Exceptionally Strong Effect of Small Structural Variations in Functionalized 3,4-Phenylenedioxythiophenes on the Surface Nanostructure and Parahydrophobic Properties of Their Electropolymerized Films

Electropolymerization of electron-rich aromatics/heteroaromatics to form conducting polymers is an easy and powerful technique to form surfaces of different nanostructures and hydrophobicity/wettability. Understanding the factors governing the growth of the polymer nanostructures and controlling the surface morphology are the big challenges for the surface and materials science. In this paper, we report the design and synthesis of a series of 3,4-phenylenedioxythiophenes (PheDOTs) substituted at the benzene ring with 2-naphthylmethyl-, 1-naphthylmethyl-, and 9-anthracenylmethyl-groups (2Na-PheDOT, 1Na-PheDOT, and 9Ant-PheDOT). They have been electropolymerized in either potentiostatic or potentiodynamic conditions to form the polymer surfaces of different morphologies. Even small changes in the structure of PheDOT monomers by varying the side groups (2-/1-naphthyl-or 9-anthracenyl-) result in the formation of very different polymer surface nanostructures: From monodirectionally growing (one-dimensional) vertically aligned nanotubes for 2Na-PheDOT to ribbonlike nanostructures (two-dimensional) for 1Na-PheDOT, and a mixture of these two structures for 9Ant-PheDOT. Moreover, the surfaces of the p[2Na-PheDOT] polymer, electrodeposited from the monomer 2Na-PheDOT and the dimer (2Na-PheDOT)2 (which have different solubilities and the reactivities on electropolymerization, but formally lead to the polymer of the same chemical structure), show very different nanostructures. In contrast to 2Na-PheDOT, which forms vertically aligned nanotubes of the polymer on the surface, the polymerization of (2Na-PheDOT)2 leads to spherical particles [three-dimensional (3D)] when Bu4NClO4 is used as an electrolyte and a membrane structure with spherical holes (3D) in the case of more hydrophobic Bu4NPF6. The importance of water for gas bubble formation (O2 and H2) during electropolymerization and creation of the surface nanostructures has been demonstrated and discussed. The formation of these different nanostructures is accompanied by different wettability of the surface, from hydrophilic (with an apparent water droplet contact angle of θw ∼40-70°) to highly hydrophobic (θw up to 129-134°). The sticky, parahydrophobic surface formed from 1Na-PheDOT showed high adhesion to water, with no water droplets moving after inclination of the surface to 90° (rose-petal effect). Copyright © 2019 American Chemical Society.Government Council on Grants, Russian FederationThe authors thank the Center Commun de Microscopie Appliquée (CCMA, Univ. Nice Sophia Antipolis) for the realization of the SEM images. E.L.K. thanks the Russia President Ph.D. Scholarship for studying abroad to visit Bangor University and also thanks Act 211 Government of the Russian Federation for financial support (contract No. 02.A03.21.0006). I.S. thanks the Erasmus+ student mobility program for supporting her internship at Bangor University. I.F.P. thanks SIFE-NPU for generous startup funding

Synthesis and Properties New Derivatives of 3,4-Phenylenedioxythiophene

This work was supported by the Russian President PhD Scholarship for studying abroad and by an Act 211 Government of the Russian Federation for financial support (contract No 02.A03.21.0006)

Trimethylsilyl hedgehogs - A novel class of super-efficient hydrocarbon surfactants

Presented here are the results for a novel class of hydrocarbon surfactants, termed trimethylsilyl hedgehogs (TMS-hedgehogs), due to the presence of silicon in the tails.</p

Ternary erbium chromium sulfides : structural relationships and magnetic properties

Single crystals of four erbium-chromium sulfides have been grown by chemical vapor transport using iodine as the transporting agent. Single-crystal X-ray diffraction reveals that in Er(3)CrS(6) octahedral sites are occupied exclusively by Cr(3+) cations, leading to one-dimensional CrS(4)(5-) chains of edge-sharing octahedra, while in Er(2)CrS(4), Er(3+), and Cr(2+) cations occupy the available octahedral sites in an ordered manner. By contrast, in Er(6)Cr(2)S(11) and Er(4)CrS(7), Er(3+) and Cr(2+) ions are disordered over the octahedral sites. In Er(2)CrS(4), Er(6)Cr(2)S(11), and Er(4)CrS(7), the network of octahedra generates an anionic framework constructed from M(2)S(5) slabs of varying thickness, linked by one-dimensional octahedral chains. This suggests that these three phases belong to a series in which the anionic framework may be described by the general formula [M(2n+1)S(4n+3)](x-), with charge balancing provided by Er(3+) cations located in sites of high-coordination number within one-dimensional channels defined by the framework. Er(4)CrS(7), Er(6)Cr(2)S(11), and Er(2)CrS(4) may thus be considered as the n = 1, 2, and infinity members of this series. While Er(4)CrS(7) is paramagnetic, successive magnetic transitions associated with ordering of the chromium and erbium sub-lattices are observed on cooling Er(3)CrS(6) (T(C)(Cr) = 30 K; T(C)(Er) = 11 K) and Er(2)CrS(4) (T(N)(Cr) = 42 K, T(N)(Er) = 10 K) whereas Er(6)Cr(2)S(11) exhibits ordering of the chromium sub-lattice only (T(N) = 11.4 K)

Drosophila Eggshell Production: Identification of New Genes and Coordination by Pxt

Drosophila ovarian follicles complete development using a spatially and temporally controlled maturation process in which they resume meiosis and secrete a multi-layered, protective eggshell before undergoing arrest and/or ovulation. Microarray analysis revealed more than 150 genes that are expressed in a stage-specific manner during the last 24 hours of follicle development. These include all 30 previously known eggshell genes, as well as 19 new candidate chorion genes and 100 other genes likely to participate in maturation. Mutations in pxt, encoding a putative Drosophila cyclooxygenase, cause many transcripts to begin expression prematurely, and are associated with eggshell defects. Somatic activity of Pxt is required, as RNAi knockdown of pxt in the follicle cells recapitulates both the temporal expression and eggshell defects. One of the temporally regulated genes, cyp18a1, which encodes a cytochromome P450 protein mediating ecdysone turnover, is downregulated in pxt mutant follicles, and cyp18a1 mutation itself alters eggshell gene expression. These studies further define the molecular program of Drosophila follicle maturation and support the idea that it is coordinated by lipid and steroid hormonal signals

Low-surface energy surfactants with branched hydrocarbon architectures

International audienceSurface tensiometry and small-angle neutron scattering have been used to characterize a new class of low-surface energy surfactants (LSESs), "hedgehog" surfactants. These surfactants are based on highly branched hydrocarbon (HC) chains as replacements for environmentally hazardous fluorocarbon surfactants and polymers. Tensiometric analyses indicate that a subtle structural modification in the tails and headgroup results in significant effects on limiting surface tensions γcmc at the critical micelle concentration: a higher level of branching and an increased counterion size promote an effective reduction of surface tension to low values for HC surfactants (γcmc 24 mN m-1). These LSESs present a new class of potentially very important materials, which form lamellar aggregates in aqueous solutions independent of dilution