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Chemistry, Chimie, Energy, Énergie, Chemical industry parachemical industry, Industrie chimique et parachimique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Physics, Physique, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Matériaux particuliers, Specific materials, Fullerènes et matériaux apparentés; diamants, graphite, Fullerenes and related materials; diamonds, graphite, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Propriétés et caractérisation, Properties and characterization, Propriétés électriques, magnétiques et optiques, Electrical, magnetic and optical properties, Addition bore, Boron additions, Aniline polymère, Polyanilines, Bore, Boron, Graphène, Graphene, Matériau dopé, Doped materials, Structure sandwich, Sandwich structures, Supercondensateur, Supercapacitors, Synthèse, Synthesis, 8105T, 8105U, and 8235C

The physicochemical property of chemically prepared graphene can be significantly changed due to the incorporating of heteroatoms into graphene. In this article, boron-doped graphene sheets are used as carbon substrates instead of graphene for loading polyaniline by in situ polymerization. Compared with the individual component and polyaniline/non-doped graphene, the sandwich-like polyaniline/boron-doped graphene exhibits remarkably enhanced electrochemical specific capacitance in both acid and alkaline electrolytes. In a three-electrode configuration, the hybrid has a specific capacitance about 406 F g―1 in 1 M H2SO4 and 318 F g―1 in 6 M KOH at 1 mV s―1. In the two-electrode system of a symmetric supercapacitor, this hybrid achieves a specific capacitance about 241 and 189 F g―1 at 0.5 A g―1 with a specific energy density around 19.9 and 30.1 Wh kg―1, in the acid and alkaline electrolytes, respectively. The as-obtained polyaniline/boron-doped graphene hybrid shows good rate performance. Notably, the obtained electrode materials exhibit long cycle stability in both acid and alkaline electrolytes (~100% and 83% after 5000 cycles, respectively). The improved electrochemical performance of the hybrid is mainly attributed to the introduction of additional p-type carriers in carbon systems by boron-doping and the well combination of pseudocapacitive conducting polyaniline.

Biochemistry, molecular biology, biophysics, Biochimie, biologie moléculaire, biophysique, General chemistry, physical chemistry, Chimie générale, chimie physique, Nanotechnologies, nanostructures, nanoobjects, Nanotechnologies, nanostructures, nanoobjets, Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie generale et chimie physique, General and physical chemistry, Etat colloïdal et états dispersés, Colloidal state and disperse state, Etudes physiques et chimiques. Granulométrie. Phénomènes électrocinétiques, Physical and chemical studies. Granulometry. Electrokinetic phenomena, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères d'origine naturelle, Natural polymers, Protéines, Proteins, Aliment, Food, Alimento, Application, Aplicación, Biopolymère, Biopolymer, Biopolímero, Encapsulation, Encapsulación, Libération, Release, Liberación, Micronutriment, Micronutrient, Micronutriente, Microstructure, Microestructura, Nanostructure, Nanoestructura, Particule colloïdale, Colloid particle, Partícula coloidal, Protéine, Protein, Proteína, Vecteur médicament, Drug carrier, Vector medicamento, Zéine, Zein, Zeina, Biopolymers, Colloidal particles, and Controlled release

The application of colloidal particles from natural materials for purposes ranging from the delivery of bioactives to interfacial stabilisation and bulk structuring have recently gained a lot of interest for applications in the field of fast moving consumer goods, nutraceuticals, agricultural formulations and medicine. Zein-a proline rich water insoluble protein obtained from natural and sustainable source has been recently researched to generate colloidal structures that can find a wide range of applications. In this paper, we review the recent progress in the preparation of colloidal structures and their further application as functional materials in the field of delivery of functional ingredients and structuring of bulk phases and interfaces.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Polycondensation, Acide gras monoinsaturé, Monounsaturated fatty acid, Acido graso monoinsaturado, Alcool polymère, Alcohol polymer, Alcohol polímero, Autocondensation, Self condensation, Autocondensación, Caprolactone copolymère, Caprolactone copolymer, Caprolactona copolímero, Copolymère insaturé, Unsaturated copolymer, Copolímero insaturado, Copolymère soufre, Sulfur copolymer, Copolímero azufre, Copolymère triséquencé, Triblock copolymer, Copolímero trisecuencia, Dithiol, Ditiol, Ester copolymère, Ester copolymer, Ester copolímero, Ester polymère, Ester polymer, Ester polímero, Etude expérimentale, Experimental study, Estudio experimental, Fonctionnalisation, Functionalization, Funciónalización, Hydroxyacide, Hydroxyacid, Hidroxiácido, Marquage fluorescent, Fluorescent labelling, Marcación fluorescente, Mercaptoalcool, Mercaptoalcohol, Modification chimique, Chemical modification, Modificación química, Point fusion, Melting point, Punto fusión, Polycondensation, Condensation polymerization, Policondensación, Polymère fonctionnel, Functional polymer, Polímero funcional, Polymère insaturé, Unsaturated polymer, Polímero insaturado, Polymère soufre, Sulfur containing polymer, Polímero azufre, Polymérisation ouverture cycle, Ring opening polymerization, Polimerización abertura ciclo, Préparation, Preparation, Preparación, Réaction surface, Surface reaction, Reacción superficie, Réticulation photochimique, Photochemical crosslinking, Fotorreticulación, Stabilité thermique, Thermal stability, Estabilidad térmica, Structure moléculaire, Molecular structure, Estructura molecular, Sulfure organique, Organic sulfide, Sulfuro orgánico, Réaction click, Réaction thiol yne, Réaction thiol ène, enzymatic polymerization, fatty acids, polyesters, thiol-ene, and thiol-yne

