Effects of applied potential on electroinitiated copolymerisation of α-methylstyrene and β-bromostyrene

Electroinitiated cationic copolymerisation of α-methylstyrene and β-bromostryene has been studied at various applied potentials. The relationship between copolymerisation potential and resulting copolymer composition was investigated. The advantages of employing constant potential electrolysis over constant current electrolysis are discussed in terms of the reactivity ratios. The reactivity ratios of the monomers are calculated according to the integrated Lewis-Mayo equation.     

Copolymers of 4-vinylpyridine with fluorinated acrylates. I. Synthesis,methylation and characterisation

The copolymerisation of fluoroacrylates with 4-vinylpyridine is described together with the characterisation and methylation of the copolymers. Determination of the reactivity ratios suggests that the comonomers tend to combine in a random manner.     

Radical Ring Opening and Vinyl Copolymerization of 2,3,4,5,6-pentafluorostyrene with 5,6-Benzo-2-methylene-1,3-dioxepane: Synthesis and Structural Characterization Using 1D and 2D NMR Techniques

Radical ring opening polymerisation behaviour of 5,6-Benzo-2-methylene-1,3-dioxepane (BMDO) during its copolymerisation with 2,3,4,5,6-pentafluorostyrene (PFS) is reported using t-butyl peroxide (TBPO) conventional radical initiator. The reactivity behaviour of PFS for its copolymerisation is compared with that of the corresponding non-fluorinated monomer styrene. The presence of five fluorine atoms affected the course of polymerisation and led to the synthesis of well defined copolymers as compared to the formation of only homo poly styrene. Structural characterisation of the copolymers was done using 1D and 2D NMR spectroscopic techniques. The microstructural characterisation showed the formation of gradient copolymers with increased reaction time and/or increased amount of BMDO in the feed. The reactivity ratios for the copolymerisation of BMDO and PFS were determined using Kelen-Tüdos method and was found to be r _BMDO = 0.35 and r _PFS = 9.9. Thermal stabilities of copolymers are also compared with that of the homopolymers.     

Analysis of the linear methods for determining copolymerization reactivity ratios,VIII. A critical reexamination of radical copolymerization of methylmethacrylate or styrene

The reactivity ratios of selected methylmethacrylate or styrene copolymerisation systems have been reviewed in terms of the extended Kelen-Tüd?s method. r-values, together with their 95% confidence limits have been calculated. Quantities δ and Q, suitable for classification of the systems, have been applied. Of the 71 reevaluated methylmethacrylate systems 40 (56.3%) were found to belong to class I and 20 (28.2%) to class I(!), i. e. 60 (84.5%) systems for which the conventional copolymerisation equation was found to be adequate. For 3 (4.2%) systems belonging to class II the two-parameter model does not hold and 8 (11.3%) systems were related to class III, i. e. systems for which the experimental data are inconsistent and the published r-values meaningless. 32 styrene copolymerisation systems were reevaluated with the following classification: 19 (59.4%) systems in class I, 5 (15.6%) systems in class I(!), 2 systems in class II and 6 (18.8%) in class III.     

RADIKALISCHE COPOLYMERISATION VON ETHYLEN MIT SALZEN DER METHACRYLSÄURE UNTER HOCHDRUCK

In order to prepare ionomers, the radical copolymerisation of ethylene with salts of methacrylic acid was investigated. The polymerisation tests were performed in a continuously operated stirred autoclave at 1800 bar, 190 to 240°C and a residence time of 60 sec. The concentration of methacrylate in the feed was varied between 0, 3 and 3, 4 wt%. For comparison ethylene homopolymers were prepared. From the polymerisation tests the conversion was determined. The resulting copolymers were analysed for their composition to calculate the reactivity ratios. Furthermore density, crystallinity and melt flow index were measured.     

