Poly(ionic liquid)s Containing Alkoxy Chains and Bis(trifluoromethanesulfonyl)imide Anions as Highly Adhesive Materials

Abstract

by judiciously adjusting the structure of ILs. ILs have been intensively studied as a "green" alternative to organic solvents for synthesis, catalysis, extraction, and separation. [2] They are also safe and versatile electrolytes for electrochemistry and energy-related applications. [3] However, their viscosities are generally two or three orders of magnitude higher than those of conventional organic solvents (molecular liquids), which inevitably lead to handling difficulties (e.g., infiltration, decantation, and dissolution), low reaction rates, competitive unimolecular side reactions, sluggish ionic transport, and significantly reduced ionic conductivity. [4] For the potential application of ILs, such high viscosities have to be deliberately avoided by choosing alternative anions such as bis (trifluoromethanesulfonimide) (TFSI − ) and dicyanamide anions with high charge delocalization [4b,5] or introducing ether groups that pack less efficiently and provide more available free volume to enable low viscosity. [6] Nevertheless, the disadvantageous high viscosities of ILs can become advantageous for special applications that require viscous materials, such as adhesion, sealing, and gelation. [7] Particularly, adhesion is the attraction between two different condensed phases when they are in contact to construct a robust joint. Adhesion involves not only the molecular interactions at the interface of two individual surfaces but also the energy within the deformed material when pulling them apart. Adhesives have been acknowledged as indispensable chemicals in daily life and in many industries ranging from packaging, labeling, housing construction, and automobile manufacturing to soft robots, wearable devices, and aerospace. [7a,b,8] Along with conventional resins and gum-based adhesives, many musselinspired and catechol-based polymeric materials had been developed as modern adhesives in the past. [9] Nevertheless, they possess inherent drawbacks such as irreversible oxidizing crosslinking, tedious synthesis, and poor cycling performance. [10] We recently reported a series of noncatechol adhesive materials produced by water-triggered supramolecular polymerization of crown ether-containing monomers, but the synthesis of such specific monomers involves complicated functionalization, which is difficult to scale up. [11] The presence of water in these supramolecular adhesives also becomes an obvious disadvantage as they cannot bear ultra-high vacuum adhesion.Adhesive materials have wide applications in diverse fields, but the development of a novel and multipurpose adhesive is a great challenge. This study demonstrates that conventional poly(ionic liquid)s (PILs) can be designed as highly efficient adhesives by simply introducing alkoxy moieties into the cationic backbone of PILs containing bis(trifluoromethanesulfonimide) (TFSI − ) anions. The incorporated flexible alkoxy chain not only reduces the glass transition temperature of PILs but also endows these materials with strong hydrogen bonding interactions, w...

Hot Melt Super Glue: Multi‐Recyclable Polyphenol‐Based Supramolecular Adhesives

“…[ 4 ] Alternatively, introduction of flexible alkoxy chains into supramolecular hot melt adhesives could enhance the mobility of polymer chains to balance the strength of cohesion and adhesion, while these strategies typically involve complex steps for the synthesis/modification of polymers. [ 1d,5 ] For example, Zhang et al. reported supramolecular hot melt adhesives composed with poly(ionic liquid)s, which incorporated alkoxy moieties of poly(ethylene glycol) (PEG) into the cationic backbone of poly(ionic liquid)s and therefore increased the adhesion strength up to 4.6 MPa.…”

Green Wood Adhesives from One-Pot Coacervation of Folic Acid and Branched Poly(ethylene imine)

“…So far, numerous adhesive materials have been developed, but most of them are catechol-based, which rely on covalently incorporating catechol into polymers or by expressing recombinant mussel adhesive proteins. , In this case, the material preparation often requires tedious synthesis, purification, and expensive reagents . The whole preparation process is time-consuming and costly, which makes it difficult for large scale-up production.…”

“…7,8 In this case, the material preparation often requires tedious synthesis, purification, and expensive reagents. 9 The whole preparation process is time-consuming and costly, which makes it difficult for large scale-up production. There are also some excellent noncatechol-based adhesives, such as low-molecular weight supramolecular adhesive comprising crown ether monomers with structural water, 10 crystal-based adhesive based on polymerization of 1-methyl-3-methylimidazolium hexafluorophosphate, N,N-dimethylacrylamide and poly(ethylene glycol) diacrylate, 11 and supramolecular hot melt adhesive fabricated from the naturally existing small molecules of thioctic acid, divinyl compounds, 1,3-diisopropenylbenzene, and Fe 3+ ions in a specific proportion.…”

Robust Antiwater and Anti-oil-fouling Double-Sided Tape Enabled by SiO2 Reinforcement and a Liquefied Surface

“…The tape should be soft with high interfacial adhesive energy to realize fast bonding, which usually sacrifices the cohesive energy and vice versa. , Although no scaling theory guides us to overcome such a trade off, it is required to obey Cannikin’s law, that is, not sacrificing one performance distinctively, the other performance is improved significantly. Recently, there are six approaches to relieve this dilemma: (1) combining dynamic bonds with bioinspired surface drainage architecture or catechol moiety, ,− (2) synergetic effect between a hydrophobic backbone and hydrophilic adhesive side branches, ,, (3) modification of poly­(ionic liquid)­s (PILs), ,, (4) sequence-controlled poly­(cation-π)­s, ,,, (5) introduction of dual cross-linking networks, , and (6) composite with nanofillers. − Nevertheless, abovementioned adhesives with a high adhesion strength usually are glue-type adhesives, which need UV, heat, an extra cross-linking agent, or long-time to cure, while hydrogel-type adhesives still cannot achieve high bonding strength limited by their weak cohesive strength.…”