CYCLOPOLYMERIZATION OF DIPROPARGYL DERIVATIVES BY Cp2MoCl2-EtAlCl2 CATALYST SYSTEM

ABSTRACT

A Cp₂MoCl₂-EtAlCl₂ catalyst system was used for the cyclopolymerization of various dipropargyl derivatives having different functionalities. These catalyst systems were found to be very effective for the polymerization of some dipropargyl monomers to give a relatively high yield of polymer. The polymerization behaviors were strongly dependent on the functionalities of dipropargyl monomers. The polymerization of such dipropargyl monomers as 1,6-heptadiyne, diphenyldipropargyl methane, diethyldipropargyl malonate, etc. proceeded well to give a quantitative yield, whereas this catalyst system was found to be less effective for the polymerization of dipropargyl monomers having perfluoroalkyl groups and quaternary ammonium salts. The polymer structure of the resulting polymers was characterized by various instrumental methods such as NMR, IR, and UV-visible spectroscopies to have a conjugated polyene backbone system with cyclic recurring units. The portion of 5- and 6-membered rings of the present conjugated cyclopolymer were also discussed.     

Synthesis of A2B star block copolymers from a heterotrifunctional initiator

We described the obtention of A₂B star block copolymers through the use of a new heterotrifunctional initiator. That way, well‐defined (PCL)₂‐arm‐PtBuMA and (PCL)₂‐arm‐PS star block copolymers have been synthesized from a heterotrifunctional initiator bearing two hydroxyl groups able to initiate ROP of CL (with AlEt₃ or Sn(Oct)₂ as coinitiator) and a bromide function able to initiate ATRP of tBuMA or styrene. Firstly, we have proceeded using a sequential process (two‐steps), leading to an intermediate macroinitiator. Secondly, attempt to polymerize these two monomers in a simultaneous process (one‐step), that is directly from the mixture of monomers, initiator, coinitiators, and solvent, has been realized and has shown that some interferences between the two polymerizations occurred, leading to an inhibition of ATRP when Sn(Oct)₂ was used and an unexpected increase in control when AlEt₃ was used as catalyst for the ROP (obtention of well‐defined (PCL)₂‐arm‐PtBuMA with pdi of 1.18). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1796–1806, 2006     

The CO_2 laser-induced radical-chain reactions between CH_3CF_2H and chlorine-atom donors CF_2ClCFCl_2, CF_3CCl_3 CFCl_3 or CF_2Cl_2

The CO_2 laser induced room temperature reactions of CH_3CF_2H or another protium-donorCH_3CHClCH_3 with chlorine-atom donors (Z--Cl) CFCl_2CF_2Cl, CF_3CCl_3, CFCl_3 or CF_2Cl_2, havebeen investigated. Some of these reactions can yield two important monomers (CF_2=CH_2 andCF_2=CFCl) for fluoropolymers simultaneously. The yield dependence of these two alkenes on experi-mental conditions has been studied. A laser-initiated chain process is supported by identifica-tion of Z--H intermediates in these reactions.     

Isomerization polymerization of β-propiolactones carrying side-chain ester groups

Based on our recent discovery of the isomerization polymerization of β-(2-acetoxyethyl)-β-propiolactone into poly-δ-ester,^1,2 we examined the generality of this phenomenon by using two related monomers. The catalysts were (EtAlO)_n and Et(ZnO)₂ZnEt. The side-chains in the monomers selected were the (CH₃)₂CHCOO? CH₂CH₂? (2) and (CH₃)CICHCOO? CH₂CH₂? (3) groups in which steric effects are almost identical but electronic effects are in opposition. The monomers yielded isomerized poly-δ-ester units, depending on the terminal substituent groups in the side-chain. These observations can be interpreted with the bicyclic intermediate proposed in the earlier work. Monomer (2) was reactive and produced a poly-δ-ester structure most readily, probably because of the higher electron density at the side-chain ester group which coordinated with the catalyst. In contrast, monomer (3) was less reactive, and the probability of isomerization was the lowest, i.e., the electron deficient side-chain ester group apparently interfered with the formation of the intermediate, especially in the Zn-catalysis. Equibinary random copolymers were prepared from (2) and (3) according to the catalyst and polymerization conditions chosen.     

