M. P. Filatova

Ring-opening polymerization of cycloolefins by tungsten(VI) chloride—acetylene catalyst systems

Abstract The ring-opening polymerization of various cycloolefins was carried out using catalytic systems for metathesis that did not contain any organometallic co-cotalysts. They were formed by the interaction of equimolar amounts of tungsten(VI) halides (WCl 6 or WOCl 4 ) with monosubstituted acetylenic hydrocarbons (phenyl-, n-butyl- or trimethylsilylacetylene). It was possible to enhance the activity of these systems by adding small amounts of oxygen-containing substances. The use of WCl 4 -phenyl-acetylene catalyst clarified the question of polymerizability of methyl-substituted cyclopentenes. It was shown that a mixture of 3-methyl- and 4-methylcyclopentenes gave polymers having a polymethylpentenamer structure. The thermodynamic parameters of this polymerization, which has an equilibrium character, were evaluated. Reactions occurring during the interaction of WCl 6 with phenylacetylene were studied by GC-MS. The data obtained indicated that the first step in the interaction is insertion of an acetylene molecule into the WCl bond. Some considerations are suggested concerning the possible pathways for formation of metal-carbene active centres. 13 C NMR study of the copolymers obtained from phenylacetylene and cyclopentene or norbornene showed that their chains included sequences with random distributions of co-monomer units. The implications of this fact for the mechanistic interrelation between the cycloolefin metathesis polymerization and the addition polymerization of acetylene are discussed.

Comparative Reactivity of Me 3 Si-substituted Norbornene Derivatives in Ring-Opening Metathesis Polymerization

Silyl substituted norbornenes and their derivatives are effective monomers in the synthesis of new prospective polymer materials for gas separation membranes by metathesis and addition polymerization. Comparative activity of norbornenes (NB), norbornadienes (NBD) and tricyclononenes (TCN) with different spatial arrangement of one or two Me3Si substituents in ring-opening metathesis polymerization (ROMP) in the presence of Grubbs initiator Cl2(PCy3)2Ru =CHPh were studied by NMR and GC. It was shown that the rate of the initiation was lower than the propagation for all monomers and the highest activity was inherent to the exo-5-trimethylsilylnorbornene (5-NBSi) and 3-trimethylsilyltricyclononene (3-TCNSi). Disubstituted TCN turned out to be more active than NB having the same number and position of the substituents. The latter were more active than the corresponding NBD. It was found that syn- and anti-isomers of 3-TCNSi polymerized with close rates in contrast to exo- and endo-substituted 5-NBSi, for which polymerization rates were substantially different. Special behavior of monomers with bulky substituents in the geminal position was observed: 5,5-NBSi2 was inactive in the presence of the 1st generation Grubbs initiator, whereas it was polymerized in the presence of the 2nd generation one. Quantum-chemical calculations were in agreement with experimental data and evidenced the influence of energy, electronic and structural properties of the norbornene-type monomers studied on their activity in ROMP.

Copolymerization of 5-(trimethylsilyl)norbornene and 5-ethylidene-2-norbornene

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) naphthenatemethylaluminoxane (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.

Modification of silicon-substituted polynorbornenes by epoxidation of main chain double bonds

Postpolymerization modification of metathesis Si-containing polynorbornenes by epoxidation of double bonds of the main chain was carried out for the first time. New polynorbornenes containing one or two side Me3Si substituents in a monomer unit and oxirane fragments in the main chain were obtained and characterized. Some features of epoxidation of polynorbornenes by 1.1-dimethyldioxirane (formed in situ) or m-chloroperbenzoic acid were studied. It was shown that m-chloroperbenzoic acid was an effective epoxidation agent, which did not affect Si−C bonds in polynorbornenes. It was found that the preparation of high-molecular-weight epoxidated polynorbornenes required one to introduce an oxidation inhibitor into the reaction mixture and to perform the reaction in toluene. Chlorine-containing solvents, such as chloroform and chlorobenzene, promoted the destruction of polynorbornenes. It was shown that the introduction of oxirane fragments into the polynorbornene main chain increased its Tg by 15−40°C.

Experimental and Theoretical Study of [2σ + 2σ + 2π]–Cycloaddition of Quadricyclane and Ethylenes Containing Three Silyl-Groups

The reaction of [2σ + 2σ + 2π]-cycloaddition of quadricyclane with olefins is an attractive way for regio- and sterospecific synthesis of norbornene derivatives (exo-tricyclononenes) with desired substituents. The presence of Cl3Si-containing groups in such compounds permits different monomer modifications for the development of new materials. Herein, for the first time the theoretical and experimental study of the behavior of different ethylenes containing three silyl-groups in the reaction of [2σ + 2σ + 2π]-cycloaddition with quadricyclane was systematically performed. Based on the data obtained for this reaction the activity scale of the ethylene derivatives was established, and the explanations for an ethylene activity were suggested. As a result, a new family of Si-containing tricyclononenes was successfully synthesized. As an example of a possible modification, the methylation of the sterically hindered cycloadducts was investigated and the conditions for full methylation were found. Considering that gas permeability of polymers increases with the increase of a number of the side Me3Si-groups, the compounds are interesting monomers for synthesis of membrane polymers possessing high gas permeability values.