The synthesis of a vinylsulfide-containing hydroxy acid (VSHA) from undecylenic fatty acid via thiol-yne monoaddition is described. Metal- and enzymatic-catalyzed polycondensation of VSHA is investigated to obtain functional polyesters with a view to further modification. Higher molecular weights are obtained when using enzymatic polymerization. Random copolymers are prepared by direct enzymatic copolymerization of VSHA and ε-caprolactone (CL) and triblock CL-VSHA-CL copolymers are obtained by consecutive VSHA self-condensation and ring-opening polymerization. The copolymers display semicrystalline behavior and a good thermal stability with no significant weight loss below 300 °C. Thiol-ene chemistry-type crosslinking and surface functionalization are employed to open new application fields. Evidence of the successful reactions is obtained by NMR, IR, and fluorescence measurements.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Réactions et propriétés chimiques, Chemical reactions and properties, Modifications chimiques, Chemical modifications, Azide, Organic azide, Azida orgánica, Complexe de cuivre, Copper complex, Cobre complejo, Cyclisation, Cyclization, Ciclización, Cycloaddition dipolaire 1,3, 1,3-Dipolar cycloaddition, 1,3-Dipolar cicloadición, Désorption laser, Laser desorption, Desorción láser, Etude expérimentale, Experimental study, Estudio experimental, Groupe terminal, End group, Grupo terminal, Impureté, Impurity, Impureza, Isolement matrice, Matrix isolation, Aislamiento matriz, Macrocycle, Macrociclo, Méthode étude, Investigation method, Método estudio, Oligomère, Oligomer, Oligómero, Polymère cyclique, Cyclic polymer, Polímero cíclico, Réaction catalytique, Catalytic reaction, Reacción catalítica, Réaction intramoléculaire, Intramolecular reaction, Reacción intramolecular, Spectrométrie masse temps vol, Time of flight mass spectroscopy, Structure topologique, Topological structure, Estructura topológica, Styrène polymère, Styrene polymer, Estireno polímero, Chimie clic, Groupe azido, Groupe propargyle, (MALDI-ToF MS), Copper-catalyzed azide-alkyne click, Cyclic oligomers, Cyclic polymers, Matrix-Assisted Laser Desorption/Ionization, Size-Exclusion Chromatography, Time-of-Flight Mass Spectrometry, and cycloaddition (CuAAC)

Polymers with a cyclic topology exhibit a range of unique and potentially useful physical properties, including reduced rates of degradation and increased rates of diffusion in bulk relative to linear analogs. However, the synthesis of high purity cyclic polymers and verification of their structural purity remain challenging. The copper-catalyzed azide-alkyne click cyclization route toward cyclic polymers has been widely used, due to its synthetic ease and its compatibility with diverse polymer backbones. Yet unoptimized click cyclization conditions have been observed to generate oligomeric byproducts. In order to optimize these cyclization conditions, and to better understand the structure of the higher molecular weight oligomers, these impurities have been isolated and characterized. Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-ToF) MS is a particularly valuable characterization tool and was used to determine that the high molecular weight impurities are predominantly cyclic oligomers. It should also be noted that the rapid analysis and small analyte requirements of this MS technique make it particularly attractive as a general tool for elucidating polymer architecture.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Polymères à propriétés spéciales, Polymers with particular properties, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Pharmacologie. Traitements medicamenteux, Pharmacology. Drug treatments, Pharmacologie générale, General pharmacology, Technologie pharmaceutique. Industrie pharmaceutique, Pharmaceutical technology. Pharmaceutical industry, Propriété biologique, Biological properties, Propiedad biológica, Amine copolymère, Amine copolymer, Amina copolímero, Cellule tumorale, Tumor cell, Célula tumoral, Ciblage, Targeting, Blancado, Copolymère bigreffé, Bigraft copolymer, Copolímero biinjertado, Copolymère biséquencé, Diblock copolymer, Copolímero bisecuencia, Copolymère soufre, Sulfur copolymer, Copolímero azufre, Copolymérisation radicalaire, Radical copolymerization, Copolimerización radical, Cytotoxicité, Cytotoxicity, Citotoxicidad, DNA, Disulfure organique, Organic disulfide, Disulfuro orgánico, Ethylène oxyde copolymère, Ethylene oxide copolymer, Etileno óxido copolímero, Ethylène oxyde polymère, Ethylene oxide polymer, Etileno óxido polímero, Etude expérimentale, Experimental study, Estudio experimental, Greffage, Grafting, Injerto, Lignée HeLa, Hela cell line, Célula HeLa, Macromère, Macromer, Macrómero, Micelle mixte, Mixed micelle, Micela mixta, Molécule asymétrique, Asymmetric molecule, Molécula asimétrica, Méthacrylate copolymère, Methacrylate copolymer, Metacrilato copolímero, Méthacrylique acide ester, Methacrylic acid esters, Plasmide, Plasmid, Plasmido, Polymère vecteur, Control release polymer, Polímero vector, Polymérisation radicalaire, Free radical polymerization, Polimerización radicalar, Polymérisation transfert atome, Atom transfer polymerization, Polimerización transferencia atomo, Potentiel électrocinétique, Electrokinetic potential, Potencial electrocinético, Préparation, Preparation, Preparación, Rayon hydrodynamique, Hydrodynamic radius, Radio hidrodinámico, Réaction successive, Successive reaction, Reacción consecutiva, Solution aqueuse, Aqueous solution, Solución acuosa, Solution micellaire, Micellar solution, Solución micelar, Transfection, Transfección, Transfert chaîne, Chain transfer, Transferencia en cadena, Trithiocarbonate organique, Organic trithiocarbonate, Tritiocarbonato orgánico, Vecteur médicament, Drug carrier, Vector medicamento, Copolymère réductible, Folique dérivé copolymère, Groupe méthacryloyle, Méthacrylate de 2-[diméthylamino]éthyle copolymère, Polyplexe, Polyplex, Ptéridine dérivé copolymère, biodegradable, brush block copolymers, gene delivery, reductive milieu, and stimuli-responsive polymers

