(272f) Optimization of the Nanofibrous Structure of Non-Woven Mats of Electrospun Biodegradable Nanocomposites Using Response Surface Methodology

Biodegradable polymer nanofibrous mats have not been particularly studied, although, they are environmentally friendly with potential applications both as filters and as reinforcing components in composite systems. Electrospinning is an alternative technique in fabrication of such membranes and filters and fiber diameters ranging from few nanometers to few micrometers can be produced. Electrospun fibers often have beads as ?by-products'. However, beads on the fibers could be used as reservoirs for drug or cell inclusion and should have quite different degradation properties from fibers. Therefore, optimization of both fiber diameter and beads density is necessary to extent electrospun mats' applications in biomedical, biotechnological and other industrial fields.

In the present work, electrospun mats of polymer-clay nanocomposites were prepared in order to study the influence of material and process parameter settings on their morphology. The polymer solution concentration, the flow rate of the injected solution and the organically-modified-clay content of the polymer matrix were the factors chosen to be investigated according to a design of experiments in the framework of response surface methodology (RSM). The applied DC voltage and the distance between the capillary tip and the collector were kept at 15 kV and 8 cm respectively in accordance with studies on similar systems [1,2]. The polymer used was the biodegradable aliphatic polyester poly(butylene succinate-co-butylene adipate) (PBSA) by the commercial name of Bionolle 3001, while the nanofiller used was organically modified montmorillonite (Cloisite 25A).

Scanning electron microscopy (SEM) imaging of the electrospun mats revealed their surface morphology and image processing of the micrographs was employed in order to determine the mean diameter of the fibers (Dfibre) and the mean diameter of the beads (Dbead) together with their number density (Nbead). Three responses were defined. The first two were the ratio (Dbead - Dfibre)/ Dfibre and the number density Nbead and were introduced to indicate the fibrous quality of the mats, while the third, indicative of the fiber thickness, was Dfibre. Regression analysis revealed quantitative relations of the above three responses, which were also verified by validation tests. Based on these results, optimal conditions can be obtained for predetermined diameters and morphologies for electrospun fibers.

References

[1] ?Biodegradable polymer nanocomposites: The role of nanoclays on the thermomechanical characteristics and the electrospun fibrous structure?, S. I. Marras, K.P. Kladi, I. Tsivintzelis, I. Zuburtikudis, C. Panayiotou, Acta Biomaterialia 4(3), 756-765(2008).

[2] ?Preparation and characterization of electrospun poly(butylene succinate-co-butylene adipate) nanofibrous nonwoven mats?, V. Tserki, I. Filippou, C. Panayiotou, Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanoengineering and Nanosystems 220(2), 71-79(2006).