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NIR Light- and pH-Responsive Graphene Oxide Hybrid Cyclodextrin-Based Supramolecular Hydrogels
摘要： Here a novel triple-responsive graphene oxide hybrid supramolecular hydrogel based on the electrostatic self-assembly between graphene oxide and a quaternized polymer and the host-guest inclusion between α-cyclodextrins and polyethylene glycol monomethylether (mPEG) was constructed. The quaternized polymer was synthesized by quaternization between pH sensitive poly(N,N-dimethylaminoethyl methacrylate) and bromine end-capped polyethylene glycol monomethylether. The supramolecular hydrogels prepared from the host-guest inclusion of polyethylene glycol monomethylether and α-cyclodextrins would turn into a mobile sol phase when the temperature increased above a certain temperature (Tgel-sol). Graphene oxide sheets not only acted as a core material to provide additional cross-linking, but also absorbed NIR light and converted NIR light into heat to trigger the gel-sol transition. The constructed graphene oxide hybrid cyclodextrin-based supramolecular hydrogels could respond to NIR light, temperature and pH, which could be beneficial for controlled release of cargoes and would hold great promise in the field of delivery systems.
关键词： graphene oxide,self-assembly,cyclodextrin,hydrogel,controlled release
更新于2025-09-23 15:23:52
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Adaptive Shape Ripening and Interparticle Bridging of L-Arginine-Stabilized Silica Nanoparticles During Evaporative Colloidal Crystal Assembly
摘要： During evaporative self-assembly of colloidal crystal films, spherical L-arginine-stabilized silica colloids adapt to different close-packed geometries by faceting and forming bridge connections with their nearest neighbors. We systematically studied the morphological changes of 37 and 138 nm diameter colloids during evaporative assembly and compared them to 65 nm St?ber silica colloids prepared without L-arginine. Colloidal crystal films were grown from particles that had been dialyzed against water or L-arginine, and tetraethylorthosilicate (TEOS) and/or L-arginine were added to solutions during colloidal film growth. Solid-state 29Si NMR spectra showed the presence of L-arginine and incompletely condensed silica in colloids grown from silica seeds in L-arginine solutions. These colloids were especially susceptible to chemical ripening during the colloidal assembly process, adopting faceted shapes that reflected the packing symmetry of the colloidal crystal films. The addition of L-arginine and TEOS accelerated these shape changes by catalyzing the hydrolysis and olation of silica, and by adding a source of silica to the solution, respectively. This chemistry provides a route to single-component and binary colloidal crystals composed of non-spherical silica building blocks.
关键词： evaporative self-assembly,colloids,silica nanoparticles,colloidal crystal,L-arginine
更新于2025-09-23 15:23:52
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Bio-Inspired Structural Colors based on Linear Ultra-High Molecular Weight Block Copolymers
摘要： Ultra-high molecular weight (UHMW) block copolymers (BCPs) are promising candidates for the fabrication of photonic materials. Here, we demonstrate the synthesis and self-assembly capability of well-defined amphiphilic UHMW BCPs with overall molar masses up to 4432 kg mol-1 obtained via living anionic polymerization. BCP micelles featuring hydrodynamic diameters in the range of the wavelength of the visible light to the near infrared region (300-1143 nm) are used for colloidal crystal formation. By varying the BCP composition brilliant structural colours can be observed. Microphase separation of the UHMW BCPs in the bulk state reveals uniform domains and showing blue to green structural color transitions. Finally, we provide examples of how BCP structural control can be used to generate reversibly switchable solvatochromatic optical sensors.
