6 research outputs found
Reversible Surface Dual-Pattern with Simultaneously Dynamic Wrinkled Topography and Fluorescence
The reversible surface patterns with
fluorescence and topography
can possibly enable information recording and reading and provide
an important alternative to realize the higher information security.
We demonstrated a reversible dual-pattern with simultaneously responsive
fluorescence and topography using an anthracene (AN) and naphthalene
diimide (NDI) containing copolymer (PAN-NDI-BA) as the skin layer,
in which the reversible photodimerization of AN can simultaneously
control the cross-linking and CT interaction between AN and NDI. Upon
irradiation with UV light and thermal treatment, the resulting pattern
assumes a reversible change between smooth and wrinkled states, and
its fluorescence changes reversibly from red to white to blue-green.
The smart surfaces with dynamic hierarchical wrinkles and fluorescence
were achieved by selective irradiation with photomasks and can be
employed for potential applications in smart displays and anticounterfeiting
Water in Oil Emulsion Stabilized by Tadpole-like Single Chain Polymer Nanoparticles and Its Application in Biphase Reaction
In
this study, tadpole-like single chain polymer nanoparticles
(TSCPNs) were efficiently synthesized by intramolecularly cross-linking
P4VP block of commercial block polymer of PMMA<sub>2250</sub>-<i>b</i>-P4VP<sub>286</sub> in <i>N</i>,<i>N</i>-dimethylformamide using propargyl bromide as cross-linking agent.
The intramolecular cross-linking reaction led to the production of
TSCPNs with a linear tail and a cross-linked head. The as-prepared
TSCPNs were then applied as emulsifier to stabilize water in chlorobenzene
emulsion, and an extremely stabilized water in oil (W/O) emulsion
was generated at a low TSCPNs concentration. The TSCPNs concentration
was as low as 0.0075 wt % versus total weight of water and chlorobenzene
for emulsion formation. The emulsifying performance of TSCPNs was
better than that of low molecular surfactant, such as Span-80. The
generated W/O emulsion provided an ideal medium for the reduction
of oil-soluble <i>p</i>-nitroanisole by water-soluble sulfide
to <i>p</i>-anisidine, an effective contact problem between
the two reactants with different solubility was well solved through
interfacial reaction
Growth of 2D Mesoporous Polyaniline with Controlled Pore Structures on Ultrathin MoS<sub>2</sub> Nanosheets by Block Copolymer Self-Assembly in Solution
The
development
of versatile strategies toward two-dimensional (2D) porous nanocomposites
with tunable pore structures draws immense scientific attention in
view of their attractive physiochemical properties and a wide range
of promising applications. This paper describes a self-assembly approach
for the directed growth of mesoporous polyaniline (PANi) with tunable
pore structures and sizes on ultrathin freestanding MoS<sub>2</sub> nanosheets in solution, which produces 2D mesoporous PANi/MoS<sub>2</sub> nanocomposites. The strategy employs spherical and cylindrical
micelles, which are formed by the controlled solution self-assembly
of block copolymers, as the soft templates for the construction of
well-defined spherical and cylindrical mesopores in the 2D PANi/MoS<sub>2</sub> nanocomposites, respectively. With potential applications
as supercapacitor electrode materials, the resultant 2D composites
show excellent capacitive performance with a maximum capacitance of
500 F g<sup>â1</sup> at a current density of 0.5 A g<sup>â1</sup>, good rate performance, as well as outstanding stability for chargeâdischarge
cycling. Moreover, the 2D mesoporous nanocomposites offer an opportunity
for the study on the influence of different pore structures on their
capacitive performance, which helps to understand the pore structureâproperty
relationship of 2D porous electrode materials and to achieve their
electrochemical performance control
