Adsorption of amphiphilic polysaccharides onto polystyrene latex particles

Adsorption properties of hydrophobically modified carboxymethylpullulans (HMCMP) with different degree of modification of alkyl chains (C8) onto polystyrene latex particles have been investigated. Hydrophobic interactions between the grafted alkyl chains and the surface are responsible for the adsorption of these polymers. Their adsorption isotherms are Langmuir type, therefore, there is only a monolayer of adsorbed polymer chains. Variations of plateau adsorbed amounts and adsorbed layer thicknesses show a competition between the number of anchors (alkyl chains) and size of loops. Desorption of adsorbed polymer chains has been tested in three different media (0.1 M NaCl, pure water and 0.01 M NaOH). The greater desorbed amount has been obtained in 0.01 M NaOH (hydrolysis of ester bonds).     

PdCl2 anchorage onto the surface of polystyrene films via oxygen and ammonia plasma treatment

The surface properties of polystyrene as a possible catalytic support for active coordinative species were investigated. To improve the surface properties, discharge treatments in the presence of oxygen and ammonia were carried out. The polymer surface was studied before and after the plasma treatments. Contact angles for the polymer surface were measured in order to determine the surface free energy. Polymer‐bound complex catalysts were prepared by anchoring PdCl₂ on the surface of the polystyrene samples. The chemical compositions were studied by X‐ray Photoelectron Spectroscopy (XPS). Plasma treatments in the presence of oxygen or ammonia caused an increase in the surface free energy of polystyrene, as a consequence of the higher concentration of oxygenated or nitrogenated functional groups, respectively, on the polymer surface. Contact angle measurements are in agreement with the corresponding values obtained by XPS. After treatment with PdCl₂, the amount of palladium anchored to the polymer surface treated with ammonia is greater than in the case of the oxygen plasma treatments; this may be explained on the basis of the higher nucleophilic character of the amine groups. No palladium was detected in the untreated polystyrene surface. © 2000 Society of Chemical Industry     

The interactions of amphiphilic latexes with surfaces: the effect of surface modifications and ionic strength

The effect of surface modifications brought about by a polymeric stabilizer on the interactions between polymer colloid particles and various substrates in aqueous media are directly measured using atomic force microscopy. The interactions of polystyrene particles with grafted hydrophilic ‘hairs’ of hydroxypropyl cellulose (denoted HPC/PS), of molecular weight ∼10⁵, with mica, silica and graphite substrates are measured. HPC/PS is found to be compatibilized so that it will interact with both hydrophobic and hydrophilic substrates. The observed jump-to contact between HPC/PS and silica is characteristic of polymer solutions and is the result of the grafted hairy layer. Further direct evidence of HPC-substrate interaction is seen in a secondary adhesion with mica. The adhesion of the particles was found to follow the order silica>graphite>mica. The magnitudes of these interactions are rationalized in terms of the interactions of each of the substrate, core polymer and surface modification. It is concluded that the combined effects of surface roughness and hairy layer collapse due to compression give rise to the observed trend.     

Stability of pigment and resin dispersions in waterborne paint

The stability of a colloidal dispersion in a waterborne paint system, which consists of dispersed pigment and polymeric particles (dispersion or emulsion) along with a water-soluble acrylic polymer, was investigated. It was found that adsorption of appropriate ultrafine particles to the relevant particles could stabilize these particles against flocculation, leading to lower viscosity and yield value. The gloss and smoothness of the resultant films are notably improved. As the stability of the colloidal particles in an aqueous system is strongly dependent on the electrostatic effect, the effect was evaluated by measuring the ζ-potentials of the relevant colloidal particles. The ζ-potential is the electric potential on the outside of the surface layer, which includes the counterions around the particle. The ζ-potentials of a series of pigments in a solution of a water-soluble polymer were determined. By arranging the pigments according to their ζ-potentials, an order of basicity-acidity was established for pigments in a waterborne system, and the order was found to be different from that of solventborne systems, thought to be due to adsorbed counterions. After dispersing the pigment sufficiently with an appropriate polymer dispersant, ultrafine particles (of size under 0.05 μm) of lower refractive indexes were adsorbed to the surface of the pigments and polymeric particles. The adsorption layer of ultrafine particles can modulate the ζ-potentials of various colloidal particles to bring them into a certain range, so that the co-flocculation tendency between different colloids is remarkably diminished providing quite stable paint compositions by both electrostatic and steric hindrance effects.     

