The effect of fluorinated surface modifying macromolecules on the surface morphology of polyethersulfone membranes

Abstract

Polyethersulfone (PES) has been recently adopted for membrane materials in applications such as ultrafiltration and haemodialysis. As a biomaterial, the factors which affect the blood compatibility of PES membranes include surface energetics, hydrophobicity, and surface morphology. Surface fluorination of materials has been found to create surfaces with improved blood compatibility and chemical stability. One novel approach to generating fluorinated polymer surfaces has included the use of fluorinated surface modifying macromolecules (SMMs). These macromolecules have been reported to establish fluorinated functional groups at surfaces of polymeric materials without significantly affecting the physical properties of the base polymer. However, to date there has been relatively little information published on the nature of the surface structure for PES materials containing these SMMs. In this study, synthesized SMMs with varying chemical compositions were characterized and blended with PES, and fabricated into flat sheet membranes. The bulk thermal transitions of PES materials were not significantly altered by the addition of 4 wt% SMMs. Contact angle data showed that the addition of SMMs in PES created more hydrophobic surfaces, accompanied by an increase in surface heterogeneity. X-ray photoelectron spectroscopy studies confirmed the presence of elemental fluorine at the surface. Through microscopy studies, it was shown that surface modification was achieved by the migration of SMM concentrated microdomains to the air-membrane interface. The generated microdomains (approximately 1-2 microm in diameter) are dispersed within the top 8 microm of the surface. The concentration of microdomains was gradually depleted from the surface to the bulk of the membrane. A schematic of the morphology for SMMs within the PES membrane surface was proposed.

Dynamic protein adsorption at the polyurethane copolymer/water interface

“…Similar investigations have been performed by other researchers to examine how pre-adsorbed fibrinogen can inhibit further protein adsorption and potential biodegradation by certain enzymes. The PU incorporated systems used for fibrinogen adsorption studies include polyester-urethanes by use of surface-modifying macromolecules containing fluorine [50], polyester-urethanes [51] and polyethersulfone [52]. These PU modified surfaces were found to reduce further protein adsorption by different extents, broadly consistent with the findings observed in this work.…”

Modification of porous polyetherimide hollow fiber membrane by dip-coating of Zonyl® BA for membrane distillation of dyeing wastewater

“…Fluorohydrocarbon macromolecules with unique properties such as high wetting resistance and good thermal stability making them useful materials in wide variety of applications. Form an extensive literature survey, almost all of the fluorinated surface modifying macromolecules (SMM) were blended with the polymer solutions in order to enhance surface hydrophobicity of the polymeric membranes for various applications (Ho et al 2000;Kim et al 2009;Essalhi & Khayet 2012;Khayet 2013;Mansourizadeh et al 2014). However, it should be noted that the complete migration of SMM to the membrane surface is the main challenge during the membrane fabrication process.…”