Adhesive device comprising an electro-responsive adhesive able to lower environmental load

Abstract

The present invention relates to a device comprising an adhesive with electrically adjustable adhesion properties, enabling bonding, debonding, and rebonding to complex surfaces upon application of an electric stimulus. The adhesive exhibits at least two distinct adhesive states, which can be reversibly switched. This switching allows the adhesive to be used for assembling, manipulating, and moving objects. The device may be configured as an adhesive tape, such as a pressure-sensitive adhesive (PSA) tape, with the adhesive applied on one or both sides of a backing. The materials are environmentally friendly, incorporating recycled and / or biobased components to partially or fully replace ionic liquids, thereby improving biodegradability, reducing CO2 footprint, and minimizing environmental impact. The device operates with low power consumption and minimal electric wear, ensuring energy efficiency, long service life, and reliable performance. Applications include industrial automation, robotic gripping of delicate objects, and temporary fixation in electronic assembly processes.

Description

[0001] tesa SE Norderstedt

[0002] ADHESIVE DEVICE COMPRISING AN ELECTRO-RESPONSIVE ADHESIVE ABLE TO LOWER ENVIRONMENTAL LOAD

[0003] TECHNICAL FIELD

[0004] The present invention relates to a device comprising an electro-responsive adhesive that is able to lower the environmental load that are imposed by systems currently in use. The device may be in the form of a gripping device for moving objects, the objects being adhered to the device by an adhesive action of the adhesive.

[0005] BACKGROUND ART

[0006] Attaching and moving objects is a task that occurs frequently in everyday life and in particular in production process, including automated production process. For moving objects, often a gripping device ("gripper") is employed that temporarily attaches to the object to be moved, e.g. mounted as part of a robot arm. The force that enables the attachment between the gripper and the object to be gripped is not particularly limited. This may include e.g. suction / vacuum, attraction by means of electrostatic or magnetic force, or mechanical interlocking.

[0007] Electro-attraction technologies have emerged as a promising solution, leveraging electrostatic forces to grip and manipulate objects without requiring suction or excessive mechanical pressure. Unlike mechanical grippers that rely on friction or suction, electro- attraction-based grippers exert minimal mechanical stress on objects. This approach enables the secure handling of delicate objects and irregular surfaces without causing damage, making it ideal for industries such as robotics, electronics, food packaging, healthcare, and material handling where precision and care are essential.

[0008] Electro-attraction gripping devices employ the principle of electrostatic attraction to adhere objects. The gripper system comprises electrodes that are strategically arranged, commonly on a dielectric surface, the electrodes typically being made from conductive materials such as metals or conductive polymers patterned onto a flexible substrate. When a voltage is applied across the electrodes, an electric field is generated, inducing opposite charges on the surface of the object and creating electrostatic attraction. The attraction force can be modulated by varying the applied voltage, allowing precise control over grip strength for objects with different weights, shapes, and surface textures.

[0009] Additionally, electro-attraction systems can be integrated with sensors and control circuits to create smart gripping devices. These systems can detect the presence of an object, measure electrostatic force, and adjust voltage in real time to maintain a secure grip. Advanced materials, such as carbon nanotubes and graphene, are being explored to further enhance the performance and versatility.

[0010] However, conventional methods often require smooth, clean, and flat surfaces or involve applying large mechanical forces that can damage delicate items. These limitations have driven the search for alternative methods that offer more flexibility and gentleness in handling diverse objects.

[0011] Robotic gripping systems incorporate a range of designs and mechanisms to enhance their gripping capabilities. For instance, US 8325458 B2 details an electro-attraction gripping device that includes multiple surfaces, each equipped with electrodes. These surfaces can be positioned against different regions of a foreign object, generating forces that hold and move the object securely. The design ensures robust handling of objects with varying shapes and sizes.

[0012] One notable feature is the use of shear grippers, as described in US 8861171 B2. A shear gripper consists of an attracting surface linked to one or more electrodes and a loadbearing structure. A controller applies voltage to these electrodes, enabling the gripper to attract and grip nearby items and exert shear forces to move them.

[0013] The adaptability of electro-adhesive gripper surfaces to conform to various shapes is addressed in US 9130485 B2. This patent describes a system where height-adjustable pins alter the gripping surface's shape, allowing it to conform to different objects. Pin-locking mechanisms secure the pins' positions, maintaining the desired shape after adjustment. This feature enhances the versatility of the gripper, making it suitable for handling objects of varying sizes, shapes, and textures. Additionally, the system can be integrated with sensors to detect the object's properties and adjust the grip accordingly. This adaptability is crucial for applications in logistics, where items of different dimensions need to be handled efficiently.

[0014] Modularity is a crucial aspect of robotic grippers, enhancing their construction and maintenance. US 2016318190 Al outlines a modular robotic gripping system that simplifies the assembly and repair of components, making the system more cost-effective and efficient. The patent describes interchangeable modules for different parts of the gripper, allowing for quick replacements and upgrades. This modular approach also enables customization of the gripper for specific tasks and environments, improving its overall functionality and performance. The ability to easily swap out components is particularly advantageous in manufacturing settings where downtime can be costly.

[0015] Devices relying on attraction by electrostatic forces also include sophisticated methods for controlling electrical energy conversion into mechanical energy, as illustrated in US 11065771 B2. Such devices employ overlapping electrodes on polymeric supports to generate voltage changes. The patent describes various configurations and control techniques for optimizing energy conversion efficiency and actuation responsiveness. These methods enhance the gripper's ability to perform complex movements and tasks, improving its overall functionality and efficiency. Effective energy conversion is essential in reducing power consumption and increasing the operational lifespan of robotic systems.

[0016] The design and manufacturing of electromechanical adhesive structures are further advanced using 3D printing techniques, as mentioned in US 11926041 B2 and KR 20210052150 A. These methods enable the creation of three-dimensional structures that manipulate adhesive force and provide tactile sensing, enhancing robotic applications beyond human capabilities. The patent details various materials and printing processes for creating high-precision structures, ensuring consistent quality and performance. These advancements enable the gripper to perform intricate tasks with high accuracy, expanding its application range. Using 3D printing for manufacturing grippers also allows for rapid prototyping and customization, which is valuable in research and development stages.

[0017] A shortcoming of such devices that attract an object by electrostatic forces is that they rely on the presence of a voltage or current, and the attraction force is lost once the power supply is disconnected. Such shortcomings can be avoided by relying on the adhesive action of an adhesive composition that does not require an electric current or voltage in order to exhibit adhesive properties, such as a pressure-sensitive adhesive composition.

[0018] However, while adhesiveness is an inherent property of such systems even in the absence of an applied voltage, adhesive systems suffer from other drawbacks, such as a limited reusability. Also, the adhesive action is typically a material propriety that is non-switchable, i.e. which is a constant material property. Accordingly, since moving / gripping requires both the creation of an attachment (e.g. via an adhesive action or by attraction), but also requires the release of the attachment, a gripping device is difficult to realize with conventional adhesives. An interesting, relatively new class of materials known as electrically debondable adhesives may be suitable to fill this gap. Electrically debondable adhesives can be categorized as either pressure-sensitive adhesives (PSA) or structural bonding types. PSA can often be used without an additional curing step but typically exhibits relatively low bonding strength. Structural adhesives provide higher bonding strength but are non-tacky at room temperature, typically require an activation step in order to exhibit high adhesivenes, and may require hours to weeks to reach their final strength. This renders the latter unsuitable for applications in which frequent and rapid changes between low and strong adhesive strengths are required.

[0019] Both types may be debondable under electric voltage with differing performance; however, a common limitation remains: they do not reliably support sequential bonding, debonding, and rebonding— a functionality required in many modern circular-economy applications, particularly where the permitted time interval between debonding and rebonding is limited.

[0020] Most of the explored electrically debondable adhesives such as PSA described in the prior art are in the shape of tapes where bonding, debonding, and rebonding is possible by application of respective electric stimuli. However, most of these adhesive devices present limited reworking capabilities, as when the tape is rebonded after debonding, the obtained adhesion strength does not reach the adhesion strength upon first bonding and may be even lower than the initial adhesion strength (prior to application of any electric stimulus, i.e. the adhesives "natural" adhesive strength). Even if the polarity of the DC voltage is changed after debonding to effect rebonding, the bonding strength does not increase or increase only very little; rather, anchorage failure between the backing and adhesive frequently occurs. A further disadvantage is their long recovery time (defined as the time without electric stimulus between debonding and the possibility for rebonding with a similar or same adhesion strength) required to achieve sufficient bonding strength upon rebonding, making rapid rebonding after debonding impossible.

[0021] In order to work properly, the adhesive strength of the adhesive should be modifiable from an initial state, prior to the application of any electric stimulus, to a bonded state that typically has a higher adhesive strength than in the initial state by applying an electric stimulus ("bonding"), while another electric stimulus (e.g. voltage, current) is able to lower the adhesive strength to be lower than in the initial state and the bonded state (so-called "debonding"). Here, the adhesive strength of the adhesive should maintain in the respective state even after the electric stimulus is cut off or is disconnected. The adhesive in the debonded state should then be again modifiable to an increased adhesive strength that preferably is similar to, or even higher than, the adhesive strength in the bonded state by application of another electric stimulus (so-called "rebonding").

[0022] Hence, new devices are required which allow reducing the recovery time between debonding and rebonding while allowing to obtain sufficiently high initial adhesion strength and sufficiently high rebonded adhesion strength, while also allowing a sufficiently low debonded adhesive strength. Put differently, there is a need for an adhesive device that provides sufficient initial bonding strength and allows the strength to be adjusted— either increased or decreased— on demand by switching the polarity of an applied stimulus such as a DC voltage. In addition, such devices should minimize continuous power requirements and associated energy losses, and be designed to limit electrode wear and material degradation to extend service life and reduce waste.

[0023] Such materials would not only enable strong adhesion but also allow controlled debonding and efficient recycling with short recovery times, addressing key challenges in circular material design.

[0024] CN 119351031 A discloses a bio-based reactive polyurethane hot melt adhesive formulated with oxide- or sulfide-based solid electrolytes, bio-derived polyol compounds, and a silane coupling agent, producing a low-free-isocyanate system that combines bonding with electrically triggered disassembly and a reduced petrochemical footprint.

[0025] EP 1814703 Bl describes a recycling process in which particles embedded in the adhesive mass expand under the supply of electrical energy, breaking the adhesive joint and enabling the clean separation of electronic components for reuse.

[0026] CN 118389082 B advances this concept with a reusable, high-shear electrified viscosityreducing tape in which most of the electrolyte is chemically bonded to the acrylate or olefin adhesive backbone, preventing electrolyte leakage and allowing repeated electric activation without loss of performance.

[0027] EP 4516868 Al introduces a curable, thermally conductive adhesive containing electrolytes and electrically conductive fillers that can be electrically or thermally debonded, providing rapid repair and recycling of electric-vehicle battery modules.

[0028] TECHNICAL PROBLEM

[0029] The known systems based on attraction by electrostatic forces have some critical issues as they generally require flat, smooth, and dielectric surfaces such as glass or plastic to function effectively, while rough, porous, or conductive surfaces significantly reduce performance. The achievable attraction force is typically lower than the adhesion strength of pressure-sensitive adhesives and is often insufficient for heavy loads or secure holding.

[0030] Further, such devices commonly demand high operating voltages, in the range of several kilovolts, which raises safety concerns and limits their use in consumer applications. Attraction is often maintained only under continuously applied voltage application, resulting in high energy consumption and immediate loss of attraction once the power supply is interrupted.

[0031] Further, such systems are sensitive to dust, humidity, and surface contamination, which rapidly degrade adhesion efficiency and reduce durability. Scalability is also limited, as the electrostatic field weakens with increasing size, distance, or surface irregularities, making large-area or flexible applications difficult.

[0032] In relation to electro-responsive adhesives, conventional systems mentioned in prior art section exhibits poor reusability, since repeated bonding and debonding cycles can degrade performance, while surface fouling further limits adhesion over time.

[0033] Overall, despite their advantages, conventional attraction and adhesion systems applicable to grippers face significant sustainability challenges that affect long-term viability and environmental impact. Most devices do not adequately address key sustainability considerations, including the use of sustainable materials and the recyclability, reusability, and repairability of components. These limitations underscore the need for greener alternatives and innovative materials strategies to reduce environmental burden.

[0034] OBJECTS OF THE INVENTION

[0035] There is a need for a device that overcome the limitations of conventional systems. In particular, there is a need for an electro-responsive adhesive system that combines the adhesive strength, as e.g. observed as inherent tack of a pressure-sensitive adhesive, with electrically tuneable adhesion.

