Highly Damping and Self‐Healable Ionic Elastomer from Dynamic Phase Separation of Sticky Fluorinated Polymers

Abstract

tion are easily imparted via designing ion-involving supramolecular polymer networks, the resistance of ionic skins to various damages is considered to be a quite challenging task without sacrificing the other properties. Noteworthily, human-like bionic soft robots may be frequently exposed to sudden shocks, strikes, or mechanical agitations with low-frequency vibrations (0.1-50 Hz), which will likely incur the malfunction or fatigue failure of internal fragile electronic elements. [4,5] Despite the recent progress in toughening self-healable ionic skins by supramolecular networks, phase separations, or hard domains to resist global and crack-related damages, [6][7][8][9] rare reports focus on improving its mechanical damping performance to isolate or eliminate the equally important shock-induced vibration damages.Damping generally describes the attenuation of unwanted vibrations by dissipating shock-related mechanical energy into heat by means of spatial momentum transfer driven by velocity gradient. [10] For elastomers, manipulating polymer viscoelasticity to enhance internal molecular frictions is considered to be the key to improving damping capacity. [11,12] In principle, when the time scales of viscoelastic relaxation and vibration are comparable (i.e., the ratio of relaxation time to vibration time defined as Deborah number, D e , is approximate to 1), maximum damping can be realized. [5,13] Unfortunately, most elastomers are poorly damping with a rather low loss factor (tan δ < 0.1) which is defined by the ratio (G′′/G′) of the loss (G′′) to storage moduli (G′). Optimizing the associating dynamics of polymer networks to the gel point can afford very high tan δ values close to 1, yet the elasticity and shape retention of the resulting materials are pretty low. [14][15][16] Shifting or broadening the glass transition region with an apparent tan δ peak to the working temperature/frequency range has been widely utilized to optimize elastomer's damping performance by copolymerization, [17] polymer blending, [18] interpenetrating network, [5,19] incorporating granules, [20] metal coordination, [21] dynamic networks, [22] etc. However, materials at the glass transition region have often limited stretchability and elastic recovery, and the relatively high moduli also hamper ionic skin-related applications in soft electronics and robotics. Alternatively, introducing additional relaxation components such as dangling chains, [13,23] polymer fluids, [12] and nematic liquid crystal orders [24] into an elastic network has been recently reported to produce highly Shock-induced low-frequency vibration damage is extremely harmful to bionic soft robots and machines that may incur the malfunction of fragile electronic elements. However, current skin-like self-healable ionic elastomers as the artificial sensing and protecting layer still lack the ability to dampen vibrations, due to their almost opposite design for molecular frictions to material's elasticity. Inspired by the two-phase structure of adipose tissue (the natura...

Polyrotaxane‐Based Functional Materials Enabled by Molecular Mobility and Conformational Transition†

“…The self‐healing properties of elastomers and gels are essential to improve the safety, extend service life, and enable multiple recycling of functional devices, especially in the field of wearable electronics. [ 96‐106 ] However, achieving high self‐healing performance, high toughness, and desirable tensile strength simultaneously remains difficult. Okumura and Ito synthesized early slide‐ ring gels, cross‐linking α‐CD molecules in different polyrotaxane chains with epichlorohydrin.…”

Microstructured Polyfluoroacrylate Elastomeric Dielectric Layer for Highly Stretchable Wide-Range Capacitive Pressure Sensors

“…However, the elasticity of PVDF-HFP is poor, and its inertness allows no facile chemical modification. Recently, polyfluoroacrylate elastomers have been reported as highly damping ionic elastomers . We reason that the copolymerization of a fluorinated acrylate with a second monomer bearing polar functional groups would be practical to obtain stretchable elastomers with tunable mechanical properties and a high dielectric constant by carefully adjusting the molar ratio of the monomers.…”

A liquid-free conducting ionoelastomer for 3D printable multifunctional self-healing electronic skin with tactile sensing capabilities

“…[1][2][3][4][5][6][7][8][9][10] As a new conductive material, elastomers can detect external stimuli caused by stretching, bending and twisting, and convert them into corresponding electrical signals such as resistance, capacitance, and current. [11][12][13][14][15] Currently, most reported conductive elastomers are mainly divided into two kinds: hydrogel-based and ionogel-based. The former is favored for its excellent mechanical and electrical performance, but it loses the function of electronic devices because the solvent evaporates easily.…”