关键词： morphology,block copolymers,structural colors,self-assembly,anionic polymerization,micellar photonic crystals,photonic materials
更新于2025-09-23 15:23:52
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Fabrication of Uniaxially Aligned Silica Nanogrooves with Sub-5 nm Periodicity on Centimeter-Scale Si Substrate Using Poly(dimethylsiloxane) Stamp
摘要： The large-area fabrication of aligned nanopatterns with sub-5 nm feature size is crucial for developing nanodevices. Highly ordered nanostructures fabricated through molecular self-assembly exhibit substantial potential for sub-5 nm patterning techniques. Previously, we had reported the fabrication of silica nanogrooves with sub-5 nm periodicity on a Si substrate by using the outermost surfaces of cylindrical surfactant micelles as a template. However, uniaxial alignment of nanogrooves on the entire substrate surface has not yet been achieved. In this study, uniaxially aligned silica nanogrooves were prepared on the entire surface of a Si substrate (2 × 2 cm) by utilizing a poly(dimethylsiloxane) (PDMS) stamp with a striped pattern. The PDMS stamp was placed on the surface of a surfactant thin film precoated on the substrate, although the stamp was not in direct contact with the substrate as in the case of the soft nanoimprint technique. The substrate was then exposed to water vapor, during which cylindrical micelles were aligned in the direction of the guide. Subsequently, by exposing the substrate to an NH3–water vapor mixture, the outermost surfaces of the aligned micelles facing the substrate were replicated with soluble silicate species. The formation of uniaxially aligned nanogrooves on the entire surface of the centimeter-scale substrate was verified by scanning electron microscopy observations and grazing-incidence small-angle X-ray scattering analysis. Thus, herein we provide a simple large-area fabrication method for uniaxially aligned nanopattern with ultra-fine pitch.
关键词： nanoimprint,nanopatterning,alignment control,directed self-assembly,liquid crystals
更新于2025-09-23 15:23:52
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Hierarchical Photonic Pigments <i>via</i> the Confined Self-Assembly of Bottlebrush Block Copolymers
摘要： Hierarchical, structurally colored materials offer a wide variety of visual effects that cannot be achieved with standard pigments or dyes. However, their fabrication requires simultaneous control over multiple length-scales. Here we introduce a robust strategy for the fabrication of hierarchical photonic pigments via the confined self-assembly of bottlebrush block copolymers within emulsified microdroplets. The bottlebrush block copolymer self-assembles into highly ordered concentric lamellae, giving rise to a near perfect photonic multi-layer in the solid-state, with reflectivity up to 100%. The reflected color can be readily tuned across the whole visible spectrum by either altering the molecular weight or by blending the bottlebrush block copolymers. Furthermore, the developed photonic pigments are responsive, with a selective and reversible color change observed upon swelling in different solvents. Our system is particularly suited for the scalable production of photonic pigments, arising from their rapid self-assembly mechanism and size-independent color.
关键词： photonic crystals,confined self-assembly,microspheres,structural colors,bottlebrush block copolymers
更新于2025-09-23 15:23:52
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Dispersion relations of elastic waves in three-dimensional cubical piezoelectric phononic crystal with initial stresses and mechanically and dielectrically imperfect interfaces
摘要： The shape of individual building blocks is an important parameter in bottom-up self-assembly of nano-structured materials. A simple shape change from sphere to spheroid can significantly affect the assembly process due to the modification to the orientational degrees of freedom. When a layer of spheres is placed upon a layer of spheroids, the strain at the interface can be minimized by the spheroid taking a special orientation. C70 fullerenes represent the smallest spheroids, and their interaction with a sphere-like C60 is investigated. We find that the orientation of the C70 within a close-packed C70 layer can be steered by contacting a layer of C60. This orientational steering phenomenon is potentially useful for epitaxial growth of multilayer van der Waals molecular heterostructures.
关键词： interface,self-assembly,epitaxy,scanning tunnelling microscopy,graphene,van der Waals heterostructures,fullerene
更新于2025-09-23 15:23:52
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Mechanism of field-induced manipulation of Cu-phthalocyanines on a Bi surface using scanning tunneling microscope
摘要： We have revisited our hypothesis [K. Nagaoka et al., Jpn. J. Appl. Phys. 57 (2018) 020301] regarding the control of the motion and assembly of copper phthalocyanine (CuPc) molecules on a Bi(001) surface using a scanning tunneling microscope (STM) tip. The proposal that the observed diffusion and condensation are not due to the adsorption/desorption of molecules via the tip by applying a bias voltage was investigated for field-induced manipulation. Our experiments show that CuPc cannot move across steps or condense on different terraces on the Bi(001) surface. When confined to a nano-scale region, the CuPc molecules assemble into ordered single-layer islands. The island position can be manipulated using the STM tip, with an almost constant number of condensed molecules remaining inside the terrace. These results allowed us to rule out the possibility of picking-up and depositing molecules by the STM tip.