[0036] Such a system should enable strong and reliable bonding on a wide range of substrates, including rough, porous, or conductive surfaces, where attraction by electrostatic force is ineffective. There is further a need for a system that operates at lower voltages, as certain objects may be sensible to high voltage, and the generation of high voltages is generally associated with an increased energy demand.

[0037] The device should also allow debonding without the need for the application of heat, light, or mechanical force, and provides reusability over multiple bonding-debonding-rebonding cycles with minimal loss of performance.

[0038] Further, there is a need for devices, e.g. based on adhesives that are transparent, flexible, and chemically resistant, suitable for use in electronics, robotics, biomedical, structural, and other advanced applications. Moreover, the device should enable repeated use and extending service life, thereby contributing to repairability, recyclability, and reduction of waste, eventually supporting environmental circularity.

[0039] In addition, by utilizing biodegradable polymers, natural fillers, and eco-friendly conductive additives to ensure that the tape materials decompose safely in environmental conditions, reducing long-term waste accumulation compared to conventional synthetic adhesives. This could address the growing demand for sustainable smart materials by combining electro-responsive adhesive technologies with green chemistry principles, thereby reducing reliance on permanent synthetic adhesives and promoting circular material life cycles.

[0040] SUMMARY OF INVENTION

[0041] The invention relates to adhesive devices and systems having electrically adjustable adhesion properties that allow bonding as well as repeated debonding and rebonding to various substrates, wherein the substrates may have simple or complex shapes or surfaces (e.g. containing holes), as well as to adhesive compositions selected from biodegradable, biocompatible, recycled, or non-PFAS sources.

[0042] The device may take the form of an adhesive tape, such as a pressure-sensitive adhesive (PSA) tape that may comprise the adhesive on one or both sides of an electrically conductive backing. The materials used in the adhesive tape can be environmentally friendly and designed to minimize waste. By incorporating recycled and / or biobased materials to partially or fully replace the common oil based chemical materials mostly used in an adhesive tape, the environmental burden is lowered.

[0043] The present invention therefore provides improvements in one or more of the following aspects: biodegradability energy consumption reduction of the overall CO2footprint production costs, and environmental impact.

[0044] The device may be in the form of, or may comprise, an electro-responsive adhesive tape and is designed to reduce the environmental burden by allowing for repeated use and / or by relying on biologically degradable materials, the latter allowing environmentally friendly disposal after the device has reached its lifetime. Such a device also is suitable in applications aiming at environmental circularities, supporting reusability, repairability, recyclability, and sustainability.

[0045] In one aspect, the device of the present invention is designed for repeated use, preferably without significant loss of functionality (adhesive strength) or a large number of re-use cycles (debonding-rebonding cycles). The device may thereby allow for easy disassembly and reassembly over (initial) bonding and several debonding and rebonding cycles.

[0046] At end-of-life, the materials may be recycled, thereby supporting sustainable manufacturing and lowering environmental burden. This not only reduces the need for frequent replacements but also ensures that the materials can be recycled at the end of their lifecycle, contributing to a more sustainable manufacturing process. Also, materials of the device (e.g., the adhesive and / or backing, if present) may be biodegradable, thereby reducing environmental burden in case recycling is not possible or is not conduced for other reasons.

[0047] The device may operate with low power consumption and exhibits minimal electric wear, ensuring energy efficiency, long service life, and reduced maintenance. Since no energy is required to maintain adhesion, substrates remain secured even during power outages. These features make the device suitable for applications requiring consistent performance, such as industrial automation, robotic gripping of delicate and varied objects with minimal risk of damage, and temporary fixation in electronic assembly processes.

[0048] By enabling remote or wireless control of adhesion strength, the invention may enhance flexibility and functionality of robotic systems, improving dexterity and adaptability in automated environments. Its sustainable design, multi-cycle bonding capability, and reworkability allow correction of misalignments during electronics assembly, reducing defects and additional processing steps. Overall, the invention provides a reliable, efficient, and environmentally responsible bonding solution that supports advanced automation while promoting a greener future

[0049] The present invention is based on the finding that, through suitable device design and material selection— particularly by incorporating materials derived from natural or recycled sources and using ionic liquids, preferably comprising deep eutectic solvents, in the adhesive composition— several of the aforementioned issues can be mitigated.

[0050] In one embodiment, the device is or comprises an adhesive tape that is configured as part of an electroadhesive gripper, enabling secure and reversible handling of objects with varied geometries, including delicate or perforated substrates, in robotic applications.

[0051] In order to achieve one or more of the above objectives, the present invention provides the following embodiments:

[0052] 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 differing from each other, wherein the device satisfies one or both of the following: i. the device is configured to move an object by adhering to the object by the adhesive force of the electro-responsive adhesive in the bonded state and moving the device together with the adhered object, and the electro- responsive adhesive is able to cycle between the bonded state and the debonded state for 50 or more times and with a recovery time of 2 minutes or less between a debonded state and a subsequent bonded state; ii. the electro-responsive adhesive is partially to fully biologically degradable.

[0053] 2. The device according to item 1, which exhibits, after application of a first respectively second electric stimulus, an adhesive strength of 0.5 N / cm to 15 N / cm or higher, such as 25 N / cm or higher such as 40 N / cm, in a bonded state, and an adhesive strength of 0.1 to 0.4 N / cm in a debonded state.

[0054] 3. The device according to item 1 or 2, wherein the adhesive comprises one or more selected from the group consisting of a) polymers derived from plants, such as cellulose and starch, as well as derivatives thereof, b) polymers derived from biologically produced monomers, and c) biologically degradable polymers, such as (poly) lactic acid, poly caprolactone, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and polyethlene glycol.

[0055] 4. The device according to item 1 or 2, wherein the adhesive comprises one or more selected from the group consisting of deep eutectic solvents, which are preferably obtained from hydrogen bond donor and hydrogen bond acceptor molecules such as urea, glycerol, succinic acid, phenyl acetic acid, menthol, choline chloride and proline chloride, histidine chloride, glucose, malic acid, citric acid, sucrose.

[0056] 5. The device according to any one of items 1 to 3, wherein the device comprises a recycled material.

[0057] 6. The device according to any one of the preceding items, wherein the first and second electric stimulus are 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, and wherein preferably the first and second electric stimulus are selected from DC or AC current or voltage in the range of 0.5 - 230 V, preferably a DC voltage in the range of 1 to 50 V, more preferably 1 to 10 V.

[0058] 7. The device according to any one of the preceding items, which comprises the adhesive and one or more electrically conductive surface(s) in the same or in different layers or regions, the different layers or regions preferably being adjacent to each other.

[0059] 8. The device according to any one of the preceding items, which is in the form of an adhesive tape or comprises an adhesive tape, the 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.

[0060] 9. The device according to any one of the preceding items, wherein the device further comprises an electrically conductive substrate in contact with the pressure sensitive adhesive.

[0061] 10. The device according to any one of the preceding items, wherein the pressure sensitive adhesive has ionic conductivity, preferably, in the range of 10’10 s / cm to 10’3 S / cm, and / or comprises one or more ionic liquids and / or one or more salts that are no ionic liquids, preferably a lithium salt. 11. The device according to any one of the preceding items, wherein the pressure sensitive adhesive is prepared by polymerizing a mixture comprising at least the following components: a) 20 to 80 wt % of acrylate monomer (al) from the group of (meth)acrylic esters containing at least one oxygen atom; and b) 20 to 80 wt % of acrylate monomer (a2) from the group of (meth)acrylic esters and / or amides containing at least one nitrogen atom; and c) 0.0 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) 0.0 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 (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.

[0062] 12. The device according to any of the preceding devices, which is, or forms part of, a gripping device that is configured for moving objects, preferably remote-controlled.

[0063] 13. A system for remotely operating the device according to the preceding items, the system comprising a device according to any one of the preceding items and a controller that is configured to provide the first and second electric stimulus to the device, the controller being operated by software or by a user input.

[0064] 14. A method of moving an object, the method comprising the steps of

[0065] (A) Applying an electric stimulus to a device as defined in any of the preceding items, the electric stimulus being a second electric stimulus for modifying the adhesive to a bonded state; (B) Attaching an object to be moved to the adhesive in the bonded state via the adhesive, the objection being in a first location,

[0066] (C) Moving the device with the attached object to a second location, and

[0067] (D) Applying an electric stimulus to the device, the electric stimulus being a first electric stimulus for modifying the adhesive to a debonded state, to thereby release the object at the second location.

[0068] 15. The method of moving an object according to item 13, wherein the steps (A) to (D) are repeated a plurality of times to move a plurality of objects, and wherein preferably the method is part of an assembly process, such as an assembly process of electronic devices.

[0069] 16. A method of reducing the number of faulty products in an assembly process that comprises comprising joining two or more different members to form an assembled part, the method including a step of preliminarily assembling members using an adhesive as defined in any of the preceding items confirming the proper alignment of the preliminary assembled members, and optionally performing an additional step of permanently joining the members if the alignment is correct, or optionally disassembling the assembled members and correcting the alignment of the members if the alignment is incorrect.

[0070] 17. Use of a device as defined in any of items 1 to 11 or of a system according to item 12 in an assembly process of electronic devices, such as computers, chips, smartphones, displays, touch panels, sensors, light sources such as LEDs or OLEDs, or other electronic devices.

[0071] Further aspects and features of the present invention will become apparent from the following description. DETAILED DESCRIPTION OF THE INVENTION

[0072] DEFINITIONS

[0073] 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.

[0074] The expression "laterally protrude" refers in the context of the present invention to any kind of lateral protrusion of the layer or layers in question and means that the layer in question extends further, particularly in the "xy" plane and hence laterally - perpendicular to the stack direction - than does the reference layer. In place of the term "lateral protrusion", terms used in the context of the present invention include "lateral extension" or "lateral extension portion". The term "lateral" is referenced here to any direction of extent of the layer plane "xy" perpendicularly to the stack direction of the layers "z". The term is therefore independent in particular of the geometric shape of the adhesive tape in the "xy" plane, which for example may be a rectangle, as is usual for adhesive tapes (see above), or else may be a square or a circle. Minor fluctuations in the dimensions of the individual layers in the "xy" plane, resulting from the die-cutting process or similar shaping processes, are not addressed herewith, in particular since such slight projections of material, in view of the dimensions, are incapable of receiving a voltage applied thereto as planned and they do not imply any additional effort in production, thus being not brought about by means of an additional method step.

[0075] 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. Whenever ranges are specified below, the upper and lower limit are included, as is any value in between.

[0076] 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.

[0077] The term "conventional adhesive" is used to denote an adhesive that is not electro- responsive.

[0078] 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 or magnitude of a physical state or property. In the present invention, a "second" element or state could be named "first" element or state, and vice versa, without changing the subject matter.

[0079] The term "initial bonding" or "initially bonded" refers to the adhesion strength of the adhesive measured by Test B (Peel Adhesion) outlined below without and prior to applying any electric stimulus. This adhesion strength may also be referred to as "natural" adhesive strength.

[0080] The term "debonding" refers to the application of an electric stimulus that decreases the adhesive strength of the adhesive, the adhesive being in the initially bonded or rebonded state prior to application of the electric stimulus.

[0081] The term "debonded adhesive strength" refers to the adhesion strength of the adhesive as measured by Test B (described below), after a first electric stimulus (e.g. voltage) for debonding (i.e. for reducing adhesive strength) has been applied, i.e. in the debonded state. The adhesive strength of a debonded adhesive is typically lower than the initial adhesive strength.

[0082] The term "bonding" refers to the process of applying an electric stimulus for increasing adhesive strength of the electrically responsive adhesive, the adhesive being in its initial state, thereby bonding the adhesive to a substrate (also referred to as adherend in the present invention). The bonding is thus the first application of an electric stimulus for increasing adhesion strength, prior to any debonding or rebonding. The term "bonded adhesive strength" refers to the adhesive strength that is observed in the Test B after an electric stimulus for increasing bonding strength has been applied to an adhesive in the initial state. The bonded state is optional, as a device may be subjected to debonding when it is in an initial bonded state, in which case no bonded state exists.

[0083] The term "rebonding" refers to the application of an electric stimulus to an adhesive that previously has been exposed to an electric stimulus for reducing the adhesion strength, i.e. to a debonding process.

[0084] The term "rebonding" refers to the third step in a sequence including subsequently initial bonding, debonding and rebonding, or the second step in sequence including debonding and rebonding, and encompasses any rebonding performed after a debonding step, such as in one or more debonding-rebonding cycles, such as bonding-debonding-(first) rebonding-(second) debonding- (second) rebonding, etc.

