Synthesis and Characterization of Polypyrrole-Coated Sulfur-Rich Latex Particles:New Synthetic Mimics for Sulfur-Based Micrometeorites

摘要

Polypyrrole (PPy)has been deposited from aqueous solution onto submicrometer-sized sulfur-rich poly-[bis(4-vinylthiophenyl)sulfide] (PMPV)latex particles.The PMPV seed particles and resulting composite particles were extensively characterized using scanning electron microscopy,X-ray photoelectron spectroscopy,FT-IR spectroscopy,helium pycnometry,Raman spectroscopy,and electrical conductivity measurements.Four-point probe measurements on pressed pellets indicate conductivities of around 6 x 10~(-5)S cm~(-1)for a polypyrrole loading of approximately 11.5%.This suggests a somewhat patchy,nonuniform polypyrrole overlayer,which is consistent with our Raman spectroscopy studies.Despite their relatively low conductivities,these polypyrrole-coated PMPV latexes can be accelerated up to hypervelocities (>20 km s~(-1))using a high voltage (2 MV)van de Graaf instrument.In view of their high sulfur contents (ca.28%),these new electrically conductive latexes are expected to be interesting synthetic mimics for understanding the behavior of sulfur-based micrometeorites,whose existence has been postulated by planetary scientists investigating signs of volcanic activity on one of Jupiter's moons (Io).