New composites based on poly(3-trimethylsilyltricyclononene-7) and organic nature fillers (calixarenes & cyclodextrins)

Herein we describe new materials for membrane gas separation process with improved selectivities towards different pairs of gases. Organic nature fillers (modified calix[4]arenes, calix[8]arenes and modified α-, β-, γ-cyclodextrins) were used as additives to poly(trimethylsilyltricyclononene-7) (PTCNSi1)in order to study correlations between structure of the filling agent and gas transport parameters of the composite membranes. It was shown a positive influence of calixarenes and cyclodextrins as additives on permselectivity of the membranes. For instance, selectivity towards H2/CH4 gas pair increased almost in 2.4 times when calix[4]arene with Et- and tert-Bu- group was introduced into polymeric matrix. Detailed study of the PTCNSi1 adsorbtion/desortion data is presented. The obtained composites were characterized by TEM, WAXD, PALS and BET analysis.

Structure and composition of guanidine acrylate, guanidine methacrylate, their homopolymers, and copolymers with diallyldimethylammonium chloride

Structures and compositions of the monomers guanidine acrylate and guanidine methacrylate, their homopolymers, and copolymers with diallyldimethylammonium chloride enriched in acrylate comonomer units were determined. It was shown that ampholytic copolymers, owing to their ionic nature, contained comonomeric guanidine acrylate or methacrylate units and diallyldimethylammonium chloride units, as well as the acrylate comonomer with the diallyl counterion and polymeric acrylate and diallyl ion pairs. It follows from IR and 1H NMR data that guanidine methacrylate has the same structure (with two hydrogen bonds) in the solid state and in solutions. Guanidine acrylate structures in the solid state and in dimethylsulfoxide are identical and analogous to guanidine methacrylate structure in this solvent. In water, the guanidine acrylate structure has another type of hydrogen bonding (with one hydrogen bond, where the proton is shifted toward the guanidine group). These features of hydrogen bonding of guanidine acrylate and guanidine methacrylate are also retained in their homopolymers and copolymers with diallyldimethylammonium chloride. It was shown that the thermal stability of the copolymers was higher than that of their homopolymers, confirming the formation of intramolecular ion pairs of oppositely charged units of ampholytic copolymers. Moreover, the thermal stability of guanidine methacrylate-diallyldimethylammonium chloride copolymers is higher than that of guanidine acrylate-diallyldimethylammonium chloride copolymers.

Binary and ternary copolymers of norbornene and its derivatives with acrylates as novel materials for optoelectronics

The free-radical copolymerization of norbornene with methacrylate, tert-butyl acrylate, acrylic acid, and decyl acrylate and the benzoyl peroxide-initiated copolymerization of tert-butyl norbornenecar-boxylate and tert-butyl acrylate are studied for the first time. Novel binary and ternary copolymers are obtained, and experimental conditions (the temperature and time of reaction, initiator concentration, and comonomer ratio) affecting the compositions, molecular masses, glass-transition temperatures, and yields of the copolymers are determined. It is ascertained that the copolymers of norbornene with methyl acrylate and tert-butyl acrylate have high transparency (93–94%) in the range 300–800 nm. Because of this fact, the copolymers show promise as matrices for creation of nanocomposite materials suitable for optoelectronic applications.

Radical Polymerization of Protonated Diallylammonium Monomers in Bidistilled Aqueous Solution: Kinetic Study

The kinetics of the radical polymerization of protonated monomers of the diallylammonium series (diallyl- and diallylmethylammonium trifluoroacetates) in bidistilled aqueous solution (quartz bidistiller) is studied in situ using 1Н NMR spectroscopy. The rates of monomer consumption and polymer accumulation in the range of 30–50°С are determined. For diallylammonium trifluoroacetate, the effective activation energy of polymerization and the constant of chain transfer to the monomer (30°С) are estimated. It is found that the initial rates of polymerization are comparable with the rates of polymerization of quaternized analogs and the constant of chain transfer to the monomer and the activation energy of polymerization are close to the analogous characteristics of polymerization in the case of quaternized diallyldimethylammonium chloride. It is shown that for polymerization in bidistilled solution, the constant of chain transfer to the monomer (30°С, 3.8 × 10–3) is more than three times lower than that for polymerization in monodistillate (30°С, 12.2 × 10–3) and the ММ of the polymers is ~2.4 times higher than the ММ of the samples synthesized in monodistillate under the same conditions. It is ascertained that standard electrolyte admixtures in distilled aqueous solution considerably affect radical chemical reactions involving protonated forms.

Epoxidation of Multiblock Copolymers of Norbornene and Cyclooctene

The epoxidation of double bonds in random multiblock copolymers of norbornene and cyclooctene is studied for the first time. The initial copolymers with different composition and average block length are synthesized via the cross-metathesis reaction between polynorbornene and polycyclooctene in the presence of the first-generation Grubbs catalyst. New multiblock copolymers containing oxirane fragments in the backbone are obtained with a yield of 85–92% through epoxidation conducted under the action of m-chloroperbenzoic acid in toluene. The kinetics of epoxidation of polynorbornene, polycyclooctene, and their multiblock copolymers in deuterochloroform and deuterobenzene is investigated via the in situ monitoring of transformation of double bonds using 1Н NMR spectroscopy. It is shown that on the whole the modification of cyclooctene units occurs more easily in copolymers than that in the homopolymer. The thermal properties of epoxidized homo- and copolymers are examined. It is found that upon epoxidation the glass-transition temperature and the melting temperature of multiblock copolymers increase by 40–50 and 20–30°С, respectively, wherein the degree of crystallinity and the temperature of melting grow with the length of the cyclooctene block.