Synthesis and properties of uniform beads based on macroporous copolymer glycidyl methacrylate–ethylene dimethacrylate: A way to improve separation media for HPLC

Monodisperse beads based on hydrolyzed macroporous poly(glycidyl methacrylate-co-ethylene dimethacrylate) for use as size-exclusion HPLC packings were synthesized by the method of “activated” swelling of polystyrene seeds followed by a suspension polymerization of both methacrylates. Effects of the type and fraction of the swelling agent, inert porogenic solvent, and cross-linking monomer on the uniformity of the particles, extent of the specific surface area, pore volume, pore size, and pore-size distribution and chromatographic properties (size-exclusion limit and column effciency) have been investigated. Trends leading to the synthesis of macroporous particles with predesigned properties for use in size-exclusion high-performance liquid chromatography in both aqueous and organic mobile phase were studied. © 1992 John Wiley & Sons, Inc.     

Preparation and properties of uniform beads based on macroporous glycidyl methacrylate–ethylene dimethacrylate copolymer: Use of chain transfer agent for control of pore-size distribution

Poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads were prepared by both standard suspension polymerization and suspension polymerization in which the suspension of monodispersed droplets of the polymerization mixture was prepared by swelling of the shape-template polymer particles with porogen diluents and monomers. The effect of bu-tanethiol, a chain-transfer agent in radical polymerization, on pore-size distribution, specific surface area, and chromatographic properties was investigated and the mechanism of its action explained. The synergic effects of the chain transfer, cross-linking monomer concentration, and content of porogenic diluent were documented. © 1993 John Wiley & Sons, Inc.     

Reactive polymers,XXXVI. The effect of polymerization conditions on the porosity and mechanical properties of macroporous suspension copolymers from glycidylmethacrylate-ethylenedimethacrylate

By the method of design of experiments, the influence of the content and the thermodynamic quality of the mixture of inert solvents (porogenic compounds), of the concentration of the crosslinking agent and initiator in the polymerization mixture and of the reaction temperature in the radical suspension copolymerization was investigated with respect to the pore size, the porosity and the mechanical properties of macroporous copolymers from glycidylmethacrylate and ethylenedimethacrylate. It was found that the predominant effect on these characteristics should be attributed to the volume of the porogenic component in the mixture, and that the pore size and porosity increase at the same time the penetration modulus and the stress-at-break decrease proportionately to this volume. The concentration of the crosslinking agent has an influence only at low crosslinking values. The polymerization temperature and concentration of the initiator have only an insignificant effect on the structure and mechanical properties.     

Reactive polymers, 47. Sorption properties of the reaction product of macroporous poly (glycidyl methacrylate-co-ethylene dimethacrylate) with 8-aminoquinoline

The sorption of Fe(III), Al(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Au(III), Pd(II), Pt(IV), and Hg(II) ions on a sorbent prepared by reacting the copolymer of glycidyl methacrylate and ethylene dimethacrylate with 8-aminoquinoline was investigated. Gold and palladium are strongly absorbed in hydrochloric acid. Results of static and dynamic tests indicate the possibility of separation of Au(III) and Pd(II) from Pt(IV) and from the other metal ions investigated in the study. The sorption of Hg(II) by the polymer increases in nitric acid.     

Methyl methacrylate–N-chlorophenyl maleimide copolymers: Effect of structure on properties

The article describes the preparation of cast acrylic sheets by copolymerizing methyl methacrylate (MMA) with varying mole fractions of N-o-chlorophenyl maleimide (OC), N-m-chlorophenyl maleimide (MC), and N-p-chlorophenyl maleimide (PC) using benzoyl peroxide as an initiator. The effect of incorporation of varying mole fraction of N-chlorophenyl maleimides in poly(methyl methacrylate) backbone on the optical, physicomechanical, and thermal properties of cast acrylic sheets were evaluated. Vicat softening temperature, glass transition temperature (T_g) and thermal stability of the copolymers increased with an increase in the maleimide content. The solar transmittance and percentage of transmittance of the copolymer sheets having low mole fractions of N-chlorophenyl maleimides (i.e., 0.025–0.085) were found to be comparable with that of PMMA. Further increase in the comonomer content resulted in a decrease in the percentage of transmittance. Copolymer sheets having low mole fractions of N-chlorophenyl maleimides (0.025–0.108) have tensile strength comparable to that of PMMA, whereas the percentage of elongation decreased. Tensile modulus increased with increasing mole fraction of N-chlorophenyl maleimides. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 527–534, 1998     

