the anti-corrosion agent that can undergo reversible electrochemical reaction is present in the form of a corrosion- protective layer on the substrate and / or the backing.

5. The device according to any one of claims 1 to 4, wherein the anti-corrosion agent has a lower standard reduction potential than the material forming the electrically conductive substrate or the backing, the absolute difference in standard reduction potentials preferably being 100 mV or more, such as 300 mV or more or 500 mV or more.

6. The device according to any one of claims 1 to 5, wherein a corrosion protective layer is formed on the substrate and / or the backing, which is made from a metal oxide, which may be a spontaneously formed oxide layer or an oxide layer formed by anodic oxidation, from a metal having a standard reduction potential of OV or less, such as - 0.2 V or less or -0.5 V or less, for example zinc or magnesium, or from an alkali metal or earth alkali metal halide, such as CaFz.

7. The device according to any one of the preceding claims, wherein the anti-corrosion agent that can undergo a reversible electrochemical reaction is present in the form of a coating on the backing and / or the substrate, the coating preferably being a polymer coating, the polymer coating preferably being electrically conductive.

8. The device according to any of the preceding claims, which exhibits an adhesive strength in the bonded state of 0.5 N / cm to 15 N / cm or higher, such as 25 N / cm or higher or 40 N / cm, and an adhesive strength in the debonded state of 0.1 to 0.4 N / cm.

9. The device according to any one of the preceding claims, wherein the electric stimulus is selected from the group consisting of an alternating current (AC), an alternating voltage, a direct current (DC), a direct voltage, or a pulsed current or voltage, which preferably is a DC or AC current or voltage in the range of 0.5 - 230 V, preferably a DC voltage in the range of 5 to 100 V or 5 to 20 V.

10. The device according to any one of the preceding claims, which is in the form of an adhesive tape comprising a backing and an adhesive layer comprising the adhesive, and wherein preferably the backing is an electrically conductive backing, such as for example a metal foil, an electrically conductive polymer, or on insulating polymer that has been treated to impart electrical conductivity, e.g. by providing a metallic film on a polymer foil.

11. The device according to any one of the preceding claims, wherein the pressure sensitive adhesive has ionic conductivity, preferably in the range of 1010S / cm to 10" 3S / cm, and / or comprises one or more ionic liquids and / or one or more salts that are no ionic liquids, preferably a lithium salt.

12. The device according to any one of the preceding claims, wherein the pressure sensitive adhesive is prepared by polymerizing a mixture comprising at least the following components:a) 35 to 70 wt % of acrylate monomer (al) from the group of (meth)acrylic esters containing at least one oxygen atom; and b) 20 to 40 wt % of acrylate monomer (a 2) from the group of (meth)acrylic esters and / or amides containing at least one nitrogen atom; and c) 0.1 wt % to 15 wt % of one or more electro-responsive compounds from the group of polymerizable zwitterionic monomers and / or non-polymerizable zwitterionic compounds, preferably one or more zwitterionic monomers; and d) 0.005 to 10 wt % of at least one initiator; and e) 0 wt % to 20 wt %, preferably 0.1 to 20 wt%, of one or more ionic liquids; and f) 0.0 wt % to 20 wt %, preferably 0.1 to 20 wt%, of one or more salts that are no ionic liquids; and g) 0.0 to 20 wt%, optionally 0.1 wt % to 20 wt %, of one or more acrylate monomers (a3), wherein the one or more acrylate monomers (a3) are different from acrylate monomers (al) and (a2); and h) optionally additives, wherein the weight fractions of the components are based on the total weight of the mixture.

13. The device according to any one of the preceding embodiments, wherein the adhesive is selected from the group consisting of acrylic-based adhesives, urethane- based adhesives, rubber-based adhesives, vinyl-based adhesives, epoxy-based adhesives, silicone-based adhesives, and mixtures thereof, and which is preferably a pressure-sensitive adhesive.

14. Use of the device as set out in any of the preceding claims in an assembly process of electric or electronic devices, the electric or electronic devices preferably being selected from the group consisting of computers, chips, smartphones, displays, touch panels, sensors, light sources such as LEDs or OLEDs, power supply units, or other electronic devices.

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