Search results for "polyelectrolyte"

Cyclodextrins in polymer synthesis: Free radical polymerization of cyclodextrin complexes withN-methacryloyl-11-aminoundecanoic acid orN-methacryloyl…

1998

The hydrophobic monomers N-methacryloyl-11 -aminoundecanoic acid (1) or N-methacryloyl-1-aminononane (2) were incorporated as guests into the cavity of heptakis(2,6-di-O-methyl)-β-cyclodextrin (Me 2 -β-CD) as a host, yielding the water compatible monomers N-methacryloyl-l 11-aminoundecanoic acid/ Me 2 -β-CD-complex (1a) and N-methacryloyl-1 -aminononane/Me 2 -β-Cl complex (2a). These complexes were polymerized radically in aqueous medium. The resulting polymers 1b and 2b which were obtained from the complexes 1a and 2a, are insoluble in water because of the unthreading of the cyclodextrin during the polymerization. The polymerization rate of 1a and 2a is high in comparison to the rate of th…

Synthesis, characterisation and properties of α,β-poly(N-2-hydroxyethyl)-dl-aspartamide-graft-maleic anhydride precursors and their stimuli-responsiv…

2009

Abstract A family of poly(amino acid)-maleic anhydride hydrogels were designed and synthesized. Water soluble polymeric precursors were prepared by partially substituting the hydroxyl groups of the α,β-poly( N -2-hydroxyethyl)- dl -aspartamide backbone with maleic anhydride, so as to provide double bonds for crosslinking and carboxylic acid groups for pH and electric field responsiveness. Reaction conditions (reactive mixture composition and catalysis) were systematically varied in order to obtain PHEA–MA precursors with different and reliable graft-maleic anhydride levels. PHEA–MA precursors were characterised by titration, Nuclear Magnetic Resonance ( 1 H NMR), Fourier-Transformed Infrare…

1995

Polystyrene-block-poly-1-azabicyclooctane[4,2,0] has been modified by protonation or alkylation of the polyamine moiety. Short chain alkyl iodides lead to quantitatively quarternized products while longer alkyl chains or alkyl-bromides give incomplete conversion. The viscosimetric behavior of the charged blockcopolymers is dominated by the polyelectrolyte block although the polyelectrolyte effect is drastically reduced by the presence of the polystyrene block. The blockcopolymers are insoluble in water, but concentrated solutions of the polymers in DMF can be diluted with any amount of water without any precipitation. Although the blockcopolymers have an amphiphilic structure they do not ex…

Cationic copolymers of ?,?-poly-(N-2-hydroxyethyl)-DL-aspartamide (PHEA) and ?,?-polyasparthylhydrazide (PAHy): synthesis and characterization

2000

In the present study the derivatization of two water-soluble synthetic polymers, α,β-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) and α,β-polyasparthylhydrazide (PAHy), with glycidyltrimethylammonium chloride (GTA) is described. This reaction permits the introduction of positive charges in the macromolecular chains of PHEA and PAHy in order to make easier the electrostatic interaction with DNA. Different parameters affect the reaction of derivatization, such as GTA concentration and reaction time. PHEA reacts partially and slowly with GTA; on the contrary the reaction of PAHy with GTA is more rapid and extensive. The derivatization of PHEA and PAHy with GTA is a convenient method to introdu…

Role of Topology and Amphiphilicity for Guest Encapsulation in Functionalized Hyperbranched Poly(ethylenimine)s

2004

The promising potential of dendrimers in a variety of areas, such as catalysis, materials science and biomedicine is related to their globular shape, large number of modifiable surface functionalities and the presence of internal reservoirs.1 Their use in liquidliquid-phase transfer protocols, based on the encapsulation of guest molecules as drug delivery vehicles for pharmaceutical application, represents an important issue.2 Unfortunately, dendrimer synthesis is timeconsuming, which currently limits practical use to laboratory scale. For that reason, hyperbranched polymers prepared from ABm-type monomers in one-step processes have gained increasing interest.3 The development of the slow m…

Dextran-Based Polycations: Thermodynamic Interaction with Water as Compared With Unsubstituted Dextran, 2 - Flory/Huggins Interaction Parameter

2011

Kinetics of Complex Formation between DNA and Cationically Charged Cylindrical Brush Polymers Observed by Stopped Flow Light Scattering

2009

The complex formation of pUC19 DNA and a cylindrical brush polymer with quaternized poly(vinyl pyridinium) side chains is investigated by stopped flow light scattering (LS). In highly dilute solutions up to two kinetic processes are observable, depending on the mole fraction of anionic charges, x(anion) . For x(anion)  0.4-0.5 only one kinetic process was identified leading to the largest complexes at x(anion)  = 0.4 well below charge stoichiometry. For 0.2 < x(anion)  < 0.4 two kinetic growth processes were identified: The initially formed complexes on the time scale of a few hundred milliseconds keep growing by an unusual fractal growth process until after several minutes they become stab…

Synthesis and properties of aromatic ionenes

1993

Cationic polyelectrolytes with aromatic segments can be synthesized by a repetitive alkylation reaction. The structure of the products, their synthesis and their solubility are described. All ionenes are not, or only in small amounts, water soluble. The best solubility can be achieved by mixtures of polar protic and aprotic solvents. Variations of the counterion produces sufficient solubility in THF. All ionenes show a typical polyelectrolyte effect. The thermal stability of aromatic ionenes and the glass transition temperature is dominated by the nature of the counterion. The molecular weight of oligomers can be described by using a combination of a conductive titration method and an ion s…

Electrically conductive TCNQ complexes of aromatic ionenes

1995

New types of complex salts of 7,7',8,8'-tetracyanoquinodimethane with aromatic ionenes and their model compounds were prepared. The electrical conductivity and the activation energy were measured and discussed in relation to their structure. The effects of the nature of the aromatic unit, and the flexibility and rigidity of the polymer backbone were compared with the corresponding model compounds. The effects of frequency and temperature are discussed in terms of the molecular structure of the complex. The electroconductivity at room temperature of the 1 :1 polymer complex salts was found to be between 2 x 10 -4 and 7 x 10 -5 S/cm, while that of the model complex salts was between 1.3 x 10 …

Unified Thermodynamic Modeling of Polymer Solutions: Polyelectrolytes, Proteins, and Chain Molecules

2013

The thermodynamic description of the systems specified in the title requires in general dissimilar theories. This contribution presents an approach that is capable of modeling all of them with a maximum of three adjustable parameters. The Ansatz starts from the Flory–Huggins theory and extends it in a 2-fold manner: The number of segments assigned to the solvent is no longer one but treated as an adjustable parameter to account for the differences in the molecular geometries and in the free volumes of the components. Furthermore, the modeling allows for effects resulting from ternary contacts of the solvent/polymer/polymer type. Examination of the acquired thermodynamic expressions by means…