Opis: A new class of polyHIPE materials has been prepared using high internal phase emulsions (HIPEs) with monomers in both phases. Resulting materials, namely hybrid polyHIPE materials, are obtained consisting of hydrophobic matrix (consisted of styrene cross-linked with DVB or dicyclopentadiene) filled with hydrophilic polymer gel (polyacrylic acid or polyNIPAM) and exhibit morphology changes according to pH and temperature of the surrounding medium. Our focus with regards to the production of hybrid polyHIPE materials was the responsiveness of such materials used for flow control. This property is beneficial for controlling the flow of the solution through the monolithic polymers. Furthermore, polyHIPE materials have also been prepared by using ring opening metathesis polymerisation of monomers, such as dicyclopentadiene and norbornene. Obtained materials have Young’s moduli in the range of hundred times higher than standard polyHIPE materials with the same level of porosity which represents a very important improvement in the development of highly porous cellular polymeric materials.Najdeno v: ključnih besedahPovzetek najdenega: ...flow of the solution through the monolithic polymers. Furthermore, polyHIPE materials have also been prepared...Ključne besede: emulsions, high internal phase emulsions, polymers, polyHIPEs, hybrid, hybrid polyHIPE materials, ROMP, flow-through, styrene, DVB, acrylic acid, NIPAMObjavljeno: 04.05.2011; Ogledov: 924; Prenosov: 45 Polno besedilo (3,71 MB)
Opis: A series of monolithic crosslinked polymers with 2,4,6-trichlorophenyl acrylate as a reactive component was prepared by free radical polymerization of the internal phases of high internal phase emulsions (HIPEs). The volume ratio of water to oil phase (void volume; 60-90%), crosslinker type (divinylbenzene or ethylenglycol dimethacrylate) and quantity (30-50 mol %) and type of porogenic solvent (chlorobenzene, toluene, chloroform, dichloroethane) were altered to study these effects on the structure and reactivity of the monolithic polymers. The polymer supports were characterizedby scanning electron microscopy (SEM), FTIR spectroscopy, elemental analysis and mercury intrusion porosimetry. SEM images revealed an open cellular structure with voids between 1 and 12 ▫$/mu$▫m and window sizes between 0.3 and 3 ▫$/mu$▫m. The porogen had an influence on the surface area, being larger with added porogen and the influence being highest with toluene. Addingtoluene also influenced the void size, increasing the average diameter from 2 ▫$/mu$▫m (no porogen) to 12 ▫$/mu$▫m (added toluene). Monolithic supports were functionalized by reaction of the ester moieties with tris(2-aminoethyl)amine derivative and by hydrolysis of the ester groups to carboxylic acids.Najdeno v: ključnih besedahKljučne besede: organic chemistry, aryl acrylates, monolythic polymers, monoliths, functionalization of polymers, emulsion templating, emulsion polymerisation, macroporous polymers, morphology, polyHIPE, polymer supports, supports, 2, 4, 6-trichlorophenyl acrylateObjavljeno: 31.05.2012; Ogledov: 174; Prenosov: 0 Polno besedilo (0,00 KB)
Opis: Preparation of highly porous (up to 80% pore volume) open-cellular monolithic cross-linked polymers from 2-hydroxyethyl methacrylate is reported. Oil-in-water and water-in-oil high internal phase emulsions are applied as porosity templates, resulting in an interconnected porous structure with void diameters between 550 nm and 18 m. Significantly larger voids were obtained inthe case of oil-in-water emulsions (between 5 and 18 m) as opposed to water in oil emulsions (approx 600 nm). Controlled coarsening exploiting limited kinetical stability of emulsions was used to obtain monoliths with larger voids, diameters being enlarged 3-fold.Najdeno v: ključnih besedahPovzetek najdenega: ...to 80% pore volume) open-cellular monolithic cross-linked polymers from 2-hydroxyethyl methacrylate is reported. Oil-in-water and...Ključne besede: organic chemistry, polymerization, monolithic polymers, HIPE, emulsions, porous materials, methacrylatesObjavljeno: 31.05.2012; Ogledov: 156; Prenosov: 0 Polno besedilo (0,00 KB)