Novel neutral-cationic brush block copolymer, poly[oligo(ethylene glycol) monomethyl ether methacrylate-co-folic acid methacrylate]-b-poly[2-(2-(2-(2-bromo-2-methylpropanoyloxy)-ethyl) disulfanyl) ethyl methacrylate-g-2-dimethylaminoethyl methacrylate], P(OEGMA-co-FAMA)-b-P(BSSMA-g-PDMAEMA), is synthesized via consecutive controlled radical polymerizations. Containing disulfide linkages bridging backbone and side chains in the cationic brush block and cancer cell-targeting ligands (folic acid) in the neutral hydrophilic block, the diblock copolymer is employed as a tumor-targeted redox-responsive degradable nonviral gene delivery vector. P(OEGMA-co-FAMA)-b-P(BSSMA-g-PDMAEMA) brush block copolymers can condense plasmid DNA (pDNA) efficiently via the formation of electrostatic polyplex micelles. Under reductive milieu, pDNA can be released due to the cleavage of disulfide linkages and accordingly pDNA-binding cationic PDMAEMA side chains. In addition, the brush block copolymer exhibits low cytotoxicity and the corresponding polyplex micelles show relatively high gene transfection efficiency.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Propriétés et caractérisation, Properties and characterization, Propriétés des solutions et des gels, Solution and gel properties, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Pharmacologie. Traitements medicamenteux, Pharmacology. Drug treatments, Pharmacologie générale, General pharmacology, Technologie pharmaceutique. Industrie pharmaceutique, Pharmaceutical technology. Pharmaceutical industry, Amine polymère, Amine polymer, Amina polímero, Amine tertiaire, Tertiary amine, Amina terciaria, Cinétique, Kinetics, Cinética, Colorant organique, Organic dye, Colorante orgánico, Effet structure, Structure effect, Efecto estructura, Effet température, Temperature effect, Efecto temperatura, Etude expérimentale, Experimental study, Estudio experimental, Gel colloïdal, Colloidal gel, Gel coloidal, Gonflement, Swelling, Inflamiento, Libération, Release, Liberación, Méthacrylate polymère, Methacrylate polymer, Metacrilato polímero, Polymère vecteur, Control release polymer, Polímero vector, Polymérisation radicalaire, Free radical polymerization, Polimerización radicalar, Polyélectrolyte, Polyelectrolyte, Polielectrolito, Préparation, Preparation, Preparación, Rhodamine, Rodamina, Triazole dérivé polymère, Triazole derivative polymer, Triazol derivado polímero, Vecteur médicament, Drug carrier, Vector medicamento, pH, Effet densité réticulation, Interaction pi pi, Polymère sensible stimuli, DMAEMA, anticancer, hydrogels, sustained release, and triazole

The purpose of this study is to develop novel triazole-containing hydrogels (TGs) as drug carrier and to investigate the sustained drug release accomplished by their time-dependent swelling behavior. The synthetic pathway of TGs includes: (1) DCC-coupling on hydroxyethyl methacrylate (HEMA) to prepare HEMA-alkyne (HA), (2) click-coupling to prepare a triazole-ring-containing monomer (TM), and (3) the synthesis of a series of TGs. The aggregation between triazole rings is found to be responsible for drug release controllability. Rhodamine 6G is studied as a model anticancer drug for release experiments. The effects of pH and temperature on the properties of sustained drug release are also studied.

Energy, Énergie, Environment, Environnement, Pollution, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Polycondensation, Pollution, Additif, Additive, Aditivo, Angle contact, Contact angle, Angulo contacto, Chargement, Loading, Cargamento, Couche mince, Thin film, Capa fina, In situ, Matériau composite, Composite material, Material compuesto, Microscopie force atomique, Atomic force microscopy, Microscopía fuerza atómica, Microscopie électronique balayage, Scanning electron microscopy, Microscopía electrónica barrido, Morphologie, Morphology, Morfología, Nanocomposite, Nanocompuesto, Nanoparticule, Nanoparticle, Nanopartícula, Osmose, Osmosis, Perméabilité eau, Water permeability, Permeabilidad agua, Perméabilité liquide, Liquid permeability, Permeabilidad líquido, Polycondensation interfaciale, Interfacial polymerization, Policondensación interfacial, Rejet, Rejection, Rechazo, Solution aqueuse, Aqueous solution, Solución acuosa, Spectrométrie FTIR, Fourier-transformed infrared spectrometry, Espectrometría FTIR, Forward osmosis, Polyamide, Silica nanoparticles, and Thin-film nanocomposite membrane

This paper presents polyamide nano-composite membrane containing silica nanoparticles (TFN) synthesized via in situ interfacial polymerization for the forward osmosis (FO) application. Different concentrations of silica nanoparticles (0.01, 0.05 and 0.1% w/v) were added to the aqueous solution as additive to improve the FO membrane performance. The prepared membranes were characterized by ATR-FTIR, SEM, AFM and hydrophilicity measurement. The structure of nanocomposite layer synthesized by interfacial polymerization was characterized by FTIR spectroscopy. The FTIR peaks confirmed the presence of polyamide layer with SiO2 nanoparticles. The morphological studies showed that the SiO2 nanoparticles were effectively attached to the FO membrane surface. The contact angle measurements showed that the hydrophilicity of FO membranes was improved with increasing SiO2 in the aqueous solution. The FO performance was measured using 10 mM NaCl solution as feed solution and 2 M NaCl solution as draw solution in both orientations. The TFN membranes showed higher water permeability and better salt rejection in the range of 0.01―0.1 wt.% silica loading in comparison with the TFC membrane. The water flux of the TFN membrane reached to a maximum of 36 ± 2 L/m2 h which is nearly 2 times as high as that of the TFC membrane and it was found that the membrane modified with 0.05 w/v.% silica nanoparticles showed the highest salt rejection (90 ± 3%).

