Preparation of Organized Mesoporous Silica from Sodium Metasilicate Solutions in Alkaline Medium Using Nonionic Surfactants

2003 ◽  
Vol 68 (10) ◽  
pp. 2019-2031 ◽  
Author(s):  
Markéta Zukalová ◽  
Jiří Rathouský ◽  
Arnošt Zukal
Keyword(s):  
Mesoporous Silica ◽  
Ethylene Oxide ◽  
Sodium Metasilicate ◽  
Spherical Particles ◽  
Structure Directing Agent ◽  
Inorganic Species ◽  
Poly Ethylene Oxide ◽  
Acidic Conditions ◽  
Poly Ethylene ◽  
Hydrolysis Of

A new procedure has been developed, which is based on homogeneous precipitation of organized mesoporous silica from an aqueous solution of sodium metasilicate and a nonionic poly(ethylene oxide) surfactant serving as a structure-directing agent. The decrease in pH, which induces the polycondensation of silica, is achieved by hydrolysis of ethyl acetate. Owing to the complexation of Na+ cations by poly(ethylene oxide) segments, assembling of the mesostructure appears to occur under electrostatic control by the S0Na+I- pathway, where S0 and I- are surfactant and inorganic species, respectively. As the complexation of Na+ cations causes extended conformation of poly(ethylene oxide) segments, the pore size and pore volume of organized mesoporous silica increase in comparison with materials prepared under neutral or acidic conditions. The assembling of particles can be fully separated from their solidification, which results in the formation of highly regular spherical particles of mesoporous silica.

scholarly journals Poly(ethylene oxide)-b-poly(l-lactide) Diblock Copolymer/Carbon Nanotube-Based Nanocomposites: LiCl as Supramolecular Structure-Directing Agent

2011 ◽  
Vol 12 (11) ◽  
pp. 4086-4094 ◽  
Author(s):  
Franck Meyer ◽  
Jean-Marie Raquez ◽  
Pierre Verge ◽  
Inger Martínez de Arenaza ◽  
Borja Coto ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Ethylene Oxide ◽  
Diblock Copolymer ◽  
Supramolecular Structure ◽  
Structure Directing Agent ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

scholarly journals Multicompartmental Mesoporous Silica/Polymer Nanostructured Hybrids: Design Capabilities by Integrating Linear and Star-Shaped Block Copolymers

Polymers ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 51
Author(s):  
Zacharoula Iatridi ◽  
Kyriaki Evangelatou ◽  
Nikolaos Theodorakis ◽  
Athina Angelopoulou ◽  
Konstantinos Avgoustakis ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Ethylene Oxide ◽  
Chemical Species ◽  
Multiple Drug ◽  
Layer By Layer ◽  
Hydrophobic Chemical ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Theranostic Applications ◽  
Multiple Drug Delivery

Poly(2-vinyl pyridine)-b-poly(ethylene oxide) (P2VP-b-PEO) linear diblock copolymer and polystyrene–poly(ethylene oxide) (PS10PEO10) heteroarm star copolymer were used as building elements to prepare organic–inorganic hybrids. By using the layer-by-layer (LbL) methodology, these elements were integrated on mesoporous silica through non-covalent interactions, namely, ionic and H-bonding. For the latter, tannic acid (TA) was used as an intermediate layer. The deposition of the various layers was monitored by thermogravimetric analysis (TGA), electrophoretic measurements, and confocal microscopy. The final silica hybrid, bearing alternating P2VP-b-PEO and PS10PEO10 star layers was capable of carrying one hydrophilic and two hydrophobic chemical species in distinct compartments. These multicompartmental organic–inorganic hybrids could be used as nanostructured carriers for pH-responsive multiple drug delivery and potential theranostic applications.

scholarly journals BEHAVIOR OF ACID HYDROLYSIS IN BLOCK COPOLYMERS COMPRISING POLYACRYLAMIDE AND POLY(ETHYLENE OXIDE)

