Synthesis of monomers is the key and most labor-consuming step in the development of highly selective membrane materials. Polyalkylenesiloxanes show promise for separation of vapors of organic components from gas mixtures. The paper considers two approaches to the synthesis of 1,1,3,3,5,5-hexamethyl-2-oxa-1,3,5-trisilacyclohexane, a monomer for preparing poly-bis(dimethylsilmethylene)dimethylsiloxane, a promising polymer material for gas-separation and pervaporation membranes. Modified synthesis procedures using both approaches, closure of the six-membered ring via formation of the Si–O–Si or Si–C bond, are suggested. Comparative analysis shows that, among organomagnesium cyclization methods, the one-step method in a diethyl ether or diethyl glycol dibutyl ether should be preferred. The suggested procedure allows reaching the monomer yield as high as 75–80% and more.

The problems of the processing of waste polymers of the main types are considered. Particular attention is paid to works related to the use of modern waste conversion methods for the production of motor fuels and valuable petrochemicals. The processes of thermal and catalytic cracking, hydroconversion, and polymer metathesis are discussed in detail.

New norbornene type monomer bearing reactive triethoxysilyl group was synthesized, and its addition homo- and copolymerization with 3-trimethylsilyltricyclonon-7-ene was studied. The target monomer was obtained using regio- and stereospecific [2σ+2σ+2π] cyclo-addition of quadricyclane with vinyltrichlorosilane followed by the reaction of the formed cycloadduct with ethanol in the presence of triethylamine. Addition polymerization was investigated over the three-component Pd-containing catalytic system (Pd complex, Na+[B(3,5-(CF3)2C6H3)4]–(cocatalyst) and tricyclohexylphosphine). The N-heterocyclic carbene Pd complex (SIPrPd(cinn)Cl) with high activity and tolerance to the Si—O—C moieties was used as a catalyst. The yields of the homo- and copolymers were 24—68% depending on the monomer (comonomer): Pd: B: PCy3 ratio. The obtained addition polymers are high-molecular-weight amorphous products, the glass transition temperature of which exceeds 300 °C. The presence of reactive Si(OC2H5)3 groups in the homo- and copolymers made it possible to carry out a hard-to-realize cross-linking involving side substituents and followed by the formation of insoluble polymers.

Polydimethylsildimethylene-dimethylsiloxane (PSDMS) and polydimethylsiltrimethylenedimethylsiloxane (PSTMS) have been first studied as pervaporation membrane materials for the recovery of butanol from aqueous media. New synthesis procedures that make it possible to obtain the monomers 2,2,5,5-tetramethyl-1-oxa-2,5-disilacyclopentane (1) and 2,2,6,6-tetramethyl-1-oxa-2,6-disilacyclohexane (2) in high yields and with high purity required for subsequent polymerization have been developed. The optimum concentration of the crosslinking agent (tetraethoxysilane (TEOS)) of 5% has been found, which provides the maximum degree of crosslinking without sacrificing high values of separation factor and permeate flux. It has been shown that the permselectivity of PSDMS or PSTMS for butanol–water is higher by a factor of 1.5 or- almost 2, respectively, than the selectivity of the industrial membrane polymer, PDMS, at comparable values of the butanol permeability coefficient.

The stereochemistry of the cometathesis of cyclododecene (CDD) with hexene-1 in the presence of the MoCl5/SiO2–Me4Sn heterogeneous catalytic system has been studied. It has been established that CDD is the mixture of cis- (Z) and trans- (E) stereoisomers with the ratio of 30/70, respectively. It has been shown that the reactivity of the E-stereoisomer of CDD in the reaction of cometathesis is higher when compared to the Z-stereoisomer. Thus, when the conversion of CDD is 92%, the ratio E/Z = 6 : 94, i.e., the amount of the E-stereoisomer decreases from 70 to 7%, while the amount of the Z-stereoisomer increases from 30 to 93%, respectively.

The catalytic activity of heterogeneous catalytic systems based on molybdenum halides immobilized onto the silica gel surface in combination with organosilicon cocatalysts has been studied in a model reaction of hexene-1 metathesis at 27 and 50°C. It has been established that quite active catalysts are formed when using 1,1,3,3-tetramethyl-1,3-disilacyclobutane or triethylsilane as cocatalysts. Tetramethylsilane has exhibited no marked activity, while tetramethyltin has turned out to be the most effective cocatalyst. Possible routes of formation of active centers have been proposed for organosilicon cocatalysts.

Addition and metathesis copolymerization of 5-(trimethylsilyl) norbornene (TMSNB) and 5-ethylidene-2-norbornene (ENB) has been studied. High-molecular-weight metathesis copolymers have been obtained on the first-generation Grubbs catalyst based on the Ru carbene complex Cl2Ru(=CHPh)(PCy3)(2) with nearly quantitative yields. Addition copolymerization has been carried out on the Ni(II) naphthenate-methylaluminoxane (MAO) catalytic system. In both cases copolymerization proceeded without participation of ethylidene double bond. Copolymers of this type are promising ones for manufacturing stable highly permeable polymeric membranes, since they are capable for crosslinking.