Mechanism of ring-opening and elimination cooligomerization of cyclic carbonates and ε-caprolactone: Formation of cyclic cooligomers

The cooligomerization reactions of the comonomers ethylene carbonate-propylene carbonate, ethylene carbonate-ε-caprolactone and propylene carbonate-ε-caprolactone initiated by the p-tert-butylphenol/KHCO₃ system were investigated by means of electrospray ionization mass spectrometry combined with liquid chromatography. Three major cooligomer series were found in each case which were identified such as cooligomers with tert-butylphenol and hydroxyl headgroups. The presence of cyclic cooligomers was also unambigously observed. In addition, cooligomers carrying carbonate linkages were also identified, however, their fraction was very small compared to the cooligomer series without carbonate linkages. Besides the cooligomerization reaction, homooligomerization of ethylene and propylene carbonate was observed, as well as no linear homooligomers of ε-caprolactone were detected. Based on the LC-ESI MS results a mechanism is proposed for the formation of cyclic co-oligomers and the chain degradation of cooligomers containing carbonate linkages.     

Cooligomerization of dominant monomers of C9 fraction of liquid pyrolysis products: comparison of heterogeneous catalytic approach with common methods

Cooligomerization of liquid products of the C9 fraction of diesel fuel pyrolysis to produce cooligomers of wide application is suggested to be carried out with silica-alumina catalysts, among which the activated bentonite clay seems to be optimal. Cooligomerization of the mixture simulating the C₉ fraction composition was studied to compare the suggested heterogeneous catalytic method with other methods of cooligomers production. Different methods have been compared in terms of yield of cooligomers and their properties, namely molecular weight and its distribution, density, unsaturation and colour. The ratio of monomer units in cooligomer has been determined and the monomers conversion degrees have been calculated for different cooligomerization methods. Reasons of structure and composition differences of cooligomers obtained by different methods are suggested.      

Synthesis of hexene-1 oligomers with indene: Feed materials for the preparation of functional additives

The influence of various factors on the hexene-1 cooligomerization with indene in the presence aluminum chloride aquacomplex was studied. Composition and structure of the synthesized cooligomers were studied by the methods of IR and PMR spectroscopy and elemental analysis.     

Synthesis and Properties of Novel Cross‐Linked Fluoroalkyl End‐Capped Oligomeric Nanoparticles Containing Adamantane Units

Fluoroalkyl end‐capped cooligomers that contain both oxime‐blocked isocyanato and hydroxyadamantyl segments are prepared by the cooligomerization of fluoroalkanoyl peroxide with the corresponding monomers under mild conditions. This fluorinated cooligomer affords new cross‐linked fluoroalkyl end‐capped cooligomeric nanoparticles that contain adamantane segments by the deprotecting reaction of oxime‐blocked isocyanato segments in cooligomers in excellent to moderate isolated yield. A variety of cross‐linked fluoroalkyl end‐capped cooligomeric nanoparticles that contain adamantane segments are also prepared by similar deprotecting reactions with this fluorinated cooligomer in the presence of adamantane‐1,5‐diol. Furthermore, we have prepared cross‐linked fluoroalkyl end‐capped cooligomers that contain oxime‐blocked isocyanato segments by the use of 2‐hydroxyethyl acrylate and poly(ethylene glycol)‐containing methacrylate monomer as comonomers, respectively. However, the deprotecting reactions of the oxime‐blocked isocyanato segments in the cooligomers do not afford the expected nanoparticles, and these cross‐linked cooligomers are found to show a gelling characteristic. The thermal stability of these cross‐linked fluorinated cooligomeric nanoparticles that contain adamantane segments increases significantly compared to that of the parent fluorinated cooligomer. More interestingly, the thermal stability of these cross‐linked fluorinated nanoparticles is almost the same as that of the fluoroalkyl end‐capped acrylic acid oligomer/SiO₂ nanocomposites (content of SiO₂ in composites: 70%). In addition, these cross‐linked fluorinated nanoparticles have been applied to the surface modification of traditional organic polymers such as poly(methyl methacrylate) to exhibit a good oleophobicity imparted by fluorine on their surface.

     

Statistical nonstationarity of the composition of styrene with methyl methacrylate in the cooligomer

It was found that the composition of cooligomer produced in the styrene(A)–methyl methacrylate(B)–CCl₄(S) system deviates from the statistical steady-state composition predicted from the Mayo-Lewis equation on the low molecular weight side when the molar ratio of [A]/[B] is large. When the molar ratio of [A]/[B] is small, however, it is not obvious whether or not this phenomenon is observed, because the cooligomer of low molecular weight cannot be obtained easily since the chain transfer constant of the poly(methyl methacrylate) radical to CCl₄ is very small in comparison, with that of the polystyryl radical. This behavior is shown to be attributable mainly to the preferential consumption of styrene monomer in the initiation step, based on the structure of the cooligomer, as inferred from the mechanism of the initiation, transfer, and termination, and the stochastic approach in which the cooligomerization process is regarded as a Markov process.     

