Fabrication and Optical Modeling of Micro‐Porous Membranes Index‐Matched with Water for On‐Line Sensing Applications. Issue 3 (20th February 2020)

• Record Type: Journal Article
• Authors: Lanfranco, Roberta; Giavazzi, Fabio; Bellini, Tommaso; Nicolò, Emanuele Di; Buscaglia, Marco
• Is Part Of: Macromolecular materials and engineering. Volume 305:Issue 3(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-02-20
• Subjects: label‐free optical sensors -- microporous membranes -- perfluoropolymers -- scattering phantom interface -- solute detectors; Plastics -- Periodicals; Polymers -- Periodicals; Polymerization -- Periodicals; 547.705
• DOI: 10.1002/mame.201900701
• Languages: English
• ISSNs: 1438-7492

Abstract

Abstract: Membranes made of perfluorinated materials having a refractive index close to that of water enable straightforward detection of water solutes at the interface, hence providing a novel sensing tool for fluidic systems. Here it is reported the production by non‐solvent induced phase separation and characterization of microporous membranes made of Hyflon AD, an amorphous copolymer of tetrafluoroethylene. Their optical turbidity when soaked in liquids having different refractive indices is studied and the data are interpreted with an optical model linking scattered light and structural features of the membrane. The average polymer and pore chord lengths obtained in this way scale with the filtering pore size measured by capillary flow porometry. Then, the optical response of the membranes when soaked in aqueous surfactant solutions is investigated and the effects of the molecular adsorption on the internal membrane surface is successfully interpreted by an extension of the model. Overall, the results show that index‐matched membranes can be designed and produced to provide a simple optical detection of the composition of the soaking liquid or to monitor the initial stage of membrane fouling. Abstract : Perfluorinated microporous membranes with refractive index similar to that of water combine filtering and optical sensing capabilities. Their opacity is sensitive to the composition of the filling liquid and to the adsorption of molecular pollutants or foulants on the internal membrane surface. A simple model derived from the random telegraph signal accounts for the optical response of different membranes.