[0085] The term "cycle" is defined as including at least the sequence: debonding - rebonding, and a device of the present application may be suitable for 50 or more of such cycles without a significant loss of adhesive strength. Here, the term "significant loss" may be understood that in the 50threbonded state, the adhesive strength is 50% or more, such as 60% or more, 70% or more, or 80% or more, e.g. 90% or more, of the first rebonded adhesive strength (each determined after the same electric stimulus for increasing bonding strength, e.g. a DC voltage of 40 V for 15 seconds, as otherwise illustrated in the example section).

[0086] The term "rebonded adhesive strength" refers to the adhesive strength of the electrically responsive adhesive as measured by Test B after a debonded adhesive has been subjected to an electric stimulus (e.g. voltage) for increasing the 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. It may be as high or higher than the bonded adhesive strength.

[0087] The term "first debonded adhesive strength" denotes the adhesive strength that is observed after applying an electric stimulus for decreasing adhesive strength to a device in the initial or bonded adhesive state, i.e. in the state prior to the application of any electric stimulus or in the state after application of an electric stimulus for increasing adhesive strength.

[0088] The term "first rebonded adhesive strength" refers to the adhesive strength of the electrically responsive adhesive as measured by Test B after a once-debonded adhesive, i.e. an adhesive having the first debonded adhesive strength, has been subjected to an electric stimulus (e.g. voltage) for increasing the adhesive strength as compared to the adhesive strength before the electric stimulus is applied. If there is no first electric stimulus has been applied for bonding from the initial state, this may be the first electric stimulus for increasing adhesive strength that is applied to the device, and in this case the adhesive strength before the electric stimulus is applied is the initial adhesive strength.

[0089] In the present invention, ionic conductivity may be determined by methods known in the art or by Test C: Ionic Conductivity set out below. In case of discrepancy, the result obtained by Test C prevails.

[0090] 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 B below.

[0091] 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 B (Peel adhesion). The absolute difference in adhesive strength between a) a bonded or rebonded state and b) a debonded adhesive states may be 1 N / cm or more , 2 N / cm or more, e.g. 3 N / cm or more, 4 N / cm or more, or 5 N / cm or more, such as 6 N / cm or more, 7 N / cm or more, or 8 N / cm or more. While there is no particular upper limit, it may be 40 N / cm or less, such as 35 N / cm or less, 30 N / cm or less, 25 N / cm or less, or 20 N / cm or less, or 15 N / cm or less.

[0092] The term "electric stimulus" refers to any electric stimulus, and may thus include any voltage, duration, or frequency. The term may denote of a DC (direct current), AC (alternating current), VDC (volts direct current), VAC (volts alternating current), Pulsed DC (pulsed direct current), Pulsed AC (pulsed alternating current). 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 1 to 50 V, 1 to 10 V, or 10 to 50 V, and may be a direct or alternating current, and preferably is a direct current. The duration of the electric stimulus is not particularly limited and may be from 0.1 to 10,000 seconds, such as from 0.5 to 1000 seconds or from 1 to 300 seconds.

[0093] 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 an adhesive.

[0094] The term "carrier" is used to denote a structural element that provides support for a layer of an adhesive, meanwhile provides electrical conductivity. The carrier may consist of only one layer which provides both supporting and electrical conductivity functions, as will be described below. Or may be formed by a backing film having a primer layer or having a primed surface, on which optionally an electrically conductive layer is provided. The primed layer or primer, and the optional electrically conductive layer, may be provided on only one or on both sides of a backing film to thereby form the carrier.

[0095] The term "electrically conductive" is well understood by a skilled person. A possible threshold may be defined at a conductivity of 1 S / cm or higher, 10 S / cm or higher, such as 100 S / cm or higher, e.g. 103S / cm or higher, 104S / cm or higher or 105S / cm or higher.

[0096] An electric stimulus may be for increasing or for decreasing adhesive strength. An adhesive whose adhesive strength can be modified by respective electric stimuli from an initial state to a first bonded state, from a first bonded state to a first debonded state, and from a first debonded state to a first rebonded state may also be referred to as electro-responsive adhesive in the present invention.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] When a property or maintenance of a property after application of an electric stimulus is defined, any electric stimulus can be used. For test purposes, an electric stimulus of e 40V for 15 seconds may be employed. When properties of one or more cycles of debonding- rebonding are defined, for test purposes the cycles may involve these electric stimuli with opposite polarity, with a time gap of 5 minutes or more between the electric stimuli.

[0102] The term "biologically degradable" may be used to denote that the respective material (e.g. an electro-responsive adhesive and / or a backing) exhibits biodegradibiltiy in a suitable test, e.g. in a CO2 evolution test according to OECD 301B. The term may be used to denote that in a 28-day-test according to OECD 301B, the biologically degradable material reaches a biodegradability of 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, or 80% or more. Biodegradability may be 100% or less (in which case the material is fully biodegradable), but also lower, such as 95% or less, e.g. 90% or less.

[0103] DESCRIPTION OF EMBODIMENTS

[0104] The device of the present invention 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 differing from each other. Here, "differing from each other" can imply any difference in terms of duration, voltage, or current, but typically is at least a difference in polarity, while duration and voltage may, but need not, be identical. By applying an electric stimulus, the adhesive state can be modified, e.g. decreased from a bonded or rebonded state to a debonded state, or increased from a debonded state to a rebonded state, or from an initial state to a bonded state (prior to any debonding). The initial ("natural") 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 B described below. A bonded 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 or bonded 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.

[0105] The bonded / rebonded state and the debonded state may differ from each other in adhesive strength by 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 or 1.5 N / cm or more. In order to allow efficient operation and ensure proper functioning as a gripping device, requiring secure attachment and release, the difference in adhesive strength between the bonded (or rebonded) state and the debonded state is preferable 3 N / cm or more, 4 N / cm or more, or 5 N / cm or more, more preferably 6 N / cm or more, such as 7 N / cm or more. If there should be differences in the absolute values in bonded / debonded adhesive strength over multiple cycles, these values in respect of the adhesive strength in the bonded (rebonded) and debonded state refer to the first debonded and first rebonded state, e.g. each after an application of a stimulus of 40V for 15 seconds with opposite polarity, as illustrated in the example. Preferably, these difference values also apply to subsequent cycles, i.e. in the 10th, 20th, 30th, 40th, or 50thcycle, and more preferably also in subsequent cycles, e.g. in the 60th, 70th, 80thor 90thcycle. Further preferably, the absolute difference in adhesive strength between the 50thdebonded and the 50threbonded state is 50% or more of the absolute difference in adhesive strength between the first debonded and the first rebonded state, preferably 60% or more, such as 70% or more, 80% or more, or 90% or more, thereby ensuring long-term functionality over a large number of cycles and thereby improving sustainability.

[0106] The bonded state typically exhibits a higher adhesive strength than the initial state. 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.

[0107] The adhesive strength in the bonded state and in the rebonded state may each be in the range from 3 - 40 N / cm, preferably 4 - 25 N / cm, and more preferably 5 to 20 N / cm, e.g. 5- 18 N / cm and the adhesive strength in the debonded state may be in the range from 0.1 - 2 N / cm. The initial adhesive strength may be within the range for the debonded or the bonded state, and is preferably within the range for the bonded state, including the preferred ranges mentioned above. The initial adhesive strength may also be from 3 to 12 N / cm, such as from 3 to 10 N / cm. These values refer to the first cycle of debonding- rebonding, but preferably also in subsequent cycles, i.e. in the 10th, 20th, 30th, 40th, or 50thcycle, and more preferably also in subsequent cycles, e.g. in the 60th, 70th, 80thor 90thcycle.

[0108] 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 determine 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 (see also Figures 1A and IB).

[0109] 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 radiation, heat, or 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. This also allows the handling (gripping) of devices / substrates that are sensitive to radiation, heat and / or pressure.

[0110] While the electro-responsive adhesive used in the present invention is not particularly limited and may e.g. be selected from the group consisting of acrylic adhesives, rubberbased adhesives, silicone adhesives, epoxy adhesives, polyurethane adhesives, cyanoacrylate adhesives, and UV-curable adhesives, in one embodiment, the electro- responsive 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 selected from ionic liquids and / or one or more selected from deep eutectic solvents, and preferably yet 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.

[0111] 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. More surprisingly, in certain embodiments the device of the present invention can achieve a rebonded adhesive strength (peel adhesion on steel) of up to 17 N / cm from the debonding state (e.g. having an adhesive strength of 0.2 N / cm or less) by applying electromotive force for as little as 60s or longer. This rebonded adhesive strength may be 85 times or more greater than the adhesive strength in the debonded state and also much higherthan the rebonded adhesive strength of adhesive compositions disclosed in the prior art which have debonding functions.

[0112] Further, it is one advantage of the present invention that the above can be met with no or only a short period of time between the end of the electric stimulus for decreasing (debonding) and the beginning of the electric stimulus for increasing (rebonding) adhesive strength. Thus, in certain embodiments the conditions are met when the time between bonding and debonding is 2 minutes (120 seconds) or less, preferably 90 seconds or less, such as or less or 60 seconds or less, such as 45 seconds or less, 30 seconds or less, 20 seconds or less, 15 seconds or less, 10 seconds or less, 5 seconds or less, more preferably 2 seconds or less, 1 second or less, or even 0.5 seconds or less.

[0113] It is a further advantage of the present invention that not only the time between the electric stimuli for decreasing and increasing can be kept short, but that the device of the present invention allows multiple debonding-rebonding cycles while maintaining a high adhesion strength in the 2ndand further rebonded states and a low adhesion in the 2ndand further debonded states even at short times between the electric stimuli for debonding and rebonding. Here, the absolute values for the adhesion strength in the 2ndand further debonded states preferably fall within the ranges given above in N / cm for the first debonded state, and the absolute values for the adhesion strength in the 2ndand further rebonded states preferably fall within the ranges given above in N / cm for the first and subsequent rebonded states.This not only applies to the 2ndrebonded state, but preferably also for subsequent states, e.g. the 10thor more rebonded / debonded state, the 20thor more rebonded / debonded state, the 30thor more rebonded / debonded state, the 40thor more rebonded / debonded state, the 50thor more rebonded / debonded state, etc. While there is no particular limit, it may have to be expected that these conditions may not be achievable for a very high number of bonding / debonding cycles, e.g., at 10,000 cycles or less, such as 5,000 cycles or less, e.g. 2,000 cycles or less, such as 1,000 cycles or less.

[0114] Electro-responsive adhesive

[0115] The adhesive used in the device of the present invention is not particularly limited as long as it allows realizing the features described above and set out in the claims. The adhesive preferably contains ionic species and is preferably ionically conductive (i.e. is electrically conductive due to the presence of ions), preferably in the range of 1010S / cm to 10-3S / cm, as this facilitates the electro-responsive properties and allows the conduction of a current my movement of the ions.

[0116] The adhesive may comprise one or more selected from ionic liquids and deep eutectic solvents, and / or one or more salts that are not ionic liquids, preferably a lithium salt. This is because one way to achieve ionic conductivity is to include an ionic liquid or deep eutectic solvent in the adhesive formulation, optionally in combination with a salt that is not ionic liquid, in particular a lithium salt. The adhesive comprising one or more ionic liquids and / or one or more salts that are not ionic liquids may be a pressure-sensitive adhesive (PSA). The use of a deep eutectic solvent may be a more environmentally friendly option as compared to ionic liquids, in particular fluorinated ionic liquids, as such materials are often not biodegradable.

[0117] In one embodiment, the PSA 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 or deep eutectic solvent (DES), and optionally a salt that is no ionic liquid or DES. In one embodiment, the PSA comprises an acrylic adhesive, an ionic liquid and a salt that is no ionic liquid or DES, which is preferably a lithium salt. In another embodiment, the PSA comprises an acrylic adhesive, a deep eutectic solvent and a salt that is no ionic liquid or DES, which is preferably a lithium salt. The acrylate monomers used for preparing the acrylic adhesive are preferably either selected from renewable or bio-based acrylates such as isosorbide diacrylate, glyceryl acrylate, itaconate acrylates, or lactate acrylates or selected from more biocompatible or water soluble variant, which support environmental circularity by being derived from renewable feedstocks and offering improved biodegradability.

[0118] An ionic liquid is a salt that is in the liquid state at or near room temperature. It is made up entirely of ions— typically a bulky, asymmetric organic cation and a weaker coordinating organic or inorganic anion. When ionic liquids are incorporated into the adhesive an electrolyte adhesive is formed. This not only gives ionic conductivity as well as adhesive properties. A salt that is no ionic liquid is thus a salt that is a solid at room temperature (25°C).

[0119] Common cations of ionic liquids include imidazolium, pyridinium, pyrrolidinium, ammonium, phosphonium, cholinium, morpholinium, piperidinium, guanidinium, thiazolium based and anions include tetrafluoroborate, hexafluorophosphate, bis(trifluoromethanesulfonyl)imide, trifluoromethanesulfonate, dicyanamide, nitrate, chloride, acetate, hydrogen sulfate, methanesulfonate.

