Acceptor-type polydiacetylene -synthesis and electric conduction

Abstract

Poly(2,4-hexadiyne)s, possessing electron withdrawing substituents at 1- and 6- positions, were found to be acceptors, and form C-T complexes with donors to increase their conductivity. 1,6-dibromohexa-2,4-diyne was polymerized in melt by heating, resulting in the formation of a black polymer, which was soluble in organic solvents. The polymer made C-T complexes with donors, such as ammonia and tetrathiafulvalene (TTF). Consequently, its conductivity increased to 10 −1Scm −1. Several conditions such as temperature and ammonia pressure, which had effect on conductivity, were investigated. 1,6-diiodohexa-2,4-diyne was also polymerized in melt by heating, in which case the polymer obtained was slightly soluble in organic solvents. The whitish polycrystal 1,6-diiodohexa-2,4-diyne film was polymerized at −30°C by UV irradiation. The brown polymer film apparently kept its initial structure, while it was amorphous according to X-ray analysis. Both the golden poly(2,4-hexadiyne-1,6-diyl ditosylate) (PTS) single crystal and the red cross-linked polyester pellet, made from 2,4-hexadiyne-1,6-diol and adipoyl dichloride, formed black C-T complexes with ammonia, their conductivity being raised to 10 −4 – 10 −6Scm −1. The strength of poly(diacetylene), when used as an acceptor or as a donor, was able to be controlled by changing its substituent. The acceptor-donor relations among poly(diacetylene)s and dopants are proposed.