Preparation of novel,liquid, solvent‐free,polyolefin‐based adhesives

An innovative procedure for functionalization of polyolefins was developed. It was found that synthesized polyolefins end‐capped with trimethoxysilane (silylated polyolefins) are new polyolefin‐based adhesives. To prepare the mentioned materials,1‐octene as a higher α‐olefin was cooligomerized with two linear, nonconjugated dienes (ie, 1,5‐hexadiene and 1,7‐octadiene) by using metallocene catalyst system, Cp₂HfCl₂/MAO, at room temperature. Then, amine‐terminated trimethoxysilane (3‐aminopropyltrimethoxysilane) was reacted with unsaturated bonds of synthesized cooligomers in the presence of palladium(II) acetate. Embedding of the dienes on 1‐octene oligomeric chains was explored by Fourier transform infrared (FTIR), ¹H, and ¹³C‐NMR spectroscopy. On the basis of the results, 1,5‐hexadiene showed both 1‐butene branch and five‐member ring. On the other hand, 1,7‐octadiene was incorporated by 1,2‐addition, forming both 1‐hexene branch and seven‐member ring in the cooligomer backbone. Mole percentage of C?C and cyclic moieties reached to a value of 28.54, 18.59% mol in 1‐octene/1,5‐hexadiene, and 38.04, 6.71% mol in 1‐octene/1,7‐octadiene cooligomers, respectively. Reaction of synthesized cooligomers with 3‐aminopropyltrimethoxysilane was confirmed by FTIR spectroscopy, which yielded targeted adhesives. To study the adhesion properties, resulting adhesives were applied to different substrates. Obtained results demonstrated that tensile shear strength of synthesized adhesives to polar substrates was 2.21% to 2.84% more than nonpolar substrates. Among studied systems, the best performance was achieved by1‐octene/1,7‐octadiene–based adhesive and Al substrate with tensile shear strength of 1.45 N/mm².     

Synthesis and characterization of thiophene/3-alkylthiophene random cooligomers

Several random cooligomers based on thiophene and β-substituted alkyl derivatives, i.e. 3-methyl- and 3-octylthiophene, have been chemically synthesized by an oxidative coupling reaction in the presence of iron(III) chloride. The powdered samples were characterized by TGA, FTIR, UV and cyclic voltammetry measurements. The influence of the alkyl substituent on the homo/cooligomer stability, conjugation length, degree of polymerization and presence of defects is discussed. Electronic Publication     

Pd complexes of (<Emphasis Type="Italic">RR</Emphasis>)- and (<Emphasis Type="Italic">SS</Emphasis>)-1,5-methylbenzyl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane as catalysts in alternating cooligomerization of CO with dienes

Alternating copolymerization of CO with norbornadiene and ethylidenenorbornene is studied in the presence of Pd complex with (SS)-1,5-methylbenzyl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane ligand. The structure of cooligomers formed and cooligomerization rate are shown to depend on the catalytic system composition and comonomer structure. The obtained cooligomers are characterized by structural methods.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 4, 2005, pp. 280–288.Original Russian Text Copyright © 2005 by Novikova, Karasik, Hey-Hawkins, Belov.     

Conformation of block cooligomer macromolecules containing a discotic block

The conformation of block cooligomers that contain a block of eight 2,6,7,10,11-pentapentyloxy-3-(3-acryloylpropyloxy)triphenylene units and a poly(tert-butyl acrylate) block with a length varying from 6 to 300 monomer units was calculated by means of molecular dynamics with the DREIDING force field. The influence of the length of the flexible-chain block of the amorphous polymer on the conformation and structure of the block cooligomer at the level of a single macromolecule was revealed. A tendency toward the screening of the short mesogen-containing block by the flexible-chain polymer block with an increase in its length was demonstrated.     

Computer simulation for the cooligomerization system

In order to clarify the kinetic features of the styrene (A)–methyl methacrylate (B)–CCl₄(S) cooligomerization system, a computer simulation was carried out. The experimental data on the degree of polymerization and the deviation of the cooligomer composition from the statistical steady-state composition were comparatively well explained by calculations based on the kinetic equations derived from the assumed reaction scheme and the values of the velocity coefficients, although the values of the four velocity coefficients in the initiation step and the velocity coefficient of the termination by the coupling of two solvent radicals were estimated. The results of the calculation of the rate of each component reaction show that the following two reactions are the most important in the initiation and in the transfer and termination steps when the [S]/([A] + [B]) ratio is large: where, A, A*, and P are styrene, polystyryl radical, and the cooligomer, respectively. Moreover, it was concluded that the deviation of the cooligomer composition from the statistical steady-state composition was caused by these two reactions.     