Metallurgy, welding, Métallurgie, soudage, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Propriétés et caractérisation, Properties and characterization, Adhérence, Adhesion, Adherencia, Biocompatibilité, Biocompatibility, Biocompatibilidad, Biomatériau, Biomaterial, Caprolactone polymère, Polycaprolactone, Caprolactona polímero, Cristallisation, Crystallization, Cristalización, Cycle thermique, Thermal cycle, Ciclo térmico, Effet mémoire forme, Shape memory effect, Efecto memoria forma, Liaison covalente, Covalent bond, Enlace covalente, Polymère réticulé, Crosslinked polymer, Polímero reticulado, Polymère semicristallin, Semicrystalline polymer, Polímero semicristalino, Procédé sol gel, Sol gel process, Procedimiento sol gel, Traitement thermique, Heat treatment, Tratamiento térmico, advanced characterization testing, biomaterial, creep and stress rupture, and mechanical

This paper investigates the shape memory capabilities of semicrystalline networks, focusing the attention on poly(e-caprolactone) (PCL) systems, a class of materials that allows to satisfy important requirements for their applications as biomedical devices, such as the good biocompatibility, the fast recovery of large temporary shape configurations, and the easy tailoring of the transformation temperatures. The materials were prepared with various crosslink densities and crosslinking methodologies; in particular, beside a thermal crosslinking based on reactive methacrylic end groups, a novel type of covalently crosslinked semicrystalline systems was prepared by a sol-gel approach from alkoxysilane-terminated PCL precursors, so as to avoid potentially toxic additives typically used for free-radical thermal curing. The materials were subjected to biological tests, to study their ability in sustaining cell adhesion and proliferation, and to thermal characterizations, to evaluate the possibility to tailor their melting and crystallization temperatures. The one-way shape memory (i.e., the possibility to set the material in a given configuration and to recover its pristine shape) and the two-way shape memory response (i.e., the triggered change between two distinguished shapes on the application of an on-off stimulus) were studied by applying optimized thermo-mechanical cyclic histories. The ability to fix the applied shape and to recover the original one on the application of heating (i.e., the one-way effect) was evaluated on tensile bars; further, to investigate a potential application as self-expandable stents, isothermal shape memory experiments were carried out also on tubular specimens, previously folded in a temporary compact configuration. The two-way response was studied through the application of a constant load and of a heating/cooling cycle from above melting to below the crystallization temperature, leading to a reversible elongation/contraction effect, involving maximum strain changes up to about 80%, whose extent may be controlled through the crosslink density.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Polycondensation, Article synthèse, Review, Artículo síntesis, Ionomère, Ionomer, Ionómero, Propriété physicochimique, Physicochemical properties, Propiedad fisicoquímica, Préparation, Preparation, Preparación, Uréthanne copolymère, Urethane copolymer, Uretano copolímero, Uréthanne polymère, Polyurethane, Uretano polímero, Utilisation, Use, Uso, Uréthanne à l'eau polymère, ionic, phase separation, polyurethanes, segmented, and waterborne polyurethane dispersions

Despite the well-established foundation of polyurethane chemistry in both industry and academia, research continues at a vigorous pace to refine synthetic processes and discover new functional materials. Incorporating ionic groups into polymers is a synthetic parameter capable of tailoring polymer properties and enabling emerging technologies. This review focuses on recent effort in the field of ion-containing segmented polyurethane copolymers. Multiple synthetic strategies to incorporate both cationic and anionic sites, including a particular focus on waterborne polyurethane dispersions and green synthetic methods, are examined. Fundamental structure-property relationships based on ionic structure, content, and placement are explored and many applications, including biomedical products and polymer electrolytes for energy devices are discussed.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Réactions et propriétés chimiques, Chemical reactions and properties, Modifications chimiques, Chemical modifications, Carboxylate, Carboxilato, Composé fluorescent, Fluorescent compound, Compuesto fluorescente, Copulation chimique, Chemical coupling, Copulación química, Diimide, Diimida, Dérivé du pérylène, Perylene derivatives, Perileno derivado, Etude expérimentale, Experimental study, Estudio experimental, Groupe terminal, End group, Grupo terminal, Modification chimique, Chemical modification, Modificación química, Polymère cyclique, Cyclic polymer, Polímero cíclico, Polymère étoile, Star polymer, Polímero estrella, Préparation, Preparation, Preparación, Tétrahydrofurane polymère, Tetrahydrofuran polymer, Tetrahidrofurano polímero, Assemblage électrostatique, Etoile 4 branches, Forme en haltère, 8-shaped polymer, ESA-CF, cyclic polymer, perylene diimide, and poly(THF)

A pair of four-armed star and dicyclic 8-shaped poly(tetrahydrofuran)s, poly(THF)s, possessing a perylene diimide group at the core position (la and lb, respectively) were synthesized by means of an electrostatic self-assembly and covalent fixation (ESA-CF) protocol. Mono- and bifunctional poly(THF)s having N-phenylpiperidinium salt end groups accompanying a perylene diimide tetracarboxylate as a counteranion were prepared by the ion-exchange reaction, and the subsequent covalent conversion by reflux in toluene afforded the corresponding core-fluorescent four-armed star and dicyclic 8-shaped poly(THF)s, (la and lb, respectively) for the use of single-molecule fluorescence microscopy measurements. .

