Search the digital library catalog

Query:	search in
	search in
	search in
	search in
Work type:	* old and bologna study programme
Language:
Search in:
Options:	Show only hits with full text
	Reset

1 - 3 / 3

Influence of Monomer Structure, Initiation, and Porosity on Mechanical and Morphological Characteristics of Thiol-ene PolyHIPEs
Stanko Kramer, Peter Krajnc, Irena Pulko, 2023, original scientific article

Keywords: porous polymers, high internal phase emulsion, HIPEs
Published in DKUM: 08.05.2024; Views: 162; Downloads: 6
Full text (1,39 MB)
This document has many files! More...

Cross-linked porous poly(acrylic acid-co-acrylamide) from high internal phase emulsions: preparation and functionalisation
Janja Majer Kovačič, Peter Krajnc, 2009, original scientific article

Abstract: By using emulsions with high volume fractions of internal phase as polymerisation media porous copolymers of acrylic acid and acrylamide, cross-linked by methylenebisacrylamide, were prepared. The ratio of acrylic acid to acrylamide were varied (molar ratios 70:30, 50:50, 30:70) in order to yield polymers with various loading of acidic functional groups. Porous polymers with an open-cellular architecture were obtained with void diameters between 2.8 μm and 3.9 μm and with interconnecting pores approx. 0.3 μm in diameter. The chemical composition of the polymers influenced the conversion degrees during the process of functionalisation of acidic groups to acid chloride, being the highest in the case of polymer with the lowest content of acrilyc acid.
Keywords: porous monoliths, copolymers, polyacrylic acid, polyacrylamide, plyHIPE, high internal phase emulsion
Published in DKUM: 17.08.2017; Views: 2286; Downloads: 140
Full text (218,85 KB)
This document has many files! More...

Aryl acrylate based high-internal-phase emulsions as precursors for reactive monolithic polymer supports
Peter Krajnc, Dejan Štefanec, Jane F. Brown, Neil R. Cameron, 2005, original scientific article

Abstract: 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.
Keywords: organic chemistry, macroporous polymers, monolithic polymer supports, emulsion polymerisation, foams, functionalization of polymers, high-internal-phase emulsions
Published in DKUM: 01.06.2012; Views: 2329; Downloads: 97
Link to full text

Search done in 0.07 sec.