Opis: Poly(high internal phase emulsion) materials were prepared from concentrated emulsions containing 4-vinylbenzyl chloride as the reactive monomer and divinylbenzene as the cross-linker. Emulsions consisted of 80 vol. % aqueous phase (water, CaCl2, initiator) and 20 vol. % of organic phase (monomers, surfactant Span 80 and a porogenic solvent). Polymerized samples were purified and investigated for morphology and porosity by scanning electron microscopy, nitrogen adsorption/ desorption and inverse steric exclusion chromatography (ISEC). It was found that no substantial additional dry porosity was achieved by the addition of solvents (as determined by nitrogen adsorption) while wet microporosity was substantially improved as determined by the ISEC method. The process of drying the polyHIPE materials also influenced the wet porosity.Najdeno v: ključnih besedahPovzetek najdenega: ...emulsions, polymerization, monolithic polymers, HIPE, porous materials, exclusion chromatography...Ključne besede: emulsions, polymerization, monolithic polymers, HIPE, porous materials, exclusion chromatographyObjavljeno: 31.05.2012; Ogledov: 237; Prenosov: 2 Polno besedilo (0,00 KB)
Opis: In this study thermosensitive polymeric microspheres obtained in former research were evaluated in vitro for their photoprotective activity. The UVA/UVB ratio was assessed at so called shelf temperature i.e. at 25°C, and at elevated temperature of 45°C. The evaluated polymers absorb higher levels of UV radiation, when heated from 25°C to 45°C. The MS1 polymer may be defined as polymer with high efficiency in the terms of gaining protection against UVAradiation, when heated. The MS2 absorbs both UVA and UVB radiation, and maybe considered, as most protective, when heated to 45°C. The equalized and less strong activity has the polymer MS3 when heated, with lipophilic radical implemented during synthesis.Najdeno v: ključnih besedahPovzetek najdenega: ...at elevated temperature of 45°C. The evaluated polymers absorb higher levels of UV radiation, when...Ključne besede: thermosensitive polymers, photoprotection, UV radiation, N-isopropylacrylamideObjavljeno: 31.05.2012; Ogledov: 167; Prenosov: 0 Polno besedilo (0,00 KB)
Najdeno v: ključnih besedahKljučne besede: polymers, biotechnology, biomedicine, chemical synthesis, cell separation, gels, tissue engineeringObjavljeno: 31.05.2012; Ogledov: 134; Prenosov: 0 Polno besedilo (0,00 KB)
Opis: An oil-in-water high internal phase emulsion consisting of acrylic acid, water, and a crosslinker (N,N-methylene bisacrylamide) as the water phase, and toluene as the oil phase was successfully stabilised to sustain thermal initiation of radical polymerisation resulting in porous open-cellular monolithic material. The type of initiator used influenced the average pore size ranging from approx. 708 nm to approx. 1 087 nm, as determined by mercury porosimetry.Najdeno v: ključnih besedahPovzetek najdenega: ...hydrophilic polymers, macroporous polymers, poly (acrylic acid), polyHIPE, supports...Ključne besede: hydrophilic polymers, macroporous polymers, poly (acrylic acid), polyHIPE, supportsObjavljeno: 01.06.2012; Ogledov: 184; Prenosov: 1 Polno besedilo (0,00 KB)
Opis: Porous monolithic polymers are objects of many studies recently due to their wide applicability. Especially in separation methods use of monoliths is growing. Usually, porous monoliths are prepared by bulk polymerisation with the use of porogenic solvents. An alternative way of preparation is to polymerise the continuous phase of an emulsion. When the volume fraction of the internal phase exceeds 74%, the emulsion is called a HIPE (high internal phase emulsion), and a polymer derived from it, a PolyHIPE. PolyHIPEs of styrene, vinylbenzyl chloride and acrylate chemistry have been prepared from awater in oil emulsion system, where monomers are dissolved in the organic phase. We describe the reversed procedure, an oil in water high internal phaseemulsion, where monomers are water soluble. Porous polymers based on acrylic acid and crosslinked with methylenebisacrylamide were prepared by using a high internal phase emulsion with toluene as the oil phase. The influence of initiator and surfactant on the morphology was studied.Najdeno v: ključnih besedahKljučne besede: organic chemistry, porous monolith polymers, polymer supports, preparation, emulsion polymerization, HIPEObjavljeno: 01.06.2012; Ogledov: 144; Prenosov: 2 Polno besedilo (0,00 KB)