Effect of Side Chains on the Low-Dimensional Self-Assembly of Polyphenylene-Based âRodâCoilâ Graft Copolymers in Solution
We synthesized a series of ârodâcoilâ
graft
copolymers containing a laterally expanded poly-<i>p</i>-phenylene (PPP) backbone grafted with nonionic polyÂ(ethylene oxide)
(PEO) or ionic polyÂ(acrylic acid) (PAA) side chains (denoted as PPP-<i>g</i>-PEO or PPP-<i>g</i>-PAA). The effect of the
side chains on the self-assembly of the graft copolymers in THFâwater
mixed solvents was investigated. The PPP-<i>g</i>-PEO copolymers
exhibited temperature-dependent self-assembly behavior, which is affected
by the grafting percentage (GP) and the degree of polymerization (DP)
of PEO. At 25 °C, which is higher than the crystallization temperature
(<i>T</i><sub>c</sub>) of the PEO chains, PPP-<i>g</i>-PEO self-assembled into ultralong helices with controlled pitches
when <i>P</i>N > 6<i>l</i><sub>m</sub>/4<i>b</i>, where <i>P</i> represents GP, <i>N</i> denotes DP of PEO, <i>l</i><sub>m</sub> expresses the
length of a repeating unit in PPP, and <i>b</i> is Kuhn
monomer length of a free jointed PEO chain; when <i>P</i>N < 6<i>l</i><sub>m</sub>/4<i>b</i>, only nonhelical nanowires
were observed. At 10 °C,
which is below <i>T</i><sub>c</sub> of PEO, PPP-<i>g</i>-PEO self-assembled into polygonal multilayer nanosheets
when <i>P</i>N â„ 85.8<i>l</i><sub>m</sub>/4<i>b</i>, while ultralong helices
or nanowires were formed when <i>P</i>N < 85.8<i>l</i><sub>m</sub>/4<i>b</i>. The PPP-<i>g</i>-PAA copolymer showed pH-sensitive
self-assembly behavior. An increase in the electrostatic repulsion
among the PAA coils in response to the pH change of the aggregate
solution from 3 to 7 resulted in the formation of multiple low-dimensional
nanostructures, including multilayer nanosheets, nanostrips, and helical
nanostrips
Multi-Dimensional Self-Assembly of a Dual-Responsive ABC Miktoarm Star Terpolymer
This letter reports the first 2D
self-assembly of ABC miktoarm
star terpolymers based on dual-responsive polycaprolactone-<i>arm</i>-polyÂ(<i>N</i>-isopropylacrylamide)-<i>arm</i>-polyÂ(2-dimethylaminoethyl methacrylate) (ÎŒ-CID),
which self-assembled into multilayer nanosheets comprising polycaprolactone
single crystals in tetrahydrofuran (THF)/methanol mixed solvents.
Interestingly, the nanosheets showed pH-responsive morphological transitions
in aqueous solutions, yielding multidimensional assemblies, including
2D hexagonal aggregates, patchy nanofibrils, and patchy vesicles,
at different pH values. The nanosheets also exhibited thermoresponsive
transition to spherical patchy micelles at a temperature above the
lower critical solution temperature (LCST) of the polyÂ(<i>N</i>-isopropylacrylamide) block. This study offers a novel system for
fundamental study on the self-assembly of miktoarm star terpolymers
Electronic Structure of Isolated Graphene Nanoribbons in Solution Revealed by Two-Dimensional Electronic Spectroscopy
Structurally well-defined
graphene nanoribbons (GNRs) are nanostructures
with unique optoelectronic properties. In the liquid phase, strong
aggregation typically hampers the assessment of their intrinsic properties.
Recently we reported a novel type of GNRs, decorated with aliphatic
side chains, yielding dispersions consisting mostly of isolated GNRs.
Here we employ two-dimensional electronic spectroscopy to unravel
the optical properties of isolated GNRs and disentangle the transitions
underlying their broad and rather featureless absorption band. We
observe that vibronic coupling, typically neglected in modeling, plays
a dominant role in the optical properties of GNRs. Moreover, a strong
environmental effect is revealed by a large inhomogeneous broadening
of the electronic transitions. Finally, we also show that the photoexcited
bright state decays, on the 150 fs time scale, to a dark state which
is in thermal equilibrium with the bright state, that remains responsible
for the emission on nanosecond time scales