Novel Copolymers of Styrene. 18. Halogen Ring-Trisubstituted Methyl 2-Cyano-3-Phenyl-2-Propenoates

Novel trisubstituted ethylene monomers, halogen ring-trisubstituted methyl 2-cyano-3-phenyl-2-propenoates, RPhCH=C(CN)CO₂CH₃, where R is 4-bromo-2,6-difluoro, 3-chloro-2,6-difluoro, 4-chloro-2,6-difluoro, 2,3,5-trichloro, 2,3,6-trichloro, and 2,4,5-trifluoro, were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of halogen ring-trisubstituted benzaldehydes and methyl cyanoacetate, and characterized by CHN analysis, IR, ¹H and ¹³C-NMR. All the ethylenes were copolymerized with styrene (M₁) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, ¹H and ¹³C-NMR. The order of relative reactivity (1/r₁) for the monomers is 3-Cl-2,6-F₂ (4.2) > 4-Cl-2,6-F₂ (3.9) > 4-Br-2,6-F₂ (1.8) > 2,3,5-Cl₃ (1.1) > 2,4,5-F₃ (0.9) > 2,3,6-Cl₃ (0.5). Relatively high T_g of the copolymers in comparison with that of polystyrene indicates a decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (3.1–3.9% wt), which then decomposed in the 500–800°C range.     

Preparation and addition polymerization of substituted 2-oxazolines

The new oxazoline-containing monomers, 4-acrylyloxymethyl-2,4-dimethyl-2-oxazoline (AOMO), 4-methacrylyloxymethyl-2,4-dimethyl-2-oxazoline (MAOMO), 4-methacrylyloxymethyl-2-phenyl-4-methyl-2-oxazoline (PMAOMO), and the previously known monomer, 2-isopropenyl-4,4-dimethyl-2-oxazoline (IPRO), were synthesized for addition polymerization studies. The monomers were homopolymerized in benzene using a free radical initiator and in aqueous media using emulsion techniques. Molecular weights of 8,000–15,000 (M?_w) were obtained for the homopolymers. Copolymerization studies were carried out with AOMO, MAOMO, and IPRO as M₁, and methyl methacrylate (MMA), methyl acrylate (MA), styrene (STY), acrylonitrile (AN), and vinyl acetate (VA) as M₂ for each case of M₁. Relative reactivity ratios for the fifteen copolymers and Q and e values for the three oxazoline monomers were determined. The r₁ values for AOMO and MAOMO copolymerizations indicated a lower value of k₁₁ than expected, presumably because of steric effects. The r₁ values in the IPRO copolymerizations were somewhat larger than expected. It was proposed that significant electron donation to the radical center of IPRO·by resonance effects occured.     

Novel Copolymers of Halogen Ring Substituted 2-Cyano-3-Phenyl-2-Propen- Amides and Styrene

ABSTRACT

Electrophilic trisubstituted ethylene monomers, halogen ring substituted 2-cyano-3-phenyl-2-propenamides, RC₆H₄CH=C(CN) CONH₂ (where R is o-Cl, m-Cl, p-Cl, p-Br, and p-F) were prepared by Knoevenagel condensation. Novel copolymers of the propenamides and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator at 80°C. The order of reactivity (1/r ₁) for the monomers (M₁=styrene) was o-Cl (1.42) > p-F (1.19) > p-Cl (0.70) > m-Cl (0.60) > p-Br (0.44).     

Photosensitized Solid-state Polymerization of Diacetylenes in Nanoporous TiO2 Structures

In situ topochemical polymerization of two diacetylene monomers within nanoporous TiO₂ thin films was carried out under visible light irradiation. One of the monomers used contains a carboxylic acid group, which could help to link the monomer onto the TiO₂ surface covalently. UV-Vis absorption and Raman studies showed that both monomers were successfully photopolymerized. These results suggest that the covalent linkage of the diacetylene to the nanoparticle through the carboxylic acid group is not needed. Since photopolymerization of diacetylene is typically induced by excitation of the monomer at λ< 300 nm, the observed red shift of the photopolymerization wavelength is attributed to the photosensitization effect of TiO₂. The morphological study of the polydiacetylene/TiO₂ nanocomposite revealed that the diacetylene monomers were polymerized in the vicinity of the TiO₂ nanoparticles. This is attributed to the fact that the electron-transfer process occurs at the interface of nanocrystalline TiO₂ (nc-TiO₂) and the diacetylene monomer and the polymerization is expected to be initiated near the nc-TiO₂ surface. Photopolymerization of the carboxylated diacetylene monomer with other oxides nanoparticles, such as ZnO and SiO₂ was also investigated.     

