Hybrid silica / polymer nanoparticles through emulsion polymerization

2000 ◽  
Vol 628 ◽  
Author(s):  
Elodie Bourgeat-Lami ◽  
Jose-Luiz Luna-Xavier ◽  
Alain Guyot
Keyword(s):  
Emulsion Polymerization ◽  
Silica Surface ◽  
Monomer Concentration ◽  
Polymer Nanoparticles ◽  
Polymer Encapsulation ◽  
Propyl Methacrylate ◽  
Hybrid Silica ◽  
Transmission Electron ◽  
Methacrylate Monomers ◽  
Positively Charged

ABSTRACTPolymer encapsulation of inorganic silica nanoparticles was performed through emulsion polymerization of styrene and methyl methacrylate monomers. Two different approaches are described. In a first one, the hydrophilic silica was modified by reacting the coupling agent, 3-trimethoxysilyl propyl methacrylate, which was involved further in propagation reactions. In a second approach, we used the 2–2'- azobis (2-amidinopropane) dihydrochloride cationic initiator to promote interactions of the positively charged growing polymer with the negatively charged silica surface. We demonstrate, using transmission electron microscopy, that the silica beads are successfully encapsulated by the two techniques giving silica/polymer nanoparticles with different morphologies. The influence of some parameters, such as the nature of the surfactant and the monomer concentration, on the efficiency of the encapsulation reaction and the morphology of the encapsulated products are reported.

scholarly journals Aggregation of Gold Nanoparticles in Presence of the Thermoresponsive Cationic Diblock Copolymer PNIPAAM48-b-PAMPTMA6

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4066
Author(s):  
David Herrera Robalino ◽  
María del Mar Durán del Amor ◽  
Carmen María Almagro Gómez ◽  
José Ginés Hernández Cifre
Keyword(s):  
Gold Nanoparticles ◽  
High Ionic Strength ◽  
Solution Temperature ◽  
Trimethylammonium Chloride ◽  
Aggregation Process ◽  
Critical Solution Temperature ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Copolymer Poly ◽  
Positively Charged

The adsorption of the thermoresponsive positively charged copolymer poly(N-isopropylacrylamide)-block-poly(3-acrylamidopropyl)trimethylammonium chloride, PNIPAAM48-b-PAMPTMA6(+), onto negatively charged gold nanoparticles can provide stability to the nanoparticles and make the emerging structure tunable by temperature. In this work, we characterize the nanocomposite formed by gold nanoparticles and copolymer chains and study the influence of the copolymer on the expected aggregation process that undergoes those nanoparticles at high ionic strength. We also determine the lower critical solution temperature (LCST) of the copolymer (around 42 °C) and evaluate the influence of the temperature on the nanocomposite. For those purposes, we use dynamic light scattering, UV-vis spectroscopy and transmission electron microscopy. At the working PNIPAAM48-b-PAMPTMA6(+) concentration, we observe the existence of copolymer structures that trap the gold nanoparticles and avoid the formation of nanoparticles aggregates. Finally, we discuss how these structures can be useful in catalysis and nanoparticles recovery.

scholarly journals Modification of Titanium Dioxide Nanoparticles with 3-(Trimethoxysilyl)propyl Methacrylate Silane Coupling Agent

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Thuy-Chinh Nguyen ◽  
Tien-Dung Nguyen ◽  
Duc-Toan Vu ◽  
Duc-Phuong Dinh ◽  
Anh-Hiep Nguyen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Tio2 Nanoparticles ◽  
Coupling Agent ◽  
Titanium Dioxide Nanoparticles ◽  
X Ray Diffraction ◽  
Nano Tio2 ◽  
Propyl Methacrylate ◽  
Transmission Electron ◽  
Before And After ◽  
Modification Of Titanium

This paper presents some characteristics, properties, and morphology of TiO2 nanoparticles (nano-TiO2) modified with various contents of 3-(trimethoxysilyl)propyl methacrylate (TMSPM) coupling agent. The treatment process was carried out in ethanol solvent at 50oC using ammonia as a catalyst for hydrolysis reaction of silane to silanol. Infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, ultraviolet-visible spectroscopy, and X-ray diffraction methods were used for determination of the characteristics, properties of nano-TiO2 before and after treatment. In addition, the contact angle and grafting efficiency of TMSPM on the surface of TiO2 nanoparticles was also evaluated. The obtained results confirmed that TMSPM was grafted to the TiO2 nanoparticles, the agglomeration of nano-TiO2 was decreased, and surface of TiO2 nanoparticles became hydrophobic after modification by TMSPM.

