The Effects of Pyrrole: Oxidant Ratios on the Permittivity of Conducting Polymer Composites

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Authors
  1. Cameron, C.G.
  2. O’Hagan, P.J.
Corporate Authors
Defence R&D Canada - Atlantic, Dartmouth NS (CAN)
Abstract
Freund’s method for cascade polymerization is proving to be a versatile method to produce conducting polymers in a processible manner. One promising avenue for this technology is the creation of composite materials which consist of a interpenetrating network of conducting polymer inside an inert host matrix. Our early work with these composites is showing that they can offer a number of unusual properties. This paper focuses on clarifying the nature of the oxidant used to date, phosphomolybdic acid (PMA), and its role in the process. Polypyrrole–polyurethane composites of varying loading levels were made and their permittivity measured, with percolation occurring near 4% v/v. The ratio of pyrrole monomer to oxidant was varied over a range from 12:1 to 1:2. Insufficient oxidant led to incomplete polymerization and hence poor permittivity. Excess oxidant left trapped ions in the composites which led to secondary dielectric effects. A ratio of around 2.5:1 appears to be a reasonable compromise. The cyclic voltammetry of PMA in tetrahydrofuran reveals a pair of quasi-reversible waves near 0.4 V and 0.6 V vs. SCE. The position of these waves is pH-dependent.

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Keywords
Permittivity;Radar absorbing materials;Conducting polymers
Report Number
DRDC-ATLANTIC-TM-2006-208 — Technical Memorandum
Date of publication
01 Nov 2006
Number of Pages
38
DSTKIM No
CA028930
CANDIS No
527128
Format(s):
CD ROM

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