[0120] Most typical are fluorinated anion ILs (TFSI-, FSI-, BF4", PF6", OTf-), which are widely used for conductivity and electrochemical stability but not ideal environmentally: they are poorly biodegradable, persistent (e.g. PFAS), and in some cases hydrolyze to release toxic HF. Thus, in certain embodiments, the electro-responsive adhesive does not comprise a fluorinated ionic liquid, and the electro-responsive adhesive is preferably fluorine-free , i..e. does not contain fluorine, or contains fluorine in an amount of 5 ppm by mass or less, e.g. 3 ppm or less or 1 ppm or less, which may be caused e.g. by catalyst residues in a polymeric adhesive.

[0121] Some ionic liquid that can fulfil circularity and sustainability and that can preferably be used instead of fluorinated ionic liquids can be selected from: EMIM OAc = l-ethyl-3- methylimidazolium acetate; EMIM EtS04= l-ethyl-3-methylimidazolium ethyl sulfate; BMIM MeS04= l-butyl-3-methylimidazolium methyl sulfate; DiMIM MeS04= 1,3- dimethylimidazolium methyl sulfate; EMIM OMs = l-ethyl-3-methylimidazolium methanesulfonate; EAN = ethylammonium nitrate, and l-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM FSI).

[0122] If, however, the omission of fluorinated compounds such as PFAS or biodegradability are not required, the ionic liquid may beselected 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-butyl-3-methylimidazolium thiocyanate (BMIM SCN), 1- 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 MeSC ), 1,3-diethylimidazolium bis(trifluoromethylsulfonyl) imide (Di El M 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 EtSC ), 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 MeSC ), 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).

[0123] Ionic liquids, deep eutectic solvents and conducting salts may be used to provide for ionic conductivity, which facilitates electro-responsiveness. Most of the ionic liquids are synthesized and not obtained from bio sources and as mentioned above also may have PFAS issues. On the other hand, there are new classes of liquid state ionic compounds called deep eutectic solvents that may overcome these drawbacks. Deep eutectic solvents are obtained from hydrogen bond donor and hydrogen bond acceptor molecules such as urea, glycerol, succinic acid, phenyl acetic acid, menthol, choline chloride and proline chloride, histidine chloride, glucose, malic acid, citric acid, and sucrose.

[0124] Some examples of deep eutectic solvents (DES) useful as the electrolyte according to the present invention include, but are not limited to, the group consisting of choline chloride : urea (1:2), choline chloride : ethylene glycol (1:2), choline chloride : glycerol (1:2), choline chloride : 1,2-propanediol (1:2), choline chloride : malonic acid (1:1), choline chloride : citric acid (1:1 or 1:2), choline chloride : oxalic acid (1:1), choline chloride : lactic acid (1:1), choline chloride : acetamide (1:2), choline chloride : formamide (1:2), choline chloride : levulinic acid (1:2), choline chloride : phenol (1:2), choline chloride : sorbitol (1:1), choline chloride : ascorbic acid (1:1), choline chloride : triazole (1:2), choline chloride : thymol (1:2), choline chloride : resorcinol (1:2), choline chloride : benzoic acid (1:2), choline chloride : mandelic acid (1:2), choline chloride : 4-aminobenzoic acid (1:2), choline chloride : imidazole (1:2), choline chloride : succinic acid (1:1), choline chloride : caffeic acid (1:1), choline chloride : asparagine (1:2), choline chloride : tartaric acid (1:1), choline chloride : glucose (1:1 or 1:2), choline chloride : xylitol (1:1), betaine : urea (1:2), betaine : citric acid (1:1), betaine glycerol (1:2), tetraalkylammonium chloride urea (1:2), tetramethylammonium chloride : ethylene glycol (1:2), ethylammonium chloride : urea (1:2), ethylammonium chloride : glycerol (1:2), ethylammonium nitrate : acetamide (1:2), n,n-dimethylglycine : urea (1:2), guanidine hydrochloride : urea (1:2), zinc chloride : urea (1:4), zinc chloride : acetamide (1:2), aluminum chloride : urea (1:1.5), aluminum chloride : acetamide (1:1.5), lithium chloride acetamide (1:2), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) urea (1:2), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) : ethylene glycol (1:2), choline nitrate : urea (1:2), choline nitrate : ethylene glycol (1:2), choline acetate : urea (1:2), choline acetate : ethylene glycol (1:2), choline acetate : glycerol (1:2), choline acetate : triethylene glycol (1:2), reline, ethaline, glyceline, choline chloride-acid mixtures, metal-salt-based systems including ZnCI2 / urea, MgCI2 / urea, Mn(NO3)2-H2O, and water-in-DES formulations, amide-based systems with lithium salts including n-methyltrifluoroacetamide + LiTFSI, methyl carbamate + lithium salts, acetamide + caprolactam, and succinonitrile-based mixtures, hydrophobic DES including long-chain ammonium + fatty acids, as well as dual-salt and ternary DES electrolytes.

[0125] Besides the DES, some ionic liquid that are can fullfil circularity and sustainability can be selected from: EMIM OAc = l-ethyl-3-methylimidazolium acetate; EMIM EtS04= l-ethyl-3- methylimidazolium ethyl sulfate; BMIM MeS04= l-butyl-3-methylimidazolium methyl sulfate; DiMIM MeS04= 1,3-dimethylimidazolium methyl sulfate; EMIM OMs = l-ethyl-3- methylimidazolium methanesulfonate; EAN = ethylammonium nitrate.

[0126] The amount of the one or more ionic liquids or DES or salt is preferably 0.1 % by weight or higher, such as 0.5% by weight or higher, 1.0 % by weight or higher, more preferably 1.5 % by weight or higher, 2.0 % by weight or higher, 2.5 % by weight or higher, or 3.0 % by weight or higher, but is 20 % by weight or less, preferably 15 % by weight or less, or 10 % by weight or less, such as 8.0 % by weight or less, relative to the total weight of the adhesive. This applies to the totality of ionic liquid and / or DES.

[0127] Further, the amount of the one or more salts that are not ionic liquids is preferably 0.1 % by weight or higher, such as 0.5 % by weight or higher, 1.0 % by weight or higher, more preferably 1.5 % by weight or higher, 2.0 % by weight or higher, 2.5 % by weight or higher, or 3.0 % by weight or higher, but is 20 % by weight or less, preferably 15 % by weight or less, or 10 % by weight or less, such as 8.0 % by weight or less, relative to the total weight of the adhesive. This applies to the totality of salts that are not ionic liquids and / or DES.

[0128] To enhance ionic conductivity, one or more plasticizers may be added to the adhesive formulation, which may be a PSA formulation. Common plasticizers are various PEG, different carbonates and water.

[0129] In one embodiment, the adhesive comprises one or more selected from the group consisting of a) polymers derived from plants, such as cellulose and starch, as well as derivatives thereof, b) polymers derived from biologically produced monomers, and c) biologically degradable polymers, such as (poly) lactic acid, poly caprolactone, poly(3- hydroxybutyrate-co-3-hydroxyvalerate) and polyethlene glycol. The use of such compounds reduces the environmental load and may facilitate achieving partial or full biodegradability. In one embodiment, the one or more selected from this group a), b) and c) exhibits biodegradability as a pure substance in a 28day test according to OECD 301B of 20% or more, preferably 50% or more, such as 70% or more.

[0130] In one embodiment, the adhesive comprises one or more selected from the group consisting of deep eutectic solvents (DES) (also referred to as ion transporters), which are preferably obtained from hydrogen bond donor and hydrogen bond acceptor molecules such as urea, glycerol, succinic acid, phenyl acetic acid, menthol, choline chloride and proline chloride, histidine chloride, glucose, malic acid, citric acid, sucrose. The use of such compounds reduces the environmental load and may facilitate achieving partial or full biodegradability, in particular when used solely as replacement of or in addition to an ionic liquid, in particular fluorinated ionic liquids.

[0131] In one embodiment, the electro-responsive adhesive (D) is a PSA that is prepared by polymerizing a mixture comprising at least the following components: a) 20 to 80 wt % of acrylate monomer (al) from the group of the (meth)acrylic esters containing at least one oxygen atom; and b) 20 to 80 wt % of acrylate monomer (a2) from the group of the (meth)acrylic esters and / or amides containing at least one nitrogen atom; and c) 0 wt % to 15 wt % of one or more electroresponsive 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) 0.1 wt % to 20 wt % of one or more ionic liquids and / or DES; and f) 0.1 wt % to 20 wt % of one or more conducting salts that are no ionic liquids and / or DES; and g) optionally 1 wt % to 20 wt % by weight 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, the solvent is disregarded when stating the weight fractions of the components.

[0132] The use of such a PSA as adhesive (D) allows obtaining a surprisingly high adhesive strength upon 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.

[0133] In one such embodiment, the PSA employed in the present invention is a pressure-sensitive adhesive polymer (random / statistical copolymer) composition. The copolymer structure is prepared by polymerizing monomers (al) and (a2) and therefore contains units derived from these monomers also containing oxygen and optionally 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: (a) high polarity to dissolve enough conducting salts and electro-responsive compounds, preferably zwitterionic monomers, (b) controlling the glass transition temperature (Tg) of the copolymer, and (c) making the adhesive effectively debondable. The latter cause can be explained as follows.

[0134] Without wishing to be bound by theory, it is assumed that debonding occurs by reactive dissolution of the PSA when an ionic liquid is present. This means that when e.g. a 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, which facilitates debonding by mechanical stress. The gas release makes the adhesive surface porous.

[0135] In one embodiment, the adhesive composition contains 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 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 electroresponsive compounds are zwitterionic compounds. In particular, zwitterionic compounds are molecules that contain both positive and negative charges but are overall neutral (betaine compounds). In one embodiment, the amount of the one or more electro-responsive compounds is from 0.1 to 15 wt %, preferably from 1 wt % to 10 wt % of the adhesive composition. The zwitterionic compound is different form an ionic liquid and a DES.

[0136] As outlined above, in one embodiment the PSA further contains salts that are no ionic liquids or DES (e.g., different Na and Li salts), facilitating the adhesive composition to be ionically conductive. The adhesive composition may also contain an ionic liquid and / or DES. The conducting salt aids in the solubilization of electro-responsive compounds, preferably zwitterionic monomers, and contributes to the entire adhesive becoming more electro- responsive.

[0137] In certain embodiments, the initial peel adhesion, i.e. the initial adhesive strength ("natural" adhesive strength), as measured with Test B described hereinafter (cf. experimental section) before the application of a DC voltage source ranges from 2.5 N / cm to 5 N / cm. After voltage application, i.e. after application of the first electric stimulus for increasing first bonding strength, the peel adhesion, i.e. the adhesive strength in the first bonded state, may increase to values higher than 5 N / cm, such as 6 N / cm or higher, or from to 8 N / cm to 12 N / cm. The same range applies for rebonded states, in particular the first, second, and / or third rebonded state.

[0138] After applying an electric stimulus for decreasing adhesive strength, the adhesive state in the debonded state is preferably less than 2.5 N / cm, such as 2.0 N / cm or less, 1.5 N / cm or less, 1.0 N / cm or less, or 0.5 N / cm or less. This applies to the first debonded state after application of the electric stimulus, but also applies to subsequent debonded states, such as the second, third or fourth debonded state.

[0139] 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 electrically conductive layer of the carrier and cure it.

[0140] In an embodiment, a UV syrup-based acrylic adhesive is mixed with one or more ionic liquids and then applied to the electrically conductive layer on a backing film and 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 electrically conductive layer as well as increasing the anchorage to the electrically conductive layer and backing film.

[0141] Below a more detailed description of the monomers that may be used in the preparation of the PSA present as adhesive (A) in the device of the present invention is given.

[0142] Monomer (al):

[0143] 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, 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 20 to 80 wt %, such as from 35 wt % to 72 wt %, e.g. 35 to 70 wt %, preferably 45 wt % to 68 wt %, more preferably 50 wt % to 66 wt %, based on the total weight of the mixture.

[0144] 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.

[0145] 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.

[0146] 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 CH2group 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.

[0147] In a more preferred embodiment, the hydrocarbon part of the alcohol component is based on polyethylene oxide (PEO) a more biocompatible monomer. 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)

[0148] In present formula (1), R1is H or CH3, R2is H, linear or branched C^-Cig alkyl, aryl, hydroxy (CrC18) alkyl, -C(=O)CH2C(=O)CH3, -CH3or -CH2CH3, preferably CH3or CH2CH3, and n is an integer between 2 and 18, preferably 2 and 15, more preferably 0 and 11. In a preferred embodiment at least one monomer (al) used has a value n between 0 and 11, preferably 0, 1, 2,3 or 4. Preferred are monomers that are liquid at 25 °C.