Radical copolymerization studies of an amphiphilic macromonomer derived from Triton X-100. Reactivity ratios determination by in situ quantitative H NMR monitoring

This article deals with the estimation of the reactivity of a novel methacrylic macromonomer with amphiphilic character derived from Triton X-100 (MT) in radical copolymerisation reaction with acrylic acid (AA). Two approaches to estimate the reactivity ratio of the macromonomer are described. The first involves the use of the Jaacks equation valid for systems with a large excess of one of the comonomers and leads to r_AA=0.31. The second method uses a low molecular weight model monomer (MTm) that reproduces the chemical structure of the macromonomer. A non-linear fitting of the experimental data of the system MTm-AA to an integrated form of the copolymerisation equation which describes the terminal model postulated by Mayo and Lewis, gave reactivity ratio values of r_MTm=2.5 and r_AA=0.30. The results obtained from the two estimations suggest that methacrylic double bond reactivity is not affected by poly(oxyethylene oxide) chain length. In situ quantitative ¹H NMR analysis was used to monitor monomer consumption and therefore to follow the course of the copolymerisation reaction in both approaches.     

Solvent effect in radical copolymerisation of N-vinylcarbazole and methylmethacrylate

Summary Radical copolymerisation of MMA(r₁) and NVC(r₂) yields values of the apparent reactivity ratios r₁ = 1.80, r₂ = 0.06 (benzene) and r₁ = 0.57, r₂ = 0.75 (methanol) at 55°C. It is suggested that the apparent increase in reactivity of NVC in methanol arises from high local monomer concentrations due to formation of microphases containing the growing copolymer chains in which NVC is preferentially partitioned. Fluorescence emission and u.v. absorption spectra for copolymers prepared in both solvents are identical and consistent with the occurrence of only very short sequences of NVC units.     

The Copolymerisation of Vinyl Chloride with Allyl Chloride

The kinetics of copolymerisation of vinyl chloride with allyl chloride in chlorobenzene and in dichloroethane solvent have been studied by a dilatometric method. The compositon of the copolymers was determined by reduction with tributyltin hydride followed by infrared examination. Molecular weights obtained by g.p.c. enable as estimate of the transfer constant for degradative transfer to allyl chloride to be made for both the chlorobenzene and dichloroethane solvent systems. The results show that allyl chloride retards vinyl chloride polymerisation by degradative transfer and that the resulting radicals combine with the growing polymer chains. The dependence of copolymer composition on the composition of the monomer feed reveals that one of the pair of reactivity ratios associated with this reaction in either solvent has a negative value.     

Zinkacrylat und andere feste Monomere als Vernetzungsmittel für ungesättigte Polyester

The peroxide-initiated copolymerisation of an unsaturated polyester with zinc acrylate, diallyl phthalate prepolymer and a solid vinyl ester resin was investigated. The curing was followed by means of gelation curves and differential scanning calorimetry. The studies showed that zinc acrylate has the highest reactivity.     

双马来酰亚胺树脂的共聚改性

介绍一种由双马来酰亚胺、取代双马来酰亚胺和二烯丙基双酚A共聚所得树脂体系,重点研究了树脂的性能如溶解性、粘度特性、凝胶时间和反应性等以及固化树脂的力学性能和耐热性等。     

Electroinitiated cationic copolymerization by direct electron transfer

Electroinitiated cationic copolymerizations of indene-4-methoxystyrene and indene-β-bromostyrene monomer couples were investigated in dichloromethane by constant potential electrolysis. Copolymer compositions were determined by i.r. spectroscopy and reactivity ratios for the monomers were calculated according to integrated Lewis-Mayo equation. The composition of copolymers and the reactivity ratios were discussed in terms of anodic peak potentials of monomers.     

Spontaneous zwitterionic copolymerisation: An undervalued and efficacious technique for the synthesis of functional degradable oligomers and polymers

The spontaneous zwitterionic copolymerisation (SZWIP) of compatible nucleophilic and electrophilic monomers is a relatively unknown and unexplored method for the synthesis of (predominantly alternating) degradable co- and terpolymers. A wide range of monomers allows for the synthesis of different polymer classes with various functionalities, including poly(aminoester)s, poly(ester amide)s and poly(phosphoester)s. In this review, we discuss this undervalued copolymerisation method and its potential for the facile preparation of functional polymeric systems. In this context, the polymers synthesised to date by SZWIP as well as recent insights into this polymerisation technique are highlighted. Post-polymerisation modifications and applications of polymers obtained by SZWIP are also discussed.     