Correlation between microstructure and physical properties in styrene–ethylene copolymers

The structural organization and the physical properties of a new copolymer styrene–ethylene have been analyzed. The composition was 80% of ethylene units, corresponding to 52% in weight, with a distribution of styrene units in the chain implying the absence of styrene–styrene sequences. The length of the polyethylene chains, limited by the insertion of the phenyl group, is not sufficient to allow good crystallization, and in fact the copolymer shows a very low crystailinity, of the order of 5–10%, and a broad melting range, with a peak centered at 120°C. The small crystalline domains are segregated into an amorphous matrix, producing a thermoplastic elastomer. The mechanical properties at large deformation were analyzed at different temperatures. The copolymer shows good elastic properties, in terms of deformation reversibility as well as of energy dissipation in the hysteresis cycles. Also the stress level and the elastic recovery are very good, if compared with others thermoplastic elastomers. © 1995 John Wiley & Sons, Inc.     

Reactive polymers,XXXV. The effect of polymerization conditions on the specific surface area of macroporous copolymers from glycidylmethacrylate-ethylenedimethacrylate

By the method of design of experiments it was investigated the effect of some components of polymerization feed as the content of inert components, crosslinking agent, initiator, thermodynamic quality of inert components and polymerization temperature on the specific surface area of the produced sorbents which were copolymers from glycidylmethacrylate and ethylenedimethacrylate. By varying the five parameters given above, it was possible to control the specific surface area within the range 0–460 m² g^?1.     

Composition analysis of crosslinked styrene–ethylene dimethacrylate and styrene–divinylbenzene copolymers by Raman spectroscopy

A method for the determination of composition and content of pendent double bonds in untreated samples of styrene–ethylene dimethacrylate and styrene–divinylbenzene copolymers from Raman spectra has been developed. By computer treatment of spectra it was shown that Raman spectra are sensitive to the distribution of components in the studied copolymers.     

Macroporous membranes. 3. Properties of macroporous membranes synthesized from glycidyl methacrylate,ethylene dimethacrylate and alkyl- or hydroxyalkyl methacrylate

A series of macroporous membrances composed either of glycidyl methacrylate and ethylene dimethacrylate with an addition of other monomer chosen from a group comprising 2-hydroxyethyl methacrylate, butyl methacrylate, octyl methacrylate or dodecyl methacrylate, or of a copolymer of 2-hydroxyethyl methacrylate and ethylene dimethacrylate were synthesized and their properties were determined. The addition of a third monomer changes the porous properties only when the concentration of the monomer in the polymerization feed is rather high. The presence of bulkier alkyl side chains in a polymer matrix raises hydrophobicity and reduces the water regain while the strength of the membrane increases.     

Reactive polymers. XXXIII. The influence of the suspension stabilizer on the morphology of a suspension polymer

Sorbents based on glycidyl methacrylate were used in an investigation of the effect of the type of the suspension stabilizer and of its concentration on the shape, size, and morphology of beads consisting of submicroscopic particles (globules). Of many stabilizers used, only poly(vinyl pyrro-lidone) and poly(vinyl alcohol) led to the formation of regular spherical beads with a surface shell. As expected, beads obtained using a stabilizer producing higher interfacial tension poly(vinyl pyrrolidone)-K 90 were much larger. A similar effect may be reached by lowering the concentration of poly(vinyl alcohol), if this lowering is accompanied by a rise in the interfacial tension. Despite this, however, the surface shell was not compact in this relatively narrow range of interfacial ten-sions.     

Effect of polymerization conditions on the melt rheological properties of vinyl chloride–vinyl acetate copolymers

Mathematical models have been developed which predict the composition, molecular weight, and melt rheological properties for vinyl chloride/vinyl acetate copolymers of inherent viscosity range 0.4–0.7 dL/g and bound vinyl acetate levels of 3.8–17.4%. The effect of polymer long chain branching on the viscous/elastic moduli ratio is discussed as well as the comparison of Tinius–Olsen melt index measurements vs. mechanical spectrometer results. The reactivity ratio for vinyl chloride/vinyl acetate comonomer pairs was remeasured and found to be significantly different from literature values.     

