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  • 1
    Electronic Resource
    Electronic Resource
    Colloid aggregation in the presence of polymers. Effects of mobility and reactivity of clusters on the flocculation kinetics (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 2919-2926 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Small spherical lattices were used to model submicronic particles in a study of polyelectrolyte induced aggregation of colloids. The colloid concentration of the suspension was investigated with a particle counter, allowing determination of the aggregate size distribution and calculation of the average colloid characteristics. Dynamic scaling describes the aggregation kinetics: the number and the weight average sizes scale with flocculation time. The temporal variation of these characteristics is interpreted in the light of simulation results, for which the influence of the cluster mobility and cluster reactivity has been independently determined. Information relative to the variation of the aggregate compactness with the aggregate size is obtained from experimental and simulation studies. When colloid–polymer complexes aggregate by forming interparticulate polymer bridges, aggregation is generally found to develop with features of the reaction limited aggregation process. In the present case, this mode was disturbed by the unusual size dependent colloid mobility. Aggregates of small size were characterized by a relatively low mobility due to their loose structure. Aggregates of large size, which emerged during the terminal step of aggregation, displayed a relatively high mobility as a result of their increased compactness. We determined that, during flocculation, the process started with characteristics of diffusion limited aggregation and ended up with features of the reaction limited process. The transitory mode showed that aggregation developed in accordance with the assumption that aggregates of different sizes might have closely related mobilities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460894
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  • 2
    Electronic Resource
    Electronic Resource
    Conformation of weakly charged polyelectrolytes at a solid–liquid interface (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 6873-6878 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The adsorption characteristics of polyelectrolyte chains on a plane surface are derived. The approach uses the mean-field arguments first developed by de Gennes [Rep. Prog. Phys. 32, 187 (1969)] and Richmond and Jones and Richmond [J. Chem. Soc. Faraday Trans. 73, 1062 (1977)] for the evaluation of the configuration probability of a neutral chain at an interface. Electrostatic interactions among monomers are treated through the linearized Poisson–Boltzmann equation. The treatment is restricted to dilute solutions and to weakly charged polyelectrolytes. Simply analytical expressions are derived for the concentration profile and the adsorption isotherm which are expressed in terms of two characteristic lengths L1 which characterizes the range of surface forces and L2, the Debye–Hückel length, which characterizes the range of electrical forces. Once these variables are fixed, it appears that the adsorption cannot exceed a critical value Γm which is tuned by the temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460267
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  • 3
    Electronic Resource
    Electronic Resource
    Surface Area Exclusion Chromatography of Diblock Copolymers from Micellar Solutions (1994)
    s.l. : American Chemical Society
    Macromolecules 27 (1994), S. 5277-5284 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00097a006
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of surface-cyanofunctionalized poly (N-isopropylacrylamide) latexes (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 1131-1139 
    Details
    ISSN: 1435-1536
    Keywords: Key words P(N-isopropylacrylamide) latex ; acrylonitrile ; cyano groups ; seeded and shot-growth polymerizations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  A series of P[N-isopropylacrylamide (NIPAM)] latexes with different contents of cyano groups were successfully prepared by either seeded or shot-growth polymerizations of an aqueous solution containing acrylonitrile (AN) onto a seed P[NIPAM] latex, respectively, and further characterized by FT-IR, 1H-NMR, elemental analysis, as well as by quasielastic light scattering (QELS) and scanning electron microscopy (SEM). All prepared surface-cyanofunctionalized P[NIPAM] latexes exhibited the same range of lower critical solution temperature (LCST) as a pure P[NIPAM] latex. The shot polymerization process proved more efficient at yielding cyano derivatized latexes than the seeded polymerization technique. The amount of incorporated cyano groups onto the particles was determined with a good correlation both by 1H-NMR and elemental analysis. The higher the amount of initially introduced AN monomer in the reaction mixture, the more cyano groups were incorporated onto the particles. The surface of the particles with high content of cyano groups appeared quite rough by SEM in comparison with that of the pure P[NIPAM] particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050355