[0149] Examples of the (meth)acrylic esters include 2-(2-ethoxyethoxy)ethyl acrylate) (EEEA, also designated as EDGA, n = 2, RT= H, R2= -CH2CH3), 2-[2-(2-methoxyethoxy)ethoxy]ethyl acrylate (n = 3, R1= H, R2= -CHs), diethylene glycol monomethyl ether methacrylate (n = 2, R1= CH3, R2= -CH3), 2-ethoxyethyl methacrylate (n = 1, R1= CH3, R2= -CH2CH3), 2- methoxyethyl methacrylate (n=l, R1= CH3, R2= -CH3) and ethylene glycol monoacetoacetate monomethacrylate (n = 1, R1= CH3, R2= -C(=O)CH2C(=O)CH3).

[0150] Monomer (a2):

[0151] 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 at least one nitrogen atom or amides containing at least one nitrogen atom and can be also biocompatible or optionally, at least water soluble. 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) (a 2) according to the invention are present in an amount of 20 wt % to 80 wt %, such as from 20 to 48 wt %, preferably 22 wt % to 38 wt %, more preferably 24 wt % to 36 wt % based on the total weight of the mixture.

[0152] 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.

[0153] 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.

[0154] 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. 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.

[0155] 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.

[0156] In a preferred embodiment, the monomer (a2) is based on the following formula (2). formula (2)

[0157] In present formula (2), R1is H or CH3, R2or R3is -H, -CH3, -CH2OH, -CH2CH2OH, -CH3 or -CH2CH3, preferably -CH3 or -CH2CH3.

[0158] In a preferred embodiment the monomer (a2) is liquid at 25 °C, however, solid monomers at 25 °C may also be used.

[0159] 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). 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.

[0160] 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.

[0161] 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,

[0162] N-(2-hydroxyethyl)methacrylamide, N-(2-hydroxypropyl)acrylamide,

[0163] N-(2-hydroxypropyl)methacrylamide, N-(l-hydroxypropyl)acrylamide,

[0164] N-(l-hydroxypropyl)methacrylamide, N-(3-hydroxypropyl)acrylamide,

[0165] N-(3-hydroxypropyl)methacrylamide, N-(2-hydroxybutyl)acrylamide,

[0166] N-(2-hydroxybutyl)methacrylamide, N-(3-hydroxybutyl)acrylamide,

[0167] N-(3-hydroxybutyl)methacrylamide, N-(4-hydroxybutyl)acrylamide,

[0168] The acrylate monomers al) and / or a2) used for preparing the acrylic adhesive are preferably either selected from or derived from renewable or bio-based acrylates such as isosorbide diacrylate, glyceryl acrylate, itaconate acrylates, or lactate acrylates, or derivatives thereof, or selected from more biocompatible or water soluble variant, which support environmental circularity by being derived from renewable feedstocks and offering improved biodegradability.

[0169] In the embodiment described above but also for all other embodiments of the electro- responsive adhesive, an ionic liquid or DES is optionally yet preferably present. If an ionic liquid or DES is present, the amount of one or more ionic liquids or DES e) may be from 0.1 wt % to 20 wt %; and the amount of one or more salts f) that are not ionic liquids is 0 wt % to 20 wt %. As the requirements of the present invention are more easily satisfied, preferably one of, and more preferably both of one or more ionic liquids or DES e) and the one or more salts f) are present. Incidentally, this applies also to other electroresponsive adhesives, i.e. those that do not contain the unit (al) and (a2). The total amount of the one or more selected from ionic liquids and DES is preferably 0.1 % by weight or higher, such as 0.5% by weight or higher, 1.0 % by weight or higher, more preferably 1.5 % by weight or higher, 2.0 % by weight or higher, 2.5 % by weight or higher, or 3.0 % by weight or higher, but is 20 % by weight or less, preferably 15 % by weight or less, or 10 % by weight or less, such as 8.0 % by weight or less. This applies to the totality of ionic liquid an DES.

[0170] Further, the amount of the one or more salts that are not ionic liquids is preferably 0.1 % by weight or higher, such as 0.5 % by weight or higher, 1.0 % by weight or higher, more preferably 1.5 % by weight or higher, 2.0 % by weight or higher, 2.5 % by weight or higher, or 3.0 % by weight or higher, but is 20 % by weight or less, preferably 15 % by weight or less, or 10 % by weight or less, such as 8.0 % by weight or less. This applies to the totality of salts that are no ionic liquids.

[0171] Ionic liquids, dES or conducting salts are preferably used to give ionic conductivity, and they should preferably be compatible / soluble with the adhesive matrix, e.g. in order to avoid phase separation / degradation. To enhance ionic conductivity, plasticizers may be added to the adhesive formulation. Common plasticizers are various PEG, different carbonates and water.

[0172] The one or more salts that are not ionic liquids are not particularly limited, but are preferably salts of the alkali metals, more preferably non PFAS salts, lithium salts. In one preferred embodiment, the salt comprises a lithium salt selected from the group consisting of lithium difluoro(oxalato)borate (LiDFOB), and lithium bis(oxalato)borate (LiBOB).

[0173] After the preparation of an adhesive mass by bulk or solution or UV prepolymer methods, the adhesive may be mixed with ionic liquids / plasticizers / curing agents (e.g., initiators or crosslinkers) or other additives (tackifier) to formulate the ion conductive liquid adhesive also called as liquid electrolyte. The next step is to coat the ion conducive adhesive on a substrate, e.g. an electrically conductive carrier, and cure it.

[0174] In a preferred embodiment, the adhesive is a UV syrup-based acrylic adhesive, mixed with ionic liquids. This may be applied to a variety of substrates, e.g. to the electrically conductive coating on a primed PET backing, and then UV cured to obtain a device of the present invention, e.g. in the form of an adhesive tape. This is preferable to a solvent cast method, as the curing often is a polymerization plus crosslinking reaction (optional) that may increase the anchorage of the adhesive to the electrically conducive coating as well as increase the anchorage to a backing film. If the device includes two distinct adhesive layers, the first layer may comprise an acrylic adhesive matrix containing inorganic salts and a zwitterionic compound, including a polymerizable zwitterionic monomer. Alternatively, it may contain an acrylic adhesive with an ammonium-based protic ionic liquid such as EAN. The second adhesive layer may be an acrylic adhesive incorporating an ionic liquid, as described herein. Both adhesives are preferably ionically conductive. Further, in one embodiment the two distinct adhesive layers are formed from different adhesive compositions, each of which is an electro- responsive adhesive. Where the magnitude of the increase or decrease in adhesive strength upon application of an electric stimulus is different for the two electro-responsive adhesive, selective bonding and debonding on demand is facilitated, as also discussed below in respect of FIG.s 4, 5, and 6.

[0175] BACKING FILM:

[0176] A backing, constituting or forming part of a carrier, is not just a film to support the adhesive layer but rather an important part of a tape. This could be made from plastic, metal, textiles, and so on. A normal adhesive layer is thin, sticky, and, overall, not a free-standing, like material. A backing is therefore often needed to provide support, dimensional stability, strength, flexibility, and ease of handling. It acts as the carrier for the adhesive layer, protects the adhesive before application, and determines 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.

[0177] 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), nylon. Metal or metalized films are not suitable for the current invention unless it has corrosion resistance. A backing can also 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).

[0178] The choice of backing is important for recyclability, resource efficiency, and reduced environmental impact. Recyclable plastics such as PET and PP are preferred due to their established recycling streams. Natural fibers (cotton, hemp, linen) or bio-based polymers can provide renewable and biodegradable alternatives. Backings with single-material designs are advantageous for easier separation and recycling, while metalized or composite backings should ideally use corrosion-resistant and recyclable metals (e.g., aluminum, copper) applied in thin layers to reduce material use. Water-based coating processes and reduced use of halogenated polymers (e.g., PVC, PTFE) further improve environmental compatibility.

[0179] The backing is not limited to the materials mentioned above. Its purpose is to provide sufficient mechanical strength and to enable strong anchorage to the electrically conductive layer as well as full fill environmental circularity needs.

[0180] In a preferred embodiment, backing films are polyethylene terephthalate) (PET) and poly(propylene) (PP) films, as these materials are widely recyclable and available in established circular material streams.

[0181] In one aspect, a metalized backing can be used, such as aluminum-coated PET (AI-PET), copper-coated PET (Cu-PET), silver-coated PET (Ag-PET), nickel-coated PET (Ni-PET), or tin- coated PET (Sn-PET). Other conductive materials such as ITO-coated PET (ITO-PET) may also be employed. Thin (e.g. 10 pm or less, such as 1pm or less, e.g. 0.5 pm or less) conductive coatings on recyclable PET backings are preferred, as they reduce the amount of critical or non-renewable metals while maintaining functionality and allowing easier recovery or recycling of the carrier after use.

[0182] In a further embodiment, the present invention uses priming / primer to the backing. Primer is used as a surface treatment to improve adhesion between the backing film and the electrically conductive (EC) layer. It may act as a bridge to ensure stable coating, strong anchorage, and durability. Primers are preferably designed to be minimal in thickness, solvent-free or water-based, and compatible with recycling of the overall carrier system. Selection of low-toxicity, halogen-free, or bio-based primer chemistries can further reduce environmental burden and improve end-of-life handling. Priming can be physical (plasma, corona, flame, chemical etching, mechanical abrasion) or chemical (thin adhesive or adhesion promoter layers, reactive primers like silanes, isocyanates, epoxies). Inorganic coatings such as ITO / FTO can also serve as primers, adding conductivity. Preferred methods combine physical and chemical priming, e.g. thin UV-cured acrylic layers that are clear, weather-resistant, and compatible with conductive coatings. While priming improves performance, it is optional if sufficient adhesion is already achieved. If the backing film is coated with any functional layers (e.g. conductive coating) except a primer, it is termed a carrier (T).

[0183] ELECTRICALLY CONDUCTIVE (EC) LAYER on BACKING FILM:

[0184] An electrically conductive layer enables current flow in adhesive tapes or multilayer materials, supporting functions like sensing, heating, or electrically controlled debonding. Suitable materials include metal foils (e.g. stainless steel, aluminum, copper), conductive polymers (e.g. PEDOT:Tos), carbon-based coatings (carbon black, graphite, graphene, CNTs), and conductive inks or fabrics with metal fillers. Preferred in this invention are intrinsically conductive polymers such as PEDOT:PSS, PEDOT:Tos, ProDOT, polyaniline, polypyrrole, polythiophene and derivatives, polyacetylene, poly(p-phenylene vinylene), polyfluorene, polycarbazole, polybithiophene, and metallo-supramolecular polymers, provided they meet requirements of stability, conductivity, and environmental circularity.

[0185] From an environmental circularity perspective, the conductive layer preferably uses materials and processes that are recyclable, low-toxicity, and compatible with sustainable end-of-life handling. Examples include recyclable metal foils (aluminum, copper), carbon materials derived from renewable or bio-based sources, and conductive polymers with reduced halogen or fluorine content, enabling easier recycling and lower environmental burden. The use of water-based dispersions (e.g., PEDOT:PSS in aqueous media) instead of solvent-based systems further improves safety and reduces emissions.

[0186] Another preferred material that can be coated of backing film to induce conductivity is carbon-based coatingsuch as graphene, carbon nanotubes (CNTs), reduced graphene oxide (rGO), pyrolytic carbon, carbon paint, carbon nanofibers, graphite, amorphous carbon, carbon black, conductive carbon ink, fullerene-based coatings, carbon-loaded polymers coatings and carbon fiber coatings. These materials are often applied as thin films on primed backing layers to provide electrical conductivity in the carrier. The preferred are those sourced from renewable or recycled feedstocks (e.g., biomass-derived carbon black, recycled graphite).

[0187] If present, an EC layer may have any thickness, and preferably has a thickness of 200 pm or less, more preferably 100 pm or less, such as 50pm or less, or 10pm or less. . ADHEREND, SUBSTRATE, OBJECT:

[0188] The adherend or substrate is the surface that comes into contact with the adhesive and, together with it, can form a capacitor-like device. The adherend is part of the object to be moved in the gripping device embodiment the present invention. Suitable adherends are preferably electrically conductive with smooth, oxidation-resistant surfaces. Examples include copper, stainless steel, aluminum, gold- or silver-coated substrates, nickel plating, ITO-coated glass, carbon-coated films, graphene, and conductive composites. Non- conductive substrates may also be used if coated with a conductive layer. Preferred adherends are stainless steel plates and silver-coated plastic substrates.