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Chimie, Chemistry, Chimie organique, Organic chemistry, Préparations et propriétés, Preparations and properties, Peptides, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Polymères à propriétés spéciales, Polymers with particular properties, Amidation, Amidación, Déprotection, Deprotection, Desprotección, Etude expérimentale, Experimental study, Estudio experimental, Groupe terminal, End group, Grupo terminal, Modification chimique, Chemical modification, Modificación química, Polymère monodispersé, Monodispersed polymer, Polímero monodispersado, Polymérisation transfert atome, Atom transfer polymerization, Polimerización transferencia atomo, Préparation, Preparation, Preparación, Styrène polymère, Styrene polymer, Estireno polímero, Support réaction, Reaction support, Soporte reacción, Synthèse peptidique, Peptide synthesis, Síntesis peptídica, Tétrapeptide, Tetrapeptide, Tetrapéptido, Rink amides, peptides, sequence-control, solid supports, and soluble supports

A soluble polystyrene-based support bearing a cleavable Rink amide moiety is synthesized and utilized for the iterative synthesis of an oligopeptide. This soluble support is obtained in three steps. First, a well-defined polystyrene segment is prepared by atom transfer radical polymerization (ATRP) using a fluorenylmethyloxycarbonyl (Fmoc)-protected amino-functional ATRP initiator. After polymerization, the Fmoc-protecting group is cleaved and the obtained primary amine is coupled to a commercial Knorr linker (also known as Rink amide linker). The formed Rink amide soluble support is characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. As a proof of concept, this soluble support is used for the synthesis of a model tetrapeptide Glycine-Lysine-Serine-Arginine. This peptide is also prepared on a commercial Rink amide resin, in order to compare the advantages and drawbacks of soluble and solid supports. It is found that the soluble support allows efficient synthesis of the model oligopeptide. Interestingly, it also allows a precise monitoring of the oligomer synthesis by SEC and NMR.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Polymères à propriétés spéciales, Polymers with particular properties, Etude expérimentale, Experimental study, Estudio experimental, Ferrocène, Ferrocene, Fluorescence, Fluorescencia, Groupe hydrophobe, Hydrophobic group, Grupo hidrófobo, Groupe terminal, End group, Grupo terminal, Modification chimique, Chemical modification, Modificación química, Phénylènevinylène dérivé polymère, Phenylenevinylene derivative polymer, Fenilenovinileno derivado polimero, Polymère conjugué, Conjugated polymer, Polímero conjugado, Polymère fluor, Fluorine containing polymer, Polímero flúor, Polymère monodispersé, Monodispersed polymer, Polímero monodispersado, Polymère silicium, Silicon polymer, Polímero silicio, Polymère téléchélique, Telechelic polymer, Polímero telechélico, Polymérisation catalyseur complexe, Complex catalyst polymerization, Polimerización catalizador complejo, Préparation, Preparation, Preparación, Réaction Wittig, Wittig reaction, Reacción Wittig, Solution organique, Organic solution, Solución orgánica, Spectre absorption, Absorption spectrum, Espectro de absorción, Groupe formylferrocényle, Groupe pentafluorophényle, Groupe terthiényle, Phénylènevinylène(2,5-bis[2-(triisopropylsilyloxy)éthoxy]) polymère, C-C coupling, conjugation, fluorescence, and metathesis

Defect-free, highly trans oligo(2,5-dialkoxy-1,4-phenylene vinylene)s [alkoxy = O(CH2)2OSiiPr3] with both repeat units (ex. 9, 15, and 31 repeat units) and end groups (aldehyde, C6F5, terthiophene, ferrocene) well-defined are prepared by a stepwise combined olefin metathesis using Mo(CHCMe2Ph)(N-2,6-Me2C6H3)[OCCH3(CF3)2]2 with subsequent Wittig-type coupling. End-functionalized oligomers with uniform distributions are also prepared by acyclic diene metathesis (ADMET) condensation using a ruthenium-carbene catalyst, followed by the above combined olefin metathesis and Wittig coupling. The effects of the repeat units and the end functional groups on the optical properties are explored; the photoluminescence quantum yields in the end-functionalized oligomers (e.g., 9 mers) are affected by the end groups.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères d'origine naturelle, Natural polymers, Protéines, Proteins, Polymères organiques, Organic polymers, Propriétés et caractérisation, Properties and characterization, Propriétés des solutions et des gels, Solution and gel properties, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Chirurgie (generalites). Transplantations, greffes d'organes et de tissus. Pathologie des greffons, Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases, Technologie. Biomatériaux. Equipements, Technology. Biomaterials. Equipments, Acide nucléique, Nucleic acid, Acido nucleico, Acrylique acide polymère, Acrylic acid polymer, Acrílico ácido polímero, Article synthèse, Review, Artículo síntesis, Biomatériau, Biomaterial, Cryogel, DNA, Elastomère, Elastomer, Elastómero, Fibre animale, Animal fiber, Fibra animal, Fibre naturelle, Natural fiber, Fibra natural, Fibroïne, Fibroin, Fibroína, Gel colloïdal, Colloidal gel, Gel coloidal, Gélification, Gelation, Gelificación, Génie tissulaire, Tissue engineering, Ingeniería de tejidos, Matériau poreux, Porous material, Material poroso, Pollution eau, Water pollution, Contaminación agua, Polymère linéaire, Linear polymer, Polímero lineal, Polyélectrolyte, Polyelectrolyte, Polielectrolito, Propriété mécanique, Mechanical properties, Propiedad mecánica, Protéine animale, Animal protein, Proteína animal, Préparation, Preparation, Preparación, Pétrole brut, Crude oil, Petróleo bruto, Pétrole, Petroleum, Petróleo, Relation structure propriété, Property structure relationship, Relación estructura propiedad, Soie, Silk, Seda, Sorbant, Sorbent, Sorbente, Echafaudage tissulaire, Cryogels, Elasticity, Porosity formation, and Swelling

