| 1. |
- Khulbe, K. C., et al.
(författare)
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Characterization of Surface Modified Hollow Fiber Polyethersulfone Membranes Prepared at Different Air Gaps
- 2006
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Ingår i: Journal of Applied Polymer Science. - : John Wiley & Sons. - 0021-8995 .- 1097-4628. ; 104:2, s. 710-721
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Tidskriftsartikel (refereegranskat)abstract
- Hollow fibers were spun from a solution of surface-modifying macromolecule blended polyethersulfone in dimethyl acetamide by using dry-wet spinning method at different air gaps and at room temperature. The air gap was varied from 10 to 90 cm. The ultrafiltration performance of hollow fibers was studied by using aqueous solutions of polyethylene glycols and polyethylene oxides of different molecular weights. Significant difference in surface morphology between the inner and outer surface of the hollow fibers was observed by atomic force microscopy (AFM). Similar results were obtained by contact angle measurement and XPS. Mean pore sizes of the inner surface and outer surface were calculated from AFM images and compared with the pore sizes obtained from mass transport data. Pore size distribution curves were drawn from both data, i.e., from AFM images and mass-transport data, both methods gave similar results.Roughness parameters of the inner and outer surfaces and the sizes of nodular aggregates on both surfaces were measured. An attempt was made to correlate the above parameters with the performance of the membranes. Unexpected values of contact angles of both inner surface and outer surface were obtained. It was observed that the studied membranes could be put into two groups: (i) the membranesfabricated between 10 and 50 cm air gap and (ii) fabricated at higher than 50 cm air gap. A plausible mechanism for the unexpected results was discussed.
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| 2. |
- Rafat, Mehrdad, et al.
(författare)
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Plasma surface modification and characterization of collagen-based artificial cornea for enhanced epithelialization
- 2007
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Ingår i: Journal of Applied Polymer Science. - : Wiley-Blackwell. - 0021-8995 .- 1097-4628. ; 106:3, s. 2056-2064
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Tidskriftsartikel (refereegranskat)abstract
- Argon plasma treatment enhanced the attachment of epithelial cells to a collagen-based artificial cornea crosslinked using glutaraldehyde (GA) and glutaraldehyde-polyethylene oxide dialdehyde (GA-PEODA) systems. The epithelialization of untreated and treated surfaces was evaluated by the seeding and growth of human corneal epithelial cells. Characterization of polymer surface properties such as surface hydrophilicity and roughness was also made by contact angle measurement and atomic force microscopy, respectively. Contact angle analysis revealed that the surface hydrophilicity significantly increased after the treatment. In addition, AFM characterization showed an increase in surface roughness through argon plasma treatment. Based on the biological and surface analysis, argon plasma treatment displays promising potential for biocompatibility enhancement of collagen-based artificial corneas. It was also found that the cell attachment to artificial cornea surfaces was influenced by the combined effects of surface chemistry (i.e., surface energy), polymer surface morphology (i.e., surface roughness), and polar interactions between functional groups at the polymer surface and cell membrane proteins.
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| 3. |
- Rafat, Mehrdad, et al.
(författare)
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Surface Characterization of Hollow Fibre Membranes Used in Artificial Kidney
- 2006
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Ingår i: Journal of Applied Polymer Science. - : John Wiley & Sons. - 0021-8995 .- 1097-4628. ; 101:6, s. 4386-4400
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Tidskriftsartikel (refereegranskat)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. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4386–4400, 2006
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