Colloid and Polymer Science

We have generated closed-cell microcellular foams from gliadin, an abundantly available wheat storage protein. The extraction procedure of gliadin from wheat gluten, which involves only the natural solvents water and ethanol, respectively, is described with emphasis on the precipitation step of gliadin which results in a fine dispersion of mostly spherical, submicron gliadin particles composed of myriad of protein molecules. A dense packing of these particles was hydrated and subjected to an atmosphere of carbon dioxide or nitrogen in a high-pressure cell at 250 bar...

Dielectric and mechanical spectroscopy methods have been employed to describe the temperature dependencies of the segmental and macromolecular relaxation rates in epoxy/hydroxy functionalized polybutadiene. Dielectric studies on the dynamics of segments of the polymer as well as the mobility of small ions trapped in the system have been carried out both as a function of temperature and pressure under isobaric and isothermal conditions, respectively.

Water interacting with a polymer reveals a number of properties very different to bulk water. These interactions lead to the redistribution of hydrogen bonds in water. It results in modification of thermodynamic properties of water and the molecular dynamics of water. That kind of water is particularly well observable at temperatures below the freezing point of water, when the bulk water crystallizes. In this work, we determine the amount of water bound to the polymer and of the so-called pre-melting water in poly(vinyl methyl ether) hydrogels with the use of Raman spectroscopy, dielectric spectroscopy, and calorimetry...

Polyurethane cationomer coats were synthesised on the basis of typical diisocyanates, properly selected polyether polyols, HO-tertiary amines and HCOOH as quaternisation reagents. The values of their surface free energy (SFE) parameters were obtained by the van Oss-Good method, with the use of the contact angle values which had been found by the goniometric method. Based on the obtained findings, empirical models were developed which made it possible to anticipate the effects of the raw material types on the SFE values of the produced coats...

The influence of solution pH (in the range 3-9) on the adsorption of polyacrylic acid (PAA) on the mixed silica-alumina surface (SA-3: SiO2 97 %-Al2O3 3 % and SA-96: SiO2 4 %-Al2O3 96 %) was investigated. The following methods were applied in experiments: spectrophotometry, viscosimetry, potentiometric titration, and microelectrophoresis, which enable determination of adsorbed amount of the polymer, thickness of its adsorption layers, surface charge density, and zeta potential of solid particles in the presence and absence of PAA, respectively...

Hydrogels based on N-isopropylacrylamide and sodium acrylate as ionic comonomer were synthesized by free radical polymerization in water using N,N'-methylenebisacrylamide as crosslinker and ammonium persulfate as initiator. The glass transition of dried copolymers poly(N-isopropylacrylamide) (PNIPA) and poly(sodium acrylate) (SA) gels and demixing/mixing transition of PNIPA-SA hydrogels swollen with increasing amounts of water were studied using conventional differential scanning calorimetry. In the crosslinked polymers, the glass transition linearly increases, and the transition range becomes broader, with increasing crosslinker content...

Soap-free emulsion polymerization (SFEP) of methyl methacrylate, butyl acrylate was conducted in water/methanol media with sodium salts of four different acidic comonomers, namely styrene sulfonic acid (NaSS), 2-acrylamide-2-methyl-1-propane sulfonic acid (NaAmps), acrylic acid (NaAA), and itaconic acid (Na2ita). It was found that the introduction of methanol as co-solvent (35 wt%) to the medium greatly decreases the amount of water-soluble polyelectrolyte in the cases NaAA and Na2ita while it does not make difference for NaSS and NaAmps...

Polymer (XAD7HP)/Ti(4+) nanocomposites were prepared through the swelling of polymer in titanium (IV) ethoxide as a titanium dioxide precursor. The nanocomposite beads exhibit relatively high porosity different than the porosity of the initial polymer. Thermal treatment of composite particles up to 200 °C in vacuum causes the change of their internal structure. At higher temperature, the components of composite become more tightly packed. Calcination at 600 °C and total removal of polymer produce spherically shaped TiO2 condensed phase as determined by XRD...

The synthesis, characterization, self-assembly, and gel formation of poly(γ-benzyl-l-glutamate) (PBLG) in a molecular weight range from ca. 7,000-100,000 g/mol and with narrow molecular weight distribution are described. The PBLG is synthesized by the nickel-mediated ring-opening polymerization and is characterized by size-exclusion chromatography coupled with multiple-angle laser light scattering, NMR, and Fourier transform infrared spectroscopy. The self-assembly and thermoreversible gel formation in the helicogenic solvent toluene is investigated by transmission electron microscopy, atomic force microscopy, small-angle X-ray scattering, and synchrotron powder X-ray diffraction...

The purpose of this investigation was to design novel pentablock copolymers (polylatide-polycaprolactone-polyethylene glycol- polycaprolactone-polylatide) (PLA-PCL-PEG-PCL-PLA) to prepare nanoparticle formulations which provide continuous delivery of steroids over a longer duration with minimal burst effect. Another purpose was to evaluate the effect of poly (L-lactide) (PLLA) or poly (D, L-lactide) (PDLLA) incorporation on crystallinity of pentablock copolymers and in vitro release profile of triamcinolone acetonide (selected as model drug) from nanoparticles...

