Ge- and sn-containing poly(p-xylylene): synthesis, structure and thermal behavior

Abstract

SUMMARY Block copolymers of unsubstituted polyb-xylylene)(PPX) and Ge-or Sn-organic bridged PPX (GePPX and SnPPX) were prepared by pyrolysis of specially synthesized organometallic p-cyclophane precursors followed by deposition and polymerization of the thus produced p-xylylene monomers. The copolymer structure and thermal behavior were investigated depending on deposition temperature (10 and -196 "C). The copolymer PPX-GePPX obtained from solid monomers deposited at -196°C (2a) consists of long quasiindependent PPX and GePPX blocks and has paracrystalline structure. Thermal treatment of 2a near 160°C yields crystalline regions of PPX along with paracrystalline aggregates of GePPX. Pyrolysis of this system near 300°C in an inert atmosphere results in the formation of Ge crystals in PPX matrix. In contrast, the copolymer PPX-GePPX produced by simultaneous deposition and polymerization at 10 "C (2a') contains shorter blocks of PPX and GePPX than the copolymer deposited at -196°C. Copolymer 2a' turns to the amorphous state during thermal treatment, and its pyrolysis does not lead to Ge-crystal formation; hence the supramolecular structure of the polymer plays an important role in inorganic phase formation. The copolymer PPX-SnPPX (2b) is formed only at a deposition temperature of -196°C; deposition at 10°C yields oligomeric resins. The structure of 2b is nearly the same as that of 2a; pyrolysis of 2b in air results in Sn02-crystal formation in a PPX matrix.

Metal‐Containing Polymers: Cryochemical Synthesis, Structure, and Physicochemical Properties

“…Organogermanium blocks of the crystalline block copolymer decompose in an inert atmosphere, giving Ge microcrystals in a PPX matrix. Thermal treatment of amorphous block copolymers in the same conditions also leads to a total loss of Ge-organic structures, however, without formation of Ge crystals [33]. So, one can conclude that the supramolecular organization of the polymer produced by the cryochemical synthesis determines the direction of thermal decomposition of organometallic polymer fragments.…”

“…Organometallic derivatives of poly-p-xylylene (PPX) with Ge and Sn atoms covalently bonded to polymer chains have been synthesized by a vapor deposition technique using bridged [2,2]-paracyclophanes with corresponding organometallic groups [32,33]. Pyrolysis of these cyclophanes, along with polymerization of the p-xylylene monomer mixture, is shown in Scheme 2.2.…”

“…Deposition of monomers at 77 K, followed by thermal low-temperature solid-state polymerization of the formed monomer composite, leads to crystalline block copolymers, whose structure, most probably, corresponds to that of microcrystalline monomer deposits. At the same time, deposition and polymerization of monomers at 283 K in conditions of high molecular mobility results in amorphous block copolymers or liquid-like oligomers [33]. The thermal decomposition of organotin units of corresponding crystalline copolymer in air yields SnO 2 microcrystals.…”

Organometallic Polymers of Germanium, Tin and Lead

“…Polycarbogermanes. Unsaturated polycarbogermanes were prepared by the anionic ring-opening polymerization of 1,1-dimethyl-1-germacyclopent-3-ene 131 Polycarbogermane and polycarbostannane block copolymers 56 134 were prepared by pyrolysis of the organogermanium and organotin bridged p-cyclophanes 55 followed by deposition polymerization of the p-xylene monomers thus produced (Scheme 29).…”

Effect of Thermal Annealing on Structure and Optical Properties of Poly(p-xylylene)–PbS Thin Films

“…By varying intensities of the corresponding flows, it is possible to control the thickness of the films, as well as monomer and filler concentrations. In general, the VDP technique allows us to use not only semiconducting (e.g., binary CdS and ZnS compounds or elemental Ge), but also metallic fillers. The structure and properties of PPX-based composites with metallic filler have been studied for silver, titanium, nickel, palladium, tin, and aluminum nanoparticles.…”