Effect of deformation on the surface composition of multicomponent polymers. II. Blends of polydimethylsiloxane–polysulfone block copolymers in polychloroprene

The effect of uniaxial stretching on the surface composition of dilute blends of polydimethylsiloxane/polysulfone 2500/44,000 and 2500/3500 block copolymers in polychloroprene is studied using X-ray photoelectron spectroscopy. The surface of the initial (unstretched) blends is found to be covered by a discontinuous copolymer overlayer with a thickness greater than the XPS sampling depth. The stretching leads to a substantial drop in the extent of the copolymer surface segregation. For the 2500/3500 block copolymer, the dependence of the surface composition of the blends on the stretching degree is well described by a homogeneous deformation model, whereas for blends of the 2500/44,000 copolymer, the stretching of the copolymer overlayer lags noticeably behind that of the polychloroprene matrix. In the blends of the 2500/3500 copolymer, the stretching has practically no effect on the distribution of the copolymer components in the near-surface region. By contrast, the 2500/44,000 copolymer shows a substantial surface depletion of siloxane with stretching. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2349–2356, 1998     

Emulsion polymerization of ethylene. IV. Effect of recipe and polymerization conditions on polymer properties

Some Physical, chemical, and solution properties of polyethylene prepared by emulsion polymerization are described and compared with those of conventional high-pressure polymer. The emulsion polymers contain an unusually large amount of low molecular weight material for the solution viscosities they exhibit. It is this low molecular weight material that contributes to the characteristic low elongation of the emulsion polymer, as well as to its wide distribution of molecular weights. The effect of changes in recipe and in conditions of polymerization on these properties is discussed. It is shown that some of the emulsifier present during polymerization becomes part of the polymer chain.     

Reactive polymers. VIII. Reaction of the epoxide groups of the copolymer glycidyl methacrylate – ethylenedimethacrylate with aliphatic amino compounds

The reaction of macroporous copolymers glycidyl methacrylate – ethylenedimethacrylate with ammonia, primary and secondary amines, diamines and hydroxyalkyl amines leading to products with wide applicability was investigated. The reaction can be carried out without or with solvent, water being quite sufficient as the latter. The effects of amine concentration, substituents, temperature and type of the solvent on the reaction course were examined. The reaction product with dimethyl amine and 2-hydroxyethyl amine was alkylated consecutively, and a strongly basic anion exchanger of second type was obtained.     

Reactive polymers,XXXVIII. Sorption of acid gases on macroporous 2,3-epoxypropyl methacrylate copolymers modified by a reaction with amines

Macroporous copolymers of 2,3-epoxypropyl methacrylate and ethylenedimethacrylate modified by aminolysis yielded sorbents with various contents of amino and hydroxy groups. The dependences of structural characteristics of these sorbents and of the sorption of sulphur dioxide on the content of crosslinking agent and on the cyclohexanol/dodecanol ratio used as the porogenic medium in the preparation of copolymers were investigated. The sorption of sulphur dioxide depends on the geometrical structure of the sorbent, concentration, chemical structure and accessibility of functional groups.     

Reactive polymers, 49. Changes in the porous structure of macroporous copolymers due to successive effects of solvents and temperature

By drying at 78°C, the macroporous terpolymer 2,3-dihydroxypropyl methacrylate-co-sodium methacrylate-co-ethylene dimethacrylate with a water retention of 3.78 g H₂O/g loses porosity which is renewed by reswelling. Drying of this terpolymer at 0–25°C by which water or methyl alcohol is removed does not disturb its porosity. Less swelling copolymers such as 2,3-dihydroxypropyl methacrylate-co-ethylene dimethacrylate with a water retention of 1.71 g H₂O/g do not lose its permanent porosity when dried. Inversion gas chromatography has made possible the determination of the glass transition temperature of these macroporous terpolymers (T_g = 45°C) by using heptane and methyl alcohol as retention acids. With respect to this, and using scanning electron microscopy the loss of porosity due to drying was interpreted as sintering of macroporous copolymers whose polymer networks swell to a higher degree on heating above T_g.     