Copolymerisation reactions of acenaphthylene at high pressures

Radical copolymerisations in the systems acenaphthylene/methyl methacrylate, and acenaphthylene/maleic anhydride, have been investigated at 60 °C, and at pressures up to 4 kbars. The effect of pressure on the rate of polymerisation of acenaphthylene in tetrachloroethylene has also been measured. The pressure acceleration of the reactions varies with the monomer ratio in the first system, but is invariant in the copolymerisation with maleic anhydride, in which an alternating copolymer is formed. The reactivity ratio of ACN is significantly lower in both systems at high pressures. The results are related to a degradative transfer reaction with acenaphthylene monomer.     

Ethylene/styrene copolymerisation by homogeneous metallocene catalysts: experimental and molecular simulations using rac-ethylenebis(tetrahydroindenyl)MCl2 [M=Ti,Zr] systems

Styrene was copolymerised with ethylene using the catalyst systems [rac-Et(H₄Ind)₂TiCl₂]/MAO and [rac-Et(H₄Ind)₂ZrCl₂]/MAO. Keeping other experimental variables under control, we tested different styrene/ethylene ratios in the reactor feed. It was found that the titanium-based catalyst showed very low activity even for ethylene homopolymerisation. In contrast, the zirconium system achieved monomer polymerisation, incorporating small amounts of styrene. When the styrene/ethylene ratio was increased, both catalyst activity and the molecular weight of the resulting copolymers decreased. However, styrene incorporation into the copolymer increased as the styrene/ethylene ratio rose. To gain insight into the copolymerisation mechanisms at play, we undertook a computational study using a high-level hybrid DFT method (B3LYP). Agreement between the experimental and theoretical results was generally good, indicating the usefulness of combined experimental/theoretical studies for clarifying mechanisms of -olefin copolymerisation using organometallic systems.     

Hydroxyl-bearing poly(α-hydroxy acid)-type aliphatic degradable polyesters prepared by ring opening (co)polymerization of dilactones based on glycolic, gluconic and l-lactic acids

The synthesis of HO-protected poly(glycolic acid-co-gluconic acid) and poly(l-lactic acid-co-glycolic acid-co-gluconic acid) by copolymerisation of l-lactide and 3-(1,2-3,4-tetraoxobutyl-diisopropylidene)-1,4-dioxane-2,5-dione (DIPAGYL) is reported. The resulting polymers were characterized by size exclusion chromatography, FT Infrared, nuclear magnetic resonance, differential scanning calorimetry and X-ray diffractometry. The composition of reaction media and the reactivity ratios of the two cyclic monomers were determined at low conversion and indicated random distributions of lactyl and gluconoglycolyl constitutive units. X-ray diffraction data showed semi-crystalline morphology, as observed for poly (lactide) stereocopolymers containing more than 90% of l-enantiomer. Deprotection of the isopropylidene-protected side chain OH was possible under acidic conditions and yielded copolymers with various degrees of hydroxylation. Deprotection of the 5-6 OH groups was fast and complete whereas that of 3-4 ones was partial and occurred at the expenses of partial degradation of the aliphatic polyester chains. T_g increased with the number of hydroxyl functions, a feature attributed to the formation of hydrogen bonds. Comparison is made with features reported previously for analogs derived from dl-lactide.     

Styrol als Rohstoff für Lackbindemittel und Lacke

Styrene as Raw Material for Paint Binders and Paints Monostyrene is highly reactive and it can undergo homopolymerisation as well as mixed polymerisation. Polystyrene, which is mainly used in thermoplastic materials, can not be employed as binder for paints; thus, for example, the films adhere neither to wood nor to metal. Polystyrene does not withstand other raw materials of paints. In contrast, monostyrene is significant as copolymerisation partner for paint binders, such as acryl resins, dispersions, styrene-containing alkyd resins and unsaturated polyester resins. In the processing of polyester resins and polyester paints, the paint manufacturers have to handle monostyrene; hence they should be aware of the reactivity, sensitivity and physiological activity of monostyrene. These aspects are dealt with too.     

