Wettability tuning of natural rubber/polyvinylpyrrolidone electrospun nonwoven mats

We report here the development of nonwoven electrospun fiber mats containing natural rubber (NR) and polyvinylpyrrolidone (PVP) blends. NR, PVP, and NR:PVP blended samples of 25:75; 50:50, and 75:25 wt.% were investigated by rheological measurements, Scanning Electron Microscopy, Atomic Force Microscopy, Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry, contact angle, and wetting time. The samples show a Newtonian behavior for ≤ 50.0 wt.% NR and a shear-thinning for higher NR content. Contact angle measurements show that the wettability of electrospun fiber mats decreases with higher NR concentrations when compared with the results of cast membranes. In addition, we demonstrate that wettability can be tuned by changing the polymer ratio in the blends, as attested by the experimental measurements and theoretical modeling. SEM and AFM images show phase separation only for cast membranes and the RMS roughness changes nonlinearly with variation in polymer ratio. Therefore, the wettability and the proposed model are more dependent on surface energy than on roughness. The association of NR:PVP was demonstrated to be successful in the production of electrospun fiber mats, exhibiting characteristics that may be of interest in biomedical applications when control of the wettability is required. Water-dissolution tests were performed for the 50NRe-spun sample and partial dissolution could be observed suggesting a promisor candidate for biomedical application with drug release.