To
mimic the velocity-sensitive ability of the human skin, we fabricate
a class of “solid–liquid” elastomers (SLEs) by
interpenetrating polyborosiloxane (PBS) with polydimethylsiloxane
(PDMS). PBS forms a dynamic network through boron/oxygen dative bonds,
while PDMS is covalently cross-linked to form a permanent network.
The permanent network affords a scaffold for the dynamic network,
endowing SLEs with high elasticity and structural stability, thereby
overcoming the inherent drawbacks such as fluidity and irreversible
deformation of conventional solid–liquid materials. Meanwhile,
the dissociation and association of the dynamic network is time-dependent.
Thus, the modulus of SLEs varies with strain rates, and if the SLEs
contain carbon nanotubes, their electric conductivity is also responsive
to strain rates. This property can be utilized to fabricate skin-like
sensors with the ability to distinguish different contact velocities.
Moreover, the dynamic network can dissipate energy and be repaired,
leading to the high stretchability and self-healing performance of
SLEs.
Due
to the dynamic nature of networks and high mobility of molecular
chains, self-healing elastomers are usually confronted with the trade-off
between self-healing efficiency and mechanical properties. Herein,
a self-healing ionomer with both high mechanical performance and high
self-healing efficiency has been successfully developed by grafting
bromobutyl rubber (BIIR) with pyridine-based derivatives. Interestingly,
the substituents on the pyridine ring can be used to regulate the
interaction forces of ionic clusters and molecular dynamics. The electron-donating
effect of the substituents facilitates stable π–π
stacking between pyridyl ions, inducing the formation of regular and
large ion aggregates, thereby improving the mechanical strength of
the ionomer. Meanwhile, the plasticizing effect of the substituents
reduces the activation energy and relaxation temperature of the ionic
aggregates, thus endowing the ionomer with a high self-healing efficiency.
As a result, the ionomer shows tensile strength as high as 8.1 ±
0.3 MPa under room temperature and self-healing efficiency of 100
± 3% at 60 °C. Therefore, this strategy can be easily extended
to other halogen-containing polymers, leading to a novel class of
self-healing ionomers that hold great promise in diverse applications.
Dative bonds are
crucial for room-temperature phosphorescence
(RTP)
of metal complexes, which are nevertheless of high cost and toxicity.
Here, we develop a class of amorphous RTP polymers based on nonmetal
dative bonds through copolymerizing vinylphenylboronic acid
and acrylamide derivatives. Nonmetal dative bonds, formed between
boron and nitrogen/oxygen atoms, can populate triplet excitons through
charge transfer and immobilize phosphors to suppress nonradiative
relaxation, leading to effective RTP lifetime in air. Moreover, the
dynamic nature of the dative bonds enables self-healing and anticounterfeiting
abilities of the RTP polymers. The concept of designing nonmetal dative
bonds can widely expand the horizon and application of RTP polymers.
Notwithstanding the substantial progress of the human skin bionics, it remains an enormous challenge to integrate skin-like softness, strain-adaptability, self-healing ability, breathability and perceptiveness in a single material. Herein, a...
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