Cyclodextrins in polymer chemistry: Influence of methylated β-cyclodextrin as host on the free radical copolymerization reactivity ratios of isobornyl acrylate and butyl acrylate as guest monomers in aqueous medium

Methylated β-cyclodextrin (me-β-CD) was used to complex the hydrophobic monomers isobornyl acrylate ( 1 ) and butyl acrylate (2) yielding the water-soluble host/guest complexes isobornyl acrylate/me-β-CD ( 1a ) and butyl acrylate/me-β-CD ( 2a ). The included monomers were copolymerized in water by free-radical mechanism and the kinetics were studied. In order to evaluate these results, the corresponding uncomplexed monomers 1 and 2 were also copolymerized in organic solution. The reactivity ratios of 1a and 2a (r _1a = 0.3, r _2a = 1.7) differ significantly from the reactivity ratios of the corresponding uncomplexed acrylates 1 and 2 in organic solution (r ₁ = 1.3, r ₂ = 1.0). In addition, we found that the weight averages of the copolymers prepared by using me-β-CD are significantly higher than those of the corresponding polymers prepared from uncomplexed monomers in organic solution.     

Electrochemical study of heteronuclear complex [Cp(CO)2MnCu(μ-C=CHPh)(μ-Cl)]2

The electrochemical behavior of the heteronuclear dimeric vinylidene complex [Cp(CO)₂MnCu(μ-C=CHPh)(μ-Cl)]₂ (I) is studied using polarography, cyclic voltammetry, and controlled-potential electrolysis on mercury and platinum electrodes in acetonitrile. The dimer is reduced in two two-electron stages: at the first stage, metal-halogen bonds are broken and binuclear monomers [Cp(CO)₂MnCu(μ-C=CHPh)(Cl)]^? are formed; at the second stage, mononuclear manganese complexes Cp(CO)₂Mn=C=CHPh, metallic copper, and chloride ions are formed. The two-electron oxidation of dimer [Cp(CO)₂MnCu(μ-C=CHPh)(μ-Cl)]₂ also results in the formation of binuclear monomers, which decompose to complex Cp(CO)₂Mn=C=CHPh, Cu²⁺ ions, and Cl^? ions.     

Copolymerisation of 2-hydroxyethyl methacrylate with siloxanyl monomers

Acryloxymethylpentamethyldisiloxane (AMS) and methacryloxymethylpentamethyldisiloxane (MMS) have been prepared and purified chromatographically. Some physicochemical properties have been measured for these monomers as well as for highly purified 2-hydroxyethyl methacrylate (HEMA). Hydroxyl group analysis on copolymers of AMS with HEMA and of MMS with HEMA, obtained by free radical copolymerisation to low conversion, enabled monomer reactivity ratios to be determined by several procedures. The average values were r_HEMA = 0.86, r_AMS = 0.55 and r_HEMA = 0.97, r_MMS = 0.33. These values have been invoked in computing integral curves for the instantaneous copolymer composition throughout the whole range of conversion.     

Synthesis and characterization of hyperbranched aromatic polyamide copolymers prepared from AB2 and AB monomers

A series of hyperbranched aromatic polyamide copolymers has been prepared and characterized from direct polycondensation of AB₂ and AB monomers. Structure of the monomers and the molar ratio of AB₂/AB showed strong influence on the properties of resulting copolymers. A small amount of AB₂ branching unit improved markedly the solubility of the resulting copolymer. Mark-Houwink parameters of the copolymers were essentially independent of the mole ratio of the monomers. The physical and mechanical properties of resulting copolymers were influenced not only by the mole ratio of monomers, but also by the structure of the monomers employed.     

