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Colloid and Polymer Science

G Kristin Jonsson, Jeanette Ulama, Malin Johansson, Malin Zackrisson Oskolkova, Johan Bergenholtz
Fluorinated spheres with grafted poly(ethylene glycol) (PEG) have been synthesized using a semi-batch emulsion polymerization in which the initiator is fed slowly to the reaction. In this way, PEG-grafted colloidal spheres can be fabricated with varying PEG chain length, different cores and varying degrees of crosslinking. The resulting batches have been characterized using disc centrifuge photosedimentometry and small-angle X-ray scattering. The size distribution is shown to be a sensitive function of the molar ratio of the reactive PEG macromonomer to fluorinated monomer, and with some optimization latices of very low polydispersity can be obtained with this simple synthesis method...
2017: Colloid and Polymer Science
S M Hosseini-Nasab, P L J Zitha
The objective of this study is to discover a synergistic effect between foam stability in bulk and micro-emulsion phase behaviour to design a high-performance chemical system for an optimized alkaline-surfactant-foam (ASF) flooding for enhanced oil recovery (EOR). The focus is on the interaction of ASF chemical agents with oil in the presence and absence of a naphthenic acid component and in situ soap generation under bulk conditions. To do so, the impact of alkalinity, salinity, interfacial tension (IFT) reduction and in situ soap generation was systematically studied by a comprehensive measurement of (1) micro-emulsion phase behaviour using a glass tube test method, (2) interfacial tension and (3) foam stability analysis...
2017: Colloid and Polymer Science
Amit Tripathi, Chunxiang Wei, Klaus Tauer
The assumption that during emulsion polymerization, the monomer molecules simply diffuse through the aqueous phase into the latex particles is a commonplace. However, there are experimental hints that this might not be that easy. Here, simulation results are discussed based on Fick's diffusion laws regarding the swelling of latex particles. The results of quantitative application of these laws for swelling of latex particles allow the conclusion that the instantaneous replenishment of the consumed monomer during emulsion polymerization requires a close contact between the monomer and the polymer particles...
2017: Colloid and Polymer Science
Giuseppe Lazzara, Richard A Campbell, Solmaz Bayati, Kaizheng Zhu, Bo Nyström, Tommy Nylander, Karin Schillén
The thermal responsive behavior of adsorbed layers of diblock copolymers of poly(N-isopropylacrylamide) (PNIPAAM) and poly((3-acrylamidopropyl)trimethylammonium chloride) (PAMPTMA(+)) with γ-cyclodextrin (γ-CD) at the solid/liquid interface has been investigated using three in situ techniques: null ellipsometry, quartz-crystal microbalance with dissipation monitoring, and neutron reflectometry. The measurements provided information about the adsorbed amounts, the layer thickness, hydration and viscoelastic properties, and the interfacial structure and composition...
2017: Colloid and Polymer Science
Anna M Szczotok, Manuel Carmona, Anna-Lena Kjøniksen, Juan F Rodriguez
The adsorption of polyvinylpyrrolidone (PVP) by the thermoregulating microcapsules has been studied. The mass ratio of PVP has been changed from 1 to 20, with respect to the lowest amount of PVP value (4.08 g). The results confirmed that a large amount of PVP was adsorbed by the polymeric shell. Experimental data were perfectly fitted by Langmuir model, obtaining at a confidence level of 95% values of 192.9 ± 0.4 g/kg and 0.18 ± 0.11 m(3)/kg for the maximum adsorption capacity and the equilibrium constant, respectively...
2017: Colloid and Polymer Science
Jessica A Bonham, Franceska Waggett, Malcolm A Faers, Jeroen S van Duijneveldt
Non-aqueous microgel particles are commonly synthesised in water, dried, and then redispersed in non-aqueous solvents. An important factor to consider when synthesising such particles is the initiator, which can determine how well the particles disperse in solvents. Polystyrene microgel particles were made with three different initiators. When a neutral, oil soluble initiator (azobisisobutyronitrile) was used the particles dispersed in toluene as well as cyclohexane and decalin. In contrast, anionic, water-soluble initiators (potassium persulfate or azobis(4-cyanovaleric acid)) created particles that only redispersed in toluene and not the other two solvents...