Polymeric gels belong to the most important class of functional polymers in modem biotechnology. They are useful materials for drug delivery systems, artificial organs, separation operations in biotechnology, processing of agricultural products, on-off switches, sensors, and actuators. Despite this fact and considerable research in this field, the design and control of gel-based devices still present some problems due to the their poor mechanical performance and slow rate of response to external stimuli. Cryogelation techniques discovered more than 30 years ago overcome these limitations by producing macroporous gels with high toughness and superfast responsivity. This chapter discusses how and why the properties of gels significantly alter upon transition from homogeneous gelation to a cryogelation regime. The formation and structure-property relationships of cryogels starting from monovinyl-divinyl monomers, as well as from linear polymer chains, are reviewed using examples from the recent literature. Some novel cryogels with a wide range of tunable properties and their applications are also presented in detail. These include DNA cryogels for the removal of carcinogens from aqueous environments, silk fibroin cryogels as mechanically strong scaffolds for bone tissue engineering applications, poly(acrylic acid) cryogels as self-oscillation systems, and rubber cryogels as reusable oil sorbent for the removal of oil spill from seawater.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Polymérisation, Polymerization, Amide polymère, Nylon, Amida polímero, Carboxamide, Carboxamida, Complexe de ruthénium, Ruthenium complex, Rutenio complejo, Composé diénique, Dienic compound, Compuesto diénico, Cristallinité, Crystallinity, Cristalinidad, Etude expérimentale, Experimental study, Estudio experimental, Hydrogénation, Hydrogenation, Hidrogenación, Mode empilement, Stacking sequence, Modo apilamiento, Modification chimique, Chemical modification, Modificación química, Polymère insaturé, Unsaturated polymer, Polímero insaturado, Polymère saturé, Saturated polymer, Polímero saturado, Polymérisation catalyseur complexe, Complex catalyst polymerization, Polimerización catalizador complejo, Polymérisation métathèse, Metathesis polymerization, Polimerización metátesis, Préparation, Preparation, Preparación, Pyridine dérivé polymère, Pyridine derivative polymer, Piridina derivado polímero, Structure cristalline, Crystalline structure, Estructura cristalina, acyclic diene metathesis, crystallization, polymer synthesis, and supramolecular polymer chemistry

The synthesis and thermal properties of a new type of precision polyethylene containing perfectly placed conformationally constraining elements after every 16 methylene units are presented. The precise placement of a 2,6-diaminopyridine moiety (DAP) is accomplished via acyclic diene metathesis (ADMET) polymerization of specially designed monomers, where the DAP serves as the conformational constraint. Polymerization of the diene-monomer (N,N'-pyridin-2,6-diyl-bis-dec-9-enamide) displaying free-amide hydrogen bonds leads to largely insoluble polymers due to self-aggregation via the hydrogen bonds and π-π stacking. However, when using the N-methyl-protected monomer N,N'-pyridin-2,6-diylbis(N-methyldec-9-enamide), the polymerization furnishes soluble polymers with molecular weights ranging from 1500 up to 60 000 g mol-1 using different Grubbs or Umicore catalysts. Matrix-assisted laser desorption/ionization (MALDI) measurements prove the structure of linear and cyclic polymers, all containing the precisely placed DAP units within the polymer. Subsequent hydrogenation with p-toluenesulfonhydrazide yields the final semicrystalline polymers, displaying an ordered lamellar crystal phase as characterized via differential scanning calorimetry (DSC) and X-ray diffraction (XRD) measurements.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères d'origine naturelle, Natural polymers, Divers, Miscellaneous, Polymères organiques, Organic polymers, Propriétés et caractérisation, Properties and characterization, Propriétés de surface, Surface properties, Acide nucléique, Nucleic acid, Acido nucleico, Adsorption liquide solide, Liquid solid adsorption, Adsorción líquido sólido, Article synthèse, Review, Artículo síntesis, Chaîne flexible, Flexible chain, Cadena flexible, Conformation, Conformación, DNA, Distribution densité, Density distribution, Distribución densidad, Effet surface, Surface effect, Efecto superficie, Fonction Green, Green function, Función Green, Interaction électrostatique, Electrostatic interaction, Interacción electrostática, Modélisation, Modeling, Modelización, Particule sphérique, Spherical particle, Partícula esférica, Polyélectrolyte, Polyelectrolyte, Polielectrolito, Propriété surface, Surface properties, Propiedad superficie, Surface plane, Plane surface, and Superficie plana