Unique dual function of La(C5Me5)[CH(SiMe3)2]2(THF) for polymerizations of both nonpolar and polar monomers

A half‐metallocene‐type complex, La(C₅Me₅)[CH(SiMe₃)₂]₂tetrahydrofuran (THF) 1 , showed the dual function of performing the controlled polymerizations of nonpolar monomers such as ethylene and styrene as well as polar monomers like methyl methacrylate, hexyl isocyanate, and acrylonitrile in high yields. On the other hand, the metallocene‐type rare‐earth metal complexes, [(C₅H₄SiMe₃)₂Y(μ‐Me)]₂ 2 and (C₅Me₅)₂YMe(THF) 3 , showed relatively low catalytic activity. The structure of complex 2 was characterized by X‐ray analysis. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1382–1390, 2001     

Molecular and electronic structure of several heterofullerene BNC58 and B2N2C56 oligomers and [B2N2C56] n macromolecule

Molecular and electronic structure of heterofullerene BNC₅₈ (C _s) and B₂N₂C₅₆ (C _2h) monomers, B₂N₂C₁₁₆ and B₄N₄C₁₁₂ dimers, and B₆N₆C₁₆₈ trimer (the last three molecules withC _2h symmetry) was simulated by the MNDO method. Clusters BNC₅₈ and B₂N₂C₅₆ are formed by replacement of carbon atoms participating in one or two of the most distant oppositely lying (6,6)-type C−C bonds in fullerene C₆₀ by B and N atoms. In one of the two studied isomers of the B₂N₂C₁₁₆ dimer, the monomers are linked by the four-membered carbon cycle, while the heteroatoms form the most distant oppositely lying bonds of the dimer. In the other isomer of the B₂N₂C₁₁₆ dimer, as well as in the B₄N₄C₁₁₂ dimer and B₆N₆C₁₆₈ trimer, the monomers are linked by four-membered B₂N₂ cycles with alternation of the atoms. For all the systems studied, the optimum geometric parameters, heats of formation, ionization potentials, and atomic charges were calculated. Dimerization energies of heterofullerenes BNC₅₈ and B₂N₂C₅₆ lie in the range from 33 to 49 kcal mol⁻¹. It was found that the B₂N₂C₁₁₆ dimer, in which the monomers are linked by the four-mernbered carbon cycle, is the most stable system. In the case of B₂N₂C₅₆ trimerization, the energy gain (compared to the triple monomer energy) is about twice as large as the dimerization energy. Molecular structure of the quasi-linear [B₂N₂C₅₆) _n macromolecule was simulated, and extended Hückel calculations of its energy band structure by the crystal orbital method were performed. It was found that the electron energy spectrum is of semiconducting type (the band gap is equal to 1.27 eV. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 431–435, March, 1999.     

Synthesis and characterization of optically active poly(2-phenylvinyl alkyl ethers) and corresponding monomers

cis-(S) (+)-2-phenylvinyl alkyl ethers having as alkyl groups 1-methylpropyl (I), 2-methylbutyl (II), and 3-methylpentyl (III) were synthesized by condensation of phenylacetylene with the corresponding sodium alcoholates. Polymerization of monomers was performed cationically with BF₃ · Et₂O or SnCl₄ in toluene or CH₂Cl₂. Specific rotations of polymers were compared with those of low molecular weight model compounds prepared by hydrogenation of monomers, and it was concluded that the difference in the rotation of poly I and model compound ([α]_D 19.3° and 5.68°, respectively) and poly II and model compound ([α]_D 11.4° and 3.00°, respectively) can be attributed to the asymmetric induction at carbon atoms of the principal polymer chain.     

Ab initioSCF-Berechnungen von JO2F3

Two possible monomers of IO₂F₃ (C_2v, trigonal-bipyramidal and C_s, tetragonal-pyramidal) have been calculated by theLCGO?MO?SCF-method. The calculations indicate the C_2v conformation to be strongly favoured by its total energy. The electronic structure of the compound is discussed on the basis of population analysis and electron density maps. A comparison of the¹⁹F-NMR spectrum of (IO₂F₃) _n , with these calculated data supports the results indicated by the energy values.     