The cavitation phenomenon was studied in isothermally and non-isothermally crystallized polypropylene and high-density polyethylene. It was found that nano-voids were not present in the crystallized samples, but were formed during their tensile deformation. The process of cavitation was initiated before reaching the yield point. The ellipsoidal voids were initially elongated perpendicularly to the deformation direction, but if the polymer (i.e., high-density polyethylene) was able to deform beyond the yield, then the reorientation of voids into the deformation direction was observed at local strains of 100-200 %...

Polyurethane elastomers coating were synthesised by using typical diisocyanates, polyether and polyester polyols and HO-tertiary amines or diols as a chain extenders. Mole fractions of structural fragments (κ exp) responsible for the polar interactions within polyurethane chains were calculated by (1)H NMR method. Obtained results were confronted with the analogous parameter values (κ theor) calculated on the basis of process stoichiometry, considering the stage of the production of isocyanate prepolymers and reaction of their extension for polyurethanes...

The coemulsification method suitable for the formulation of microcapsules of n-eicosane coated with a polysiloxane is developed. This method allows to synthesize core-shell microcapsules of paraffin which have the shape of spheres or distorted spheres and are designed for the use as phase change materials. The microcapsules are formed in aqueous phase by the precipitation of n-eicosane together with modified polyhydromethylsiloxane from a common solvent which is miscible with aqueous media. The polysiloxane is modified by the attachment of silylvinyl and alkoxy functions before coemulsification with the paraffin...

The properties of a dendronized linear polymer (DP) in dilute solutions depending on solvent quality and temperature are described. The polymer has a contour length of L c = 1,060 nm. The sample of the fourth generation (PG4) was analyzed in the thermodynamically good solvents dioxane, chloroform, and methanol. The wormlike macromolecule has a persistence length l p = 7 nm in dioxane and a cross-section radius determined by small angle X-ray scattering (SAXS) of R c (SAXS) = 2.8 nm. The bulk density of PG4 determined by SAXS was compared with solution density...

A novel route was introduced to synthesize dense polyacrylamide (PAM) onto the glass slide surface. To investigate the surface chemistry of the PAM on the glass slides, X-ray photoelectron spectroscopy (XPS) was utilized to obtain detailed chemical state information on the PAM layer constituents. The XPS peak data were consistent with the presented model of the PAM on the glass slide surface. Scanning electron microscopy and atomic force microscope data indicated the presence of PAM on the glass slides, which consist of nodules...

This article introduces tri-cationic hemicyanine dye employed as a visible-light photoinitiator of acrylic monomers polymerization. This dye, in combination with borate anions, was found to be a very effective photoinitiating system. The kinetics of trimethylolpropane triacrylate polymerization was studied by a microcalorimetric method. The photoredox pair concentration, the co-initiator structure as well as the light intensity strongly affected the progress of the polymerization, leading, for example, to an increase in the polymerization rate and quantum yield of the process...

A series of Co(III) carboxylate based upon N,N,O,O-tetradentate Schiff base ligand framework have been prepared. X-ray diffraction analysis confirms that these Schiff base Co(III) carboxylate are all monomeric species with a six-coordinated central Co in their solid structures. The activities and polycarbonate selectivity of these complexes toward the copolymerization of epoxide (cyclohexene oxide and propylene oxide) and carbon dioxide have been investigated in the presence of bis(triphenylphosphine)iminium chloride...

After the surface silylation with 3-methacryloxypropyltrimethoxysilane, silica nanoparticles were further modified by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The immobilization of DOPO on silica nanoparticles was confirmed by Fourier transform infrared spectroscopy, UV-visible spectroscopy, magic angle spinning nuclear magnetic resonance, and thermogravimetric analysis. By incorporating the DOPO-immobilized silica nanoparticles (5 wt%) into polypropylene matrix, the thermal oxidative stability exhibited an improvement of 62 °C for the half weight loss temperature, while that was only 26 °C increment with incorporation of virgin silica nanoparticles (5 wt%)...

A simple and green chemical method has been developed to synthesize stable bare and capped silver nanoparticles based on the reduction of silver ions by glucose and capping by poly(α,γ,L-glutamic acid) (PGA). The use of ammonia during synthesis was avoided. PGA has had a dual role in the synthesis and was used as a capping agent to make the silver nanoparticle more biocompatible and to protect the nanoparticles from agglomerating in the liquid medium. The synthesized PGA-capped silver nanoparticles in the size range 5-45 nm were stable over long periods of time, without signs of precipitation...

The shape, porosity, and surface hydrophilicity of hematite particles formed from a forced hydrolysis reaction of acidic FeCl3 solution were controlled by using a trace of polymers (0.001 and 0.003 wt%). The spherical particles were produced on the systems with polyvinyl alcohol (PVA) and polyaspartic acid (PAS). In the case of polyacryl amide (PAAm), slightly small spherical particles were precipitated at 0.003 wt%. However, polyacrylic acid (PAAc) and poly-γ-glutamic acid (PGA) gave ellipsoidal particles...