| dc.description | A study about the synthesis of composite fibers of polypyrrole (PPy) dispersed in polylactic acid (PLA)
by the electrospinning method is presented in this work. For this purpose, PPy particles were
polymerized by plasma using glow discharges in a vertical tubular reactor with synthesis power from
20 to 100 W. In each synthesis two fractions were obtained, one soluble and another insoluble, the
latter was divided into two, films and particles. Only the particles were used in this work, that were
dispersed in PLA solutions, obtaining homogeneous dispersions, which were subsequently injected
in an electrospinning machine designed and built by the UAEM-ININ work team to obtain the
electrospinning fibers. The characterization of polymers and fibers was carried out by Scanning
Microscopy (SEM), Infrared Spectroscopy (IR), X-Ray Photoelectron Spectroscopy (XPS),
Absorption Spectroscopy (UV-Vis), Contact Angle and Electrical Conductivity.
The results indicate that the particles are spherical with diameters between 0.05 and 3.54 μm as a
function of the energy applied in the synthesis. The composite PPy/PLA fibers have diameter from
0.05 to 13.99 μm with protuberances on the surface, tentatively indicating that they are PPy particles
embedded in the fibers. The fibers are partially aligned.
The chemical structure of PPy particles have =C-H and N-H groups derived from pyrrole and multiple
bond formation due to dehydrogenation of pyrrole during synthesis to form cross-linked PPy
structures. In the chemical structure in PPy/PLA fibers, PLA structure predominates over that of PPy.
The electromagnetic absorption of PPy particles and PPy/PLA fibers is intense in the UV region and
is reduced in the Visible region, depending on the synthesis power and the diameter of the fibers.
Hydrophilicity in the materials was evaluated by means of the contact angle between particles and
fibers with solutions similar to those of the spinal cord whose values for the particles are between 70°
and 88° and for the fibers between 110° and 147°. These results suggest that the PPy particles are
hydrophilic (<90°) and the PPy/PLA fibers are hydrophobic (>90°). The moisture-free electrical
conductivity of the PPy particles was in the 10-8
to 10-2 S/m range and that of the composite fibers of
PPy/PLA were in the 10-8 -10-4 S/m interval. Conductivity is important in the spinal cord since the neuronal communication in the central nervous system is by ionic pulses | |