Synthesis and characterization of epoxy functionalized cooligomers based on chlorotrifluoroethylene and allyl glycidyl ether

The synthesis of functionalized fluorocooligomers based on chlorotrifluoroethylene (CTFE) and allyl glycidyl ether (AGE) under radical copolymerization is presented. The compositions of comonomers in the cooligomers were determined by three different analyses viz: from ¹H and ¹⁹F NMR spectroscopy by using 1,3‐bis(trifluoromethyl) benzene as the external standard, epoxy equivalent weight value, and elemental analyses. The compositions determined by three methods were matching reasonably well and showed that the resulting poly(CTFE‐co‐AGE) cooligomers exhibit a tendency for alternation. The distribution of the monomers in the cooligomers was proposed based on the assessment of the reactivity ratios, r_i, of both comonomers. These values were determined from the kinetics of radical copolymerization of CTFE with AGE from Fineman‐Ross, Kelen‐Tudos, and extended Kelen‐Tudos methods which led to the assessment of the average reactivity ratios as: r_CTFE = 0.20 ± 0.03 and r_AGE = 0.15 ± 0.08 at 74 °C. The lower M_n values substantiated the formation of cooligomers rather than copolymers. The formation of cooligomers was attributed to the chain transfer to AGE (by hydrogen abstraction from AGE) from the allylic transfer. The poly(CTFE‐co‐AGE) cooligomers were soluble in most of the common organic polar solvents. An optimization of cooligomer yields was investigated by using ethyl vinyl ether as a third comonomer and from different initiators. The thermal stabilities of the cooligomers, obtained by thermal gravimetric analysis, showed a 5% weight loss at temperatures over 225 °C under air. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3587–3595, 2010     

端羟基丁二烯丙烯腈共低聚物的合成及其力学性能Ⅱ.均匀组成的液体共聚物的合成

根据共聚物组成的计算方法,合成了组成均匀的端羟基丁二烯与丙烯腈液体共聚物并用ＮＭＲ观察和计算了该液体聚合物的序列分布,测定了力学性能     

丁二烯与丙烯腈共低聚反应中共聚物组成的控制

在二元共聚反应中,为了制备具有均匀组成的共聚物,对于分批聚合,在反应过程中须补加消耗较快的单体以保持单体的浓度比为常数。本工作提出了为控制共聚物组成在反应过程中补加单体的计算方法,它不仅适用于丁二烯与丙烯腈的共低聚反应,也适合于其它二元共聚反应。用这种方法制备了具有均匀组成的丁二烯与丙烯腈共低聚物。     

端羟基丁二烯-丙烯腈共低聚物控制组成的计算方法与合成

针对二元共聚反应,在分批聚合中制备组成相同的共聚物,提出了为控制共聚物组成在反应过程中补加活性较大单体的计算方法。并根据这种方法合成了端羟基丁二烯-丙烯腈共低聚物。该方法也可用于其它二元共聚反应。     

Preparation of novel cross-linked fluoroalkyl end-capped cooligomeric nanoparticles–encapsulated cytochrome c in water and ionic liquids

Cross-linked fluoroalkyl end-capped acrylic acid cooligomer containing poly(oxyethylene) units can form the nanometer size-controlled fine particles in aqueous solutions, and these cross-linked nanoparticles interact with cytochrome c (Cyto-c) to afford the corresponding cooligomeric nanoparticles–encapsulated Cyto-c effectively. Interestingly, we can easily isolate the fluorinated nanoparticles–encapsulated Cyto-c powder by the simple centrifugal separation of the corresponding aqueous solutions. The cross-linked fluorinated cooligomer also enables an effective transfer of Cyto-c from aqueous solution to ionic liquids such as 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide to afford the immobilized Cyto-c with the corresponding fluorinated cooligomer in quantitatively immobilized ratio (～100%). The immobilized Cyto-c exhibited a good dispersibility in the parent ionic liquid to afford the nanometer size-controlled fluorinated particles–encapsulated Cyto-c. Similarly, the cross-linked fluorinated cooligomer in ionic liquids such as 3-methylpyrazolium tetrafluoroborate (3MP-BF4) interacted with Cyto-c to afford the corresponding nanoparticles–encapsulated Cyto-c in quantitatively encapsulated ratio (～100%). These cross-linked fluorinated nanoparticles–encapsulated Cyto-c in water and ionic liquids were applied to the oxidation of guaiacol with hydrogen peroxide, and an extremely higher catalytic activity for this oxidation was observed in the ionic liquid (3MP-BF4).     

