| | SLO | ENG | Cookies and privacy

Bigger font | Smaller font

Search the digital library catalog Help

Query: search in
search in
search in
search in
* old and bologna study programme

Options:
  Reset


1 - 10 / 11
First pagePrevious page12Next pageLast page
1.
HYBRID PolyHIPE MATERIALS
Sebastijan Kovačič, 2011, dissertation

Abstract: 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.
Keywords: emulsions, high internal phase emulsions, polymers, polyHIPEs, hybrid, hybrid polyHIPE materials, ROMP, flow-through, styrene, DVB, acrylic acid, NIPAM
Published: 04.05.2011; Views: 2264; Downloads: 199
.pdf Full text (3,71 MB)

2.
Acrylic acid "reversed" polyHIPEs
Peter Krajnc, Dejan Štefanec, Irena Pulko, 2005, original scientific article

Abstract: 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.
Keywords: hydrophilic polymers, macroporous polymers, poly (acrylic acid), polyHIPE, supports
Published: 01.06.2012; Views: 1369; Downloads: 61
URL Link to full text

3.
Pressure drop characteristics of poly(high internal phase emulsion) monoliths
Ita Junkar, Tine Koloini, Peter Krajnc, Damjan Nemec, Aleš Podgornik, Aleš Štrancar, 2007, original scientific article

Abstract: 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.
Keywords: organic chermistry, polymers, monoliths, PolyHIPE, hydrodynamic properties, pressure drop
Published: 01.06.2012; Views: 1156; Downloads: 65
URL Link to full text

4.
Microcellular open porous poly(divinyl adipate)
Marko Turnšek, Peter Krajnc, 2013, published scientific conference contribution

Keywords: polimeri, polyHIPE
Published: 10.07.2015; Views: 601; Downloads: 12
URL Link to full text

5.
Crosslinked 2-hydroxyethyl methacrylate within emulsion templating
Muzafera Paljevac, Karel Jeřábek, Peter Krajnc, 2013, published scientific conference contribution

Keywords: polimeri, polyHIPE
Published: 10.07.2015; Views: 567; Downloads: 20
URL Link to full text

6.
Poly(styrene-co-divinylbenzene-co-2-ethylhexyl)acrilate membranes with interconnected macroporous structure
Urška Sevšek, Silvo Seifried, Črtomir Stropnik, Irena Pulko, Peter Krajnc, 2011, original scientific article

Abstract: A combination of doctor blading and emulsion templating was used to prepare macroporous poly(styrene-co-divinylbenzene-co-2-ethylhexylacrylate) and poly(styrene-co-divinylbenzene) membranes with an interconnected porous structure. Water in oil high internal phase emulsions including monomers in the oil phase were cast onto a glass plate and polymerised at elevated temperature. After purification porous polyHIPE membranes were obtained. The volume ratio of aqueous phase (75 % or 85 %) and the molar ratio of divinylbenzene (2 % or 4 %) were varied, while the addition of chlorobenzene to the oil phase influenced the viscosity of the emulsions. A comonomer, 2-ethylhexylacrylate substantially improved the flexibility of the membranes. All yielding membranes were characterized by measuring their cast thicknesses and flow densities for deionised water. Scanning electron microscopy was used to study the morphological features of the membranes.
Keywords: membrane, porous polymers, polyHIPE, emulsions
Published: 10.07.2015; Views: 1002; Downloads: 81
.pdf Full text (668,83 KB)
This document has many files! More...

7.
Tailoring the mechanical and thermal properties of dicyclopentadiene polyHIPEs with the use of a comonomer
E. H. Mert, Christian Slugovc, Peter Krajnc, 2015, original scientific article

Abstract: The effect of adding a comonomer to dicyclopentadiene in high internal phase emulsions (HIPEs) on the properties of ring-opening metathesis polymerisation (ROMP) derived polyHIPEs has been investigated. With this aim, dicylopentadiene was copolymerised with norbornene in surfactant stabilized high internal phase emulsions. Morphological, mechanical and thermal properties of the resulting materials were investigated with regard to the monomer ratio. The interconnected pore structure was observed for the resulting poly(dicylopentadiene-co-norbornene) polyHIPEs. Furthermore, the new polyHIPE copolymers were found to have an improved thermal stability compared to the poly(dicylopentadiene) homopolymer.
Keywords: mechanical properties, emulsion templating, polyHIPE, dicyclopentadiene, norbornene
Published: 07.08.2017; Views: 336; Downloads: 176
.pdf Full text (1,39 MB)
This document has many files! More...

