Effects of preparation routes on the physical and rheological properties of isosorbide-based thermoplastic polyurethanes.

Unlabelled: Biomass-derived isosorbide (ISB) is a promising alternative to petroleum-based monomers in industrial plastics. In this study, ISB-based thermoplastic polyurethanes (ISB-TPUs) were prepared using ISB as a biomass chain extender, and the effects of the preparation route on the structural and physical properties of the resultant polymers were investigated. Prepolymer methods were more suitable for obtaining the desired molecular weights (MWs) and physical properties of ISB-TPUs than the one-shot method.

Selective ion transport through three-dimensionally interconnected nanopores of quaternized block copolymer membranes for energy harvesting application.

A concentration gradient in an aqueous solution is a promising source of energy that can be converted into electrical energy by an ion-exchange polymer membrane. In concentration-gradient energy harvesters, ion transport through nanoporous channels is an emerging approach to enhance the energy conversion efficiency. Since massive but selective ion transport could be realized through nanochannels, the theoretical calculations predicted that nanoporous membranes can extract significantly larger energy than the conventional non-structured membranes.

Core-satellite assemblies of Au@polydopamine@Ag nanoparticles for photothermal-mediated catalytic reaction.

Engineering plasmonic nanoparticles (NPs) into superstructures comprising two or more distinctive materials is highly desirable because these assemblies can unfold new properties that differ from those exhibited by their individual counterparts. In addition, metal NPs such as Au NPs and Ag NPs have played a major role in environmental remediation. In this study, we designed a heterogeneous NP assembly composed of an Au core and Ag satellite by utilizing a mussel-inspired polydopamine (PDA) strategy.

Dielectric control of porous polydimethylsiloxane elastomers with Au nanoparticles for enhancing the output performance of triboelectric nanogenerators.

Taking advantage of the triboelectrification effect and electrostatic induction, triboelectric nanogenerators (TENGs) provide a simple and efficient path to convert environmental mechanical energy into electric energy. Since the generation of surface charges and their density on triboelectric materials are the key factors in determining TENG performance, many efforts have been undertaken to engineer the structures and chemistry of triboelectric materials. Among others, dielectric control of triboelectric materials is an emerging approach because the dielectric constant is intimately correlated with the capacitance of materials.

Metal-enhanced fluorescence in polymer composite films with Au@Ag@SiO nanoparticles and InP@ZnS quantum dots.

For white light-emitting diode (LED) applications, semiconductor quantum dots (QDs) have been widely utilized as efficient down-converters to change the blue color of the light source into different emission colors. Because QDs offer spectral tunability over the entire visible light range, as well as improved color purity, they have rapidly replaced conventional phosphor-based white LEDs. However, for the sustainable growth of QD-mediated LEDs, the amount of QDs required must be reduced by enhancing the color-conversion efficiency.

Tuning of volume phase transition for poly(N-isopropylacrylamide) ionogels by copolymerization with solvatophilic monomers.

Ionogels are crosslinked polymer networks that swell in ionic liquids (ILs) and exhibit high conductivity and chemical stability. Combined with a representative thermally responsive polymer, poly(N-isopropylacrylamide) (PNIPAm), previously studied ionogels fulfilled the requirements for smart responsive materials, but their transition temperature in hydrophobic ILs exceeded that which could be used for practical applications. In this study, we prepared transition temperature tunable ionogels via copolymerization of NIPAm with solvatophilic N,N'-diethylacrylamide (NDEAm).

Triazine-based Polyelectrolyte as an Efficient Cathode Interfacial Material for Polymer Solar Cells.

A novel polyelectrolyte containing triazine (TAZ) and benzodithiophene (BDT) scaffolds with polar phosphine oxide (P═O) and quaternary ammonium ions as pendant groups, respectively, in the polymer backbone (PBTAZPOBr) was synthesized to use it as a cathode interfacial layer (CIL) for polymer solar cell (PSC) application. Owing to the high electron affinity of the TAZ unit and P═O group, PBTAZPOBr could behave as an effective electron transport material. Due to the polar quaternary ammonium and P═O groups, the interfacial dipole moment created by PBTAZPOBr substantially reduced the work function of the metal cathode to afford better energy alignment in the device, thus enabling electron extraction and reducing recombination of excitons at the photoactive layer/cathode interface.

