Acta Chimica 80. (1974)

1. szám - Hardy Gyula–Cser Ferenc–Nyitray Károly: Investigations in the field of solid state polymerization, XXXII. – Topotactic solid state polymerization of vinylene carbonate

Acta Chimica Academiae Scientiarum Hungaricae, Tomus 80 (l),pp. 41 — 48 (1974) INVESTIGATIONS IN THE FIELD OF SOLID STATE POLYMERIZATION. XXXII TOPOTACTIC SOLID STATE POLYMERIZATION OF YINYLENE CARBONATE Gy. Hardy, F. Cser and K. Nyitray (Research Institute for the Plastics Industry, Budapest) Received April 12, 1973 In the polymerization of vinylene carbonate single crystals, a new crystalline phase appears with cell dimensions a’ = 11.02 Á, 6’ = 9.39 A, and c’ > 4.8 Á, as determined from Weissenberg diffractograms. Densities of the polymerizing systems are higher than those expected on the basis of the additivity rule. The first period of the polymerization has a linear kinetic character and can he regarded as a topo­­tactic, heterogeneous, solid state reaction. In the advanced stage of polymerization, a stable binary polymer/monomer system is formed preceded by an intermediate melting. The precipitated polymer is amorphous with a chain period of 3.23 Á which is longer than that of the primarily formed crystalline polymer (3.13 Á). For the struc­ture of the crystalline polymer, a 3, helix is proposed consisting of syndiotactic segments. In our previous papers [1, 2], the characteristics of solid state polymer­ization of vinylene carbonate (VC) were reported. It was established that the course of direct solid state polymerization showed stepwise kinetic character from 0 to 12°C. The initial linear section of the kinetic curve was supposed to represent a topotactic process on the basis of our studies on binary systems. Crystal structure of the VC monomer was also solved [3], identifying the location of vinyl groups in the (010) and (020) planes of the crystal lattice. Along axis a in the plane, 4 C. . .C atomic distances are less than 4 Á; a C. . .C distance of 3.78 Á also exists at an angle of about 60° to the plane. Thus the conditions of a topotactic reaction [4, 5] are redundantly ensured. The present paper aims at determining the character of the topotactic reaction and at explaining the formation of an essentially amorphous polymer. Experimental X-Ray single crystal patterns Single crystals were grown at a rate of 10~3 cm sec-1 from purified VC in a glass capillary tube 0.6 mm in diameter, using a gas stream of —10°C. The crystal was purified by repeated zone melting then its temperature was adjusted to —3 + 2°C. Single crystals 15 mm long were obtained. Axis c of the needle-shaped crystal was directed at an angle of 41° to the axis of the capillary tube, i.e. the needle axis was perpendicular to the (201) plane of the Acta Chim. (Budapest) 80, 1974

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