[0189] In a further embodiment, the adherend or substrate can be flat, porous, perforated, or mesh-type materials. Unlike vacuum suction methods, which require airtight and flat surfaces, the present adhesive device can also operate effectively on substrates where suction is impractical. Such substrates may include porous ceramics, perforated metals, wire meshes, woven fabrics, nonwovens, foams, or 3D-printed lattice structures. The adhesive layer can conform to these surfaces, forming mechanical interlocking or noncontact, thereby enabling bonding, debonding, or re-bonding operations even on non-flat and porous objects in the event of an application of a DC voltage.

[0190] Preferred porous or mesh-type substrates include perforated stainless steel, conductive carbon fiber meshes, ITO-coated glass fabrics, and conductive polymer-coated textiles, which combine conductivity with surface roughness to enhance adhesion performance

[0191] In one embodiment, the device may comprise a recycled material, e.g. as part of the backing or other constituent other than the adhesive.

[0192] BRIEF DESCRIPTION OF FIGURES

[0193] FIG. 1 schematically illustrates embodiments of an adhesive tape that is or may form part of the device of the present invention, namely a single-layered, single-sided adhesive tape comprising layer (D) of electro-responsive adhesive and an electrically conductive carrier (T). The electrically conductive carrier (T) can be defined as a combination of a backing film (F), primer layer (P) and electrically conductive layer (EC).

[0194] FIG. 2 schematically illustrates embodiments of an adhesive tape that is or may form part of the device of the present invention, namely a double-sided adhesive tape comprising an electrically conductive carrier (T) disposed between layer (D) of electro-responsive adhesive and a layer 2S of conventional adhesive. FIG. 3 schematically illustrates embodiments of an adhesive tape that is or may form part of the device of the present invention, namely a double-sided adhesive tape comprising an electrically conductive carrier (T) disposed between two layers (D) of adhesive.

[0195] FIG. 4 schematically illustrates embodiments of an adhesive tape that is or may form part of the device of the present invention, namely a single-layered, single-sided adhesive tape comprising layer (D) of adhesive and carrier (T) laminated on an electrically conductive substrate S. Electrically conductive substrate serves as target adherend.

[0196] FIG. 5 and FIG. 6 schematically illustrate the bonding and debonding setup, respectively, for the adhesive device from FIG. 7.

[0197] FIG. 7 and FIG. 8 schematically illustrate one possible design of an electro-adhesive gripping device constructed in a loop configuration, utilizing the adhesive tape disclosed in the present invention. The device may utilize any of the single-layered or single-sided adhesive tape configurations illustrated in FIG. 1. In both embodiments, the layer (D) of adhesive is oriented toward the external surface of the loop, while the electrically conductive carrier (T) is positioned on the internal surface. In both figures, the region labeled W denotes the contact interface between the electro-adhesive gripping device and the target substrate. FIG. 7 illustrates the initial contact state, whereas FIG. 8 shows an enhanced contact condition achieved either by the application of an electrical stimulus or by mechanical pressure, thereby increasing the overlap area.

[0198] Additional configurations and design variations of electro-adhesive gripping devices employing the adhesive tape of the present invention are considered within the scope of this disclosure.

[0199] FIG. 9 schematically illustrates a representative example of how the electro-adhesive gripping device, as described in FIG. 7 and FIG. 8, may appear when integrated with a collaborative robotic system. This depiction is intended to demonstrate one possible implementation and does not limit the scope of the invention.

[0200] DEVICE DESIGNS

[0201] The device of the present invention may take any form or shape, as long as in the gripper embodiment it is configured to move an object by adhering to the object by the adhesive force of the electro-responsive adhesive in the bonded state and moving the device together with the adhered object, or it is partially to fully biologically degradable.

[0202] The configuration to move an object may already be satisfied by a device in adhesive tape form, as will be discussed in more detail below. However, the device may comprise additional members that facilitate moving an object (adherend) from one place in space to another. The device may for instance be part of, or mounted on, a robot arm that is operated by a user or according to a pre-defined software program (see Figure 9). The device may also include elements or members that facilitate manual operation, such as a handle that may also include an internal power source, such as a battery, or which may be connected to a power source by a cable. The device may also include one or more buttons or sensors by which a use can control the electric stimulus for increasing or decreasing adhesive strength of the adhesive, thereby switching the device from a bonded (or rebonded) state to a debonded state.

[0203] The device may contain the adhesive in the form of a loop-shaped adhesive tape, as will be described in detail below and of which an embodiment is shown in Figures 7 and 8. A skilled person will however realize that the shape is not essential for the function, and that a similar device within the scope of the present invention can be constructed e.g. by using an adhesive tape that is bonded to a substrate, the substrate being part of a member that can be moved manually or by suitable machinery (e.g. an electric motor, as in a robot arm) and wherein the adhesive forms the outermost layer of the member.

[0204] In one embodiment, the device is or comprises an adhesive tape. In the embodiment of an adhesive tape, the device contains in addition to the adhesive (typically present in the form of an adhesive layer) at least a carrier. The carrier may take the form of a backing that preferably is electrically conductive. This can be achieved by using a backing that is as such electrically conductive, such as a metal foil, by providing a conductive coating, or by blending an insulating backing material (such as a polymer, e.g. PET) with conductive particles.

[0205] 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.

[0206] The device of the present invention also includes a capacitor-like device, for example wherein an electro-responsive adhesive layer is disposed on an electrically conductive carrier and / or a substrate / adherend, or wherein two electrically conductive substrates sandwich the electro-responsive adhesive, such as an electror-esponsive PSA, with or without interposing elements such as additional layers.

[0207] The adhesive tape according to one embodiment of the present invention may be present 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.

[0208] 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.

[0209] 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 on top of another along the z direction.

[0210] In one embodiment, the present invention pertains to a device as defined in the claims, which is a capacitor-like adhesive device comprising: a) a primed backing film that is primed on at least one side thereof; b) an electrically conductive coating on the primed side of the backing film; c) an electro-responsive adhesive (D) prepared directly on said electrically conductive coating by polymerization or crosslinking; and wherein the device is configured to bond strength increase (bond) of the adhesive tape formed by a), b) and c) to the electrically conductive substrate upon application of a first electric stimulus between the electrically conductive coating and the conductive substrate; wherein the adhesive device is further configured to debond from the electrically conductive substrate upon application of an electric stimulus for decreasing adhesion strength, which may be an electric stimulus with opposite in polarity to the first electric stimulus; wherein the electrical stimuli comprises a DC (direct current), AC (alternating current), VDC (volts direct current), VAC (volts alternating current), Pulsed DC (pulsed direct current), Pulsed AC (pulsed alternating current), preferably a direct current (DC) or alternating current (AC), or pulsed voltage; and wherein the adhesive tape, formed by the above components a), b) and c), in the device is capable of repeatedly switching adhesion strength under applied electromotive force, enabling bonding, debonding, and rebonding of the tape to the electrically conductive adherend's surface.

[0211] According to an embodiment of the capacitor-like adhesive device, an electroresponsive adhesive (A) is placed between an electrically conductive coating present on a backing (the backing and the electrically conductive coating together forming a carrier) and an electrically conductive substrate. The adhesive strength of the tape to an electrically conducive substrate's surface can be controlled by properties of the electric stimulus, e.g. voltage polarity, voltage level, and duration of the applied voltage. For example, an electrically conductive coating of PEDOT:PSS [Poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate)] or PEDOT:Tos [Poly(3,4- ethylenedioxythiophene):p-toluenesulfonate] or carbon may be applied onto a primed PET film to prepare the carrier of this embodiment of the present invention. An electroresponsive adhesive layer may then coated on top to form a single-layered, singlesided adhesive tape. When the resulting tape formed by the components a), b) and c) is laminated onto a conductive substrate such as a steel plate (the adherend d), an adhesive device of this embodiment of the present invention is realized. Upon applying a positive DC voltage forming the electric stimulus to the steel plate (bonding), the adhesive strength between the tape and the steel plate is increased. While reversing the polarity of the DC voltage [negative voltage to the steel plate], adhesive strength is reduced, allowing the tape to be removed easily and cleanly, with little or no residue from the steel plate. This bonding-debonding process can be repeated multiple times (at least 50 times) by applying respective stimuli or increasing and decreasing adhesive strength.

[0212] The ability to provide for such repeated bonding and debonding is not achieved in the prior art, where debonding typically occurs on the side where the negative DC voltage is applied (i.e. at the cathode side)— whether it's the substrate or the backing or carrier. If debonding occurs at the side of the backing or carrier, this is usually considered a structural failure (anchorage failure) of the device rather than true debonding, given that the device is thereby disassembled or destroyed. True debonding usually refers to the adhesive separating cleanly from the substrate with little or no residue. It is a surprising finding of the present invention is that debonding occurs only at the electrically conductive substrate side, even when the polarity is reversed (i.e., negative voltage applied to the backing or carrier); instead of causing anchorage failure, the bonding strength of the adhesive tape to the substrate increases.

[0213] In the above, the electro-responsive adhesives (A) and (D) may be the same or different, and may each be an electro-responsive adhesive as described herein.

[0214] In preferred embodiments, the priming means increasing the anchorage strength between the electrically conductive coating and the backing. This might 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 film backing 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.

[0215] In preferred embodiments, the electrically conductive coating comprises materials that exhibit adequate electrical conductivity and hydrophobicity. In one embodiment, the carrier having the conductive coating may be a metalized polymer film. The coating must be resistant to corrosion in electrolyte-rich environments, should offer good weatherability, and form a strong bond with the carrier. In the present invention, this layer may for example be applied onto a primed surface of a backing by either in situ polymerization of monomers of intrinsically conductive polymers or by directly coating an aqueous dispersion or viscous ink onto the primed surface.

[0216] In the above embodiment, the backing having the conductive coating is considered as a carrier. Typically, a backing is non-conductive, such as made from insulating polymers like PET. This may be replaced by a carrier that is inherently conductive, e.g. a metal foil, by a conductive polymer, in which case a conductive coating can be dispensed with. All of these may jointly refer to as electrically conductive carrier.

[0217] The adhesive, as present in e.g. the adhesive tape of the invention, 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 directly on the electrically conductive carrier, e.g. on an electrically conductive coating on a primed backing. ADHESIVE TAPE DESIGN

[0218] The following further illustrates possible configurations of the adhesive device in the form of a tape 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.

[0219] According to preferred embodiments, the adhesive device of the present invention is a pressure-sensitive adhesive tape. As described above, the adhesive tape of the present invention comprises different structures.

[0220] FIG. 1 depicts an embodiment of the device of the present invention in the form of a singlelayered, single-sided adhesive tape of the present invention. The adhesive tape comprises an electrically conductive layer (EC) on a primer (P), backing film (F), forming the carrier (T) and on the electrically conductive layer side of the carrier (T), an adhesive layer formed by the electro-responsive adhesive (D), i.e. the layer (D). This tape can be converted into loop shape design as shown in FIG. 7 and 8 to enable gripping applications.

[0221] Another adhesive (2S) may be provided on the other side of the carrier, as illustrated in FIG. 2. The adhesive (2S) may be a conventional transfer tape, i.e. an adhesive whose adhesive strength cannot be modified by applying an electric stimulus.

[0222] FIG. 3 illustrates a single-layered, double-sided adhesive tape according to the first aspect of the present invention. The tape comprises, or consists of, a carrier (T) formed by a backing film (F) that is primed (P) on both sides, followed by an electrically conductive coating (EC) applied to each primed surface. Electro-responsive adhesive layers (D) formed from the electro-responsive adhesive are formed on both conductive sides of the carrier (T).

[0223] PREPARATION OF DEVICE AND METHOD FOR MODIFYING THE ADHESION STRENGTH

[0224] When the device of the present invention in any form is disposed on an electrically conductive substrate, another embodiment of an adhesive device of the present invention is constructed (FIG.s 4-6). The electrically conductive substrate is, or is part of, the object to be moved when the device of the present invention is configured to move an object.

[0225] FIG. 4 shows an adhesive device, according to an embodiment of the invention, constructed by a single-layered, single-sided tape (FIG. 1) disposed on an electrically conductive substrate (S). In this setup, connecting the negative terminal of DC voltage source to the conductive carrier (T) and the positive terminal of DC voltage source to the substrate (S) and applying a DC voltage for example 5 to 50 V for 30 s to 5 min, increases the adhesion strength between the adhesive layer (D, comprising the electro-responsive adhesive (D)) and the conductive substrate (S), thereby achieving bonding of the adhesive tape to the conductive substrate S (FIG. 5).

[0226] However, if the connection is reversed, e.g. the negative terminal of the DC voltage source is connected to the substrate (S) and the positive terminal is connected to the carrier (T), and a DC voltage, preferably in the range of 10 to 50 V, for 30 s to 5 min, is applied, the adhesion strength of (D) of electro-responsive adhesive with respected to electrically conductive (S) substrate decreases, thereby facilitating debonding of the adhesive tape from the substrate (S) (FIG. 6).

