Impact of synthetic talc on PLLA electrospun fibers

Poly(L-lactic acid) (PLLA) is an important biomaterial with application as surgical meshes, sutures, and in artificial tissue. Here we prepared novel fibers by electrospinning solutions containing PLLA and a specially synthesized talc (ts), characterized by the presence of aliphatic chains in the structure and completely soluble in the electrospinning solutions. Even a small amount of ts (2 wt.-%) in the toluene/chloroform solvent increases the solution viscosity, most likely because of specific interactions between talc and PLLA. Morphological characterization demonstrated that homogenous fibers, of neat PLLA and PLLA/ts, are obtained by proper choice of electrospinning conditions. Among the parameters studied, relative humidity (Rh) was found significantly to affect fiber morphology. Morphological homogeneity increases by increasing Rh. In contrast to fibers containing a commercial talc, which is insoluble in the electrospinning mixture, and whose aggregates render the fiber irregular, in the case of PLLA/ts fibers the dispersion of the synthetic talc is achieved at the nanometric length scale. Electrospun mats based on PLLA/ts showed a much higher water contact angle than the neat PLLA mats, the contact angle increasing from 92° to ca. 140°, thus highlighting that a superhydrophobic PLLA surface is obtained by dispersing synthetic talc into PLLA fibers, widening the potential for biomedical applications of this material. Fiber properties of superhydrophobic PLLA were studied by means of differential scanning calorimetry (DSC), static and real-time wide angle X- ray diffraction (WAXD), and water contact angle measurements. Talc was found to promote the development of a small amount of crystallinity during the electrospinning process, and to favor the development of the α crystallographic form during annealing.