X-ray diffraction study of poly(3-n.decylpyrrole), polypyrrole, and their monomers

Abstract

The structure of the organic intrinsically conducting polymers polypyrrole and poly(3-n.decylpyrrole) was investigated by x-ray diffraction. The liquid monomers pyrrole and 3-n.decylpyrrole were also measured. From the analysis of all the data, information on the molecular and intermolecular correlations in the polymers was obtained. Both the polymeric systems are found to maintain a substantial planarity of the aromatic rings, i.e., the alkylic substituent in poly(3-n.decylpyrrole) does not affect the planarity of the compound. Possible effects related to the size of the counterion are also discussed.

Neutron and x-ray scattering study of fully deuterated poly(3-n.decylpyrrole)

“…͑7͒. All the distances R i j within a trimer are actually known 17,25,33 and are not expected to be substantially modified by the deuteration process. Therefore, only the meansquared displacements B i j and the weights w i j were left as free parameters.…”

“…The instrument configuration was the same as the previous measurements on P3DP. 25 The scattering angle was varied in steps of 0.5°over an angular range corresponding to the exchanged wave vector interval 0.5 рQр14 Å Ϫ1 . Scattering from the Al cell and the environmental background were also measured.…”

“…About 10 4 counts per point were accumulated for the deuterated sample resulting in a constant relative statistical error equal to Ϯ1% on the measured intensity. The measurements on the nondeuterated powder aimed at checking the reproducibility of the previous x-ray data 25 and no data reduction was applied to this set of experimental raw data.…”

“…In Ref. 25, exploiting the com-parison with the companion P3DP sample oxidized with Fe(ClO 4 ) 3 , it was concluded that the structural arrangement of the system could be affected by the size of the counterion (Cl Ϫ or ClO 4 Ϫ ), which prevents the formation of crystalline ordering inside the sample to a different extent. The data in Fig.…”

“…23,24 An extensive investigation of the molecular structure of P3DP and 3DP was carried out by wide-angle x-ray scattering. 25 The polymer was found to have a substantially coplanar structure of the heteroaromatic rings, with the alkyl group chains kinked out of the ring planes. Moreover, an average distance of ϳ3.5 Å between the parallel planes of the pyrrole rings was obtained.…”