Structure and morphology of plasma polyfuran particles

Abstract

A study about the chemical structure, morphology and electric conductivity of polyfuran spherical particles synthesized by rf plasma glow discharges is presented in this work. This kind of particles is difficult to obtain with other syntheses at lower energy. The particles had average diameter that increased linearly with the energy of synthesis, from 172 to 456 nm with 2.91 nm/W growth rate. The chemical structure of the particles was analyzed by XPS relating the formation energy of the polymeric chemical groups with their C1s and O1s atomic orbital energies. The analysis indicated that almost all alpha C configurations of the initial furan molecules transformed into unions of monomers to construct linear polymers. On the other hand, almost all beta configurations remained unreacted in the furan rings and those that reacted transformed into the networked unions of the polymeric structure, approximately 10 %. The percentages of fragmentation, hydrogenation and resonance groups in the structure were also calculated. The particles thermally degraded in one phase from 200 to 600 °C, centered at 425 °C, suggesting that all synthesized particles have similar structure. The electric conductivity of the particles was between 10⁻¹¹ and 10⁻⁰⁹ S/m, increasing with the temperature, in which it is probable that the contact resistance among particles rule the transference of charges. The electronic activation energy was in the interval of semiconductors, from 0.031 to 3.83 eV.