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  • 5
    Electronic Resource
    Electronic Resource
    Cationic amino-containing N-isopropyl- acrylamide–styrene copolymer latex particles: 1-Particle size and morphology vs. polymerization process (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 219-231 
    Details
    ISSN: 1435-1536
    Keywords: Key words Emulsion polymerization ; styrene ; N-isopropylacrylamide ; cationic monomer ; batch and shot process ; particle size and morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Cationic hydrophilic copolymer latexes were synthesized at 70 °C either by batch or two-step emulsifier-free emulsion poly-merization of styrene (St), N-iso-propylacrylamide (NIPAM), and aminoethylmethacrylate hydro-chloride (AEM) using 2,2′-azobis (2-amidinopropane) dihydrochloride as initiator. At first, batch polymerization kinetics were followed by gas chromatography (GC), revealing that NIPAM rapidly homopolymerized, before the polymerization of styrene had started. Particle size analysis by quasi-elastic light scattering (QELS) and transmission electron microscopy (TEM) showed that monodispersed particles were obtained with the formation of a poly[NIPAM] rich shell. Adding a small amount of the cationic monomer caused a strong decrease of the particle size without affecting the size monodispersity. When a shot process was used, a narrow particle size distribution was maintained, provided that the monomer addition was performed at a relatively high conversion of the first batch step. The poly[NIPAM] rich shell layer was larger with the shot process, but increasing the amino-containing monomer in the recipe resulted in a dramatic decrease of the thickness. Combination of transmission, scanning and atomic force microscopy techniques showed that these hydrophilic particles exhibited odd-shaped structures, the unevenness being dependent upon the performed process. Kinetic data and particle morphology information were inferred for discussion of the polymerization mechanism of this system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050232
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  • 6
    Electronic Resource
    Electronic Resource
    Characterization of cross-linked poly(N-isopropylmethacrylamide) microgel latexes (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 905-913 
    Details
    ISSN: 1435-1536
    Keywords: Key words Poly(N-isopropylmeth- acrylamide) ; Electrokinetic mobility ; Colloidal stability ; Critical coagulation concentration ; Critical flocculation temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  This article reports the colloidal and physicochemical characterization of crosslinked poly (N-isopropylmethacrylamide) (poly[NIPMAM]) latexes. The latex particles were first characterized by determining the lowest critical solubility temperature by measuring the optical density variation as a function of temperature. In addition, the electrophoretic mobility behaviors of all latexes were examined as a function of pH and temperature. Finally, the colloidal stability was investigated by determining the critical coagulation concentration and the critical flocculation temperature, and the corresponding results were discussed by taking into account both the effect of salinity and temperature on the solvency of poly[NIPMAM].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050470
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  • 7
    Electronic Resource
    Electronic Resource
    Cationic amino-containing N-isopropyl- acrylamide-styrene copolymer particles: 2-surface and colloidal characteristics (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 920-929 
    Details
    ISSN: 1435-1536
    Keywords: Key words Poly(styrene/N-iso-propylacrylamide) latexes ; particle size ; electrokinetic properties ; colloidal stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  In a previous paper [1], the synthesis of various polystyrene– poly[NIPAM] core–shell latexes bearing cationic amidino and/or amino charges has been described. Several colloidal properties of these cationic latexes have been charac-terized such as: particle size, surface charge density, electrophoretic mobility and finally colloidal stability. Due to the poly[NIPAM]-rich layer in the shell, it was found that temperature played a significant role on all these properties, a LCST around 33 °C being exhibited. In addition, ionic strength was also found to affect the colloidal behavior of these latexes, the largest effect being observed with latexes having both amidino and amino surface charges. The critical coagulation concentra-tions (CCC) of the various latexes above and below the LCST were determined, highlighting the contribution of electrostatic and steric repulsive forces to the stability of these particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050329
