Search results for "polymers"

Hydrophilic and hydrophobic copolymers of a polyasparthylhydrazide bearing positive charges as vector for gene therapy

2008

BACKGROUND: The design of polymeric vectors for gene delivery provided with specific properties is one of the most critical aspects for a successful gene therapy. These polymers should be biocompatible as well as able to carry efficiently DNA to target tissues and to transfect it into cells. RESULTS: The formation of complexes of poly[(α,β-asparthylhydrazide)–poly(ethylene glycol)] and poly[(α,β-asparthylhydrazide)–hexadecylamine] copolymers functionalised with glycidyltrimethylammonium chloride (PAHy–PEG-GTA and PAHy–C16-GTA, respectively) with DNA was studied. The effects of the introduction of hydrophilic (PEG) or hydrophobic (C16) moieties on the chains of PAHy–GTA copolymers, such as t…

TI: Cyclophosphazenes as polymer modifiers

2003

The utilization of cyclophosphazenes as polymer modifiers is reviewed, with particular concern to their exploitation as versatile chain extenders, possibly for recycle problems, crosslinkers, to enhance mechanical properties of polymeric materials, branchers, to selectively introduce ramifications in linear polymers, and compatibilizers, to favor the formation of blends between originally incompatible organic macromolecules. The great versatility of the synthetic methods put forward for these substrates, together with the ease of controlling their modification, functionalization and reactivity are important parameters for the evaluation of which type of use is more feasible for these trimer…

Die Darstellung von Gelen als stationäre Phase für die Gelchromatographie

1970

Bei vernetzten Copolymeren aus athylvinylbenzol/Divinylbenzol sowie Vinylacetat/Divinyladipat wird der Einflus der Herstellungsbedingungen auf die Eigenschaften der vernetzten Polymeren untersucht. Homogen-vernetzte Gele eignen sich vor allem zur Trennung von Oligomeren; mit heterogen-vernetzten Gelen konnen Polymere getrennt werden. Es wird gezeigt, das bei der heterogen-vernetzenden Polymerisation die Heterogenitat der Copolymeren mit sinkendem Solvatationsvermogen der Inertkomponente wachst; dies fuhrt gleichzeitig zu einer Erhohung des Aussechlusmolekulargewichtes. The influence of the mode of synthesis on the characteristics of crosslinked polymers is examined for crosslinked copolymer…

Dextran-Based Polycations: Thermodynamic Interaction with Water as Compared With Unsubstituted Dextran, 1 - Volumetric Properties and Light Scattering

2011

1986

Preparation and mechanical characterization of fibres from a new copoly(ether-ester-amide) are reported. The mechanical characteristics are slightly lower than those of polyamide 6, but satisfactory for textile use, and the fibres have larger moisture absorption. This gives rise to more comfortable fibres preventing the accumulation of electrostatic charges. Die Herstellung und mechanische Charakterisierung von Fasern aus einem neuen Copoly(ether-ester-amid) werden beschrieben. Die mechanischen Eigenschaften sind etwas schlechter als die von Polyamid 6, aber ausreichend fur textile Anwendungen. Die Fasern weisen eine grosere Feuchtigkeitsabsorption auf. Dies fuhrt zu einem angenehmeren Verh…

Liquid crystal polymers (LCP) as processing aids and reinforcing agents. A study of nylon 6/LCP blends

1989

Influence de petites quantites d'un copolyesteramide thermotropique sur les proprietes mecaniques et la mise en œuvre du polyamide 6

1986

A procedure is described for the preparation of a block copolymer with A-B-A sequences in which ω-ω′-dihydroxy-poly-(ethylene glycol) is inserted between two polymeric monoacidic chains of polycaproamide and bonded to them by means of ester links. The resulting material was characterized. The copolymer is isomorphous with the polycaproamide. Thermal treatments induce a crystalline transition γ α as in polycaproamide. The influence of the moisture content on the glass transition temperature and on the storage modulus is discussed. Ein Verfahren zur Herstellung eines Blockcopolymers mit A-B-A-Sequenzen wird beschrieben. In dem Copolymer ist ω-ω′-Dihydroxy-polyethylenglycol uber Esterbindungen…

Tuneable pH-regulated supramolecular copolymerisation by mixing mismatched dendritic peptide comonomers

2015

Charged phenylalanine-rich dendritic peptides form highly stable and pH-switchable rod-like supramolecular copolymers, when co-assembled with a matching oppositely charged dendritic comonomer. Here, we demonstrate that by mismatching a strong with a weak β-sheet encoded comonomer, both the stability and the pH-triggered disassembly of the copolymers shifts drastically from pH 4.2 to biologically relevant pH 5.8.

Enhanced polyurethanes based on different polycarbonatediols

2012

Segmented thermoplastic polyurethanes (PUs) were prepared from 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butanediol (BD) and different macrodiols with a molar mass of 1000. Properties of those PUs based on polycarbonatediol (PCD) were compared with their homologous based on polyesterdiol and polyetherdiol as macrodiols. The proportion used in this study was macrodiol:BD:MDI = 1:2:3, in mole ratio. The hard segment weight percentage is 48 wt% for different PUs. Thermogravimetric analysis, differential scanning calorimetry, differential mechanical analysis, Fourier transform infrared-attenuated total reflection spectroscopy, as well as mechanical properties and retention on flexural prope…

Photoactive Hybrid Materials based on Conjugated Porous Polymers and Inorganic Nanoparticles

2021

This review explores the current state‐of‐the‐art for functional photoactive hybrids containing inorganic nanoparticles (magnetic and metal) and conjugated organic porous polymers (CPPs). Albeit new in the field, with the first hybrid material of this kind reported in 2012, those materials have gained increasing interest in applications such as sensing, heterogeneous catalysis, photocatalysis, and lithium‐ion batteries (LIBs). This review describes the two main synthetic strategies for those materials, namely, 1) using the chemical and morphological features (e.g., porosity and complexation sites) of CPPs to in situ form nanoparticles and 2) fabricating the nanoparticle for templating CPPs.…