Self-supporting liquid
crystalline physical gels with facile electro-optic
response are highly desirable, but their development is challenging
because both the storage modulus and driving voltage increase simultaneously
with gelator loading. Herein, we report liquid crystalline physical
gels with high modulus but low driving voltage. This behavior is enabled
by chirality transfer from the molecular level to three-dimensional
fibrous networks during the self-assembly of 1,4-benzenedicarboxamide
phenylalanine derivatives. Interestingly, the critical gel concentration
is as low as 0.1 wt %. Our findings open doors to understanding and
exploiting the role of chirality in organic gels.
The
fast capacity decay of existing anode materials at a high rate
is a thorny problem that hinders the thriving development of sodium
ion batteries (SIBs). Herein, we present a unique anode material constructed
via cuprous sulfide hollow nanospheres (CuS HNs), which can achieve
ultrafast sodiation-desodiation at high rate (20 A g–1) and stable cycling 2000 times without obvious capacity degradation
(250.1 mAh g–1, capacity retention of 93%). As far
as we know, this excellent rate performance is superior to most of
the other currently known metal oxides/sulfides anode materials for
SIBs. It is believed that the contribution for high-rate sodium storage
of CuS HNs mainly comes from the synergistic effect between hollow
nanosphere structure and surface pseudocapacitive behavior. The open
hollow nanostructure allows the pseudocapacitive storage simultaneously
on the inner and outer surfaces of the nanospheres. Meanwhile, the
pseudocapacitive behavior can relieve the large stress of nanospheres
at high rate and retain the structural stability of electrode materials.
The feature of ultralfast charging and discharging of CuS HNs without
obvious capacity sacrifice would be expected to provide a strong boost
for the large-scale application of SIBs.
Liquid crystalline physical gels (LCPGs) have attracted
increasing
interest because of their mechanical properties and stimulus–response
behaviors. However, due to their gelator properties such as thermal
stability, gelation capability, and compatibility in liquid crystals,
development of LCPGs with high performances still remains a huge challenging
task. Herein, four novel gelators ((l)-PH, (d)-PH,
(l)-P2H, and (d)-P2H) based on 1,4-benzenedicarboxamide
phenylalanine derivatives containing one or two ethylene glycol groups
have been designed and synthesized. It is found that the ethylene
glycol group plays a significant role in improving the compatibility
between the gelator and the liquid crystal. All of the prepared compounds
can form stable LCPGs in P0616A. In particular, the storage modulus
of LCPG with 9.0 wt % of (l)-PH with one ethylene glycol
unit is higher than 106 Pa, which is similar to SmC gels
and advantageous over previously reported nematic LCPGs. Furthermore,
the prepared gels display a strong Cotton effect with hand-preferred
twisted fiber networks and the self-assembled aggregates of (l)-PH can induce P0616A to form a cholesteric fingerprint structure.
Thus, these low molecular weight gelators provide a strategy to construct
high-performance cholesteric LCPGs for the realization of LC device
applications.
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