Study by gas-liquid chromatography of the interactions between linear or branched polystyrenes and solvents in the temperature range 60°–200°C

Thermodynamic interactions between linear or branched polystyrene and various solvents have been studied by gas chromatography below and above the glass transition temperature. In the lower temperature range (<80°C) interactions between non-solvent probes (alkanes) and the polymer are restricted to adsorption phenomena; analysis of these effects leads to an estimation of the specific surface area of the inert support which is actually accessible to the polymer. In the higher temperature range (140°–200°C) the activity coefficients at infinite dilution and the Flory χ interaction parameters have been calculated taking into account both diffusion and adsorption of the probe into the polymer.     

Surface composition of polystyrene

The physical and chemical properties of bulk polymers are well understood and have been measured exhaustively for numerous systems, but the properties of polymer surfaces are quite often different from those observed in the bulk and are usually not as easily measurable. Since many polymer properties vary with molecular weight, it is of interest to determine whether or not there is any segregation in a homopolymer system based on molecular weight. In particular, does the surface of a polymer sample have the same molecular weight composition as the bulk? The current work answers this question for a polystyrene system. Through the use of secondary ion mass spectrometry and tagged polystyrene, it has been shown that surface and bulk molecular weight composition are indistinguishable within the limits of the experimental method's sensitivity. The sensitivity of the technique is documented using samples artificially created with different surface and bulk molecular weight compositions.     

Synthesis and properties of amphiphilic nonspherical SPS/PS composite particles by multi-step seeded swelling polymerization

Amphiphilic nonspherical particles have asymmetric surface physical and chemical properties. Such a unique structure makes them suitable for applications in many areas, such as chemical and biological sensors, colloidal surfactants, self-assembly, building blocks of complex superstructures, and materials engineering. In this study, amphiphilic sulfonated polystyrene/polystyrene (SPS/PS) composite particles with controllable morphologies are synthesized by combining modified treatment and multistage seeded swelling polymerization. Core-shell SPS particles were first obtained by modifying cross-linked PS particles with concentrated sulfuric acid, and the surface of SPS particles was a hydrophilic sulfonated polystyrene layer. With further twice seeded swelling polymerization, new hydrophobic PS oil phase sprouted on the strong hydrophilic surface even without any surfactant assistance in aqueous media. The morphologies of these SPS/PS composite particles could be adjusted by changing the crosslinking density of the seed microspheres, the sulfonation temperature and the swelling ratio of monomer/seed. These polymer composite particles can be used as solid surfactants.     

载体材料表面化学组成对蛋白质吸附行为的影响研究进展

蛋白质在载体表面的吸附行为,如其吸附速率、吸附量以及取向和构象的变化,在很大程度上依赖于载体材料的表面化学组成。调控载体材料的表面化学组成已成为控制蛋白质吸附行为的重要手段。本文主要对载体材料表面不同组成对蛋白质吸附行为的影响进行了归纳。介绍了材料表面的功能基团包括疏水基团（甲基和含氟基团）和亲水基团（羟基、氨基和羧基）对蛋白质吸附行为的影响。另外,在载体材料表面接枝聚合物链是一种常用的有效调控表面化学组成的方法。重点介绍了材料表面接枝不同聚合物链时,聚合物链的种类、长度、密度和链的结构对蛋白质吸附行为的影响。     

Effect of charge density,molecular weight,and hydrophobicity on polycations adsorption and flocculation of polystyrene latices and silica

Adsorption and flocculation behavior of two series of synthetic polycations was investigated in dispersions of silica and polystyrene latices with various particle size and surface charge densities. Polycations of the first series (polydiallyldimethyl ammonium chloride‐PDADMAC) varied in molecular weight only, while polycations of the second series (derivatives of polymethacrylic acid) varied in both molecular weight and hydrophobicity. We have found that maximum adsorbed amount of high molecular weight PDADMAC on latex particles was nearly independent of the surface charge density when the particle size was comparable to the polymer coil dimensions in solution. Both low and high molecular weight PDADMACs were efficient flocculants, although significantly lower amounts of high molecular weight polyelectrolyte were required for the phase separation in the dispersions due to particles aggregation through “charge patch” mechanism. The increase of polymer hydrophobicity leads to higher adsorbed amounts and broadening of flocculation window by polycations of the second series on both substrates. However, no strong enhancement of segment–surface interactions on hydrophobic substrates was observed. Since formation of multilayers upon adsorption was also excluded, the difference in adsorption and flocculation behavior was related to the more compact conformation of hydrophobically associating derivatives in solution and at the interface. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3422–3429, 2006     

Preferential adsorption coefficient of polymers

The recent formulation of the preferential adsorption coefficient, λ, which takes into account differences in molecular contact surface and in free volume, is tested by comparing theoretical with experimental values of λ from the literature. Seven different systems containing polystyrene and poly(methyl methacrylate) are considered. Agreement between theory and experiment is reached by treating the contact surface of the polymer as a fitting parameters, s. The adjusted values of s are: (a) systematically higher than the ones calculated from chain geometry; (b) largest in systems containing specific interactions (methanol). The connection between this enhanced apparent contact surface of the polymer and the ternary interaction parameter of the classical theory of λ, is analysed.     

