Structure of poly(p-phenylene sulfide).

We have examined the unit-cell structure of the important high- temperature and high-strength polymer, poly(p-phenylene sulfide) (PPS); this has recently been in dispute, with two different models proposed from oriented and unoriented polycrystalline specimens, respectively. Having obtained the first single crystals of PPS from solution and from thin films of the melt (the latter in both flat-on and edge-on orientations), we determined the lattice dimensions of the orthorhombic unit cell using electron diffraction. These are bar under a = 8.68 angstroms, bar under b = 5.66 angstroms, and bar under c = 10.26 angstroms, in agreement with the original model based upon alternating +-45degrees inclinations of the phenyl rings to the plane of the sulfur bonds.