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Keywords:

  • conductivity;
  • gamma;
  • plasma;
  • polymers;
  • pyrrole

Abstract

This work presents a study about the effect of gamma irradiation in plasma polymers derived from pyrrole. Gamma rays modify the whole energetic equilibrium between the nucleus and the electron clouds which results in rearrangements of atoms, molecules and in modifications in the properties of irradiated materials. Two types of interactions were analyzed, in polypyrroles synthesized from irradiated monomers, and in polypyrroles irradiated after the synthesis. The doses studied were 18 and 40 kGy. The polymers were synthesized by plasma at 13.56 MHz and 100 W. The results indicated that the exposure to gammas promoted dehydrogenation and creation of groups with double and triple bonds. The multiple bonding was reflected in the electrical conductivity which increased up to 9 orders of magnitude, from 10−11 in non irradiated polymers to 10−2 S/m in the polymers synthesized with monomers irradiated at 40 kGy. Another effect of gammas was the increase in the roughness of polymers which affects the hydrophilicity, this property was evaluated by measuring the contact angle of polymers with a Krebs-Ringer solution. The angles reached up to 72° in surfaces with the greatest pores.