Hybrid organic-inorganic materials using zirconium based NBBs and vinyl trimethoxysilane: Effect of pre-hydrolysis of silane

Various Nano Building Blocks (NBBs) such as polyhedral silsesquioxanes (POSS), functionalized metal oxide particles and transition metal oxoclusters have been already developed and used to improve thermal and mechanical properties of organic polymers. The NBBs ideal for the preparation of hybrid materials and nanocomposites are monodispersed, well-defined objects capped with polymerisable functions suitable for copolymerisation with organic monomers.In this study zirconium oxoclusters (ZrNBB) were obtained as a crystalline precipitate by reaction between zirconium propoxide and vinylacetic acid. They were post-functionalised by copolymerisation with vinyl trimethoxysilane in different molar ratios. The hybrid samples were prepared both with the organosilane pre-hydrolysis step and without adding water. Hybrid materials were obtained through the radical polymerization process by adding benzoyl peroxide (BPO). Silane pre-hydrolysis prevents bulk samples from being obtained.The polymerization process was studied using differential scanning calorimetry (DSC), and the shear storage modulus (G′) and loss modulus (G″) of hybrid polymers were investigated by dynamic mechanical spectroscopy (DMS). Multinuclear liquid- and solid-state NMR analyses and Fourier transform infrared (FTIR) spectroscopy were used to characterize the reagents and hybrid materials, and to study the influence of the synthesis conditions on condensation and polymerization.     

Effects of Ultrasonic Vibration on the Electroinitiated Copolymerisation of Styrene and Isoprene

Copolymerisation of styrene and isoprene by constant potential electrolysis in dichloromethane was achieved at different polymerisation potentials. Effect of ultrasonic vibration on the rate and the yield of polymerisation has been discussed. The composition of the copolymers was found to be affected by the vibration as well as the polymerisation potential (E_pol). At E_pol=+3.30 V we found that r₁=r₂ and mole percents of isoprene and styrene in copolymer were equal to each other. Equality was also observed on reacted monomer concentrations, at that potential, which can be called critical polymerisation potential. At E_pol values above or below the critical polymerisation potential none of the above-mentioned properties were equal. Monomer reactivity ratios were determined by the integrated Lewis-Mayo equation. Ultrasonic vibration as well as polymerisation potential was found to affect reactivity ratios.     

Polymers from acrylonitrile polymerized in the presence of vinylsulphone dyes

The properties of a series of ‘copolymers’ of acrylonitrile and various vinylsulphone dyes are discussed. Information relating to molecular size, the nature of the linkage between the chromophore and the backbone and the reactivity ratios of the two ‘monomers’ is given. These reactivity ratios are calculated from extinction coefficients on the assumption that there is no appreciable breakdown of the chromophore during polymerization. Factors governing the role of the dye in the polymerization process are considered in some detail. Thermal analysis techniques have been used to investigate the thermal stability of the products of polymerization. The thermograms have been used to assess the potential of these materials as pigments and to study the nature of their decomposition.     

Effects of the side chain density of polycarboxylate dispersants on dye dispersion properties

Comb‐like polycarboxylates were synthesised by copolymerisation of methacrylic acid and nonylphenol polyethylene glycol methacrylate ester, and can be used as dye dispersants. In order to achieve good dispersive ability, three polycarboxylates were synthesised, each having a different side chain density. The side chain density of polymers was controlled by different ratios of monomers in the copolymerisation process. Acidic polymers were neutralised using sodium hydroxide. These polymers exhibit good dispersing performance, such that carboxylate groups are adsorbed onto the dye particle surface and the side chains enable the formation of a thick layer, thus providing the steric hindrance effect. Improvement of dye dissolution in the presence of polycarboxylates was studied. Polymers with a lower side chain density demonstrated a higher dye dissolution in water, which could be as a result of more effective adsorption of dispersant on the dye surface (CI Disperse Blue 79). The dyeing performance of the prepared dye dispersions on polyester was investigated. Spectrophotometric analysis of dyed fabrics using synthesised polycarboxylates demonstrates that there should be an optimum side chain density of polymer in order to control both dye solubility and dispersive ability. The result of turbidimetry and particle size analysis have proven this phenomenon. A comb‐like polycarboxylate with optimum side chain density was a better dye dispersant compared with a commercial sodium naphthalene sulphonate compound, as a result of its better heat stability.