scholarly journals Adsorption studies and release of selected dyes from functionalized mesoporous MCM-41 silica

2014 ◽  
Vol 12 (2) ◽  
pp. 233-241 ◽  
Author(s):  
Dawid Lewandowski ◽  
Anna Olejnik ◽  
Grzegorz Schroeder
Keyword(s):  
Azo Dyes ◽  
Silica Surface ◽  
Dye Adsorption ◽  
Guest Molecules ◽  
Release Studies ◽  
Dissolution Apparatus ◽  
Adsorption And Release ◽  
Electrically Charged ◽  
Positively Charged ◽  
Mcm 41

AbstractFunctionalized mesoporous MCM-41 silica was subjected to adsorption and release studies of encapsulated guest molecules of three chosen dyes. These mesoporous systems were composed of three different capping reagents introduced by grafting method on the silica surface to control the release of dye molecules at two different pH values. The amounts of dyes adsorbed on the silica surface were measured using ultraviolet-visible (UV-VIS) spectrophotometry. The efficiency of grafting was calculated on the basis of differential thermal analysis (TG) results and elemental analysis. The release profiles were determined for all obtained systems using USP Dissolution Apparatus 2. Adsorption of the two azo dyes used was the most efficient after the positively charged functionalization and lower after functionalization with neutral and negatively charged capping reagents, while the phthalocyanine dye adsorption was almost functionalization-independent. Grafting efficiency was the highest for neutral capping reagent and much lower for electrically charged molecules of other reagents. Release studies showed clearly that desorption was pH-dependent for azo dyes and pH independent for Alcian Blue. The adsorption and release seem to be connected with the electrical charge of all constituents of these systems. Results obtained can be used for further analysis of different electrically charged molecules.

Comparing emulsion polymerization of methacrylate-monomers with different hydrophilicity

Polymer ◽  
2005 ◽  
Vol 46 (4) ◽  
pp. 1017-1023 ◽  
Author(s):  
A.M. Imroz Ali ◽  
Klaus Tauer ◽  
Milos Sedlak
Keyword(s):  
Emulsion Polymerization ◽  
Methacrylate Monomers

Copolymerization of two bromine containing methacrylate monomers with methylmethacrylate. Determination of reactivity ratios by in situ quantitative 1H NMR monitoring

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Ichim Ionut Cameliu ◽  
Marius Ciprian Rusu ◽  
Mihai Rusu ◽  
Popa Marcel ◽  
Christelle Delaite ◽  
...  
Keyword(s):  
Side Chain ◽  
Random Structure ◽  
Reactivity Ratios ◽  
Medical Implants ◽  
Propyl Methacrylate ◽  
H Nmr ◽  
Methacrylate Monomers ◽  
Methacrylic Monomers

AbstractAn important method used to make medical implants radiologically visible is based on introduction of radiopaque bromine or iodine containing methacrylic monomers. Thus, 2-(2-bromopropionyloxy) propyl methacrylate (BPPM) and 2-(2-bromoisobutyryloxy) propyl methacrylate (BIPM) were synthesized with the aim to use them as radiopaque agents. The free radical initiated copolymerization of BPPM and BIPM with methyl methacrylate (MMA) were performed directly in a thermostatic cell of the NMR spectrometer. The copolymer compositions obtained from 1H NMR spectra led to the determination of the reactivity ratios (rMMA = 1.08 ± 0.12; rBPPM = 1.01 ± 0.13 and rMMA = 0.95 ± 0.09; rBIPM = 0.95 ± 0.1). The reactivity ratios of these two monomers is similar to that of MMA suggesting that the length of the bromine containing monomers side chain does not affect significantly the reactivity of the methacrylic double bond. From the results we conclude the copolymers to have random structure.

scholarly journals Effect of Nanoparticles Surface Charge on the Arabidopsis thaliana (L.) Roots Development and Their Movement into the Root Cells and Protoplasts

2019 ◽  
Vol 20 (7) ◽  
pp. 1650 ◽  
Author(s):  
Anna Milewska-Hendel ◽  
Maciej Zubko ◽  
Danuta Stróż ◽  
Ewa Kurczyńska
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Surface Charge ◽  
Physical Barrier ◽  
Root Cells ◽  
Plant Body ◽  
Transmission Electron ◽  
A Cell ◽  
Living Organisms ◽  
Positively Charged

