Lucia Pricop

Synthesis of polysulfone block copolymers containing polydimethylsiloxane

The synthesis of polysulfone-polydimethylsiloxane (PSU-PDMS)linear block copolymers has been carried out in solution by condensation of chloro-terminated bisphenol A, diphenylsulfone and α, ω-di (hydrogensilyl)-polydimethylsiloxane with Si−C bond. 1H-NMR spectra of the block copolymers allow the estimation of siloxane and polysulfone ratio. The molecular weight of the polysulfone and polysiloxane oligomers and the block copolymers was determined by GPC. Thermogravimetric analysis indicates a thermal stability of block copolymers up to 400°C and allows estimation of the process activation energy. Microphase separation of the block copolymers was observed by differential scanning calorimetry (DSC).

Graft Copolymers Polydimethylsiloxane–Polyethyleneoxide. Synthesis and Characterization

A series of polydimethylsiloxane–polyethyleneoxide graft copolymers were obtained by hydrosilylation reactions of the α-allyl,ω-acetate-polyethyleneoxide with polysiloxane copolymers containing Si–H groups. The structures and the properties of these copolymers were determinated by 1HNMR, 13C NMR and IR spectra, gel permeation chromatography, viscosity measurements, differential scanning calorimetry, transmission electron microscopy and surface tension measurements.

Reaction Conditions Study in Linear H-Functional Polysiloxane Synthesis

Abstract A reaction conditions study in the synthesis of methyl-hydropolysiloxanes was proposed taking into account the variation of some parameters, such as conversion, amount of active hydrogen, intrinsic viscosity, molecular weight versus the reaction time, amount of catalyst and reaction temperature. Methylhydropolysiloxanes were obtained using a bulk heterogeneous polymerization-equilibration reaction of octamethyl-cyclotetrasiloxane (D4), linear methylhydrosiloxane (L-31) and hexamethyl-disiloxane (HMDS), in the presence of styrene-divinylbenzene sulfonic acid copolymer (VIONI-CS-34C) as catalyst.

POLYDIMETHYLSILOXANE-POLYALKYLENEOXIDE BLOCK COPOLYMERS

The synthesis of polydimethylsiloxane-polyalkyleneoxide block copolymers has been carried out in solution by hydrosilylation reaction of preformed α,ω-bis(dimethylhydrosilyl) polydimethylsiloxane (HcPDMS) oligomers to allyl end-capped polyalkyleneoxide (PAO), in the presence of Pt catalyst. The were characterized by IR, 1H-NMR, 13C-NMR spectrometry, and gel permeation chromatography. The thermal stability was determined by thermogravimetric analysis.

Synthesis and micellization of polydimethylsiloxane– carboxy-terminated poly(ethylene oxide) graft copolymer in aqueous and organic media and its application for the synthesis of core-shell magnetite particles

Abstract An amphiphilic graft copolymer having an average of 7-8 carboxyesterterminated poly(ethylene oxide) grafted sequences on each polydimethylsiloxane main chain was obtained by a multistep procedure. Through fluorescence, surface tension and laser diffractometry methods the graft copolymer was proved to undergo micellization in aqueous media. In water, the critical micellization concentrations (CMC) are dependent on pH. Two CMC values were established for pH = 4, i.e. CMC1 = 1.01 g/L and CMC2 = 1.73 g/L corresponding to the transition from single chain to multiple chain micelles and to intermicellar aggregation, respectively. Between CMC1 and CMC2, the dimensions of micelles increased from 18 nm to 46 nm. The graft copolymer was proved to efficiently act as surfactant in the preparation of magnetite particles with a hydrophobic siloxane shell.

Glycidoxypropylsilane-functionalized Magnetite as Precursor for Polymer-covered Core-shell Magnetic Particles

Surface-functionalized core-shell magnetic particles were obtained by reacting the hydroxyl groups on the surface of pre-prepared magnetite particles with 3-glycidoxypropyltrimethoxysilane. Fourier transform infrared spectra indicated that epoxy silane molecules were chemically bound onto the surface of magnetite particles through Fe—O—Si linkages. As proved by atomic force microscopy and environmental scanning microscopy combined with energy dispersive X-ray spectroscopy, particles with average core diameter and shell width of about 700 and 70 nm, respectively, were obtained. The covered magnetite particles showed a lower saturation magnetization (46 emu g 1) as compared to the uncoated magnetite (64 emu g 1).

Piperazinyl-Modified Polysiloxanes and their Cu (II) Complexes

The paper deals with the synthesis and physico-chemical characterization of polydimethylsiloxanes modified with piperazinyl ligand groups and of their Cu(II) complexes. 1H NMR, Fourier transform infrared, UV-VIS and electron spin resonance spectroscopy were used to follow the structure of the coordination compounds. Three different types of copper bonding to the macromolecular ligand were identified. An uniform distribution of Cu(II) cations into the polymeric material was evidenced by an environmental scanning electron microscopy/microanalysis by energy dispersive spectrometry combined method.

Polysulfone-Polydimethylsiloxane Block Copolymers Containing Si-O-C Bonds

ABSTRACT Polysulfone-polydimethylsiloxane block copolymers containing Si-O-C bonds were synthesized through the condensation reactions of α,ω-di(hydrogensilyl)polydimethylsiloxane and α,ω-di(chlorosilyl) polydimethylsiloxane oligomers with hydroxy-terminated poly-sulfone, in solution. The synthesized compounds were characterized using IR, 1H-NMR and 13C-NMR spectrometry, GPC and DSC analysis. All data agree with the proposed structures.

Improved Physico-chemical Properties of Mesoporous Carbon by Functionalization with Aminopropyl-polydimethylsiloxane (AP-PDMS)

The present research reports on the synthesis and properties of mesoporous carbon (MC) surface with functionalized aminopropyl-polydimethylsiloxane (AP-PDMS). The aim of MC surface modification was focused on the improvement of its electrical properties (EC electric conductivity), as well as its sorption capacity for cesium ions. In order to anchor AP-PDMS molecules, an intermediate functionalization step of the MC surface with carboxylic groups was carried out. In this respect, two different methods, namely: (i) sonication in the presence of the hydrogen peroxide (MC-COOH) and (ii) gas-plasma activation (MCA) have been considered for carbon surface oxidation. Further, AP-PDMS component was crosslinked to the COOH-reached carbon surface. Fourier transform infrared spectroscopy (FT-IR) and energy dispersion spectroscopy (EDX) were used to confirm the presence of AP-PDMS molecules on MC surface. Morphological and textural properties of the obtained composites have been investigated by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption–desorption measurements, as well as their electrical properties (EC). The obtained results reveal the grafting of silane-containing component onto MC surface, an improved electrical conductivity of the synthesized composites toward MC sample. Also, the functionalization proved to be efficient in the sorption process of the cesium ions from aqueous solutions, despite the fact that the materials surface became hydrophobic.