Search results for "assembly"
showing 10 items of 768 documents
Multi-scale structural analysis of xyloglucan colloidal dispersions and hydro-alcoholic gels
2020
Xyloglucans are highly branched, hydroxyl rich polyglucans that for their abundance in nature, biocompatibility, film forming and gelation ability may take a prominent role in the design and fabrication of biomedical devices, including in situ forming scaffolds for tissue engineering, wound dressings and epidermal sensors. The understanding and exploitation of their self-assembly behavior is key for the device performance optimization. A multi-scale analysis, conducted combining small-angle X-ray scattering, both static and dynamic light scattering at large and small angles, and rheological measurements, provides a description of the supramolecular organization of this biopolymer, from the …
Crystallization of silica opals onto patterned silicon wafer
2006
We report on fabrication of high quality opaline photonic crystals from large silica spheres, self-assembled in hydrophilic trenches of silicon wafers by using a drawing apparatus with a combination of stirring. The achievements here reported comprise a spatial selectivity of opal crystallization without special treatment of the wafer surface, a filling of the trenches up to the top, leading to a spatially uniform film thickness, particularly an absence of cracks within the size of the trenches, and finally a good three-dimensional order of the opal lattice even in trenches with a complex confined geometry, verified using optical measurements. The opal lattice was found to match the pattern…
Mesoscopic structural organization in fluorinated room temperature ionic liquids
2018
The presence of fluorous tails in room-temperature ionic liquids imparts new properties to their already rich spectrum of appealing features. The interest towards this class of compounds that are of ionic nature with melting point less than 25 degrees C is accordingly growing; in particular, compounds bearing relatively long fluorous tails have begun to be considered. In this invited presentation, we show recent results arising from the systematic study of structural properties of a series of fluorinated room temperature ionic liquids, with growing fluorous chain length. At odd with the current understanding of this class of compounds, we show experimentally that they are characterized by t…
Simultaneous photonic and excitonic coupling in spherical quantum dot supercrystals
2020
Semiconductor nanocrystals, or quantum dots (QDs), simultaneously benefit from inexpensive low-temperature solution processing and exciting photophysics, making them the ideal candidates for next-generation solar cells and photodetectors. While the working principles of these devices rely on light absorption, QDs intrinsically belong to the Rayleigh regime and display optical behavior limited to electric dipole resonances, resulting in low absorption efficiencies. Increasing the absorption efficiency of QDs, together with their electronic and excitonic coupling to enhance charge carrier mobility, is therefore of critical importance to enable practical applications. Here, we demonstrate a ge…
Faceting and structural anisotropy of nanopatterned CdO(110) layers
2005
CdO(110) layers with a self-organized surface structure have been grown on (10math0) sapphire (m plane) substrates by metal-organic vapor phase epitaxy. The epitaxial relationships between layer and substrate have been determined and a crystallographic model that accounts for the CdO in-plane orientation, which results in a reduced lattice mismatch when the CdO[001] direction is perpendicular to the sapphire c axis, has been proposed. Although the measured lattice parameters indicate that the layers are almost fully relaxed, an anisotropic mosaicity is detected with symmetrical rocking curves attaining minimum values when measured along the CdO[math10] direction. The layer morphology consis…
Combining magnetic field induced locomotion and supramolecular interaction to micromanipulate glass fibers: toward assembly of complex structures at …
2011
The formation of ordered complex structures is one of the most challenging fields in the research of biomimic materials because those structures are promising with respect to improving the physical and mechanical properties of man-made materials. In this letter, we have developed a novel approach to fabricating complex structures on the mesoscale by combining magnetic-field-induced locomotion and supramolecular-interaction-assisted immobilization. We have employed a magnetic field to locomote the glass fiber, which was modified by the layer-by-layer self-assembly of magnetic nanoparticles, to desired positions and have exploited the supramolecular interaction to immobilize glass fiber onto …
Supramolecular assembly of pyrene-tetrathiafulvalene hybrids on graphene: Structure-property relationships and biosensing activity
2021
Two different molecular receptors (1 and 2) incorporating one and three pyrene units to promote the π–π interaction with the basal plane of graphene are reported. In order to modulate the electronic properties of graphene, the new receptors are endowed with an electron-donor tetrathiafulvalene moiety (exTTF). The resulting non-covalent hybrids have been characterized by different analytical, spectroscopic and microscopic techniques (TGA, Raman, UV-Vis absorption, TEM and XPS), and the supramolecular interaction of the molecular systems with graphene has been investigated by theoretical calculations. The electrochemical behavior of the pyrene-exTTF hybrids onto distinct graphene-based materi…
Functionalized Calix[8]arenes, Synthesis and Self-assembly on Graphite
2005
With the intention of building hollow tubular structures by self-assembly, we have designed and successfully synthesized a series of calix[8]arene derivatives. Their phenolic units were functionalized in p-position by various groups which are able to interact via hydrogen bonding or π−π stacking. Ethynyl, amide, urea, or imide links were chosen for the covalent attachment of these functional groups, to ensure the adjustment of an optimal distance for their interaction. Two different kinds of nanostructures self-assembled on a highly oriented pyrolytic graphite (HOPG) surface were found by scanning force microscopy: parallel aligned nanorods in which the calixarene molecules are adsorbed ed…
Substrate templating upon self-assembly of hydrogen-bonded molecular networks on an insulating surface.
2012
M olecular self-assembly on insulating surfaces, despite being highly relvant to many applications, generally suffers from the weak molecule–surface interactions present on dielectric surfaces, especially when benchmarked against metallic substrates. Therefore, to fully exploit the potential of molecular self-assembly, increasing the infl uence of the substrate constitutes an essential prerequisite. Upon deposition of terephthalic acid and trimesic acid onto the natural cleavage plane of calcite, extended hydrogen-bonded networks are formed, which wet the substrate. The observed structural complexity matches the variety realized on metal surfaces. A detailed analysis of the molecular struct…
Surface-Assisted Self-Assembly of a Hydrogel by Proton Diffusion
2018
International audience; Controlling supramolecular growth at solid surfaces is of great importance to expand the scope of supramolecular materials. Here we describe a dendritic benzene-1,3,5-tricarboxamide peptide conjugate whose assembly can be triggered by a pH jump. Stopped flow kinetics and mathematical modeling provide a quantitative understanding of the nucleation, elongation, and fragmentation behavior in solution. To assemble the molecule at a solid-liquid interface, we use proton diffusion from the bulk. The latter needs to be slower than the lag phase of nucleation in order to progressively grow a hydrogel outwards from the surface. Our method of surface-assisted self-assembly is …