Increasing usage of gold nanoparticles (AuNPs) in different industrial areas inevitably leads to their release into the environment. Thus, living organisms, including plants, may be exposed to a direct contact with nanoparticles (NPs). Despite the growing amount of research on this topic, our knowledge about NPs uptake by plants and their influence on different developmental processes is still insufficient. The first physical barrier for NPs penetration to the plant body is a cell wall which protects cytoplasm from external factors and environmental stresses. The absence of a cell wall may facilitate the internalization of various particles including NPs. Our studies have shown that AuNPs, independently of their surface charge, did not cross the cell wall of Arabidopsis thaliana (L.) roots. However, the research carried out with using light and transmission electron microscope revealed that AuNPs with different surface charge caused diverse changes in the root’s histology and ultrastructure. Therefore, we verified whether this is only the wall which protects cells against particles penetration and for this purpose we used protoplasts culture. It has been shown that plasma membrane (PM) is not a barrier for positively charged (+) AuNPs and negatively charged (−) AuNPs, which passage to the cell.

scholarly journals Hydrolysis of Functional Monomers in a Single-bottle Self-etching Primer—Correlation of 13C NMR and TEM Findings

2006 ◽  
Vol 85 (5) ◽  
pp. 422-426 ◽  
Author(s):  
N. Nishiyama ◽  
F.R. Tay ◽  
K. Fujita ◽  
D.H. Pashley ◽  
K. Ikemura ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Null Hypothesis ◽  
Functional Monomers ◽  
Resin Infiltration ◽  
Transmission Electron ◽  
Human Dentin ◽  
Methacrylate Monomers ◽  
One Year ◽  
Hydrolysis Of ◽  
C Nmr

Self-etching primers/adhesives that combine acidic methacrylate monomers with water in a single bottle are hydrolytically unstable and require refrigeration to extend their shelf-lives. This study tested the null hypothesis that one year of intermittent refrigeration of a 4-MET-containing simplified self-etching primer does not result in hydrolytic changes that are identifiable by transmission electron microscopy and 13C NMR spectroscopy. Human dentin was bonded with UniFil Bond immediately after being unpacked, or after one year of intermittent refrigeration at 4°C. Fresh and aged primers were analyzed by NMR for chemical changes. Ultrastructural observations indicated that there was an augmentation in etching capacity of the aged adhesive that was not accompanied by resin infiltration or effective polymerization. New NMR peaks detected from the aged ethanol-based primer confirmed that degradation occurred initially via esterification with ethanol, followed by hydrolysis of both ester groups in the 4-MET. Hydrolysis of functional methacrylate monomers occurs despite intermittent refrigeration.

Assembly of Nanoparticles from Bioactive Peptides and Chitosan

2011 ◽  
Vol 1312 ◽  
Author(s):  
B. Hu ◽  
Q. R. Huang ◽  
X. X. Zeng
Keyword(s):  
Electrophoretic Mobility ◽  
Bioactive Peptides ◽  
Molecular Chain ◽  
Mass Ratio ◽  
Ph Values ◽  
Transmission Electron ◽  
Low Salt ◽  
Liquid Chromatography Tandem Mass ◽  
Positively Charged ◽  
Critical Ph

ABSTRACTAssembly of nanoparticles from bioactive peptides, caseinophosphopeptides (CPPs) and chitosan (CS) at physiological conditions and various CS/CPPs mass ratios have been systematically studied using a combination of turbidimetric titration, dynamic light scattering (DLS), electrophoretic mobility (zeta-potential) and transmission electron microscopy (TEM). Peptides, incorporated with CS forming nanoparticles, have already been prepared and identified using liquid chromatography-tandem mass spectrometry (LC-MS-MS). They are characteristic with different amount of clusters of phosphorylated seryl residues. At low salt concentration, an increase of CS/CPP mass ratio shifted the critical pHϕ1, which designated the formation of CS/CPP nanocomplexes, as well as pHmax, representing the neutralization of positive and negative charge to higher pH values. The peptide-polymer binding mechanism was analyzed according to the results of DLS, electrophoretic mobility, and TEM. First, negatively charged CPPs absorbed to positively charged CS molecular chain to form intrapolymer nanocomplexes saturated with CPPs (CPPNP). Then, the negatively charged CPPNP was bridged by added positively charged CS. Finally, novel nano-scaled spherical brushes were formed as additional CS molecule absorbed back to and bound the CPPNP. Phosphorylated groups in the CPPs might be the dominant sites for interaction with –NH3+ on the CS molecular chain.

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