Surface characterization of hollow fiber membranes used in artificial kidney

Abstract

ABSTRACT:The internal and external curved surfaces of polysulfone hollow fiber membranes were characterized by atomic force microscopy (AFM), contact angle measurement (CAM), and scanning electron microscopy (SEM) with the aim of improving the membrane surface properties for blood compatibility. Novel approaches were applied to evaluate a number of properties, including the roughness, pore size, nodule size, and wettability of the surfaces of the hollow fibers. CAM studies were carried out by directly observing the liquid meniscus at the surfaces of hollow fibers. Observation of the meniscus and measurement of the contact angle became possible by using an imaging system developed in our laboratory. AFM and SEM studies were also conducted on the surfaces of the hollow fiber membranes by cutting them at an inclined angle. The effect of the molecular weight of poly(ethylene glycol) (PEG) in the polymer blend on the surface properties of the hollow fibers was studied. Increasing the PEG molecular weight increased the average pore size whereas it decreased the contact angle. The contact angle depended on the microscopic surface morphology, including nodule size and roughness parameters. The theoretical prediction along with the experimental data showed that the measured contact angle would be greater than the value intrinsic to the membrane material because of the formation of composite surface structures.

Preparation of PVDF-CTFE hydrophobic membranes for MD application: Effect of LiCl-based mixed additives

“…It has been confirmed that the membrane pore structure, roughness and the crystallites in membrane surface have tremendous impacts on membrane hydrophobicity [31,46,47]. In this study, the contact angles with water, glycerol, and diiodomethane were measured to indicate the membrane hydrophobicity, and the results were presented in Table 4.…”

Preparation and characterization of PVDF flat-sheet membranes for direct contact membrane distillation

“…It can be found that the nodule size of the composite membrane was smaller than that of the pure PVDF membrane. According to the modified Young's equation proposed by Rafat et al [34], the membrane surface contact angle was determined by the ratio of the mean surface roughness to the mean surface nodule size (R a /l n ), the contact angle would become higher with an increase in R a /l n for PVDF membrane. Although both the membrane surface nodule size and roughness were smaller than those of the pure PVDF membranes, the contact angles declined slightly for the composite membranes.…”

Preparation and properties of PVDF composite hollow fiber membranes for desalination through direct contact membrane distillation

“…It has been demonstrated that the hydrophilic/hydrophobic property of hollow fiber is related to surface roughness [36]. An atomic force microscope (AFM) (NanoScope IIIa, Digital Instruments, USA) was employed to analyze the surface states of the prepared membranes.…”