Melt polymerization of copoly(ethylene terephthalate–imide)s and thermal properties

Copoly(ethylene terephthalate–imide)s (PETI) were prepared by melt polycondensation of bis(2-hydroxyethyl)terephthalate (BHET) and imide containing oligomer, i.e., 4,4′-bis[(4-carbo-2-hydroxyethoxy)phthalimido]diphenylmethane(BHEI). The apparent rate of poly-condensation reaction was faster than that of homo poly(ethylene terephthalate) (PET) due to the presence of imide units. The PETI copolymers with up to 10 mol % of BHEI unit in the copolymer showed about the same molecular weight and carboxyl end group content as homo PET prepared under similar reaction conditions. The increase in T_g of copolymer was more dependent on molar substitution of BHEI than on substitution of BHEN, reaching 91°C with 8 mol % BHEI units in the copolymer from T_g = 78.9°C of homo PET. In the case of PETN copolymer, 32 mol % of bis(2-Hydroxyethyl)naphthalate (BHEN) units gave T_g of 90°C. The maximum decomposition temperature of PETI copolymer was about the same as that of homo PET by TGA analysis. The char yield at 800°C was higher than that of homo PET. © 1996 John Wiley & Sons, Inc.     

Effect of spray drying conditions and feed composition on the physical properties of black mulberry juice powder

In this study, the effects of some processing parameters on moisture content, water activity, drying yield, bulk density, solubility, glass transition temperature (T_g), and microstructure of spray dried black mulberry (Morus nigra) juice powders were investigated. A pilot-scale spray dryer was employed for the spray drying process and maltodextrin with different dextrose equivalent (6, 9, and 20DE) and gum Arabic were used as carrier agent. Independent variables were inlet air temperature (110, 130, and 150 °C), compressed air flow rate (400, 600, and 800 L/h), concentration of drying aids (8, 12, and 16%) and percent replacement of maltodextrin (6 and 9DE) by gum Arabic and maltodextrin 20DE (25, 50, and 75%). Between the different drying aids, maltodextrin 6DE shows the best effect on the properties of black mulberry juice powders. The process drying yield ranges from 45 to 82%. The highest drying yield (82%) and solubility (87%) refer to the blend of maltodextrin 6DE and gum Arabic. The lowest moisture content powders (1.5%) produced at the compressed air flow rate of 800 L/h. Inlet air temperature negatively influenced the bulk density due to the increase of powder's porosity. The lower the bulk density, the higher the solubility of powder is. With regard to morphology, powders produced with maltodextrin and gum Arabic presented the smallest size.     

Reactive polymers,XXVII. Kinetics of chemical reactions of metal ions with functional groups of glycidyl methacrylate — ethylenedimethacrylate copolymers modified by ethylenediamine

The conditions were followed which influence the rate of uptake of Cu(II) and Ag(I) ions by a copolymer of glycidyl methacrylate with ethylene dimethacrylate modified by ethylenediamine. In addition to the particle size (0.1–1 mm) of the chelating resin, the concentration of cations in solution affects substantially the rate of sorption. It follows from the calculated rate of diffusion and from the rate constants of the chemical reaction that the reaction kinetics is decisive for particles below 0.1 mm, whereas with increasing particle size the inner diffusion begins to play a more important role and becomes finally the rate-determining mechanism. The obtained results are supported by observations of morphology.     

Control of morphology and properties in multicomponent polymers based on polystyrene/polyester block copolymers

Abstract

The morphology and properties of multicomponent polymers based on polystyrene/polyarylate block copolymers (PS–b–PAr) are investigated. The PS–b–PAr molecule was synthesised by a novel procedure using carboxy terminated polystyrene. The architectures of the PS–b–PAr copolymers were predicted by a kinetic simulation model. Based on the results of the simulation and analysis of morphology, both the optical and mechanical properties of the PS–b–PAr are explained. The domain size, which dominates the transparency, was found to be sensitive to the purity of the block copolymer, while the birefringence was determined not only by the PS/PAr ratio but also by the length of each segment. On the basis of the experimental analyses, conditions were designed for the synthesis of PS–b–PAr copolymers with high transparency and low birefringence. The mechanical properties of the PS–b–PAr were controlled by modification of the miscibility between the PS and PAr segments. Acrylonitrile was introduced into the PS chain as a miscibility modifier. The volume fraction of the interfacial layer increased with the increase in miscibility. In particular, around the acrylonitrile concentration at which the miscibility reaches a maximum, the flexural strength was dramatically improved, changing the fracture behaviour from brittle to ductile. Furthermore, the PS–b–PAr copolymer was used as a compatibiliser for several immiscible polymer blend systems, including high impact polystyrene–polycarbonate and polyamide 6–acrylonitrile/butadiene/styrene. In these applications the PAr unit was used not as a macromolecular anchor but as a reactive unit. The experimental results showed that PS–b–PAr could compatibilise these blend systems effectively via an in situ reaction between the PAr chain and either polycarbonate or polyamide 6 during the melt mixing process.