Polyelectrolytes are macromolecules composed of charged monomers and exhibit unique properties due to the interplay of their flexibility and electrostatic interactions. In solution, they are attracted to oppositely charged surfaces and interfaces and exhibit a transition to an adsorbed state when certain conditions are met concerning the charge densities of the polymer and surface and the properties of the solution. In this review, we discuss two limiting cases for adsorption of flexible polyelectrolytes on curved surfaces: weak and strong adsorption. In the first case, adsorption is strongly influenced by the entropic degrees of freedom of a flexible polyelectrolyte. By contrast, in the strong adsorption limit, electrostatic interactions dominate, which leads to particular adsorption patterns, specifically on spherical surfaces. We discuss the corresponding theoretical approaches, applying a mean-field description for the polymer and the polymer-surface interaction. For weak adsorption, we discuss the critical adsorption behavior by exactly solvable models for planar and spherical geometries and a generic approximation scheme, which is additionally applied to cylindrical surfaces. For strong adsorption, we investigate various polyelectrolyte patterns on cylinders and spheres and evaluate their stability. The results are discussed in the light of experimental results, mostly of DNA adsorption experiments.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Polymérisation, Polymerization, Acrylamide dérivé polymère, Acrylamide derivative polymer, Acrilamida derivado polímero, Amidation, Amidación, Aminolyse, Aminolysis, Aminolisis, Anhydride organique, Organic anhydride, Anhídrido orgánico, Copulation chimique, Chemical coupling, Copulación química, Etude expérimentale, Experimental study, Estudio experimental, Groupe aminé, Amino group, Grupo aminado, Groupe carboxyle, Carboxyl group, Grupo carboxilo, Groupe terminal, End group, Grupo terminal, Hydrolyse, Hydrolysis, Hidrólisis, Imide, Imida, Modification chimique, Chemical modification, Modificación química, Nanoparticule, Nanoparticle, Nanopartícula, Or, Gold, Oro, Particule métallique, Metal particle, Partícula metálica, Polymère greffé, Graft polymers, Polymère monodispersé, Monodispersed polymer, Polímero monodispersado, Polymère téléchélique, Telechelic polymer, Polímero telechélico, Polymérisation radicalaire, Free radical polymerization, Polimerización radicalar, Préparation, Preparation, Preparación, Réaction surface, Surface reaction, Reacción superficie, Transfert chaîne, Chain transfer, Transferencia en cadena, Trithiocarbonate organique, Organic trithiocarbonate, Tritiocarbonato orgánico, Acrylamide(N,N-diméthyl) polymère, Acrylamide(N-isopropyl) polymère, Addition fragmentation réversible, Groupe mercapto, Polymère greffé nanoparticule, Polymère hétérotéléchélique, Polymère thermosensible, RAFT, dual-responsive particles, gold nanoparticles, and heterotelechelic polymers

Heterotelechelic, hydrophilic polymers with a primary amine and thiol group at the α- and ω-chain end, respectively, are synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization in a straightforward and versatile way and subsequently used for the design of dual-responsive polymer/gold nanohybrids. Therefore, a phthalimido-containing chain transfer agent (CTA) is synthesized and used for the polymerization of the hydrophilic monomers N-isopropylacrylamide (NIPAM) and N,N-dimethylacrylamide (DMA). After polymerization, the trithiocarbonate functionality at the ω-chain end, originating from the CTA, is converted into a thiol upon aminolysis. In the next step, the phthalimido α-chain end is hydrolyzed into a primary amine, resulting in heterotelechelic, hydrophilic polymers. End-group conversions are monitored by 1H NMR spectroscopy, MALDI-TOF MS analysis, and UV-Vis spectroscopy, confirming that quantitative modifications are obtained during each stage. The amino groups of these heterotelechelic polymer chains are modified with citraconic anhydride, after which the obtained polymers are grafted with the thiol group onto citrate-stabilized gold nanoparticles resulting in the creation of dual-temperature- and pH-responsive gold particles.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Polymérisation, Polymerization, Aluminium Composé organique, Aluminium Organic compounds, Aluminio Compuesto orgánico, Activité catalytique, Catalyst activity, Actividad catalítica, Catalyseur complexe, Complex catalyst, Catalizador complejo, Complexe chloro, Chloro complex, Complejo cloro, Complexe hapto, Hapto complex, Complejo hapto, Effet substituant, Substituent effect, Efecto sustituyente, Etude expérimentale, Experimental study, Estudio experimental, Polymère syndiotactique, Syndiotactic polymer, Polímero sindiotáctico, Polymérisation catalyseur complexe, Complex catalyst polymerization, Polimerización catalizador complejo, Polymérisation stéréospécifique, Stereospecific polymerization, Polimerización estereoespecífica, Structure cristalline, Crystalline structure, Estructura cristalina, Styrène polymère, Styrene polymer, Estireno polímero, Stéréospécificité, Stereospecificity, Estereoespecificidad, Synthèse chimique, Chemical synthesis, Síntesis química, Titane IV Complexe, Titanium IV Complexes, Titanio IV Complejo, Aluminoxane(méthyl), catalysts, polymerization, styrene, and syndiotactic polymers

Cp'TiCl2(N-(6-(2-(diethylboryl)phenyl)pyrid-2-yl)SiMe3), [Cp' = C5H5 (3), C5(CH3)5 (4)], and the aminoborane-free half-titanocene analogs with the general formula: Cp'TiCl2(N-(biphenyl-3-yl)SiMe3); [Cp' = C5H5 (7), C5(CH3)5 (8)] are synthesized and used in the polymerization of styrene. All the pre-catalysts are active in styrene polymerization, >90% syndiotactic poly(styrene) (st-PS) is produced, exceeding that of their ansa-homologues (C5(CH3)5) TiCl2(6-(2-(diethylboryl)phenyl)pyrid-2-ylamido)(dimethylsilyl) (9) and (C5(CH3)5)TiCl2(3-biphen-3-ylamido)(dimethylsilyl) (10) both in activity and molecular weight. Pre-catalyst 8 allows for the synthesis of high-molecular-weight st-PS with activities up to 5000 kgst-PS molcat-1 h-1. Implications of the 2-(diethylboryl)phenyl)pyrid-2-yl group on polymerization activity and molecular weight are discussed.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Préparation, cinétique, thermodynamique, mécanisme et catalyseurs, Preparation, kinetics, thermodynamics, mechanism and catalysts, Polymérisation, Polymerization, Agrégation moléculaire, Molecular aggregation, Agregación molecular, Colorant organique, Organic dye, Colorante orgánico, Copolymère biséquencé, Diblock copolymer, Copolímero bisecuencia, Copolymère greffé, Graft copolymer, Copolímero injertado, Copolymère vivant, Living copolymer, Copolímero viviente, Dithioester, Ditioester, Ethylène oxyde copolymère, Ethylene oxide copolymer, Etileno óxido copolímero, In situ, Molécule asymétrique, Asymmetric molecule, Molécula asimétrica, Méthacrylate copolymère, Methacrylate copolymer, Metacrilato copolímero, Nanoencapsulation, Nanoencapsulación, Polymérisation radicalaire, Free radical polymerization, Polimerización radicalar, Polymérisation solution, Solution polymerization, Polimerización solución, Spectre dimension, Dimension spectrum, Espectro dimensión, Styrène copolymère, Styrene copolymer, Estireno copolímero, Styrène, Styrene, Estireno, Transfert chaîne, Chain transfer, Transferencia en cadena, Addition fragmentation réversible, Morphologie agrégat, Séquence greffée, Séquence linéaire, dispersion polymerization, encapsulation, living radical polymerization, morphologies, nanoparticles, and reversible addition fragmentation chain transfer (RAFT)