The influence of charge density and steric factor of aminated chloromethyl polystyrene homologs in bilirubin adsorption

Bilirubin, a bile pigment, was studied for its extent of adsorption on substituted aminechloromethyl polystyrene by UV spectrophotometry. By performing simple displacement reactions on chloromethyl polystyrene with secondary and tertiary amines, the amount of charge density and steric factor on substituted nitrogen atom have been varied. Adsorption isotherms of bilirubin at 0°C by different amine–chloromethyl polystyrene homologs suggest the existence of electrostatic interaction of polymeric resin with bilirubin moiety. Results of adsorption of bilirubin to polymeric resin have shown that the extent of adsorption of bilirubin depends on the unit charge, and on the structure of the substituted amine–chloromethyl polystyrene. The effects of porosity of resin on bilirubin adsorption have also been discussed.     

IGC study of surface properties of adsorbed styrene/methacrylic acid diblock polymers

An inverse gas chromatographic study has been carried out on a styrene/methacrylic acid diblock polymer adsorbed on particulates of varying acid/base interaction potential. Acid/base interactions between polymer and substrate were shown to result in the selective adsorption of copolymer moieties, leading to interphase surface compositions that varied with thickness. At higher interphase thicknesses, bulk and surface compositions became similar; however, depending on the interaction potential of the adsorbent, the interphase thicknesses at this point varied from 100 to 1000 Å. Adsorbed diblock interphases are to be considered nonisotropic in local composition and molecular conformation. These properties may make possible designing diblock interphases to meet specific compatibilization requirements in polymer composites. © 1994 John Wiley & Sons, Inc.     

Sorption of dissolved organics from aqueous solution by polystyrene resins—I. Resin characterization and sorption equilibrium

The results of sorption equilibrium studies indicate that adsorption is only one of the three mechanisms involved in removing organics from aqueous solution by polystyrene resins. The other two mechanisms are associated with the resin's capability to incorporate organics into their polymer matrix while swelling. To describe the overall sorption behaviour, it is not sufficient to characterize the resin structure by estimating pore size distribution and internal surface area of the dry polymers. The amount of swelling in different organic solvents must also be evaluated as an important structural parameter of polystyrene resins. The role of the different mechanisms depends on both the resin structure and the physical and chemical properties of the solute. The solute's affinity for the polystyrene surface can be correlated with the solute's benzene-water partition coefficient. A heuristic model is presented which relates the sorption capacity to both the resin and solute properties.     

Peculiarities of the pigment-binder interaction in polyurethane-based compositions

Some regularities of polymer adsorption from dilute solutions are considered in relation to the quality of a solvent, solution concentration, the nature of a polymer and an adsorbent, and other factors. The thickness of adsorption layers is determined and it is shown that this parameter substantially affects the aggregation stability of solutions of compositions, as well as their service properties as a whole. It is established that as polyurethane solution concentration increases from 2 to 20%, the thickness of adsorption layers on rutile titanium dioxide and carbon black particles rises in proportion to the concentration. It is shown that the closer the chemical nature of a polymer is to that of a sorbent, the thicker the adsorption layers are on the surface of the same pigment.     

Encapsulation of TiO2 particles with polystyrene and polymethyl acrylic acid and the pigmentary performances

TiO₂ particles were directly encapsulated with polystyrene and polymethyl acrylic acid by a surfactant-free polymerization method. TiO₂ particles were uniformly encapsulated with polystyrene by Van der Waals force and effectively encapsulated with polymethyl acrylic acid by chemical bonding. Encapsulation of TiO₂ particles with polystyrene and polymethyl acrylic acid significantly enhanced the organic dispersibility and dispersion stability of TiO₂ particles in toluene because the surface property of TiO₂ particles was changed from hydrophilicity to organophilicity after polymer encapsulation. The brightness and whiteness of the polymer-encapsulated TiO₂ particles were similar to that of the naked TiO₂.     