Short-range ordered photonic structures of lamellae-forming diblock copolymers for excitation-regulated fluorescence enhancement.

Photonic crystals can be represented by periodic nanostructures with alternating refractive indices, which create artificial stop bands with the appearance of colors. In this regard, nanodomains of block copolymers and the corresponding structural colors have been intensively studied in the past. However, the practical application of photonic crystals of block copolymers has been limited to a large degree because of the presence of large defects and grain boundaries in the nanodomains of block copolymers.

Directed Self-Assembly of Block Copolymer Micelles onto Topographically Patterned Surface.

We report a facile method to control directed self-assembly (DSA) of spherical micelles of block copolymers (BCPs) by topographically patterned surface. A cylinder-forming polystyrene-block-poly(2-vinylpyridine) copolymer [Mn,PS = 175 kg/mol, Mn,P2VP = 70 kg/mol, and polydipersity index (PDI) = 1.08] was phase-separated on a thin film of poly(vinyl alcohol) (PVA) by solvent annealing.

Core-Corona Functionalization of Diblock Copolymer Micelles by Heterogeneous Metal Nanoparticles for Dual Modality in Chemical Reactions.

Nanoscale assemblies composed of different types of nanoparticles (NPs) can reveal interesting aspects about material properties beyond the functions of individual constituent NPs. This research direction may also represent current challenges in nanoscience toward practical applications. With respect to the assembling method, synthetic or biological nanostructures can be utilized to organize heterogeneous NPs in specific sites via chemical or physical interactions.

pH-Responsive assembly of metal nanoparticles and fluorescent dyes by diblock copolymer micelles.

Hybrid assemblies consisting of metal nanoparticles (NPs) and fluorophores are quite interesting because the intrinsic properties of fluorophores can be engineered in the assembled structure. In this regard, we utilized the self-segregation properties of block copolymer micelles to organize metal NPs and fluorophores simultaneously in a specific arrangement. From the viewpoint of assembly methods, we first encapsulated Au NPs in the PS cores of polystyrene-block-poly(acrylic acid) (PS-PAA) micelles.

Photothermally triggered fast responding hydrogels incorporating a hydrophobic moiety for light-controlled microvalves.

Iron oxide nanoparticles dispersed within a thermally responsive poly(N-isopropylacrylamide) (PNIPAm) hydrogel matrix effectively convert the photo energy of visible light of modest intensity into thermal energy, providing the efficient means to trigger changes in volumetric swelling of hydrogels. However, long irradiation time (on the order of minutes) and modest volume change limit their applications that need fast response and/or large volume change. In this work, we found that the degree of volume change triggered by light could be maximized by adjusting the lower critical solution temperature (LCST) of the hydrogels.

Switching off FRET in the hybrid assemblies of diblock copolymer micelles, quantum dots, and dyes by plasmonic nanoparticles.

Recently, it has been noticed that surface plasmon resonance of metal nanoparticles can alter the intrinsic properties of nearby fluorophores. Field enhancement and radiative decay engineering are major principles for understanding a number of experimental observations such as enhanced and quenched emission of fluorophores in the vicinity of metal nanoparticles. At the same time, there are apparent similarities between surface-plasmon-coupled fluorescence and fluorescence resonance energy transfer (FRET), as both are near-field through-space interactions.

Ordered complex nanostructures from bimodal self-assemblies of diblock copolymer micelles with solvent annealing.

We report the formation of ordered complex nanostructures from single-layered films of mixtures of polystyrene-poly(2-vinylpyridine) (PS-P2VP) and polystyrene-poly(4-vinylpyridine) (PS-P4VP) diblock copolymer micelles by THF (tetrahydrofuran) annealing. We first examined the influence of THF vapor on PS-P2VP and PS-P4VP micelles in their single-layered films. Due to the different solubility of PS-P2VP and PS-P4VP copolymers in THF, a hexagonal array of PS-P2VP micelles was changed into cylindrical nanodomains, but that of PS-P4VP micelles was not changed.