Nanoparticles with various morphologies such as micelles, worm-like/rod-like and spherical vesicles are made using a polymerization-induced self-assembly (PISA) approach via a one-pot RAFT dispersion polymerization. On polymerization/self-assembly, we report a concurrent highly efficient loading of guest molecules within the nanoparticle structures. Different nanoparticle morphologies, such as spherical micelles, worm-like, rod-like, and spherical vesicles, are achieved by gradually increasing the number-average degree of polymerization (DPn) of the PST block via increasing polymerization times (in a poor solvent) as determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. In parallel, a guest molecule (Nile Red) is encapsulated during the polymerization without disturbing the morphology or the polymerization kinetics.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères organiques, Organic polymers, Propriétés et caractérisation, Properties and characterization, Divers, Miscellaneous, Autodiffusion, Self diffusion, Autodifusión, Etude théorique, Theoretical study, Estudio teórico, Modélisation, Modeling, Modelización, Mélange polymère, Polymer blends, Polymère cyclique, Cyclic polymer, Polímero cíclico, Polymère linéaire, Linear polymer, Polímero lineal, Relation composition propriété, Property composition relationship, Relación composición propiedad, Modèle liaison fluctuante, Bond-fluctuation model, Cyclic polymers, Mean-squared displacement, and Ring-linear blends

We use the bond-fluctuation model to measure self-diffusivity of asymmetric blends of cyclic and linear polymers, where the number of monomers in the cyclic and linear polymer are different. We consider two series of asymmetric blends and vary the relative composition. In particular, Nc = 300 and NL = 150, and Nc = 150 and NL = 300, where Nc and NL are the number of monomers in the cyclic and linear polymers, respectively. Compared to cyclic polymers, the self-diffusivity of linear polymers is relatively insensitive to the blend composition, and is approximately within a factor of two of the pure linear self-diffusivity. In sharp contrast, the self-diffusivity of cyclic polymers exhibits a strong order of magnitude variation with the blend microenvironment. The latter data appear to be consistent with trends expected from previous simulations of symmetric cyclic-linear blends, as a function of the fraction of linear polymer.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Physicochimie des polymeres, Physicochemistry of polymers, Polymères d'origine naturelle, Natural polymers, Divers, Miscellaneous, Polymères organiques, Organic polymers, Propriétés et caractérisation, Properties and characterization, Propriétés des solutions et des gels, Solution and gel properties, Article synthèse, Review, Artículo síntesis, Cinétique, Kinetics, Cinética, Densité charge, Charge density, Densidad carga, Diffusion lumière, Light scattering, Difusión luz, Effet pH, pH effect, Efecto pH, Effet température, Temperature effect, Efecto temperatura, Force ionique, Ionic strength, Fuerza iónica, Force surface, Surface forces, Interpolymère, Interpolymer, Interpolímero, Microscopie force atomique, Atomic force microscopy, Microscopía fuerza atómica, Mécanisme formation, Formation mechanism, Mecanismo formacion, Méthode étude, Investigation method, Método estudio, Polyélectrolyte, Polyelectrolyte, Polielectrolito, Protéine, Protein, Proteína, Solution chimique, Chemical solution, Solución química, AFM, DLS, PEC, PEM, Relaxation time, and Rheology

Polyelectrolyte complex formation is a well-studied subject in colloid science. Several types of complex formation have been studied, including PEMs, macroscopic polyelectrolyte complexes, soluble complexes and polyelectrolyte complex micelles. The chemical nature of the complex-forming polyelectrolytes and the environmental conditions (e.g., pH, ionic strength and temperature) influence the final structural properties of these complexes. This chapter deals with the kinetics of polyelectrolyte complex formation and discusses how ionic strength, charge density and pH influence the dynamics of the complexes, which can range from glass-like (solid) precipitates to liquid-like phases. The switching between the glass-like and liquid-like phase as a function of the ionic strength has a strong analogy to the phase behaviour of polymer melts as function of temperature. By performing calorimetry during complex formation it has been found that the enthalpy of complex formation of systems that form glass-like phases has an opposite sign to the enthalpy of systems that form liquid-like phases, i.e., the formation of glass-like phases is exothermic and the formation of liquid-like phases is endothermic. The free energy (ΔfG), enthalpy (ΔfH) and entropy (ΔfS) of polyelectrolyte complex formation and how they vary as a function of the ionic strength will be discussed. Results from dynamic light scattering (DLS) titrations, Atomic Force Microscopy (AFM), surface force measurements and rheology will be used to illustrate how differences in kinetics show up in experiments on colloidal micellar systems. In the section on DLS titrations, three-component systems containing two oppositely charged polyelectrolytes and protein molecules will be discussed. This chapter concludes with a section dedicated to the complex formation of oppositely charged protein molecules.