GE-CONTAINING AND SN-CONTAINING POLY(P-XYLYLENE) - SYNTHESIS, STRUCTURE AND THERMAL-BEHAVIOR

Block copolymers of unsubstituted poly(p-xylylene)(PPX) and Ge- or Sn- organic bridged PPX (GePPX and SnPPX) were prepared by pyrolysis of sp ecially synthesized organometallic p-cyclophane precursors followed by deposition and polymerization of the thus produced p-xylylene monomer s. The copolymer structure and thermal behavior were investigated depe nding on deposition temperature (10 and -196 degrees C). The copolymer PPX-GePPX obtained from solid monomers deposited at -196 degrees C (2 a) consists of long quasi-independent PPX and GePPX blocks and has par acrystalline structure. Thermal treatment of 2a near 160 degrees C yie lds crystalline regions of PPX along with paracrystalline aggregates o f GePPX. Pyrolysis of this system near 300 degrees C in an inert atmos phere results in the formation of Ge crystals in PPX matrix. In contra st, the copolymer PPX-GePPX produced by simultaneous deposition and po lymerization at 10 degrees C (2a') contains shorter blocks of PPX and GePPX than the copolymer deposited at -196 degrees C. Copolymer 2a' tu rns to the amorphous state during thermal treatment, and its pyrolysis does not lead to Ge-crystal formation; hence the supra molecular stru cture of the polymer plays an important role in inorganic phase format ion. The copolymer PPX-SnPPX (2b) is formed only at a deposition tempe rature of -196 degrees C; deposition at 10 CC yields oligomeric resins . The structure of 2b is nearly the same as that of 2a; pyrolysis of 2 b in air results in SnO2-crystal formation in a PPX matrix.