Electroactive polymers (EAPs) can behave as actuators, changing their shape in response to electrical stimulation. EAPs that are controlled by external electric fields--referred to here as field-type EAPs--include ferroelectric polymers, electrostrictive polymers, dielectric elastomers and liquid crystal polymers. Field-type EAPs can exhibit fast response speeds, low hysteresis and strain levels far above those of traditional piezoelectric materials, with elastic energy densities even higher than those of piezoceramics. However, these polymers also require a high field (>70 V micro m(-1)) to generate such high elastic energy densities (>0.1 J cm(-3); refs 4, 5, 9, 10). Here we report a new class of all-organic field-type EAP composites, which can exhibit high elastic energy densities induced by an electric field of only 13 V micro m(-1). The composites are fabricated from an organic filler material possessing very high dielectric constant dispersed in an electrostrictive polymer matrix. The composites can exhibit high net dielectric constants while retaining the flexibility of the matrix. These all-organic actuators could find applications as artificial muscles, 'smart skins' for drag reduction, and in microfluidic systems for drug delivery.

[structure: see text] 3,5,7-Tris(arylmethyl)-1-aza-adamantanetrione donor-sigma-acceptor compounds have been synthesized in four steps. Computational and (1)H NMR analyses rationalize the solubility, gelation, and conformational properties of the C3-symmetric molecules toward employing sigma-coupled donor-acceptor interactions in molecular self-assembly.

The atomic structure of recently synthesized thiolate-protected Au 76 cluster is theoretically predicted via a simple structural rule summarized from the crystal structures of thiolateprotected Au 44 (SR) 28 , Au 36 (SR) 24 , and Au 52 (SR) 32 clusters. We find that Au 76 (SR) 44 (N = 7) and recently reported Au 52 (SR) 32 (N = 4), Au 44 (SR) 28 (N = 3), Au 36 (SR) 24 (N = 2), and Au 28 (SR) 20 (N = 1) belong to a family of homologous Au 20+8N (SR) 16+4N clusters whose Au cores follow a one-dimensional polytetrahedral growth pathway. The Au 76 (SR) 44 cluster is predicted to contain an anisotropic facecentered-cubic (fcc) Au core, which can be viewed as combination of two helical tetrahedra Au 4 chains and is remarkably different from the well-known spherical Au core in ligand-protected gold clusters in the size region of 1−2 nm. The intense near-infrared (NIR) absorption of Au 76 (SR) 44 is attributed to the synergistic effect of anisotropic Au core structure and ligand protections. A plausible cluster-to-cluster transformation mechanism is further suggested.

[reaction: see text] Directional intramolecular interactions play a critical role in the self-assembly of donor-sigma-acceptor molecules in solution. Amide functions on the periphery of the tricyclic core stabilize a C3-symmetric monomer conformation by intramolecular hydrogen bonding and dipole-dipole interactions. The molecules are effective organogelators and show long-range ordering in the bulk.

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Oligomeric amyloid-beta (Aβ) peptides are considered as the most toxic species in Alzheimer's disease (AD). Monitoring of the Aβ aggregation profiles is critical for elucidating the oligomer toxicity and may serve as a therapeutic target for AD. By immobilizing the capture antibodies of A11 and OC that are specific to the oligomers and fibrils, respectively, in separate fluidic channels, a novel surface plasmon resonance (SPR) biosensor was designed for monitoring the oligomeric and fibrillar species of Aβ(1-42) simultaneously. The influence of curcumin, Cu(2+) and methylene blue on the amount of toxic oligomers and fibrils was evaluated. The half maximal inhibitory concentration (IC50) of curcumin and methylene blue was determined. The formation of Aβ fibrils was also validated by the thioflavin T (ThT) fluorescence assay. The results demonstrate the utility of SPR as an analytical tool for rapid and comprehensive monitoring of Aβ aggregation and screening of Aβ modulators.

Polymer composites with high dielectric constant (high-k) have a broad application in the energy storage field. However, the balance between high dielectric constant, low dielectric loss, and low filler content is hardly achieved. In this work, single-layered MXene nanosheets with a thickness of ∼1 nm and a lateral size of ∼560 nm were prepared by in situ hydrofluoric acid (HF) method, and MXene/poly­(vinylidene fluoride-co-hexafluoropropylene) composites were prepared by a simple solution casting method. The morphologies, crystalline behaviors, and dielectric properties of the composites were fully investigated. At 1 kHz, composites have a high dielectric constant of 539 and a low dielectric loss of 0.06 when the content of MXene is 4.0 wt%. High dielectric constant is strongly related to the enhancement of interfacial polarization and the formation of microcapacitor structure. Possible microscopic mechanisms about the role of MXene in improving the dielectric constant of composites were elucidated by means of Ag nanoparticles. Moreover, finite element modeling conducted by COMSOL Multiphysics shows that low dielectric loss is attributed to the parallel arrays of nanosheets that can inhibit the conduction of leakage current. This work brings a good inspiration for the structure design of dielectric materials.

Flexible Ag@C-NC/PVDF nanocomposite materials with low percolation threshold and dielectric constant of 295 at 1 kHz.