Biocompatible hollow poly(methyl acrylic acid-co-N-isopropylacrylamide-co-ethyleneglycol dimethacrylate)@cellulose succinate (P(MAA-co-NIPAAM-co-EGDMA)@CS) microspheres have been synthesized by employing uniform silica-MPS microspheres as template. Silica spheres were synthesized via Stöber method involving tetraethyl orthosilicate. The surface of resulting silica Stöber microspheres was modified using 3-methacryloxypropyltrimethoxysilane (MPS), a polymerizable silane coupling agent. The above reagent introduces carbon–carbon double bonds on microspheres’ surface. This strategy uses the copolymerization of the following monomers, methacrylic acid (MAA), N-isopropyl acrylamide (NIPAAM) and the ethyleneglycol dimethacrylate (EGDMA), which was used as cross-linker, aiming at fabricating the first shell. Distillation precipitation polymerization method was carried out with 2,2-azobis(2-methylpropionitrile) as initiator in acetonitrile aiming at coating the inorganic microspheres with organic shell of the above-mentioned copolymer. In continuation, cellulose succinate and cellulose powder was absorbed through electrostatic interactions onto microspheres’ surface and the isolated product was cross-linked through esteric bonds formation. The cellulose succinate hollow microspheres were obtained after the silica core removal. The resulting spheres were characterized by Fourier transform infrared spectroscopy and observed by scanning and transmission electron microscopy. Dynamic light scattering was used to study the hydrodynamic diameter of the synthesized microspheres. The anticancer drug daunorubicin was loaded in the spheres, and its release behavior was evaluated at acidic and slightly basic pH conditions, aiming at evaluating its behavior at the healthy and pathogenic tissues. 相似文献
Monodisperse titania/polymer core-shell microspheres were prepared by a two-stage reaction with titania as core and poly(ethyleneglycol
dimethacrylate) (PEGDMA) as shell, in which the titania cores were synthesized by a sol-gel method and subsequently grafted
with 3-trimethoxysilyl methacrylate as the first-stage reaction to incorporate the vinyl groups on the surface of inorganic
core. The PEGDMA shell was then encapsulated over the MPS-modified titania core by distillation precipitation polymerization
of ethyleneglycol dimethacrylate in neat acetonitrile during the second-stage polymerization via capture of the radicals of
EGDMA with the aid of the reactive vinyl groups on the surface of inorganic core without any stabilizer or surfactant. The
shell thickness of the core-shell hybrid microspheres was controlled by the feed of EGDMA monomer during the polymerization.
The resultant titania particles and core-shell microspheres were studied by transmission electron microscopy, Fourier-transform
infrared spectra, X-ray photoelectron spectroscopy, and thermogravimetric analysis. 相似文献
Iron oxide (Fe3O4) magnetic nanoparticles as movable cores were used to synthesize yolk–shell nanoparticles with pH‐responsive shell composed of ethylene glycol dimethacrylate (EGDMA)‐crosslinked poly(acrylic acid) (PAA) via two different routes. In the first more common route, Fe3O4 nanoparticles were coated with silica layer via the Stöber process to yield Fe3O4@SiO2 core–shell nanoparticles, subsequently used as seeds in the distillation precipitation copolymerization of AA and EGDMA to yield Fe3O4@SiO2@P(AA‐EGDMA). The silica layer was selectively removed through alkali etching to yield Fe3O4@air@P(AA‐EGDMA). In the second route, Fe3O4 nanoparticles without any stabilization were used as seeds in the distillation precipitation copolymerization of AA and EGDMA to yield Fe3O4@P(AA‐EGDMA) core–shell nanoparticles. The nanoparticles were subsequently dispersed in acidic medium of pH = 2. Yolk–shell Fe3O4@air@P(AA‐EGDMA) nanoparticles were formed through deswelling of crosslinked PAA because of protonation of carboxyl groups at low pH values. Various techniques were utilized to investigate the characteristics of the synthesized core–shell nanoparticles. Formation of yolk–shell nanostructure was observed for both synthesis routes, namely etching of silica layer and deswelling approaches, from vibrating sample magnetometry and transmission electron microscopy results. Both types of nanoparticles showed pH‐responsive behaviour, i.e. decrease in absorption with increase in pH, as examined using UV–visible spectroscopy. 相似文献
Spherical and swellable gel beads were obtained by the suspension polymerization of poly(ethylene glycol) methacrylate macromonomer
(PEG-MA). The average size and size distribution properties, the equilibrium swelling behaviour and the protein adsorption
characteristics of PEG-MA-based gel beads were determined. In the suspension polymerization system, the organic phase including
monomer, cross-linker and diluent solution was dispersed in an aqueous medium by using poly(vinylpyrrolidone) as the stabilizer.
