Developing autonomous self-healing materials for applications in harsh conditions is challenging because the reconstruction of interaction in material for self-healing will experience significant resistance and fail. Herein, a universally self-healing and highly stretchable supramolecular elastomer is designed by synergistically incorporating multi-strength H-bonds and disulfide metathesis in polydimethylsiloxane polymers. The resultant elastomer exhibits high stretchability for both unnotched (14000%) and notched (1300%) samples. It achieves fast autonomous self-healing under universal conditions, including at room temperature (10 min for healing), ultralow temperature (−40 °C), underwater (93% healing efficiency), supercooled high-concentrated saltwater (30% NaCl solution at −10 °C, 89% efficiency), and strong acid/alkali environment (pH = 0 or 14, 88% or 84% efficiency). These properties are attributable to synergistic interaction of the dynamic strong and weak H-bonds and stronger disulfide bonds. A self-healing and stretchable conducting device built with the developed elastomer is demonstrated, thereby providing a direction for future e-skin applications.
Via Bischler–Napieralski cyclization
of amide precursors
as the key step, a series of diazapyrene derivatives were designed
and successfully synthesized. Their crystal structures, optoelectronic
properties, and acid-responsive feature were investigated, which demonstrated
that the doping of nitrogen atoms to the pyrene framework remarkably
modulates their physical and chemical properties.
5,6,12,13‐Tetraazaperopyrenes with different number of tert‐butyl groups (c‐TAPP‐T, c‐TAPP‐H) were synthesized, via four‐fold Bischler–Napieralski cyclization as the key step. As deduced from the single‐crystal structures and optical properties, N‐doping and substitution type allow for a precise control of intermolecular interactions. Compared to the reported 1,3,8,10‐tetraazaperopyrenes, significantly different packing modes were found in 5,6,12,13‐tetraazaperopyrenes. Going from c‐TAPP‐T to c‐TAPP‐H, two additional tert‐butyl groups lead to different preferential growth directions, affording 1D and 2D microcrystals, respectively. Most importantly, both microcrystals exhibit excellent optical waveguide properties with extraordinarily low loss coefficients and unique polarization features. Although c‐TAPP‐H possesses a rigid and planar core, its crystals display an exceptional mechanochromic fluorescence, which, again, depends on the mode of molecular packing.
The effect ofN-alkyl chain lengths on the mechanochromism of Ir(iii)-based phosphors is studied. Reversible switching of the emission colour is achieved by using the Ir(iii) material as a medium.
A novel type of discotic polycyclic aromatic hydrocarbon (PAH) based on an enlarged dibenzo[a,c]phenazine core has been developed. The large conjugated mesogenic core with increased dipole moment derived from S,N heteroatoms facilitates the formation of highly ordered columnar superstructures both in solution and bulk. Columnar mesophases, including liquid crystal (LC) and plastic crystal (PC) assemblies could form unprecedentedly based on the same PAH core. The cores are delicately modulated by the peripherical alkoxy chains. Both mesogens have mechanochromic fluorescent (MCF) character, which is also structure dependent and correlated with the different mesophase formation. For the first time, MCF properties can be realized in such a large conjugated mesogenic system.
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