Cyclopenta[c]selenophene based cooligomers and their polymers: comparative study with thiophene analogues

Selenophene and thiophene capped cyclopenta[c]selenophenes were synthesized and characterized. Crystal structure determination of some representative compounds revealed that the substitution at 3,4-position in the form of cyclopentane ring of selenophene or thiophene does not make any significant twist in the trimer backbone, making the cooligomer nearly planar. All the cooligomers were electrochemically polymerized and compared with thiophene capped cyclopenta[c]thiophene polymer. DFT calculations predict that the cyclopentane substitution on the third repeating unit (and in general) of one dimensional polymer neither disturb the planarity nor causes any significant twist on the polymeric backbone unlike the 3,4-dialkyl substitution. The electrochemically prepared selenophene based polymers showed low band gap compared to that of thiophene analogues. Cyclopentane substitution on selenophene as well as thiophene makes the resulting polymer oxidatively more stable when compared to more familiar poly-ethylenedioxythiophene (PEDOT) or poly-ethylenedioxyselenophene (PEDOS) systems. Alternate polymers of cyclopenta[c]selenophenes (CPS)/cyclopenta[c]thiophene (CPT) and thiophene/selenophene possess the energy of HOMO and LUMO significantly lower than that of homopolymers of CPS and CPT, however, possess higher band gap than PCPS.     

Simplified treatment of cooligomerization kinetics

Equations for the degree of polymerization and the cooligomer composition in the styrene (A)–methyl methacrylate (B)–CCl₄(S) system were derived from the assumed reaction scheme by the use of some assumptions for simplification, and their appropriateness was examined. The chain transfer constants of the growing radicals of styrene (C_SA) and methyl methacrylate (C_SB) to CCl₄, which were estimated from the apparent chain transfer constants C_SAB in the cooligomerization system, agreed with the homooligomerization values. This means that the degree of the polymerization of the cooligomer can be expressed by the equation: where P_n is the degree of polymerization of the cooligomer and P_nO is that when no chain transfer agent (CCl₄) is added; r_A and r_B are the monomer reactivity ratios of monomers A and B in this system. The cooligomer composition deviated from the statistical steady-state composition on the low molecular weight side, and this deviation was explained by the equation:      

Cooligomerization of carbon monoxide with cyclic olefins on supported palladium catalysts

The cooligomerization of CO with cyclic olefins, such as norbornene, 5-vinyl-2-norbornene, and dicyclopentadiene, in toluene in the presence of supported palladium catalysts containing 2,2’-bipyridine as a ligand is studied. It is shown that, during copolymerization, opening of the double bond in a ring occurs, while in the case of 5-vinyl-2-norbornene, vinyl bond C=C is not involved in the reaction. When ethylene is added to the reaction mixture, it does not participate in polymer-chain growth. The yield of the process is commensurable with the yield attained in the case of a homogeneous catalytic system, and the conversion of olefins is as high as 47%. The copolymers in the solid state occur in the form of spiroketal structures that, during dissolution, transform into ketone structures to different extents.     

Binary cooligomers of 2-propenylphenol with 1-heptene and 1-decene as antimicrobial additives for lubricating oil I-12A

Binary cooligomers of C₇ and C₁₀ α-olefins with 2-propenylphenol were synthesized in the presence of a complex catalyst based on aluminum chloride, toluene, and ethyl chloride (1:3.0:0.6 mol). Tests of the cooligomers as antimicrobial additives to I-12A oil showed that, in concentrations of 0.25 and 0.5%, they inhibit fungal growth, being superior to 8-hydroxyquinoline (reference) in the efficiency of action.     

离子液体对稠油的改质降黏作用影响因素研究

合成了烷基咪唑型离子液体\[BMIM\]\[AlCl₄\],研究了稠油含硫量、含水量、过渡金属盐、温度等对离子液体进行稠油改质降黏作用的影响。实验结果表明,稠油含一定硫量是进行稠油改质降黏的必要条件。用\[BMIM\]\[AlCl₄\]离子液体对稠油进行有效的改质降黏时,稠油含水量应小于10%。环烷酸镍(NiNaph）与离子液体复配使用对稠油改质降黏具有增效作用。用质量分数为5%的\[BMIM\]\[AlCl₄\]离子液体在一定条件下处理新疆稠油,可使稠油降黏率达到60%,沥青质降低78%。用\[BMIM\]\[AlCl₄\] 离子液体对新疆稠油进行改质降黏的最佳温度为65℃~85℃。