The diluent solution was prepared by mixing cyclohexanol and octanol at different volume ratios. The suspension polymerization
experiments were designed in two separate parts. In the first part, ethylene glycol dimethacrylate was selected as the cross-linker
and swellable PEG-MA-based gel beads were obtained by changing the cross-linker concentration, the monomer/diluent ratio and
the stirring rate. In the second part, a more hydrophobic structure, divinylbenzene (DVB) was tried as a cross-linker. In
this part, PEG-MA-DVB copolymer beads were obtained by changing the DVB/PEG-MA feed ratio. Then, the hydrophicility of the
resulting gel beads could be controlled by changing the feed ratio of hydrophilic macromonomer to hydrophobic cross-linker.
This property was also used to control the extent of nonspecific protein adsorption onto the surface of the gel beads. The
non specific albumin adsorption onto the gel beads decreased with increasing PEG-MA content. No significant nonspecific adsorption
at the isoelectric point of albumin was detected onto the gel beads produced with the higher PEG-MA/DVB feed ratios. For specific
albumin adsorption, a triazinyl dye (i.e., cibacron blue, CB F3G-A) was covalently attached onto the surface of the copolymer
beads via terminal hydroxyl groups of PEG-MA. The results of albumin adsorption experiments with the CB F3G-A carrying beads
indicated that an appreciable specific albumin adsorption capacity could be obtained with the gel beads produced with a PEG-MA/DVB
feed ratio of 1.5/4.0.
Received: 16 August 1999/Revised: 27 December 1999 相似文献
Daidzein-imprinted poly(methacrylamide-co-acrylic acid) composite membranes with different ratios of methacrylamide (MAM) versus acrylic acid (AA) were prepared via UV initiated photo-copolymerization on the commercial filter paper with ethylene glycol dimethacrylate (EGDMA) as cross-linker and mixed cellulose ester as agglutinant. Infra-red (IR) spectroscopy and scanning electron microscope (SEM) were used to visualize the surface of the membranes. Binding and recognising properties of the imprinted composite membranes to daidzein and its analogues genistein were evaluated by static adsorption experiment. It was found that the daidzein-imprinted membranes showed high selectivity to daidzein, with the highest selectivity when the composite membrane with the ratio of MAM vs AA as 4:1. The results suggested that the molecularly imprinted composite membranes were potentially useful for daidzein enrichment. 相似文献
Core–shell microparticles that consist of poly(vinyl neodecanoate) (VND) crosslinked with poly(ethylene glycol dimethacrylate) (EGDMA) as the core and poly(ethylene glycol methacrylate) (PEGMA) ( = 360 or = 526 g · mol?1) as the shell have been synthesized using suspension polymerization by a conventional free radical polymerization process. Interfacial tension and stability tests show that PEGMA acts as an amphiphilic macromonomer and is located on the oil/water interface of the suspension system, thus forming an outer layer during the polymerization. Kinetic studies of the monomers' conversion of VND, EGDMA, and PEGMA have been carried out using 1H NMR spectroscopy. EGDMA and PEGMA were found to have faster reaction rates compared to VND. Moreover, scanning electron microscopy showed that the polymerization of these particles starts from the shell and finishes towards the core. Consequently, the resulting microsphere is found to have a multi‐layer structure. Biotin was covalently bound to the surface by the PEGMA hydroxy groups. Conjugation of biotin with streptavidin PE (phycoerythrin) was subsequently carried out. Confocal microscopy was used to confirm the presence of fluorescing streptavidin. The amount of avidin conjugated to the microspheres was calculated by the release of a 2‐(4‐hydroxyphenylazo)benzoic acid/avidin complex using UV/vis spectroscopy. One avidin molecule was found to occupy 7 nm2 on the surface of the microspheres.
Abstract Polystyrene‐supported polyoxyethylene (PSPOE) bound permanganate with varying crosslinking agents have been prepared and used as a new class of recyclable oxidizing agents for low molecular weight alcohols and aldehydes. The effect of the nature of crosslinking agents on the oxidation reactions was studied in detail. The crosslinking agents used were ethyleneglycol dimethacrylate (EGDMA), 1,4‐butanediol dimethacrylate (BDDMA), and 1,6‐hexanediol diacrylate (HDODA). Polymer supports were synthesized by free radical suspension polymerization. Chloromethylation was done using the Friedel‐Crafts reaction. A cyclic polyether type compound was developed by the reaction of functionlized resin with polyethylene glycol (PEG600) and sodium. Polystyrene‐supported polyoxyethylene was equilibrated with potassium permanganate in benzene to give the oxidizing agent. The results reveal that the reactivity of HDODA‐crosslinked system shows higher reactivity than the BDDMA, and EGDMA‐crosslinked systems. This is due to higher flexibility of the HDODA‐crosslinked system compared to the BDDMA, and EGDMA‐crosslinked systems. The effect of solvent, temperature, and molar concentration of the reagent on oxidation were carried out using benzoin to benzil as the model reaction. For a less flexibile EGDMA‐crosslinked resin, tetrahydrofuran (THF) is the best solvent, for BDDMA‐crosslinked system dioxane and for the highly flexible HDODA‐crosslinked system CHCl3 is found to be best. In all cases, the reactivity of the reagent increased with an increase in temperature and molar excess of the reagent. 相似文献