The effect of molecular orientation on the conductivity of iodine intercalates of 1,4-trans-polybutadiene

Synthetic Metals, 41-43 (1991) 1597

1597

T H E EFFECT OF MOLECULAR ORIENTATION ON T H E CONDUCTIVITY OF IODINE INTERCALATES OF 1,4-trans-POLYBUTADIENE. A.H.Alberts, E.W.Meijer,.M.Savelsberg,E.E.Havinga*,P.J.Lemstra, Technical University Eindhoven,Department of Polymer Chemistry, Technical University Eindhoven, P.O.Box 513, Eindhoven The Netherlands 5300MB, (*Philips Research Laboratories) Of three polybutadienes, 1,4-c/s-PB, 1,2-syndio-PB and 1,4-trans -PB, only the latter forms an intercalate with iodine.Maximum conductivity of 1,4-trans-PB/12 is 0.9.10"2 cm'l in ambient atmosphere.lntercalation in stretch-oriented samples, obtained via calendering or solid state coextrusion (1) is impaired leading to markedly lower conductivities. Calendering of the unstretched intercalate at roomtemperature caused an immediate loss of conductivity by a factor of 10'0 ! //~'N

~

1,4-cis-PB

no intercalate ~

1,2-syndio-PB no intercalate "~;"~"~.,'~.~>',

1,4-tratts-PB intercalate

Table 1. ratio 1,4-trans-PB/l~ (weight increase max.)

EDR

Conductivity Scm"

0.6

0

0.9.10'

0.2

5

0.4.10 .5

0.1

10

8.2.10`7

These observed are explained in terms of preferred intercalation of the halogen in amorphous domains of the polymeric material. The effect of enhanced molecular orientation with respect to conductivity is adverse. These results undermine a conclusion reached by Thakur (2) in a study of iodine intercalates of polydienes, implying that a conjugated backbone is not a necessary prerequisite for an effective organic conductor. REFERENCES (l)N.van Aerie, M.Savelsberg, C.W.M.Bastiaans, P.J.Lemstra, Polymer 1989, in press. (2) A.J.Thakur, Macromolecules, 1988, 21, 661; of. the projected impact of this paper on the general concept of conductivity in organic materials, highlighted in "Conducting Rubber Bounces Back", P. Calvert, Nature, 1988, 333, 296. Elsevier Sequoia/Printed in The Netherlands