[0227] The adhesive tape in the described adhesive device can be reused multiple times for bonding, debonding, and rebonding. For instance, after debonding, the same tape can be reapplied to the substrate and bonded again by applying electrical stimulus (e.g. DC voltage). Debonding can then be triggered by reversing the polarity of the applied DC voltage. The tape remains functional for repeated use by simply laminating it onto an electrically conductive substrate and applying DC voltage. This cycle can be repeated without a significant loss in adhesive strength compared to the initial bonding.

[0228] From an environmental circularity perspective, the ability to reuse the same tape for multiple bonding cycles reduces material consumption, waste generation, and the need for replacement adhesives. Extending product lifetime through repeated use directly supports sustainability goals by conserving resources and minimizing environmental impact.

[0229] Methods, System and Uses

[0230] As derivable from the above, the device of the present invention can be used in a method of modifying the adhesive strength of the device, the method comprising the application of one or more electric stimuli for increasing and / or decreasing the adhesive strength of the adhesive. Here, the one or more electric stimuli may be a DC (Direct Current), AC (Alternating Current), VDC (Volts Direct Current), VAC (Volts Alternating Current), Pulsed DC (Pulsed Direct Current), Pulsed AC (Pulsed Alternating Current), and may preferably have a DC voltage of 1 to 50 V and / or a duration of 1 second to 30 minutes. Preferably, the DC voltage or current can be supply from a battery, a DC bench power supply, a potentiostat / galvanostat, an AC-to-DC adapter, a DC-DC converter, a USB power source or power bank, or a solar panel with a regulator. The method may involve one or more cycles of debonding-rebonding, such as 2 or more cycles, 3 or more cycles, or 4 or more cycles, e.g. 5 or more cycles. There is no particular upper limit, but in practice 10 or less of such cycles may be needed.

[0231] The present invention also relates to an adhesive system capable of modifying the adhesive strength of an adhesive, preferably a pressure-sensitive adhesive, by applying one or more electric stimuli, the adhesive system comprising a device as described above; and a controller that is configured to apply an electric stimulus to the device. The controller can control a DC power supply, RFID systems, printed batteries, capacitors, energy-harvesting circuits, and / or may also operate remotely via wireless interfaces such as Bluetooth, WiFi, or NFC. In one embodiment, the system may be a system for remotely operating the device, the system comprising a device and a controller that is configured to provide an electric stimulus to the device, the controller being operated by software or by a user input.

[0232] That is, in the adhesive system, the one or more electric stimuli may be applied using a controller that is operated by a user (i.e., manual operation) or are applied using a controller according to a pre-defined program (automatic operation). In one embodiment, the user or the pre-defined program provides electric stimuli of increasing voltage and / or duration over several cycles, for example to thereby compensate for a possible loss in the magnitude of the change of adhesion strength over several cycles.

[0233] The automatic operation may also involve further variables or conditions, e.g. the fulfilment of pre-defined criteria. Such criteria may e.g. involve conditions that are acquired by a sensor, such as temperature or humidity, or may include a security of ID check in order to avoid unauthorized usage. The security or ID check may involve identification of an individual by software means, or a password check.

[0234] The present invention also includes, as one aspect, a method of moving an object, the method comprising the steps of

[0235] (A) Applying an electric stimulus to a device as described herein, the electric stimulus being a second electric stimulus for modifying the adhesive to a bonded state; (B) Attaching an object to be moved to the adhesive in the bonded state via the adhesive, the objection being in a first location,

[0236] (C) Moving the device with the attached object to a second location, and

[0237] (D) Applying an electric stimulus to the device, the electric stimulus being a first electric stimulus for modifying the adhesive to a debonded state, to thereby release the object at the second location.

[0238] Here, the object to be moved is, or comprises, the above-described adherent. The object, or at least the surface in contact with the adhesive, is typically electrically conductive.

[0239] In step (B), an electric stimulus for increasing adhesive strength to be in the bonded state is applied, thereby increasing adhesive strength and attaching the object via the adhesive force of the electro-responsive adhesive in the bonded or rebonded state. With the object (adherend) thus attached, the device can be moved to a separate location which is spaced apart from the first location. At the second location, a further electric stimulus for decreasing adhesive strength is applied (debonding), allowing to release the object at the second location.

[0240] The object may be present on an electrically conductive support at either or both of the first and second location, the supports preferably having oppositive voltage with each other, while also the voltage applied to the adhesive from the device side has opposite polarity in steps (A / B) and (D).

[0241] Steps (A) and (B) may be performed sequentially, but are typically performed simultaneously. Further, several cycles of steps (A) to (D) are typically conducted in sequence.

[0242] In one embodiment of the present invention, several cycles of steps (A) to (D) are performed sequentially. Here, the total time form the beginning of step (A) to the end of step (D) is 10 minutes or less, such as 5 minutes or less, e.g. 3 minutes or less, 2 minutes or less, such as 1 minute or less. While there is no particular lower limit, it may be 1 second or more, such as 2 seconds or more.

[0243] The time between the end of step (D) and the beginning of step (A) in one or more cycles may be 10 minutes or less, e.g. 5 minutes or less, such as 2 minutes or less, 1 minute or less, such as 30 seconds or less, 15 seconds or less, or 10 seconds or less. While there is no particular lower limit, it may be 1 second or more.

[0244] The weight of the object to be moved is not particularly limited, but is typically 250 g or less, 200 g or less, such as 150 g or less, 100 g or less, or 50 g or less. This however also depends on the size of the device and the surface area of the device formed b the electro- responsive adhesive.

[0245] The surface area of the area formed by the electro-responsive adhesive is not particularly limited, but may be 0.2 cm^ or more, such as 0.5 cm^ or more or 1.0 cm^ or more. This may be the total area that comes into contact with the adherend.

[0246] The steps (A) to (D) may be repeated a plurality of times to move a plurality of objects, and preferably the method is part of an assembly process, such as an assembly process of electronic devices. The object to be moved may thus be an electric or electronic part, such as a transistor, chip or wired board, or a member of a computers,, smartphone, display, touch panels, sensors, light sources such as LEDs or OLEDs, or other electronic devices. Such electric or electronic parts are particularly susceptible to high voltages and damage by physical forces, so that the gentle and non-demanding operation of the device of the present invention may provide for particularly significant benefits.

[0247] The ability of the adhesive used in the present invention to perform repeated debonding- rebonding cylces also allows its use in a method of reducing the number of faulty products in an assembly process that comprises comprising joining two or more different members to form an assembled part, the method including a step of preliminarily assembling members using an adhesive as defined in any of the preceding claims confirming the proper alignment of the preliminary assembled members, and optionally performing an additional step of permanently joining the members if the alignment is correct, or optionally disassembling the assembled members and correcting the alignment of the members if the alignment is incorrect. Here, in particular an adhesive that is partially or fully biodegradable may reduce the environmental burden, while also the number of faulty parts (which otherwise may have to be discarded) allows waste reduction. The step of preliminarily assembling the parts may be part of method of using objects, as described above, where the second location is the assembly position of the moved member.

[0248] In further embodiments, the invention also relates to the use of the adhesive device, e.g. in the form of the above-described tape, for bonding, debonding, and rebonding in a wide range of applications, including robotics (e.g. robotic grippers), haptics, printing plate mounting on printing sleeves in flexoprint processes, sensing, consumer electronics, microelectronics, optoelectronics, biomedical devices, battery or cell phone mounting, printing, packaging, assembly, and automation processes. The device is particularly useful where strong, reversible bonding is needed without heat, light, or pressure. The reusability of the tape enables product repair, disassembly, and recycling, reduces waste, supports extended product lifetimes, and lowers carbon footprint in manufacturing and end-of-life processes.

[0249] EXAMPLES

[0250] The present invention is illustrated below by 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.

[0251] RAW MATERIALS

[0252] (a) Backing films:

[0253] PET film of different thicknesses

[0254] Etched PET film

[0255] Fabric (cloth)

[0256] PP film

[0257] (b) Electrically conductive coating materials:

[0258] PEDOT :PSS aqueous dispersion from Ossila

[0259] PEDOT:PSS ink from Sigma Aldrich

[0260] PEDOT:PSS nano particles aqueous dispersion from Sigma Aldrich EDOT monomer with different derivatives from TCI

[0261] (c) Acrylate monomers:

[0262] 2-(2-Ethoxyethoxy)ethyl acrylate (EEEA or EDGA)

[0263] N,N-Dimethylacrylamide (DMAA)

[0264] Butyl acrylate (BA) Benzyl acrylate

[0265] Methyl acrylate (MA)

[0266] Acrylic acid (AA)

[0267] 2-(Methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate) (MPC) from TCI

[0268] 3-[[2-(Methacryloyloxy)ethyl]dimethylammonio]propionate (CBMA) from TCI

[0269] (d) Initiators:

[0270] 2,2-Dimethoxy-2-phenylacetophenone (Irgacure 651) from Sigma-Aldrich

[0271] 1-Hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184) from Sigma-Aldrich

[0272] (e) Ionic liquids: l-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM FSI) from Proionic 1-Methyl-l-propylpyrrolidinium bis(fluorosulfonyl)imide (Pyrl3 FSI) from TCI l-Ethyl-3-methylimidazolium hexafluorophosphate (EMIM PFe) from Sigma-Aldrich l-Butyl-3-methylimidazolium hexafluorophosphate (BMIM PFe) from Sigma-Aldrich l-Butyl-3-methylimidazoliumtetrafluoroborat (BMIM BF4) from Sigma-Aldrich

[0273] (f) Ionically conducting salts:

[0274] Sodium chloride from Sigma-Aldrich

[0275] Lithium triflate (LiOTf), lithium triflouromethanesulfonate) from Sigma-Aldrich

[0276] Lithium tetrafluoroborate (UBF4) from Sigma-Aldrich

[0277] (g) Electrically conductive substrate / adherend:

[0278] ASTM steel plate

[0279] (h) Other materials):

[0280] Water as plasticizer

[0281] Crosslinkers: Erisys 240, polyethylene glycol) diacrylate (PEGDA)

[0282] Oxidant: Iron(lll) p-toluenesulfonate hexahydrate from Sigma Aldrich

[0283] Butanol from Sigma Aldrich

[0284] Different types of PEGs (PEG 200, PEG 400 and similar kinds)

[0285] Different types of carbonates as ethylene carbonate (EC), vinylene carbonate (VC)

[0286] The advantages of the present invention can be illustrated through gripping applications, e.g. showing how objects can be repeatedly picked up, transferred, and released without vacuum. The invention demonstrates not only its core gripping function but also its wider impact on environmental circularity. The ability to switch adhesion on and off supports frequent reuse, since the same adhesive element can be employed in multiple cycles without loss of performance. Repairability and recyclability are realized because the functional adhesive layer can be replaced or regenerated while maintaining the overall device structure. These aspects together contribute to sustainability, as material consumption and CO2emissions are reduced through extended service life and repeated use. Thus, gripping examples serve as representative demonstrations of how the invention can achieve reusability, repairability, recyclability, and sustainability.

[0287] EXPERIMENTAL EXAMPLE 1:

[0288] Example 1 describes the preparation of a device e.g. single-layered, single-sided adhesive tape (FIG. 1) and its use to build an adhesive loop (FIG. 6 and 7) for gripping application.

[0289] The process includes: i. Electrically conductive (EC) coating on primed PET ii. Ion-conductive adhesive coating on the EC layer of the primed-PET backing iii. Adhesive loop preparation

[0290] (i) Electrically conductive coating preparation on the primed-PET backing: First a primed PET backing of thickness 50 to 178 pm was cut in a dimension (30 x 15) cm. Next, PEDOT:PSS ink or aqueous dispersion with a solid content of 3 to 5 wt % was coated on the primed side of the PET backing either using a doctor blade coater or by lamination coater and then dried at 2 times at 100 °C for 10 min. This results in a blue EC layer on primed-PET named as carrier. The visual light transmission of the carrier was found in the range of 40 to 70 %.

[0291] It should be noted that the primed PET backing is prepared by curing a very thin layer of acrylic adhesive (1-5 pm) comprising a UV-curable syrup of 45:55 wt% EDGA:DMAA with Irgacure 651 and Irgacure 184 as photoinitiators, cured at an intensity of 3000 mW-s / cm2.

[0292] If ITO-coated PET is used, no further primer is required, as the ITO layer itself functions as a primer.

