Structural studies of crystalline poly(p‐phenylene oxides) I. Poly(p‐phenylene oxide)

Abstract

Using X-ray diffraction the structure of crystalline poly(p-phenylene oxide), 9 has been determined. The unit cell is orthorhombic, with the dimensions: a = 8.07 A, b = 5.54 A, and c (fiber axis) = 9.72 A. The unit cell contains four monomeric units. TWO molecular chains pass through a unit cell, one through the center, the other through a corner. Two monomeric units are contained in the fiber identity period. The space group is Pbcn -0:;. The oxygen atoms and the centers of gravity of the phenylene groups are at special positions. The oxygen atoms of one molecular chain are arranged in a zig-zag manner in the (100) plane. The oxygen bond angle is about 124'. The rotation angle of the phenylene groups round the 0-0 axis has been determined by comparing calculated and observed intensities. ZUSAMMENFASSUNG: Die Struktur von kristallinem Poly(p-phenylenoxid), -[ -0 -0 -] , 9 wurde mit Hilfe von Rontgenstrahlbeagungsmethoden ermittelt. Die Einheitszelle ist orthorhombisch; die Dimensionen sind folgende: a = 8,07 A, b = 5,54 A und c (Faserachse) = 9,72 A. Die Einheitszelle enthalt vier monomere Einheiten. Zwei Molekiilketten laufen durch eine Elementarzelle, eine durch das Zentrum und eine durch eine Ecke. Die Periode in der Richtung der Faserachse enthiilt zwei monomere Einheiten. Die Raumgruppe ist Pbcn -Dit. Die Sauerstoffatome und die Zentren der Phenylengruppen befinden sich an speziellen Stellen. Die Sauerstoffatome einer Molekiilkette sind in der (100)-Ebene im Zickzack angeordnet. Der Sauerstoffvalenzwinkel betrkigt etwa 124'. Der Rotationswinkel der Phenylengruppen um die 0-0-Achse herum wurde durch Vergleichen von berechneten und beobachteten Intensitaten ermittelt. *) Part of this paper was presented a t the Microsymposium on Structure of Organic Solids, Prague, Czechoslovakia, 1968, Communication C 4. -[--(r>-O-],

Molecular modelling of poly(aryl ether ketones). I. Aryl��aryl interactions in crystal structures

“…Furthermore the ring conformation at the global minimum was, in each case, close to that obtained in X-ray studies. Thus for PEK the calculated value of ~ 32 ° compares with an observed twist angle of 34 ° [4] whilst in PE the approximate experimental value of about 40 ° [1] is in reasonable agreement with the calculated twist angle of 36-38 °. The energy differences between the calculated and experimental minima are, in each case, very small.…”

“…Poly(phenylene oxide), PE [1], poly(aryl ether ketone), PEK [2][3][4] and poly(aryl ether ether ketone), PEEK [5][6][7][8] (Fig. 1) have broadly similar crystal structures but exhibit some differences in the unit cell parameters, ring conformations and structural variation with temperature.…”

Poly(P‐phenylene sulfide) hexafluoroarsenate: A novel conducting polymer

“…PPO is known to have a crystal structure very like that of PPS; 6 thus it is tempting to attribute the difference in results to the lack of low lying d-orbitals in the oxygen derivative. This argument is complicated, however, by the known greater ease of oxidation of organosulfur compounds compared to their oxygen analogs.…”

“…these systems are expected to be more flexible than the parent poly(p-phenylene) and perhaps to display better processing characteristics. 6 and poly(p-phenylene sulfide) (X=S) 7 are soluble polymers with well defined glass transition temperatures and melting points. We now find that poly(p-phenylene sulfide) (PPS) is also capable of being doped to high levels of conductivity using the strong electron acceptor arsenic pentafluoride.…”

Crystallographic Equivalence of Ether and Ketone Groups in Poly(aryl ether ketone)s

“…[1] They pointed out that the crystal structures of PEK and PEEK are similar to that of poly(phenylene oxide) (PPO). [2] After that, many studies on the crystal structures of PEEK and the related polymers of PAEKs were performed. [3 -13] It has been shown that the chains in PEEK crystals adopt an extended conformation with the phenylene rings alternating an angle of ca.…”