A Fast Room‐Temperature Self‐Healing Glassy Polyurethane

Abstract

We designed and synthesized acolorless transparent glassy polyurethane assembled using low-molecular-weight oligomers carrying al arge number of loosely packed weak hydrogen bonds (H-bonds), which has ag lass transition temperature (T g)u pt o3 6.8 8 8Ca nd behaves unprecedentedly robust stiffness with at ensile Youngsm odulus of 1.56 AE 0.03 GPa. Fast room-temperature self-healing was observed in this polymer network:t he broken glassy polyurethane (GPU) specimen can recover to at ensile strength up 7.74 AE 0.76 MPaa fter healing for as little as 10 min, whichi s prominent compared to reported room-temperature self-healing polymers.T he high density of loose-packedh ydrogen bonds can reversibly dissociate/associate belowT g of GPU (that is secondary relaxation), which enables the reconfiguration of the damaged network in the fractured interfaces,despite the extremely slow diffusion dynamics of molecular chains under room temperature.T his GPU shows potential application as an optical lens.

A Stiff yet Rapidly Self‐Healable Elastomer in Harsh Aqueous Environments

“…[44] From the α relaxation peak in Figure 3B, it was revealed that the average relaxation time (τ max ) was only 0.09 s at 25 °C, indicating a fast diffusion dynamic of polymer segments (Figure S11, Supporting Information). [44][45][46] This result indicates that even with the high stiffness, our PBMA-PEA material can still maintain fast segmental movements, leading to rapid healing performance, which is consistent with our rheological tests (Figure S12, Supporting Information).…”

“…It could be seen that the kinetic rate of ester moieties was much faster than that of phenyl moieties. According to the Arrhenius function, [46,48,49] the E a values of ester moieties was very small, only 9.07 kJ mol −1 , in comparison, the E a values of phenyl moieties was as high as 90.85 kJ mol −1 , one order of magnitude higher than that of ester moieties. This indicated that the self-healing process may be related to motions and diffusions of ester moieties.…”

A Puncture‐Resistant and Self‐Healing Conductive Gel for Multifunctional Electronic Skin

“…[16] In the modification of polyurethane, the thermal stability and mechanical properties are often adjusted by tuning the ratio of soft and hard segments. [17] Based on the synergistic mechanism of soft segment and hard segment, we selected thioctic acid, sodium methacrylate sulfonate, and polyaniline as the ingredient of our materials. As a small natural molecule, thioctic acid not only has the characteristics of anti-inflammatory, antibacterial, and good biocompatibility, but also can act as a strong reducer, which can be regarded as a free-radical trapper.…”

A High Strength but Fast Fracture‐Self‐Healing Thermoplastic Elastomer

“…[ 4b,6,9 ] Herein, isophorone diisocyanate (IPDI) (hard segment), poly(ɛ‐caprolactone) diol (PCL) (soft segment) and 4‐aminophenyl disulfide (DTDA) (hard segment) were specifically selected to fabricate the PUU. Among them, the steric hindrance of asymmetric alicyclic structure of IPDI provides sufficient chain mobility while retaining the remarkable mechanical properties, [ 6,10 ] the carbonyl groups of PCL provide bonding motifs for forming H‐bonds to enhance mechanical strength and maintain toughness as soft segment simultaneously, and the rapid reaction kinetics of aromatic disulfide bonds promote polymer chain movements. [ 5a,6 ] To avoid the adverse effects of crystallization or aggregation of hard segments on self‐healing, we chose one‐step synthesis procedure to prepare PUU elastomer, making it a disordered structure.…”