[0293] (ii) Ion-conductive adhesive coating on the EC layer of the primed-PET backing: Several adhesive compositions of the invention were produced with the successive steps of a) prepolymer preparation, i.e., UV syrup preparation; b) formulation of the liquid electrolyte, i.e., dissolving ionic liquid (PFAS free) or DES, photoinitiator, and / or other monomers or additives (plasticizer) and crosslinkers into the UV syrup; and c) coating and curing of the liquid electrolyte between the EC layer of primed-PET and a siliconized PET liner (RF02). The curing process is related to UV polymerization. See the details below for steps a) to c). Step a)

[0294] A 45:55 wt% mixture of EDGA:DMAA acrylic monomers with 0.0063 wt% Irgacure 651 was prepared in a glass reactor, degassed under N2for 30 minutes, and irradiated with UV light (365 nm, 0.5 mW / cm2) under stirring. Polymerization was stopped when the reaction temperature increased by AT = 26 °C. The resulting UV syrup was cooled, stored in the dark, and had a viscosity of 2000-4000 cP with a refractive index of 1.44-1.45.

[0295] Step b)

[0296] The UV syrup from step a) was blended with other ingredients as summarized in Table 1. The adhesive has a composition of 80-90 wt% UV syrup from step a), 5-15 wt% ionic liquid (e.g. EMIM FSI, EMIM BF4, BMIM BF4), 0.055-0.15 wt% Irgacure 184, 0.5-5 wt% plasticizer (PEG 200, water, or carbonate solvent), and 0.5-2 wt% crosslinker. The mixtures were rolled until fully dissolved and are referred to as liquid electrolytes once homogeneous.

[0297] Step c)

[0298] The liquid electrolytes from step b) were coated at 20-80 pm between two films, such as (PEDOT:PSS-primed-PET) backing and a siliconized PET liner, and then UV-cured. Some parts of the EC layer were left uncoated to allow electrical connection to an external DC power supply. After removing the liner, a single-layered, single-sided adhesive tape (carrier T) was obtained. Curing was carried out with fluorescent UV-A lamps (350-400 nm, 14 mW / cm2) for 200-360 s, giving a total UV dose of 2800-5000 mW-s / cm2.

[0299] (iii) Adhesive loop preparation:

[0300] The adhesive tape obtained from step c) was in (30 x 15) cm size in dimension and then cut to 28 cm in length and 2 cm in width. The strip was converted into a loop shape design by joining two ends of the strip and where the adhesive is exposed to outside. The loop has about 14 cm. At both ends when the backing is ITO coated PET, then a small copper tape was applied on the ITO side to ensure better connectivity with the DC power supply. However, for the PEDOT:PSS-primed-PET backing, application of copper tape is optional. The composition of a loop shaped device is listed in the table 1.

[0301] The loop adhesive tape or device was left to dwell for several days in a lab environment, therefore, interfacial contact is improved between the adhesive and the electrically conductive layer, as well as the adhesive absorbing some moisture from the air, which results in faster bonding / debonding operations. Use of ITO primed PET or ITO coated PET shows faster response due to the higher electrical conductivity of the transparent conductive oxides (TCOs). It is also important to note that the loop shaped design is not limited but an example approach that allows to control define pressure and area of the loop tape when brough to the object of interest that needs to be moved off during gripping operation. Sometimes it may happen that the adhesive of the device may show more tackiness properties depending on the substrate type, in such case the adhesive may need to heat up or rubbing to reduce the surface tackiness.

[0302] The device described above is one preferred example of a gripping application, but it is not limited to the only the loop shape design. In this example, the loop form can be used to move electrically conductive objects from one location to another. Such gripping technology is especially useful for smooth, flat, fragile, porous, or perforated objects that cannot be handled effectively by conventional methods such as suction. Below one examples given to realize how the adhesive can be used for gripping applications. The examples are to realize the use of the device without wishing thereby to subject the present invention to any unnecessary limitation.

[0303] An operation procedure is described below to move a square shaped one side shiny 35.61 g stainless-steel object from location 1 to location 2 using the loop tape of the present invention as described above. This object has a dimension of (40 x 40 x 3) mm with a hole of 9 mm diameter in the middle, was selected intentionally to demonstrate that the tape can even more porous objects that are not suitable for normal vacuum suction gripping.

[0304] The object was first placed keeping the shiny part upward on an electrically conductive substrate (location 1), which was already connected to the positive terminal of a first external DC power supply. The negative terminal of this supply was connected to the copper tape region of the PEDOT:PSS-primed-PET. The same loop tape was also connected to a second DC power supply, with its positive terminal attached to the loop (on copper tape side) and the negative terminal of the power supply connected to a second conductive substrate (location 2), where the object would be placed. Both power supplies provided 30-40 V DC.

[0305] When the adhesive loop was pressed onto the object (shiny side) at location 1, the electrically triggered bonding property of the tape enabled bonding between the adhesive of the loop and object. The loop was then manually moved about 500 mm to the location 2, where the object was transferred into the second substrate. Due to the adhesive's electrically induced debonding capability, the object was gently released at location 2. This procedure was repeated multiple times to transfer the objects between the two locations. Table 1: Example of loop tape's compositions that are used to show the gripping function of the present invention.

[0306] Besides the pick-and-place applications as mentioned above, additional experiments are carried out to obtain more quantitative data on the force generated or drops, when the adhesive bonds to the conductive surfaces or debond from bonded states. These tests, described below. 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 30 pm to 80 pm

[0307] Test A: Bonding / Debonding Test:

[0308] A stainless-steel plate (130 mm x 50 mm) was fixed flat on the lower holder of a tensile tester from Lloyd Instruments LRX universal testing machine by AMETEK and connected to the positive terminal of an external DC power supply. While the electrically conductive part of the loop tape was attached to the upper holder of the tester and connected to the negative terminal of the same power supply. A DC voltage of 30-40 V was applied. The loop tape was then lowered downward onto the steel plate at a speed of 300 mm / min, and once contact was made between loop tape and the steel plate, the electrically triggered bonding was activated by circuit completion. The contact area was ~ [5x2 = 10] cm2. Contact was maintained for 15 s for reliable operation, after the loop tape was pulled upward at 300 mm / min. The maximum peak force was recorded, until the loop is fully detached from the steel plate, representing the electrically induced bonding force. The maximum force can be presented as N / cm2or as N / cm, because the actual contact area is hard to measure accurately (the loop doesn't make a perfectly flat, defined area, therefore later one was preferred. The same test was also carried out, reversing the polarity of the DC power source [connecting positive terminal to PEDOT:PSS-primed-PET and negative to the ASTM steel plate] to realize the debonding force between ASTM steel plate and loop tape as well as one test without voltage applications. The results are summarized in table 2.

[0309] The results confirm that the adhesive loop shows very low adhesion to the steel plate at normal state (without voltage application); however, upon voltage application, the bonding strength can either be increased or decreased, enabling the adhesive of the present invention to be used in gripping applications.

[0310] Test B: Peel Adhesion Test:

[0311] A standard peel adhesion tests were also carried out in contrast to bonding force test. A single-layered, single-sided adhesive tape was cut with a width of 20 mm and a length of 150 mm. The adhesive tape was applied onto a cleaned ASTM steel plate (cleaned with acetone after removing the protective film) by gentle hand pressure using a lamination squeegee, after peeling off the siliconized PET liner. The other side of the adhesive tape already has carrier based on PEDOT:PSS on -ITO-PET backing. Then the whole setup was pressed by rolling back and forth over five times using a 4 kg roller.

[0312] The setup was then vertically hooked to the bottom holder of a tensile testing instrument (ZwickRoell Z020), and the carrier (e.g. PEDOT:PSS-ITO-PET) was attached to the upper holder of the instrument.

[0313] For peel adhesion measurement, the PEDOT :PSS-ITO-PET carrier was pulled off at an angle of 180° with a velocity of 300 mm / min, while applying a DC voltage of 30 V with positive terminal of the external DC power supply connected to the ASTM steel plate and negative terminal to the carrier. The maximum force was recorded in N / cm for a complete peel of the adhesive tape from the ASTM steel substrate. The values reported here are the average of two individual measurements.

[0314] Test C: Ionic Conductivity:

[0315] The ionic conductivity, more specifically DC conductivity was measured by EIS (Electrochemical Impedance Spectroscopy) from the log-log plot of real part of the AC conductivity over an angular frequency by extrapolating the plateau region to the zerofrequency using the Dyre fit function (e.g. empirical model for frequency-dependent conductivity in disordered systems). 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 1 Hz. A transfer tape (no carrier) of circular dimension with a diameter of 18 mm was applied between two circular steel plate electrodes. The tape thickness was 30 pm to 150 pm.

[0316] Table 2: Result.

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 differing from each other, wherein the device satisfies one or both of the following: i. the device is configured to move an object by adhering to the object by the adhesive force of the electro-responsive adhesive in the bonded state and moving the device together with the adhered object, and the electro- responsive adhesive is able to cycle between the bonded state and the debonded state for 50 or more times and with a recovery time of 2 minutes or less between a debonded state and a subsequent bonded state; ii. the electro-responsive adhesive is partially to fully biologically degradable.

2. The device according to claim 1, which exhibits, after application of a first respectively second electric stimulus, an adhesive strength of 0.5 N / cm to 15 N / cm or higher, such as 25 N / cm or higher such as 40 N / cm, in a bonded state, and an adhesive strength of 0.1 to 0.4 N / cm in a debonded state.

3. The device according to claim 1 or 2, wherein the adhesive comprises one or more selected from the group consisting of a) polymers derived from plants, such as cellulose and starch, as well as derivatives thereof, b) polymers derived from biologically produced monomers, and c) biologically degradable polymers, such as (poly) lactic acid, poly caprolactone, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and polyethlene glycol.

4. The device according to claim 1 or 2, wherein the adhesive comprises one or more selected from the group consisting of deep eutectic solvents, which are preferably obtained from hydrogen bond donor and hydrogen bond acceptor molecules such as urea, glycerol, succinic acid, phenyl acetic acid, menthol, choline chloride and proline chloride, histidine chloride, glucose, malic acid, citric acid, and sucrose.

5. The device according to any one of claims 1 to 3, wherein the device comprises a recycled material.

6. The device according to any one of the preceding claims, wherein the first and second electric stimulus are 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, and wherein preferably the first and second electric stimulus are selected from DC or AC current or voltage in the range of 0.5 - 230 V, preferably a DC voltage in the range of 1 to 50 V, more preferably 1 to 10 V.

7. The device according to any one of the preceding claims, which comprises the adhesive and one or more electrically conductive surface(s) in the same or in different layers or regions, the different layers or regions preferably being adjacent to each other.

8. 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.

9. The device according to any one of the preceding claims, wherein the device further comprises an electrically conductive substrate in contact with the pressure sensitive adhesive.

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

11. 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) 20 to 80 wt % of acrylate monomer (al) from the group of (meth)acrylic esters containing at least one oxygen atom; and b) 20 to 80 wt % of acrylate monomer (a2) from the group of (meth)acrylic esters and / or amides containing at least one nitrogen atom; and c) 0.0 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; ande) 0 wt % to 20 wt % of one or more ionic liquids and / or deep eutectic solvents; and f) 0.0 wt % to 20 wt % of one or more salts that are no ionic liquids or deep eutectic solvents; and g) optionally 1 wt % to 20 wt % by weight 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.

12. The device according to any of the preceding devices, which is, or forms part of, a gripping device that is configured for moving objects, preferably remote-controlled.

13. A system for remotely operating the device according to the preceding claims, the system comprising a device according to any one of the preceding claims and a controller that is configured to provide the first and second electric stimulus to the device, the controller being operated by software or by a user input.

14. A method of moving an object, the method comprising the steps of(A) Applying an electric stimulus to a device as defined in any of the preceding claims, the electric stimulus being a second electric stimulus for modifying the adhesive to a bonded state;(B) Attaching an object to be moved to the adhesive in the bonded state via the adhesive, the objection being in a first location,(C) Moving the device with the attached object to a second location, and(D) Applying an electric stimulus to the device, the electric stimulus being a first electric stimulus for modifying the adhesive to a debonded state, to thereby release the object at the second location.

15. The method of moving an object according to claim 13, wherein the steps (A) to (D) are repeated a plurality of times to move a plurality of objects, and wherein preferably the method is part of an assembly process, such as an assembly process of electronic devices.

16. A method of reducing the number of faulty products in an assembly process that comprises comprising joining two or more different members to form an assembled part, the method including - a step of preliminarily assembling members using an adhesive as defined in any of the preceding claims confirming the proper alignment of the preliminary assembled members, and optionally performing an additional step of permanently joining the members if the alignment is correct, or optionally disassembling the assembled members and correcting the alignment of the members if the alignment is incorrect.

17. Use of a device as defined in any of claims 1 to 11 or of a system according to claim12 in an assembly process of electronic devices, such as computers, chips, smartphones, displays, touch panels, sensors, light sources such as LEDs or OLEDs, or other electronic devices.

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