Search results for "Copolymer"
showing 10 items of 1003 documents
Copolymerization of Ethylene with Selected Vinyl Monomers Catalyzed by Group 4 Metal and Vanadium Complexes with Multidentate Ligands: A Short Review
2021
This paper gives a short overview of homogeneous post-metallocene catalysts based on group 4 metal and vanadium complexes bearing multidentate ligands. It summarizes the catalytic behavior of those catalysts in copolymerization of ethylene with 1-olefins, with styrenic monomers and with α,ω-alkenols. The review is focused on finding correlations between the structure of a complex, its catalyst activity and comonomer incorporation ability, as well as the microstructure of the copolymer chains.
Temperature tuned threading and de-threading of cyclodextrin in a cationic block copolymer
2010
Threading and de-threading of cyclodextrin in a thermosensitive cationic block copolymer in water and at the silica/water interface
2010
Synthesis and characterization of ethylene-1-hexene copolymers prepared by using MgCl2(THF)2-supported Ziegler-Natta catalysts
2000
Ethylene was copolymerized with 1-hexene over vanadium (VOCl3 and VCl4) and titanium (TiCl4) catalysts supported on MgCl2(THF)2 and activated with Et2AlCl. So far these catalyst systems have not been known as initiators of ethylene-1-hexene copolymerization. The vanadium catalysts were more active than the titanium catalyst and, at identical comonomer concentrations in the feed, gave rise to a greater incorporation of 1-hexene into the copolymer. Even at relatively low fractions of 1-hexene, the MgCl2(THF)2-supported catalysts affected much the copolymer properties like density, melting point and crystallinity.
Synthesis and characterization of poly(L,L-lactide)-b-polyethylene glycol) diblock copolymers as plasticizers and their effect on the hydrophilicity …
2011
"Click" on PLGA-PEG and hyaluronic acid: gaining access to anti-leishmanial pentamidine bioconjugates
2018
Pentamidine (Pent), an antiparasitic drug used for the treatment of visceral leishmaniasis, has been modified with terminal azide groups and conjugated to two different polymer backbones (PLGA-PEG [PP] copolymer and hyaluronic acid [HA]) armed with alkyne end-groups. The conjugation has been performed by Copper Catalyzed Azido Alkyne Cycloaddition (CuAAC) using CuSO4/sodium ascorbate as metal source. The novel PP-Pent and HA-Pent bioconjugates are proposed, respectively, as non-targeted and targeted drug delivery systems against Leishmania infections. Moreover, Pent has been encapsulated into PP nanoparticles by the oil-in-water emulsion method, with the aim to compare the biological activi…
Control of Morphology and Corona Composition in Aggregates of Mixtures of PS-b-PAA and PS-b-P4VP Diblock Copolymers: Effects of Solvent, Water Conten…
2014
The morphologies and corona compositions in aggregates of mixtures of PS-b-PAA and PS-b-P4VP diblock copolymers are influenced by controllable assembly parameters such as water content, block copolymer molar ratios, and solvent effects as well as the hydrophilic block lengths and block length ratios. All these factors can affect the morphology of the aggregates as well as their corona composition, the latter especially in vesicles, where two interfaces are involved. The morphologies and corona compositions of the aggregates were investigated by transmission electron microscopy and electrophoretic mobility, respectively. They depend, to a large extent, on the solubility of P4VP and PAA in th…
Control of Corona Composition and Morphology in Aggregates of Mixtures of PS-b-PAA and PS-b-P4VP Diblock Copolymers: Effects of pH and Block Length
2014
The corona compositions and morphologies in aggregates of mixtures of amphiphilic polystyrene-block-poly(acrylic acid) (PS-b-PAA) and polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers are influenced by controllable assembly parameters such as the hydrophilic block length and solution pH. The morphologies and corona compositions of the aggregates were investigated by transmission electron microscopy and electrophoretic mobility, respectively. When mineral acids or bases are present during aggregate formation, they can exert a strong influence on the corona composition. Morphology changes were also seen with changing pH, as well as changes in corona composition, specifica…
Spektrofotometryczna metoda oznaczania składu kopolimerów etylen/1-heksen
2000
Zmodyfikowano znaną z literatury spektrofotometryczną (FT-IR) metodę oznaczania składu kopolimerów etylenu z α-olefinami i wykorzystano ją do oznaczania składu kopolimerów etylenu z 1-heksenem o bardzo dużym ciężarze cząsteczkowym (~ 106) (tabela 1). Wyprowadzono zależność umożliwiającą obliczenie zawartości 1-heksenu w kopolimerach etylen/1-heksen na podstawie stosunku wartości absorbancji pasm ACH31379 / ACH21369 [równanie (8)] oznaczonych po separacji odpowiednich pasm analitycznych (rys. 7 i 8). Ustalono też, że absorbancji pasm z zakresu 722 cm-1 nie powinno się wykorzystywać w proponowanej metodzie ilościowej (tabela 1).
Studies of intermolecular heterogeneity distribution in ethylene/1-hexene copolymers using DSC method
2002
The investigation of the intermolecular composition distribution of an ethylene/1-hexene copolymers using DSC method has been carried out. The known methods: step crystallization (SC) and successive self-nucleation/annealing (SSA) have been adapted for this purpose, and particularly, the optimal condition of the process have been chosen to enable the best fractional crystallization of the copolymer. The method has been applied for fractionation of two ethylene/1-hexenecopolymers synthesized with supported vanadium and zirconocene catalysts and having similar concentrations of 1-hexene. Although metallocene catalysts are known from their more homogeneous structure of active sites in comparis…