8.
Tkivni inženiring hrustančnega tkiva na biosintetičnem polimernem polyHIPE nosilcu
Jakob Naranđa, 2017, doctoral dissertation

Abstract: Tkivni inženiring hrustančnega tkiva še vedno nudi številne možnosti za izboljšavo, navkljub intenzivnim raziskovalnim naporom v zadnjem času. Razvoj umetnih materialov in 3-D celičnih nosilcev ima pomembno vlogo pri regeneraciji hrustančnega tkiva. Zanimiv pristop pri izdelavi celičnih nosilcev predstavlja izgradnja s pomočjo emulzij. Nastali material, imenovan polyHIPE (PHP), je sintetični visoko porozen polimer, ki ga pripravimo s polimerizacijo visokega deleža notranje faze emulzij (HIPEs – high internal phase emulsions). Glavni cilj te doktorske disertacije je raziskati možnosti za tvorbo hrustančnega tkiva znotraj celičnih nosilcev pripravljenih iz PHP materiala. Proizvodnjo PHP nosilcev smo posebej prilagodili tkivnemu inženiringu hrustanca, tako da smo pripravili porozne (85 %) strukture s primarno velikostjo por v območju 50–170 m. Pokazali smo, da je PHP material biokompatibilen s človeškimi sklepnimi hondrociti, kar smo ovrednotili s pomočjo testa za preživetje celic (Live/Dead kit) in histološko analizo. Opazovali smo hondrocite z okroglimi jedri, ki so bili organizirani v večceličnih plasteh na površini PHP nosilca in so rastli približno 300 m v notranjost nosilca. Kopičenje kolagena tipa 2 smo dokazali s pomočjo imunohistokemije, molekularna analiza je pokazala izražanje hrustančno specifičnih genov z ugodnim razmerjem kolagena tipa 2 in tipa 1. Dodatno so bili PHP vzorci biološko razgradljivi, njihove osnovne mehanske lastnosti pa primerljive z nativnim sklepnim hrustancem. Izsledki raziskave dokazujejo, da je zasnovan PHP celični nosilec primeren za nadaljnjo uporabo v tkivnem inženiringu hrustančnega tkiva.
Keywords: humani sklepni hrustanec, tkivni inženiring, biokompatibilni celični nosilec, sintetični polimer, polyHIPE, diferenciacija hondrocitov
Published: 17.10.2017; Views: 499; Downloads: 70
.pdf Full text (24,38 MB)

9.
Microcellular open-porous polystyrene-based composites from emulsions
Sebastjan Huš, Mitja Kolar, Peter Krajnc, 2014, original scientific article

Abstract: Series of cross-linked polystyrene samples were prepared using an emulsion templating approach, where monomers were contained in the continuous phase of the emulsion, while the droplet aqueous phase induced primary pores, connected with a number of secondary pores. Emulsions with a high fraction of the droplet phase (HIPEs) were used and stabilised with a combination of a surfactant (sorbitan monooleate) and various types of particles (charcoal powder, copper powder and carbon nanopowder). The morphology of the resulting porous polymer depends on the type and amount of the particles added to the emulsion; however, in all the cases open-cellular morphology was formed. The size of the primary pores (cavities) ranged from 5 µm to 25 µm, while the size of the secondary interconnecting pores was from 1 µm to 5 µm. The materials were investigated using scanning electron microscopy and nitrogen adsorption/desorption.
Keywords: polyHIPE, porous polymers, nanocomposites, porosity, polystyrene
Published: 16.03.2017; Views: 566; Downloads: 68
.pdf Full text (1,06 MB)
This document has many files! More...

10.
Polyester type polyHIPE scaffolds with an interconnected porous structure for cartilage regeneration
Jakob Naranđa, Maja Sušec, Uroš Maver, Lidija Gradišnik, Mario Gorenjak, Andreja Vukasović, Alan Ivković, Marjan Rupnik, Matjaž Vogrin, Peter Krajnc, 2016, original scientific article

Abstract: Development of artificial materials for the facilitation of cartilage regeneration remains an important challenge in orthopedic practice. Our study investigates the potential for neocartilage formation within a synthetic polyester scaffold based on the polymerization of high internal phase emulsions. The fabrication of polyHIPE polymer (PHP) was specifically tailored to produce a highly porous (85%) structure with the primary pore size in the range of 50–170 μm for cartilage tissue engineering. The resulting PHP scaffold was proven biocompatible with human articular chondrocytes and viable cells were observed within the materials as evaluated using the Live/Dead assay and histological analysis. Chondrocytes with round nuclei were organized into multicellular layers on the PHP surface and were observed to grow approximately 300 μm into the scaffold interior. The accumulation of collagen type 2 was detected using immunohistochemistry and chondrogenic specific genes were expressed with favorable collagen type 2 to 1 ratio. In addition, PHP samples are biodegradable and their baseline mechanical properties are similar to those of native cartilage, which enhance chondrocyte cell growth and proliferation.
Keywords: polyester, polymerization, polyHIPE
Published: 23.06.2017; Views: 584; Downloads: 201
.pdf Full text (1,24 MB)
This document has many files! More...

Search done in 0.17 sec.
Back to top
Logos of partners University of Maribor University of Ljubljana University of Primorska University of Nova Gorica