关键词： STM,phthalocyanine,self-assembly,field-induced manipulation,bismuth,surface science
更新于2025-09-23 15:23:52
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Layer-by-layer self-assembly of polyaniline nanofibers/TiO2 nanotubes heterojunction thin film for ammonia detection at room temperature
摘要： In this paper, for the first time, polyaniline nanofibers/TiO2 nanotubes (PANI/TiO2) heterojunction thin film has been prepared on Pt interdigital electrodes by layer-by-layer self-assembly method and applied in room temperature NH3 detection. It is found that the optimal self-assembly layer number is three (PANI/TiO2-3) compared to one layer (PANI/TiO2-1) and five layers (PANI/TiO2-5). The PANI/TiO2-3 thin film sensor possesses superior response characteristics compared with our other PANI based sensors, including higher response value (336%@5 ppm NH3), acceptable response/recovery time (110 s/1086 s@5 ppm NH3), low detection limit (0.5 ppm), and remarkable selectivity. The enhanced gas sensing performances could be ascribed to the tremendous variation of the carrier concentration caused by the p-n junctions as well as the increased specific surface area and pore volume. This work not only offers a superb strategy to fabricate heterojunction thin film but also accelerates the development of room-temperature operable NH3 sensors.
关键词： Ammonia detection,Layer-by-layer self-assembly,Polyaniline/TiO2 heterojunction,Thin film,Room temperature operation
更新于2025-09-23 15:23:52
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Ordered Array of Metal Particles on Semishell Separated with Ultrathin Oxide: Fabrication and SERS Properties
摘要： Metal particles in gap cavities provide an interesting system to achieve hybrid local surface plasmon modes for local field enhancement. Here, we demonstrate a relatively simple method to fabricate Ag nanoparticles positioned on Ag semishells separated by a thin (~5 nm) dielectric layer. The obtained structure can provide strong local electric field enhancement for surface-enhanced Raman scattering (SERS). The fabrication of the ordered array structure was realized by nanosphere self-assembly, atomic layer deposition, and metal thin-film dewetting. Numerical simulation proved that, compared to the conventional metal semishell arrays, the additional Ag particles introduce extra hot spots particularly in the valley regions between adjacent Ag semishells. As a result, the SERS enhancement factor of the metal semishell-based plasmonic structure could be further improved by an order of magnitude. The developed novel plasmonic structure also shows good potential for application in plasmon-enhanced solar water-splitting devices.
关键词： particle in cavity,nanosphere lithography,surface-enhanced Raman scattering (SERS),surface plasmonic,monolayer self-assembly
更新于2025-09-23 15:22:29
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Chiral Recognition of L- and D- Amino Acid by Porphyrin Supramolecular Aggregates
摘要： We report of the interactions between four amino acids lysine (Lys), arginine (Arg), histidine (His), and phenylalanine (Phe) with the J-aggregates of the protonated 5,10,15,20-tetrakis(4-sulfonatophenyl)-porphyrin H4TPPS. Several aspects of these self-assembled systems have been analyzed: (i) the chiral transfer process; (ii) the hierarchical effects leading to the aggregates formation; and, (iii) the influence of the amino acid concentrations on both transferring and storing chiral information. We have demonstrated that the efficient control on the J-aggregates chirality is obtained when all amino acids are tested and that the chirality transfer process is under hierarchical control. Finally, the chiral porphyrin aggregates obtained exhibit strong chiral inertia.
关键词： porphyrin,self-assembly,amino acid,circular dichroism,supramolecular chirality
更新于2025-09-23 15:22:29