The synthesis and 1H NMR study of vinyl organometallic monomers: (η5-C5H4CHCH2)M(CO)2(NO) (M = Cr,Mo, W) and (η5-C5H4CHCH2)M(CO)2 (M = Co,Rh, Ir)

A reaction between 6-methylfulvene and lithium diisopropylamide in THF solution produces vinylcyclopentadienyllithium in yields of 85–95%. The ¹H NMR spectrum of this air-sensitive organlithium reagent has been recorded in THF-d₈. Reactions of vinylcyclopentadienyllithium with Group VIB metal hexacarbonyls followed by treatment with N-methyl-N-nitroso-p-toluenesulfonamide afford the new vinyl organometallic monomers (η⁵-C₅H₄CHCH₂)M(CO)₂(NO) (M = Mo, W). Vinylcyclopentadienyllithium also serves as a convenient precursor to a series of (η⁵-vinylcyclopentadienyl)dicarbonylmetal monomers of cobalt, rhodium, and iridium. The ¹H NMR spectra of these vinylcyclopentadienylmetal derivatives have been compared as a function of the metal.     

Living and stereoselective polymerization of [2.2]-paracyclophan-2-ENE derivatives

Paracyclophene based monomers can be polymerized in a living fashion using the alkylidene initiator Mo(NAr)(CHCMe₂Ph)(OCMe(CF₃)₂)₂. The cis-specific nature of the polymerization is critical, since small amounts of trans olefin in the backbone renders the material insoluble. These polymers have complex photophysical behavior, probably a consequence of the close proximity of chromophores along the polymer backbone. Polymerization of 9-(tert-butyldimethylsilyloxy)-[2.2]-paracyclophan-1-ene produces a new precursor material which furnishes PPV under remarkably mild conditions.     

Synthesis and stability study of dental monomers containing methacrylamidoethyl phosphonic acids

Three new dental monomers containing methacrylamidoethyl phosphonic acids were synthesized. The structures of the synthesized monomers were determined with electrospray mass spectrometry (ESMS), Fourier transform infrared, and NMR. The hydrolytic stabilities of the synthesized monomers and a commercial monomer, 2‐methacryloyloxyethyl phosphoric acid (MEP; used as a control), were studied with flow injection (FI)/ESMS, ¹H NMR, and ³¹P NMR analysis of a CD₃OD/D₂O (4:1 v/v) solution of each monomer before and after storage at 60 °C for 2 months. The ¹H NMR and ³¹P NMR chemical shifts of the monomers 2‐methacrylamidoethylphosphonic acid ( I ) and N,N′‐[4,4′‐(propane‐2,2‐diyl)‐bis(phenoxy‐2‐hydroxypropyl)]‐bis(2‐methacrylamidoethylphosphonic acid) ( II ) showed little change after storage at 60 °C for 2 months, but those of MEP changed significantly. FI/ESMS also showed that MEP was nearly completely decomposed, whereas monomers I and II remained largely intact. MEP could react with H₂ZrF₆ to form ternary zirconium fluoride complexes that were partially soluble in methanol, but all the monomers containing phosphonic acids formed precipitates. This study demonstrates that ESMS is a more sensitive and effective method than NMR for studying the hydrolytic stability or degradation of dental monomers. The new monomers containing methacrylamidoethyl phosphonic acids have higher hydrolytic stability than methacrylate phosphate monomers and may be used in dental bonding agents and other dental materials. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 99–110, 2007     

Binding Study of the [Ru(NH3)5pz]2+ Complex to Bile Anion Aggregates through Kinetic Measurements

The electron transfer reaction between [Ru(NH₃)₅pz]²⁺ and [Co(C₂O₄)₃]^3? was studied in the presence of monomers and aggregates of bile salts (sodium deoxycholate, sodium taurodeoxycholate, and sodium glycocholate) at 298.2 ± 0.1 K. The results show a decreasing rate constant with the successive addition of bile salts. To rationalize the trends of the reaction rate on the [bile salts], two models were used. One of them takes into account the aggregation feature by considering a stepwise self‐association between monomers, whereas the other assumes the formation of a critical micellar concentration. Binding constants between [Ru(NH₃)₅pz]²⁺ species and deoxycholate or taurodeoxycholate aggregates were higher than that for glycocholate aggregates. These results are consistent with the way in which the monomers are added to form the bile anion aggregates.