SIMPLE SYNTHESIS OF SMART CONDUCTIVE POLYANILINE NANOPARTICLES

SILVESTRE BONGIOVANNI; M.A. MOLINA; C.R. RIVAROLA; C.A. BARBERO

Berlin

Conferencia; 12th International PAT Conference; 2013

Polyaniline nanoparticles (PANI NP) are small objectswhich are suitable as multifunction vectors for insertionof bioactive principles into living cells[1]. Poly(N-isopropylacrylamide)(PNIPAM) is a termoresponsive polymerwhich suffers a coil to globule transition at ca. 32 °Cfrom a hydrophilic to a hydrophobic state. Hydroxypropylcellulose(HPC) is an anphyphilic macromolecule witha similar thermosensitive behavior, with a transitiontemperature of ca. 50 °C. On the other side, it is knownthat conductive polymers strongly absorb electromagneticradiation, particularly in the microwave range, withheating up of the polymer[2].Conductive polyaniline nanoparticles are synthesizedby oxidation of aniline with persulfate in acid media, inthe presence of polymeric stabilizers: polyvinilpyrrolidone(PVP), chrondroitin sulfate (CS), poly(N-isopropylacrylamide)(PNIPAM) and hydroxylpropylcellulose(HPC). The size of the nanoparticles depends on the natureof the polymeric stabilizer. The nanoparticles stabilizedby thermoresponsive polymers (PNIPAM and HPC)aggregate when the temperature reaches the phasetransition temperature (Tpt = 32 oC for PNIPAM orTpt = 42 oC for HPC) while those stabilized with PVP orCS are unaffected by the temperature (Fig 1). The dispersionsare restored when the temperature is loweredbelow Tpt.Polymerization in the presence of a mixture of twopolymers of different stabilizing capacity (PVP and PNIPAM)allows tuning both the size and thermoresponsiveproperties of the nanoparticles. UV-visible spectroscopymeasurements show that the nanoparticles dispersionchanges their electronic properties with the pH of theexternal solution. Turbidimetric measurements showthat the aggregation of the nanoparticles stabilized withPNIPAM could be achieved by external temperaturechanges, irradiation with microwaves and NIR laser light.Finally, stabilization with biocompatible CS, HPC or PNIPAMproduces dispersion useful in biological applications.