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Electrically conducting biodegradable polymer composites (polylactide-polypyrrole and polycaprolactone-polypyrrole) for passive resonant circuits



Electrically conducting biodegradable polymer composites made of polypyrrole (PPy) nanoparticles embedded in poly(L-lactide) (PLLA) or poly(ε-caprolactone) (PCL) are prepared by chemical oxidative polymerization. They will be used as electrical conductors for fabricating biodegradable passive resonant circuits for bioimplants. For both composites, the conductivity exhibits a percolation threshold at ∼6 wt% of PPy. Several reactants are tested, the polymerization process resulting in the highest conductivity uses iron(III)chloride hexahydrate (FeCl3), sodium dodecyl benzene sulfonate, and p-nitrophenol (pNPh), for both poly(L-lactide)-polypyrrole (PLLA-PPy) and poly(ε-caprolactone)-polypyrrole (PCL-PPy). Conductivities of 2.7 ± 0.8 S cmε1 (PLLA-PPy) and 7.8 ± 2.3 S cm−1 (PCL-PPy) are reached for a PPy content of 40 wt%. The PPy particle, observed by SEM, forms agglomerates having a size of 0.6–3.5 μm. The samples have similar PPy particle distributions over the entire cross sections. The conductivity as a function of time is investigated, being 34–70% of the initial value for samples stored in nitrogen, whereas it is less than 1% for samples stored in body-like conditions, bringing the conclusion that a biodegradable packaging will be required to protect the resonant circuits from body fluids. Finally, the biocompatibility of the polymer composites is evaluated with cytocompatibility tests on dermal human fibroblast cells, showing promising results in particular for composites having a low PPy content. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers