JOURNAL OF MATERIALS SCIENCE LETTERS 8 (1989) 157-158 Poly(p-phenylene sulphide) single crystals LUCIO D'ILARIO, ANTONELLA PIOZZI Dipartimento di Chimica. Universita "'La Sapienza'" 00185 Roma. Italy Polymers exhibiting electrical conduction characteris- tics in the range of semiconductors and conductors are no longer unusual materials, although their properties have not yet been unambiguously explained. The infusibility, insolubility and the air instability of polyacetylene have not allowed a clear characteriz- ation of this material that, in many respects, could be the most interesting one. Poly(p-phenylene sulphide) (PPS), even if not so attractive as polyacetylene, is known as a high-performance polymer, noticeable for its mech- anical, thermal and electrical insulating properties [1], with the important characteristic of being fusible and melt-processable. In addition, upon doping with a strong Lewis acid such as AsF 5 [2-5], its electrical conductivity rises to ~ 1 f~ ~cm -~. Moreover, being soluble, PPS is easily characterizable in terms of phys- ico-chemical properties. The crystal structure of PPS in the melt-crystallized, stretched-film form has already been assessed [6] and only very recently the crystalliz- ation from dilute solutions of c~-chloronaphthalene has been reported in the literature [7]. The possibility offered by the crystalline form of PPS to establish unequivocal correlations between the polymer structure and its electrical properties has stimulated us, independently from the above- mentioned reference, to obtain single crystals of PPS from dilute solutions of diphenyl ether. Here we want to present the preliminary results of our investigation. The polymer used for our experiments is Ryton-V1 (Phillips Petroleum Company), the molecular weight being (Mn) = 11 000 to 12000. The crystallization experiments were carried out in an ad hoc-designed ,'? (D x 100. 60 20 L 0.i7 0.47 0.76 20 (deg) Figure 2 Small-angle X-ray scattering curve of PPS single-crystal powder. dry thermostat arranged within an aluminium cylin- drical block, electrically heated (consistency of tem- perature +0.5K). The crystallization temperature (Tc) range examined was 150 to 220°C. The polymer was dissolved under a nitrogen atmosphere in diphenyl ether (c = 0.1 wt %) near to the boiling temperature of the solvent (Tb = 257.9°C). The precipitated materials were filtered at the crystallization tempera- ture, always taking care to avoid contact with air, and then washed with ethyl alcohol. Finally the crystals were dried in vacua. Figure 1 Electronmicrograph of PPS singlecrystals precipitated at T c = 196.4°C from diphenyl ether solution (e = 0.1 wt %). Magnification 160000 ×. 0261-8028/89 $03.00 + .12 © 1989 Chapman and Hall Ltd. 1 57