Opis: Water-in-oil high-internal-phase emulsions (HIPEs), containing 4-nitrophenyl acrylate and 2,4,6-trichlorophenyl acrylate as reactive monomers, were prepared and polymerized, and highly porous monolithic materials resulted. The novel materials were studied by combustion analysis, Fourier transform infrared spectroscopy scanning electron microscopy, mercury porosimetry, and N2 adsorption/desorption analysis. With both esters, cellular macroporous monolithic polymers were obtained: the use of 4-nitrophenyl acrylate resulted in a cellular material with void diameters between 3 and 7 m and approximately3-m interconnects, whereas the use of 2,4,6-trichlorophenyl acrylate yielded a foam with void diameters between 2 and 5 m, most interconnects being around 1 m. The resulting monoliths proved to be very reactive toward nucleophiles, and possibilities of functionalizing the novel polymer supports were demonstrated via reactions with amines bearing additional functional groups and via the synthesis of an acid chloride derivative. Tris(hydroxymethyl)aminomethane and tris(2-aminoethyl)amine derivatives were obtained. The hydrolysis of 4-nitrophenylacrylate removed thenitrophenyl group, yielding a monolithic acrylic acid polymer. Furthermore,functionalization to immobilized acid chloride was performed very efficiently, with more than 95% of the acid groups reacting. The measurement of the nitrogen content in 4-nitrophenyl acrylate poly(HIPE)s after various times of hydrolysis showed the influence of the total pore volume of the monolithic polymers on the velocity of the reaction, which was faster with themore porous polymer.Najdeno v: ključnih besedahPovzetek najdenega: ...analysis. With both esters, cellular macroporous monolithic polymers were obtained: the use of 4-nitrophenyl acrylate...Ključne besede: organic chemistry, macroporous polymers, monolithic polymer supports, emulsion polymerisation, foams, functionalization of polymers, high-internal-phase emulsionsObjavljeno: 01.06.2012; Ogledov: 166; Prenosov: 0 Polno besedilo (0,00 KB)
Opis: Today, monoliths are well-accepted chromatographic stationary phases due to several advantageous properties in comparison with conventional chromatographic supports. A number of different types of monoliths have already been described, among them recently a poly(high internal phase emulsion) (PolyHIPE) type of chromatographic monoliths. Due to their particular structure, we investigated the possibility of implementing different mathematical models to predict pressure drop on PolyHIPE monoliths. It was found that the experimental results of pressure drop on PolyHIPE monoliths can best be described by employing the representative unit cell (RUC) model, which was originally derived for the prediction of pressure drop on catalytic foams. Models intended for the description of particulate beds and silica monoliths were not as accurate. The results of this study indicate that the PolyHIPE structure under given experimental condition is, from a hydrodynamic point of view, to some extent similar to foam structures, though any extrapolation of these results may not provide useful predictions of pressure versus flow relations and further experiments are required.Najdeno v: ključnih besedahPovzetek najdenega: ...organic chermistry, polymers, monoliths, PolyHIPE, hydrodynamic properties, pressure drop...Ključne besede: organic chermistry, polymers, monoliths, PolyHIPE, hydrodynamic properties, pressure dropObjavljeno: 01.06.2012; Ogledov: 157; Prenosov: 1 Polno besedilo (0,00 KB)