2017: Colloid and Polymer Science
Stanislaw Jung, Aneta Petelska, Piotr Beldowski, Wayne K Augé, Tahlia Casey, Dominik Walczak, Krzysztof Lemke, Adam Gadomski
This mini review is focused on the emerging nexus between the medical device and pharmaceutical industries toward the treatment of damaged articular cartilage. The physical rationale of hyaluronic acid and phospholipid preparations as tribological surgical adjuvants for repaired articular cartilage surfaces is explored, with directions for possible new research which have arisen due to the therapeutic advance of the physiochemical scalpel. Because synovial joint lubrication regimes become dysfunctional at articular cartilage lesion sites as a result of the regional absence of the surface active phospholipid layer and its inability to reform without surgical repair, hyaluronic acid and phospholipid intra-articular injections have yielded inconsistent efficacy outcomes and only short-term therapeutic benefits mostly due to non-tribological effects...
2017: Colloid and Polymer Science
Anna Mozrzymas
The molecular connectivity indices were used to derive the simple model relating the critical micelle concentration of cationic (chloride) gemini surfactants to their structure. One index was selected as the best to describe the effect of the structure of investigated compounds on critical micelle concentration consistent with the experimental results. This index encodes the information about molecular size, the branches, and also the information about heteroatoms. The selected model can be helpful in designing novel chloride gemini surfactants...
2017: Colloid and Polymer Science
Björn Lindman
Surfactants have been the basis for applications in several industrial sectors for a long time. However, fundamental research was 50 years ago still limited to a small number of academic groups and even basic aspects were controversial. The field has since undergone an enormous expansion and the improved understanding has laid the basis of numerous new products as well as been the basis of important parts of nano-science and -technology.The present author has during 50 years in academia devoted most of his research to amphiphilic compounds, including both surfactants and polymers...
2016: Colloid and Polymer Science
Małgorzata Wiśniewska, Stanisław Chibowski, Teresa Urban, Dariusz Sternik, Konrad Terpiłowski
The stability mechanism and thermal properties of the system alumina-anionic polyacrylamide (PAM) was studied. The polymer's adsorption properties in dependence on the following parameters solution pH (in the range 3-9), temperature (in the range 15-35 °C), and carboxyl groups' content in the PAM chains (in the range 5-30 %) were examined. The turbidimetry method was applied for determination of the suspension stability of alumina in the presence of PAM. The obtained results indicate that the polymer addition improves significantly Al2O3 suspension stability at pH 6 and 9 (in the whole examined temperature range)...
2016: Colloid and Polymer Science
Aleksandra Szcześ
After an hour contact with a phospholipase A2 (PLA2) solution, only the outer leaflet of the dipalmitoylphosphatidylcholine (DPPC) bilayers supported on mica surface underwent hydrolysis whose products, i.e., palmitic acid and lysophospholipid, accumulated on the bilayer surface. Only calcite was present on the bare mica and enzymatically unmodified and modified supported DPPC bilayers soaked for 2 weeks at 25 and 37 °C in a solution of initial pH equals to 7.4 and 9.2 containing calcium and bicarbonate ions at their concentrations about those of human blood plasma...
2016: Colloid and Polymer Science
Sławomir Drozdek, Urszula Bazylińska
The present work is focused on the long-term stability and in vitro cellular internalization of newly designed biocompatible polyester nanocapsules prepared via nanoprecipitation approach with mean diameter <165 nm and narrow size distribution, dedicated to theranostic applications. We monitored the optical, morphological, and biological properties of the nanocarriers loaded by multifunctional cargo, i.e., paclitaxel (PTX) and a fluorescent marker: coumarin-6 (CR-6) or Nile Red (NR), by fluorescence and UV-vis spectroscopy (encapsulation efficiency), dynamic light scattering (average size expressed as hydrodynamic diameter, D H), zeta potential (ζ, colloidal stability), atomic force microscopy (AFM, imaging), and confocal laser scanning microscopy (CLSM, nanocapsule visualization, and cellular internalization in vitro by human breast cancer MCF-7/WT cells)...
2016: Colloid and Polymer Science
Jens Meissner, Albert Prause, Bhuvnesh Bharti, Gerhard H Findenegg
The adsorption of lysozyme and ß-lactoglobulin onto silica nanoparticles (diameter 21 nm) was studied in the pH range 2-11 at three different ionic strengths. Since the two proteins have a widely different isoelectric point (pI), electrostatic interactions with the negative silica surface lead to a different dependence of adsorption on pH. For lysozyme (pI ≈ 11), the adsorption level increases with pH and reaches a value corresponding to about two close-packed monolayers at pH = pI. In the multilayer adsorption region near pI, added electrolyte causes a decrease in adsorption, which is attributed to the screening of attractive interactions between protein molecules in the first and second adsorbed layer...