Highly ordered hexagonal arrays of hybridized micelles from bimodal self-assemblies of diblock copolymer micelles.

We demonstrate the formation of highly ordered hexagonal arrays of hybridized polystyrene-poly(4-vinyl pyridine), PS-PVP, micelles with controllable size by solvent annealing techniques. Because the formation of hybridized micelles was prohibited in the mixture solutions of two different-sized PS-PVP micelles, single-layered films with bimodal self-assemblies of small and large micelles were fabricated from the mixture solutions by adjusting their mixing ratios. When the single-layered films were solvent annealed by saturated vapor of tetrahydrofuran (THF), on the other hand, small and large PS-PVP micelles in the bimodal self-assemblies merged together to form hybridized micelles.

Inhibition of amyloid peptide fibrillation by inorganic nanoparticles: functional similarities with proteins.

Aggregation of amyloid-β peptides (Aβ) into fibrils is the key pathological feature of many neurodegenerative disorders. Typical drugs inhibit Aβ fibrillation by binding to monomers in 1:1 ratio and display low efficacy. Here, we report that model CdTe nanoparticles (NPs) can efficiently prevent fibrillation of Aβ associating with 100–330 monomers at once.

Controlled light emission in spin-assisted layer-by-layer assemblies with fluorophores.

We report controlled light emissions from spin-assisted layer-by-layer (LbL) thin films containing a donor-acceptor pair of fluorescent dyes. Based on their spectral overlap, we selected rhodamine 123 (R123) and rhodamine B (RB) as the donor and acceptor, respectively. For the construction of multilayered thin films, a complex of each dye and poly(sodium 4-sulfonate) (PSS-R123 and PSS-RB) was prepared and then alternately spin coated with poly(allyamine hydrochloride) (PAH).

Controlled fluorescence resonance energy transfer between ZnO nanoparticles and fluorophores in layer-by-layer assemblies.

We controlled the fluorescence resonance energy transfer (FRET) between ZnO nanoparticles and rhodamine B (RB) within multilayered thin films prepared by the layer-by-layer (LbL) assembling method. Positively charged ZnO nanoparticles and RB-labeled poly(allyamine hydrochloride) (RB-PAH) were accurately incorporated into LbL assemblies of polyelectrolytes. The distance between ZnO nanoparticles and RB-PAH was adjusted by varying the number of layers of pure polyelectrolytes, leading to the controlled FRET from ZnO nanoparticles to RB-PAH.

Self-assembled arrays of zinc oxide nanoparticles from monolayer films of diblock copolymer micelles.

A hexagonal array of optically active ZnO nanoparticles was synthesized in situ on the solid substrate by utilizing a single-layered film of diblock copolymer micelles as a nanostructured template.

Localized synthesis of polypyrrole in the nanopattern of monolayer films of diblock copolymer micelles.

A single-layered array of polystyrene-block-poly(4-vinylpyridine), PS-PVP, micelles in hexagonal order, fabricated by spin coating, was employed as a nanostructured template for synthesis of polypyrrole, a conducting polymer, in nanometer-sized domains. Oxidative catalysts of FeCl3 for the polymerization were selectively loaded in spherical PVP nanodamains so that they were hexagonally arranged over the film but confined in the nanometer range. The vapor-phase polymerization of pyrrole was localized in the PVP nanodomains, leading to a morphological transition from spherical to wormlike domains.

Directed self-assembly of two kinds of nanoparticles utilizing monolayer films of diblock copolymer micelles.

We demonstrated a self-assembly of two different kinds of nanoparticles simultaneously directed on a monolayer film of diblock copolymer micelles via physical and chemical arrangements. We first incorporated gold nanoparticles physically around the micelles of a monolayer film of PS-PVP micelles having a short-range hexagonal order. Iron oxide nanoparticles were then synthesized chemically in the PVP core area of the ordered micelles, resulting in a mosaic nanopattern of magnetic iron oxide nanoparticles surrounded by metallic gold nanoparticles.