Adsorption of Hydroxypropyl Methyl Cellulose in an Aqueous System Containing Multicomponent Oxide Particles

The adsorption behavior of a hydroxypropyl methyl cellulose (HPMC) polymer in aqueous suspensions of alumina, silica, kaolin, and talc powders, two-component combinations, and one three-component combination was determined. Powders were well characterized by chemical analysis, XRD, DRIFT, SEM, particle size, surface area, and density analyses. The zeta-potential of each powder in aqueous suspension was determined over a range of pH to determine particle charging and the isoelectric point for each material. Alumina and silica powders having heavily hydroxylated surfaces were observed not to adsorb the HPMC polymer over a range of pH. The layer-type minerals talc, which was noticeably hydrophobic, and kaolin, which had differently hydrated basal planes, adsorbed the HPMC polymer but in different amounts per unit of surface area. In the two-component systems, HPMC polymer adsorption for systems of dispersed particles of like electrical charge (kaolin + silica, talc + silica or alumina, and kaolin + talc) was proportionate to the sum of the fraction x specific surface area x adsorption capacity for each particle type. In systems where particles had an opposite electrical charge (kaolin + alumina, kaolin + talc + alumina), the HPMC polymer adsorption was significantly lower than that calculated for a dispersed system. SEM analysis showed very fine, nonadsorbing alumina particles predominantly on the faces of the adsorbing kaolin particles that apparently masked polymer adsorption. Results suggested a hydrophobic mechanism for the HPMC polymer adsorption and adsorption on only one face of the kaolin particles.     

Protein–polymer interaction: Transfer loading at interfacial region of PES-based membrane and BSA

The adsorption of proteins onto polymeric surfaces is encountered in many natural and industrial processes and is a prerequisite to their efficient identification, separation, and purification by methods such as chromatography, and filtration. Nevertheless, the exact nature of the adsorption mechanisms and interfacial interactions is not easy to identify for a given protein–polymer system. Here, we aim to document the adsorption mechanism of a protein–polymer system by investigating the adsorption as well as desorption phenomenon of a protein [bovine serum albumin (BSA)] from the polymeric surface [polyethersulfone (PES)]. The analyses performed to document the adsorption mechanism of the BSA–PES system include scanning electron microscope (SEM), attenuated total reflection-Fourier transform infrared (FTIR), contact angle, zeta potential, surface charge density measurement, and Derjaguin–Landau–Verwey–Overbeek (DLVO). Here, SEM and FTIR identified the physical and chemical properties of pure PES and PES–BSA membranes. The low water contact angle of the PES–BSA membrane confirms its applicability for tissue engineering applications. Further, the zeta potential, surface charge density measurement, and DLVO analyses were performed to document the adsorption mechanism. The adsorption of BSA particles on the PES surface was carried out for pH values that ranged from 4 to 10 for contact times that ranged from 1 to 3 days. A monotonic increase in the zeta potential of the PES–BSA system indicated considerable adsorption of BSA particles on the PES surface. Further, BSA adsorption was very strong for pH values greater than 4.7 which confirms to strong electrostatic interactions between BSA and PES. The strong electrostatic interaction is also collaborated by low desorption rate, which was only ∼22% for pH 10 after 3 days of contact. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47931.     

Interfacial characterizations of iron ore concentrates affected by binders

Binders are widely used to modify the interfacial characteristics and improve the ballability of iron ore particles. Funa is a natural polymer binder. It was developed and used in the production of iron ore pellets in China. In this paper, the interfacial interactions between Funa and a magnetite concentrate were investigated by measurements of surface tension, contact angle, wetting heat, zeta potential as well as by Infrared Spectroscopy (IRS) analysis as compared to bentonite binder. Results show that Funa behaves like surfactants and possesses the characteristics of colloid particles. It decreases the surface tension of water from 73 to 65 dyn cm⁻¹. The binder reduces the contact angle of the concentrate sharply from 46° to 0° at a dosage of 0.6% and hence greatly improves the hydrophilic character of the concentrate. Zeta potential measurements show that the surface of the magnetite concentrate is negatively charged and the addition of Funa causes more negative surface charges. IRS analysis shows that the binder adheres to the concentrate surface by chemical adsorption. It was also shown that bentonite has little effects on the surface tension, contact angle, wettability and Zeta potential. No chemical adsorption of bentonite on the concentrate was observed.     

Particle-assisted fabrication of honeycomb-structured hybrid films via breath figures method

Particle-assisted fabrication of honeycomb-structured hybrid films was carried out by employing particles as stabilizers in the breath figures (BF) method. Such a procedure tested the possibility of the combination of Pickering emulsions and breath figures, which are two classical self-assembly processes. Regularly patterned porous polystyrene film with particles decorating the inside walls of the open pores can be readily prepared. Silica particles were used as a model candidate to study the influence of both physical and chemical factors, including size, wettability, and application quantity, of the particles on BF pattern formation. Different assembling characteristics of the particles under different circumstances are also discussed. To further extend the application of such particle-assisted, bottom-up surface patterning technique to other kinds of particles, polystyrene particles and poly(N-isopropylacrylamide)-co-acrylic acid microgels were employed to serve as stabilizers in BF method. As expected, all three kinds of particles, including solid inorganic, solid polymeric and microgel ones, succeeded in assisting in the formation of BF arrays in polymer films. The introduction of Pickering-emulsion effect into BF method can provide new possibilities to develop particle-functionalized porous surface.