F. Švec

Hydrolysed macroporous glycidyl methacrylate-ethylene dimethacrylate copolymer sorbent for size-exclusion high-performance liquid chromatography of synthetic polymers and biopolymers

Les groupes epoxy sont hydrolyses pour ameliorer leur hydrophilicite. Separation de proteines, de polystyrene

Hydrolyzed macroporous glycidyl methacrylate-ethylene dimethacrylate copolymer with narrow pore size distribution : A novel packing for size-exclusion high-performance liquid chromatography

Abstract By means of chromatographic methods and mathematical treatment, commercial inorganic and polymeric packings were compared with macroporous glycidyl methacrylate-ethylene dimethacrylate copolymers prepared by the usual polymerization techniques. It was found that the pore size polydispersity of the usual polymeric sorbents is several times higher than that of the inorganic sorbents. For this reason, they are better suited for the separation of mixtures of macromolecules with freely mobile chains than of globular proteins. This was demonstrated by the separation of eleven polystyrene standards and benzene, which was identical with that which can be accomplished only by using a mixed sorbent consisting of several types of silica. Purposeful interferences with the polymerization mixture, i.e., a change in the porogenic mixture, allowed synthesis of polymeric beads in which the pore size distribution was almost identical with that of inorganic packings.

Reactive polymers: 61. Reaction of macroporous poly(glycidyl methacrylate-co-ethylene dimethacrylate) with phenol

Abstract A series of sorbents differing substantially in the content of phenyl groups were prepared by a base-catalysed reaction of poly(glycidyl methacrylate- co -ethylene dimethacrylate) with phenol. Methods are described for quantitative determination of the degree of substitution of epoxide groups by phenol, based on 13 C nuclear magnetic resonance and infra-red spectroscopy and on elemental analysis (C, H); the last method was found to be inappropriate, however, owing to the large error involved. Infra-red spectroscopy is the method of choice for determining the degree of substitution. By studying the local properties of the regression surface, a polynomial equation was derived for the dependence of the degree of substitution of epoxide groups by phenol on the mole ratios phenol/epoxide and sodium hydroxide/phenol. The time dependence of the extent of reaction was also studied. The maximum degree of substitution attained was 0.65.

E.p.r. study of spin-labelled glycidyl methacrylate-ethylene dimethacrylate and styrene-divinylbenzene suspension copolymers in the swollen state

Abstract Reactive groups of homogeneous or macroporous copolymers glycidyl methacrylate-ethylene dimethacrylate and styrene-divinylbenzene containing different amounts of crosslinking agents have been modified in the reaction with an amino derivative of stable nitroxide. The spin-labelled copolymers thus formed were swollen in thermodynamically good or bad solvents and studied by the electron paramagnetic resonance (e.p.r.) method. Two types of spin labels were found in the majority of these copolymers at suitable temperatures and their concentrations were determined. According to our interpretation, the spin labels subjected to rapid rotational diffusion belong to the modified groups localized on chains attached to the inner surface of macroporous copolymers while the spin labels subjected to the very slow rotational diffusion belong to the modified groups localized inside highly crosslinked globules forming the inner structure of the macroporous copolymers. In the less highly crosslinked homogeneous copolymers the modified groups carrying the spin labels subjected to very slow and rapid rotational diffusion are localized in, respectively, the more crosslinked and less crosslinked domains of the polymer beads.

An investigation of the morphology of glycidyl methacrylate copolymers using inverse size-exclusion chromatography

Abstract Properties of glycidyl methacrylate—ethylene dimethacrylate copolymers were investigated by using inverse size-exclusion chromatography. The structure of macropores was described by means of the cylindrical pore model. The swollen polymeric matrix was characterized on the basis of Ogstons model of porous structure. The polymer density was found to be considerably higher than that of analogous copolymers of styrene and divinylbenzene. Macroporous polymers contain a very loosely crosslinked polymeric fraction which does not occur in gel types. Changes in the structure of polymers investigated in this study caused by swelling are discussed on the basis of differences between the specific surface areas as determined by inverse size-exclusion chromatography and by nitrogen sorption.

Gas chromatographic and sorption properties of macroporous metahcrylate copolymers

Abstract The chromatographic properties of copolymers of 2,3-epoxypropyl methacrylate and 2,3-epithiopropyl methacrylate with ethylene dimethacrylate and of their derivatives modified with amines were investigated by means of gas chromatography and by the sorption of sulphur and carbon dioxides. The relative retention volumes and the changes in the free energy of adsorption of various compounds depend on the extent of the specific surface area of copolymers and on the content of functional groups. A study of the sorption of different compounds revealed that with increasing specific surface area the non-specific interactions increase while specific interactions decrease. This suggests that the accessibility of functional groups decreases with increasing extent of cross-linking of the sorbent.

Reactive polymers: XL. Study of the internal structure of thermally treated polymeric sorbents based on glycidyl methacrylate copolymers

Abstract A decrease in the specific pore volume and specific surface area and an overall narrowing of the pore distribution are the main changes in the internal structure of thermally treated copolymers based on glycidyl methacrylate-ethylene dimethacrylate. They are also colsely connected with changes in the chromatographic properties of polymeric sorbents thus treated. The decrease in the pore volume may be directly correlated with the decrease in the retention volumes.

Reactive polymers : XLI. Effect of the content and distribution on polar groups on the polarity of glycidylmethacrylate polymeric sorbents

Abstract Photeelectron spectroscopy has revealed that the distribution of polar groups (carboxylic and epoxy groups) in macroporous copolymers based on glycidylmethacrylate (GMA)—ethylene dimethacrylate (EDMA) is not uniform, but that their concentration increases starting from the surface towards the centre of the globules. Heat treatment of these copolymers gives rise of conformational changes, which in turn cause an increase in the concentration of polar groups on the surface of the globules, and thus also a rise in polarity. Differences between the modified Rohrschneider constants on the copolymers GMA—EDMA and methyl methacrylate (MMA)—EDMA were used in order to evaluate the participation of epoxy groups in the overall polarity of glycidylmethacrylate polymeric sorbents.