A new and highly robust light-responsive Azo-UiO-66 for highly selective and low energy post-combustion CO₂ capture and its application in a mixed matrix membrane for CO₂/N₂ separation

A new and robust generation-2 light-responsive MOF with UiO-66 topology applicable for post combustion CO2 capture has been successfully synthesized and is described in this article. Azo-UiO-66 shows a satisfactory performance for CO2/N2 separation as observed through high CO2/N2 selectivity. Furthermore, due to the presence of azobenzene groups, Azo-UiO-66 also exhibits a very efficient CO2 photoswitching uptake, a characteristic that has never been observed in any generation-2 light-responsive MOF. Combined together with its robust character, this makes Azo-UiO-66 a promising candidate for highly selective and low energy CO2 capture applications. To further apply this material, Azo-UiO-66 was incorporated in Matrimid to form mixed matrix membranes (MMM). Composites with up to 20 wt% of Azo-UiO-66 were fabricated and tested. The resulting MMM showed increased performance in terms of CO2 permeability and CO2/N2 selectivity compared with the similar MOF-based MMM composites. This then shows another promising application of Azo-UiO-66 as a filler to enhance polymeric membrane performance for CO2 separation

Lateral force microscopy study of the friction between silica surfaces in electrolyte solutions

Lateral force measurements between a polished silica wafer and a colloidal silica particle in monovalent electrolyte solution environment (LiCl, NaCl, CsCl) were performed using an Atomic Force Microscope (AFM). Analysis of the friction versus load data, in LiCl case, indicates that increasing the electrolyte concentration, the intensity of the friction force decreases. The effects of the counterions on lateral forces show that friction coefficients gradually decrease from pure Dl water to 1.0M LiCl. Lateral forces versus scan rate graphs show a typical behavior for all investigated systems: transition and saturation region. These results are consistent with the idea that strongly hydrated ions have a lubrication effect in silica-silica interactions

Flexible pneumatic micro-actuators: Analysis and production

Compliant pneumatic micro-actuators are interesting for applications requiring large strokes and forces in delicate environments. These include for instance minimally invasive surgery and assembly of microcomponents. This paper presents a theoretical and experimental analysis of a balloon-type compliant micro-actuator. Finite element modeling is used to describe the complex behavior of these actuators, which is validated through prototype experiments. Prototypes with dimensions ranging from 11mm × 2mm × 0.24mm to 4mm × 1mm × 0.12mm are fabricated by a newly developed production process based on micromilling and micromolding. The larger actuators are capable of delivering out-of-plane strokes of up to 7mm. Further, they have been integrated in a platform with two rotational and one translational degree of freedom. © 2011 Published by Elsevier Ltd