Ionic transport plays a central role in key technologies relevant to energy, and information processing and storage, as well as in the implementation of biological functions in living organisms. Here, we introduce a supramolecular strategy based on the non-destructive chemical patterning of a highly ordered self-assembled monolayer that allows the reproducible fabrication of ion-conducting surface patterns (ion-conducting channels) with top -COOH functional groups precisely definable over the full range of length scales from nanometre to centimetre. The transport of a single layer of selected metal ions and the electrochemical processes related to their motion may thus be confined to predefined surface paths. As a generic solid ionic conductor that can accommodate different mobile ions in the absence of any added electrolyte, these ion-conducting channels exhibit bias-induced competitive transport of different ionic species. This approach offers unprecedented opportunities for the realization of designed ion-conducting systems with nanoscale control, beyond the inherent limitations posed by available ionic materials.
Effective control of chemistry at interfaces is of fundamental importance for the advancement of methods of surface functionalization and patterning that are at the basis of many scientific and technological applications.Aconceptually new type of interfacial chemical transformations has been discovered, confined to the contact surface between two solid materials,w hichm ay be induced by exposure to X-rays, electrons or UV light, or by the application of electrical bias. One of the reacting solids is aremovable thin film coating that acts as ar eagent/catalyst in the chemical modification of the solid surface on which it is applied. Given the diversity of thin film coatings that mayb eu sed as solid reagents/catalysts and the lateral confinement options provided by the use of irradiation masks,c onductive AFM probes or stamps,a nd electron beams in such solid-phase reactions,t his approach is suitable for precise targeting of different desired chemical modifications to predefined surface sites spanning the macroto nanoscale.Recent exploratory experiments conducted by us with the purpose of devising acomprehensive methodology of surface chemical functionalization and patterning led to the rather surprising discovery that the top CH 3 groups of highly ordered OTSmonolayers (monolayers self-assembled from n-octadecyltrichlorosilane precursor molecules,S iCl 3 À(CH 2 ) 17 À CH 3 ) [1, 2] may be quantitatively converted to COOH with full preservation of the composition and structure of the monolayer hydrocarbon core using various thin-film coatings as oxidizing reagents.T he conversion of OTSi nto OTSox (surface-oxidized OTS) is implemented upon exposure of the coated OTSm onolayer to different sources of electromag-netic radiation or electrons (see Scheme 1f or some representative examples). Reaction route (a) in Scheme 1w as discovered by accident in experiments involving electron beam (e-beam) deposition of different metals (Ag, Al, Au,Ti) on OTSm onolayers on silicon (OTS/Si) or quartz (OTS/Q) covered with 4-10 nm-thick PVA( polyvinyl alcohol) film coatings.D epositing the same metals (under identical experimental conditions) on bare OTS monolayers did not affect their composition and structure in any measurable manner, whereas using at ungsten target in the e-beam evaporator operated under conditions below the threshold evaporation of this metal was found to convert OTSinto OTSox as in the actual deposition of metals on the PVAsurface.Finally,using thermal instead of e-beam metal deposition on PVA-coated OTSm onolayers did not affect their composition and structure either.T hese observations suggested that, in the presence of as ource of oxygen (here the thin PVAc oating), the surface oxidation of OTSisinduced by the radiation that accompanies the metal evaporation in e-beam evaporators (X-rays,s econdary and scattered electrons and UV light, emitted when energetic electrons strike am etal target) [3] rather than by the metal deposition itself.T hat each of the different components of this radiation may induce ...
We study the formation of silver colloids and the effect of an additive on their growth by measuring the kinetics of silver reduction in the presence of anisic acid, combined with transmission electron microscopy. The kinetics show an initial fast reduction of 1−3% of the total silver present in the solution, then a plateau region with hardly any reduction going on, and finally a region of accelerated growth and aggregation. The results are interpreted quantitatively in terms of the adsorption of the additives on the silver clusters at the early stages of the reaction and a slow-down of their subsequent growth. This is an example for the use of additives to achieve a control over the size distribution of colloidsdetermining the average size of the particles and the width of the distribution.
The difference in the heterogeneous binding of Mg(2+), Ca(2+) and Sr(2+) ions by 1-thioglycerol (TG) and 1,4-dithiothreitol (DTT) spontaneously adsorbed monolayers on Au has been studied following the changes in the double layer capacity. A mathematical treatment, based on calculating the electrochemical potential difference at the monolayer-electrolyte interface, has followed our recent work which dealt with the acid-base equilibrium at the interface as a means of calculating the pK of ionizable SAMs and their binding with Cd(2+). Experimentally, spontaneously adsorbed monolayers of TG and DTT were assembled on Au surfaces and studied by impedance spectroscopy and alternating current voltammetry (ACV). The capacity was measured for each of the modified surfaces at increasing concentrations of the divalent metal ions separately. The goal of this study has been to examine the effect of metal ion binding by similar ligands that are differently attached onto the surface. TG and DTT monolayers differ in their flexibility, which is a result of their attachment to the surface through one and two arms, respectively. The general trend of the apparent heterogeneous association constants of the divalent metal ions, which were calculated from the capacity measurements, was substantially different from the classical Irving-Williams series that is applicable to homogeneous systems. This difference could be nicely explained by the reduction of the degree of freedom and flexibility of the attached ligands.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.