2018 ◽  
pp. 60-63
Author(s):  
L. Kunitskaya ◽  
T. Zheltonozhskaya
Keyword(s):  
Drug Delivery ◽  
Block Copolymers ◽  
Ethylene Oxide ◽  
Acid Hydrolysis ◽  
Diblock Copolymers ◽  
Successful Implementation ◽  
Intracellular Space ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Hydrolysis Of

Polymeric micelles self-assembled from amphiphilic block copolymers have been intensively investigated as nano-carrier systems for tumor-targeted drug delivery. Diblock copolymers PEO-b-PAAm (DBC) and thriblock copolymers PAAm-b-PEO-b-PAAm (TBC) contained biocompatible chemically complementary polyacrylamide and poly(ethylene oxide) formed micellar structures in aqueous solutions which have hydrophobic complex “core” formed by the hydrogen-bonded PEO/PAAm chains and hydrophilic “corona” of the surplus segments of PAAm blocks. The ability of DBCs and TBCs to bind the anticancer drug doxorubicin was established. This opened the new prospects for using such copolymers as nanocontainers for toxic and poorly soluble drugs. Successful implementation of DBC and TBC micelles for drug delivery requires the presence a special vectors, particularly galactose, in the micellar “corona”. Such vectors can recognize corresponding receptors on a cellular surface, interact with them, and penetrate into the intracellular space by the endocytosis pathway. In order to introduce the galactose vectors into DBC or TBC micelles, the corona forming PAA blocks have to contain the corresponding active groups, such as –OH, –COO–, –NH2. Therefore, the methods of DBCs (TBCs) functionalization are particularly important since it allows to input the necessary saccharides and also to expand the applications of micellar nanocarriers to encapsulate and delivery of both the drug substances and genetic materials. In the present work, the polymer-analogous conversion of DBCs and TBCs by the acid hydrolysis of PAAm blocks at 50°C was studied. Kinetic investigations of the hydrolysis reaction of DBCs (TBCs) in comparison with pure PAAm were performed by potentiometric titration. It was established that the process of acid hydrolysis of diblock- and thriblock copolymers depends on the blocks length and occurs more intensive in the block copolymers which have longest PEO and PAA chains. The reasons for this phenomenon are discussed. The fact is that hydrolysis of DBCs samples develops efficiently in comparison with TBCs ones attributed to the steric obstacles which appears in TBCs micelles because of their more complicated structure.

Sol-gel synthesis of silica–based mesoporous powders

2004 ◽  
Vol 848 ◽  
Author(s):  
Lidia Armelao ◽  
Gregorio Bottaro ◽  
Renzo Campostrini ◽  
Stefano Gialanella ◽  
Marco Ischia ◽  
...  
Keyword(s):  
Sol Gel ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Structure Directing Agent ◽  
Template Removal ◽  
Guest Species ◽  
Poly Ethylene Oxide ◽  
Acidic Conditions ◽  
Poly Ethylene ◽  
Sol Gel Synthesis

ABSTRACTMesoporous silica powders have been synthesized starting from aqueous solutions of Si(OCH2CH3)4 (TEOS) under acidic conditions, using non-ionic alkyl poly(ethylene oxide) oligomer (Brij76) as a structure-directing agent. Template removal was performed by thermal treatment in air as well as by ethanol extraction. The annealing process (400 - 600°C) resulted in more efficient elimination of the organic molecules, thus yielding hexagonal (p6mm) mesopor-ous materials with pore volume and specific surface area ranging between 0.58 – 0.41 cm3/g and 900 – 700 m2/g, respectively. The systems were characterized by X-Ray Diffraction (XRD), N2 BET adsorption, Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Particular attention was focused on the evolution of the system mesostructural and porous features as a function of the template removal procedure. The obtained mesoporous networks are suitable as matrices for the development of nanocomposite systems in which the dispersion or the growth of various guest species (clusters, molecules…) can be addressed into the host mesopores.

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