Simple synthesis of smart conductive and polyaniline nanoparticles

S. BONGIOVANNI ABEL; M.A. MOLINA; C. RIVAROLA; M. KOGAN; C. BARBERO

Berlín

Conferencia; 12th International Conference Polymers for Advanced Technologies; 2013

Polyaniline nanoparticles (PANI NP) are small objects which are suitable as multifunction vectors for insertion of bioactive principles into living cells . Poly(N-isopropylacrylamide) (PNIPAM) is a termoresponsive polymer which suffers a coil to globule transition at ca. 32 °C from a hydrophilic to a hydrophobic state. Hydroxypropylcellulose (HPC) is an anphyphilic macromolecule with a similar thermosensitive behavior, with a transition temperature of ca. 50 °C. On the other side, it is known that conductive polymers strongly absorb electromagnetic radiation, particularly in the microwave range, with heating up of the polymer . Conductive polyaniline nanoparticles are synthesized by oxidation of aniline with persulfate in acid media, in the presence of polymeric stabilizers: polyvinilpyrrolidone (PVP), chrondroitin sulfate (CS), poly(N-isopropylacrylamide) (PNIPAM) and hydroxylpropylcellulose (HPC). The size of the nanoparticles depends on the nature of the polymeric stabilizer. The nanoparticles stabilized by thermoresponsive polymers (PNIPAM and HPC) aggregate when the temperature reaches the phase transition temperature (Tpt = 32 oC for PNIPAM or Tpt = 42 oC for HPC) while those stabilized with PVP or CS are unaffected by the temperature (Fig 1). The dispersions are restored when the temperature is lowered below Tpt. Polymerization in the presence of a mixture of two polymers of different stabilizing capacity (PVP and PNIPAM) allows tuning both the size and thermoresponsive properties of the nanoparticles. UV-visible spectroscopy measurements show that the nanoparticles dispersion changes their electronic properties with the pH of the external solution. Turbidimetric measurements show that the aggregation of the nanoparticles stabilized with PNIPAM could be achieved by external temperature changes, irradiation with microwaves and NIR laser light. Finally, stabilization with biocompatible CS, HPC or PNIPAM produces dispersion useful in biological applications.