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  • 8
    Electronic Resource
    Electronic Resource
    Hydrophilic magnetic polymer latexes. 1. Adsorption of magnetic iron oxide nanoparticles onto various cationic latexes (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 846-855 
    Details
    ISSN: 1435-1536
    Keywords: Key words Cationic latexes ; Hydrophilic particles ; Iron oxide ; Adsorption ; Electrostatic interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract With a view to preparing monosized hydrophilic functional magnetic latex particles based on a two-step strategy using anionic iron oxide and cationic polymer latexes, the adsorption step was systematically investigated for a better control of the subsequent encapsulation step. The iron oxide nanoparticles were first obtained according to the classical precipitation method of ferric and ferrous chloride salt using a concentrated sodium hydroxide solution, whereas the polystyrene (PS), P(S/N-isopropylacrylamide (NIPAM)) core–shell and PNIPAM latexes were produced via emulsion and precipitation polymerizations, respectively. The polymer and inorganic colloids were then characterised. The adsorption of iron oxide nanoparticles onto the three types of polymer latexes via electrostatic interaction was studied as a function of iron oxide particle concentration, charge density and the cross-linking density of the hydrophilic layer. The maximum amounts of magnetic nanoparticles adsorbed onto the various latexes were found to increase in the following order: PS 〈 P(S/NIPAM) 〈 P(NIPAM). This significant difference is discussed by taking into account the charge distribution in the hydrogel layer and diffusion phenomena inside the cross-linked hydrophilic shell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050461
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  • 9
    Electronic Resource
    Electronic Resource
    Hydrophilic magnetic polymer latexes. 2. Encapsulation of adsorbed iron oxide nanoparticles (1999)
    Springer
    Colloid & polymer science 277 (1999), S. 1041-1050 
    Details
    ISSN: 1435-1536
    Keywords: Key words Encapsulation ; Magnetic polymer particles ; Hydrophilic ; Submicron size ; Carboxylic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The encapsulation of seed polymer particles coated by anionic iron oxide nanoparticles has been investigated using N-isopropylacrylamide as a main monomer, N,N-methylene bisacrylamide as a crosslinking agent, itaconic acid as a functional monomer and potassium persulfate as an anionic initiator. The magnetic latexes obtained have been characterized with regard to particle size, iron oxide content and electrophoretic mobility. All these properties have been examined by varying several polymerization parameters: reaction medium, monomer(s) and crosslinking agent concentrations, nature of seed latexes and type of polymerization (batch versus shot process). The magnetic content in the polymer microspheres strongly depends on the polymerization procedure (i.e., encapsulation process) and varies between 6 and 23 wt%, and monodisperse magnetic polymer particles were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050488
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  • 10
    Electronic Resource
    Electronic Resource
    Surface functionalization of polystyrene latex particles with a liposaccharide monomer (1995)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 6 (1995), S. 455-464 
    Details
    ISSN: 1042-7147
    Keywords: liposaccharide monomer ; surface activity ; polystyrene latex ; functionalization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Emulsifier-free latexes with immobilized carbohydrate residues have been prepared by batch or seed (co)polymerization of styrene in the presence of 11-(N-p-vinylbenzyl)amido undecanoyl maltobionamide (LIMA). The critical micelle concentration and the molecular surface area of LIMA were determined by surface tension and fluorescence measurements. Batch polymerization of LIMA with styrene was first performed using potassium persulfate, proving the efficiency of LIMA as emulsifier. Seed copolymerization was then investigated using polystyrene seed particles with varying experimental conditions (especially the LIMA surface coverage). Material balance of LIMA between aqueous phase and particles was obtained by separating both phases by ultracentrifugation and it was found that the surfaceactive monomer is preferentially on or in the particle (nearly 100% in batch and at most 70% in seed copolymerization). The presence of the carbohydrate residues at the particle surface was directly evidenced by 1H-nuclear magnetic resonance, electron spectroscopy for chemical analysis and electrophoretic mobility.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1995.220060706
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