China 
Africa 
Explore chapters and articles related to this topic
Rubber–Silica Hybrid Nanocomposites
Published in Anil K. Bhowmick, Current Topics in ELASTOMERS RESEARCH, 2008
Abhijit Bandyopadhyay, Anil K. Bhowmick
Where M is a silicon or transition metal and R is an alkyl group. From the reactions shown in Scheme 3.1, it is obvious that metal alkoxide is first hydrolyzed in the presence of water and then the product in the hydrolysis reaction condenses to produce metal oxide. Water and alcohol are the two by-products of the sol–gel reaction. Silicon alkoxide (e.g., tetraethoxysilane (TEOS)) [10] is the most commonly used metal alkoxide due to its mild reaction condition. Various routes are used to prepare polymer–inorganic hybrids using sol–gel process. These are solution method, soaking method, in situ polymerization, and simultaneous sol–gel reaction method, and the multistep method of formation of functionalized cluster of metal oxide and its subsequent polymerization with monomers. The degree of molecular association of the metal alkoxide (oligomerization) has a significant influence on the sol–gel reaction and hence on the resultant morphology and properties. The nature and size of the ligand and the central metal atom can also dictate the reaction rate. For example, with the same tetraethoxy ligand (OC2H5)4, the degree of association follows the order thorium > hafnium > zirconium > titanium > silicon [11].
Glass Nanospheres and Artificial Opals
Published in Giancarlo C. Righini, Glass Micro- and Nanospheres, 2019
A. Chiappini, C. Armellini, A. Carpentiero, L. Pasquardini, A. Vaccari, S. Pelli, V. Piccolo, A. Lukowiak, G. C. Righini, R. Ramponi, D. Zonta, M. Ferrari
The best-known method to synthesize monodisperse SiO2 spheres was originally developed by Stöber et al. [20] and relies on the hydrolysis (1) of a silicon alkoxide and successive condensation (2) of alcohol and water to form siloxane groups: Si(OC2H5)4 + 4H2O → Si(OH)4 + 4C2H5OHSi(OH)4 → SiO2 + 2H2O
Adsorption on Silica and Active Carbon
Published in Rolando M.A. Roque-Malherbe, Adsorption and Diffusion in Nanoporous Materials, 2018
Moreover, an alternative method for the synthesis of amorphous silica comprise the reaction of alkoxides with water, provided, in this case, silicic acid is initially generated by the hydrolysis of a silicon alkoxide, formally a silicic acid ether. Then the silicic acids produced can experience self-condensation or condensation with the alkoxide [3]. Consequently, the global reaction continues as a condensation polymerization to form high molecular weight polysilicates that connects to generate a network whose pores are filled with solvent molecules, that is, a gel is formed [9,33,34].
Fabrication of gold-immobilized quantum dots/silica core–shell nanoparticles and their multimodal imaging properties
Published in Particulate Science and Technology, 2022
M. Tayama, T. Inose, N. Yamauchi, K. Nakashima, M. Tokunaga, C. Kato, K. Gonda, Y. Kobayashi
The toxicity of particles should be reduced, and the dispersion of the particles can be enhanced by coating them with silica shells, a representative chemically stable and harmless material (Bagheri et al. 2018; Chen et al. 2018). Silica particles can be fabricated easily by a sol-gel method, and silicon alkoxide is often used as a silica source. Several researchers have extended the sol-gel process using silicon alkoxide to coat QDs, i.e., the synthesis of core–shell particles comprising QD as a core and silica as a shell (QD/SiO2) (Ma, Li, and Zhong 2014; Oliveira et al. 2019; Elzorkany et al. 2019). Our research group has developed the synthesis route for QD/SiO2 particles by the sol-gel process (Kobayashi et al. 2010a, 2010b, 2012, 2013a, 2015a), and evaluated the in vitro and in vivo fluorescence imaging ability of the QD/SiO2 colloidal solution (Kobayashi et al. 2013a, 2015a).
A review on multifunctional nanotechnological aspects in modern textile
Published in The Journal of The Textile Institute, 2022
Prashant D. Sarvalkar, Shubham D. Barawkar, Omkar S. Karvekar, Pandurang D. Patil, Saurabh R. Prasad, Kiran Kumar Sharma, Neeraj R. Prasad, Rajiv S. Vhatkar
Silica sol is produced by hydrolysing silicon alkoxide (Si(OR)4). The OH- group reacts with the silicone alkoxide precursor (Si(OR)4), removing the alkoxide group and forming silanol as a consequence. The H+ ion reacts with the alkoxide group, resulting in the production of alcohol as a by-product. The rate of reaction is accelerated in an acidic environment. As illustrated in the following reactions (Figure 2a), each monomer of Methyl tri-methoxy silane (MTMS) has one non-hydrolysable Si – CH3 group (this group imparts the material superhydrophobic properties due to the presence of the methane (-CH3) group) (Rao et al., 2003; Venkateswara Rao et al., 2006, 2009).