Conducting polypyrrole-coated leathers

Conducting polymers are promising materials applicable as interfaces in various functional materials given they intrinsically possess electronic and ionic conductivity. Herein, a conducting polymer, polypyrrole (PPy) was explored for surface modification of three different leathers via in-situ oxidation of pyrrole in the absence and the presence of two stabilizing polymers, hydroxypropylcellulose and poly(N-vinylpyrrolidone). Colloidal dispersed PPy assemblies were formed with colloidal stabilizers along with PPy-coated leathers and hampered the formation of PPy precipitates that would otherwise contaminate the leather surface. The surface-modified bio-based composites were characterized by FTIR and Raman spectroscopy, and optical and scanning electron microscopy. PPy was deposited on collagen fibers on both sides of the leather. The thickness of the PPy layer varied between 24 and 200 μm. Mechanical properties of the leathers manifested themselves by the decrease in tensile strength and elongation at break after the modification process. Sheet resistances were in the range of 100–103 kΩ/sq with the highest values observed for materials modified in the presence of the polymeric stabilizers. Different sheet resistances were obtained for the top and bottom sides of the leathers depending on the surface finishing. Furthermore, the modified leathers were subjected to cyclic bending tests and the variation in their resistivity was studied. The conductivity and electroactivity of the modified materials may serve as guidance for the rational design of intelligent leathers in the footwear, as heating elements, and in energy storage.