2015: Colloid and Polymer Science
K Kang, J K G Dhont
Concentrated dispersions of highly charged rod-like colloids (fd-virus particles) in isotropic-nematic coexistence exhibit a dynamical state when subjected to low-frequency electric fields [Soft Matter, 2010, 6, 273]. This dynamical state consists of nematic domains which persistently melt and form on time scales typically of the order of seconds. The origin of the dynamical state has been attributed to a field-induced, cyclic dissociation and association of condensed ions [Soft Matter, 2014, 10, 1987, Soft Matter, 2015, 11, 2893]...
2015: Colloid and Polymer Science
Piotr Król, Bożena Król, Marek Zenker, Jan Subocz
The research was planned to test electrical properties of polymer films made from polyurethane cationomers with 0-2 wt.% graphene admixture. The cationomers were synthetized in the reaction of 4,4'-methylenebis(phenyl isocyanate), polycaprolactone diol (M = 2000), N-methyldiethanolamine, and formic acid. It was found that addition of approx. 2 wt.% of graphene causes the loss of volume resistivity by three orders of magnitude and percolation threshold is already set at approx. 1 wt.%. The frequency characteristic of a real part of permittivity ε' and imaginary part of permittivity ε″ were measured for the tested films...
2015: Colloid and Polymer Science
W Gospodarczyk, M Kozak
Gemini surfactants and their interactions with proteins have gained considerable scientific interest, especially when amyloidogenic proteins are taken into account. In this work, the influence of two selected dicationic (gemini) surfactants (3,3'-[1,8-(2,7-dioxaoctane)]bis(1-dodecylimidazolium) chloride and 3,3'-[1,12-(2,11-dioxadodecane)]bis(1-dodecylimidazolium) chloride) on two model proteins, bovine serum albumin (BSA) and hen egg white lysozyme (HEWL), have been investigated. A pronounced and sophisticated influence on BSA structure has been revealed, including a considerable change of protein radius of gyration as well as substantial alteration of its secondary structure...
2015: Colloid and Polymer Science
Wojasiński Michał, Duszyńska Ewa, Ciach Tomasz
Hydroxyapatite Ca10(PO4)6(OH)2 nanoparticles have been successfully synthesized by the wet chemical precipitation method at 60 °C in the presence of biocompatible natural surfactant-lecithin. The composition and morphology of nanoparticles of hydroxyapatite synthesized with lecithin (nHAp-PC) was studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Size distribution for nanoparticles was measured by nanoparticle tracking analysis in NanoSight system...
2015: Colloid and Polymer Science
Marcin Kozanecki, Marcin Pastorczak, Lidia Okrasa, Jacek Ulanski, Jeong Ae Yoon, Tomasz Kowalewski, Krzysztof Matyjaszewski, Kaloian Koynov
Copolymers of 2-(2-methoxyethoxy)ethyl methacrylate (poly(MEO2MA)) are regarded as bioinert replacements of poly(N-isopropylacrylamide) in some biomedical applications. Networks of poly(MEO2MA) of various architecture form thermo-responsive hydrogels. Here, we present dielectric and mechanical spectroscopy studies on segmental motions and network relaxation processes in linear poly(MEO2MA) and its networks - bare network and the network grafted with short poly(MEO2MA) chains. We show that the α process assigned to the segmental motions of poly(MEO2MA) is independent on the polymer topology and the glass transition temperature, T g, associated with this process equals 235-236 K for all investigated systems...
2015: Colloid and Polymer Science
Janina Kabatc, Katarzyna Kostrzewska, Katarzyna Jurek
N-Methylpyridinium esters derivatives of 2-methylbenzothiazole hemicyanine dyes photoinitiators/photosensitizers derived from N-propyl-3-[N-2-methylbenzothiazolo]-4-pyridyno phenylacetic acid ester diiodide and N-propyl-3-[N-2-me]thylbenzothiazolo]-4-pyridino diphenylacetic acid ester diiodide were synthesized and proposed as new photoinitiators of polymerization of 2-ethyl-(2-hydroxymethyl)-1,3-propanediol triacrylate under argon laser exposure at 514 nm. These compounds exhibit a strong absorption around 520 nm...
2015: Colloid and Polymer Science
Kinga Jurczuk, Andrzej Galeski, Matthew Mackey, Anne Hiltner, Eric Baer
Wide-angle X-ray scattering in conjunction with pole figure technique was used to study the texture of poly(vinylidene fluoride) (PVDF) α and γ phase crystals in nanolayered polysulfone/poly(vinylidene fluoride) films (PSF/PVDF) produced by layer-multiplying coextrusion. In all as-extruded PSF/PVDF films, the PVDF nanolayers crystallized into the α phase crystals. A large fraction of those crystals was oriented with macromolecular chains perpendicular to the PSF/PVDF interface as evidenced from the (021) pole figures...
2015: Colloid and Polymer Science
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