Properties of poly(lactic acid) and poly(ethylene oxide) solvent polymer mixtures and nanofibers made by solution blow spinning

Abstract

The properties of mixtures of poly(lactic acid) (PLA) and poly(ethylene oxide) (PEO) were studied in polymer solutions by dilute solution viscometry, and in-solution blow-spun nanofibers were studied by microscopy (scanning electron and transmission electron microscopy) and thermal and spectral analysis. Three mixtures of PLA and PEO (3:1, 1:1, and 1:3) were solution-blended in chloroform. Dilute solvent viscometry indicated that the 3:1 mixture of PLA and PEO had a higher miscibility coefficient value than the other mixtures. The neat polymers and mixtures were solution-blow-spun into nanofibers. The fiber diameters were smallest in the neat polymers. Transmission electron micrographs revealed a core/sheath structure for the sample mixtures. X-ray analysis indicated that the crystallinity was positively correlated with the PEO content. Fibers from the mixtures had contact angle measurements similar to those of the neat PEO. Fourier transform infrared and Raman spectroscopy of the mixtures indicated interactions between ester and ether groups, which were attributed to dipole-dipole interactions between the ester groups of PLA and the ether groups of PEO.

In vitro antimicrobial activity of solution blow spun poly(lactic acid)/polyvinylpyrrolidone nanofibers loaded with Copaiba (Copaifera sp.) oil

“…This result indicates that the polymer concentration and the spinning variables (polymer injection rate and spinning pressure) used were suitable for the spinning process to occur without forming either fiber beads or films [32]. This result is consistent with our previous studies in which spinning conditions were thoroughly optimized [32,33].…”

“…The presence of Copaiba oil also contributes to higher contact angles since this herbal medicine has a hydrophobic nature. The addition of PVP, a hydrophilic polymer, on the other hand, resulted in the reduction of the hydrophobicity and the contact angle of samples, suggesting that some PVP is exposed on the surface of the fibers in the fiber mats [39,33]. As shown in Table 2, addition of PVP, in all groups, led to a statistically significant (p b 0.001) reduction of the contact angle, when compared to PLA fibers.…”

“…Some fibers showed a bamboo-like structure that is characteristic of the neat PLA fiber structure [33]. This result suggests the possibility that the PVP was either eliminated from fiber structure or was not incorporated in the fibers to begin with.…”

“…Stretching of polymer solution to form fibers can be difficult, less efficient, and less stable when viscous polymeric solutions are used. Viscous polymeric solutions and polymer mixtures with poor compatibility can produce fibers with a greater variability in diameter [36,33].…”

“…At the nozzle tip, the aerodynamic drag and shear forces caused by the pressurized gas exiting the nozzle are combined to form a cone similar to the Taylor's cone formed at the nozzle tip in the electrospinning process. Fiber bundles are jettisoned from the nozzle tip in the SBS process towards a collector placed at a fixed working distance [31][32][33]. SBS has been successfully used in a series of controlled release studies including progesterone and linalool [34,35].…”