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 PMMA₂₂₅₀-<i>b</i>-P4VP₂₈₆ 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 MoS₂ 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 MoS₂ nanosheets in solution, which produces 2D mesoporous PANi/MoS₂ 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/MoS₂ 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^–1 at a current density of 0.5 A g^–1, good rate performance, as well as outstanding stability for charge–discharge 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 structure–property 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 “Rod–Coil” Graft Copolymers in Solution

We synthesized a series of “rod–coil” graft copolymers containing a laterally expanded poly-<i>p</i>-phenylene (PPP) backbone grafted with nonionic poly­(ethylene oxide) (PEO) or ionic poly­(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 THF–water 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>_c) 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>_m/4<i>b</i>, where <i>P</i> represents GP, <i>N</i> denotes DP of PEO, <i>l</i>_m 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>_m/4<i>b</i>, only nonhelical nanowires were observed. At 10 °C, which is below <i>T</i>_c of PEO, PPP-<i>g</i>-PEO self-assembled into polygonal multilayer nanosheets when <i>P</i>N ≥ 85.8<i>l</i>_m/4<i>b</i>, while ultralong helices or nanowires were formed when <i>P</i>N < 85.8<i>l</i>_m/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>-poly­(<i>N</i>-isopropylacrylamide)-<i>arm</i>-poly­(2-dimethylaminoethyl methacrylate) (μ-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 poly­(<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