Structure of Polyphenylsilsesquioxane Particles Prepared by Two-Step Acid-Base Catalyzed Sol–Gel Process and Formation of Hollow Particles

2007 ◽  
Vol 7 (9) ◽  
pp. 3307-3312 ◽  
Author(s):  
Kenji Takahashi ◽  
Kiyoharu Tadanaga ◽  
Akitoshi Hayashi ◽  
Atsunori Matsuda ◽  
Kiyofumi Katagiri ◽  
...  
Keyword(s):  
Sol Gel ◽  
Acid Base ◽  
Hollow Particles ◽  
Sol Gel Process

Preparation of SiO2 Antireflective Film by a Base/Acid Two-Step Catalyzed Sol-Gel Process

2013 ◽  
Vol 860-863 ◽  
pp. 845-848 ◽  
Author(s):  
De Yi Li ◽  
Kun Peng ◽  
Ling Ping Zhou ◽  
Jia Jun Zhu
Keyword(s):  
Raw Materials ◽  
Salt Spray ◽  
Sol Gel ◽  
Acid Base ◽  
Gel Method ◽  
Antireflective Film ◽  
Sol Gel Process ◽  
Acid Catalyzed ◽  
Antireflective Films ◽  
Silica Sols

SiO2 antireflective films were prepared by two-step catalyzed sol-gel method with TEOS as the raw materials, acid and ammonia as catalyst. Effects of the ratio of acid-catalyzed and base-catalyzed silica sols on the transmittance and stability of SiO2 film were investigated. The transmittance can be adjusted by change the ratio of base-catalyzed sols, and a higher transmittance can be obtained in the higher ratio of base-catalyzed coatings. A higher stability of SiO2 film in salt spray can be obtained in higher ratio of acid-catalyzed AR coatings. AR coatings with excellent transmittance and stability can be obtained by adjusting the ratio of acid/base catalyzed silica sols.

Thermoplastic and thermosetting properties of polyphenylsilsesquioxane particles prepared by two-step acid-base catalyzed sol-gel process

2007 ◽  
Vol 41 (3) ◽  
pp. 217-222 ◽  
Author(s):  
Kenji Takahashi ◽  
Kiyoharu Tadanaga ◽  
Atsunori Matsuda ◽  
Akitoshi Hayashi ◽  
Masahiro Tatsumisago
Keyword(s):  
Sol Gel ◽  
Acid Base ◽  
Sol Gel Process

Study on the Sol-Gel Process of TEOS by React-IR

2011 ◽  
Vol 110-116 ◽  
pp. 1401-1405 ◽  
Author(s):  
Hua Hua Zhou ◽  
Wei Xue ◽  
Fang Li ◽  
Yan Fei Qin
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Polymerization Rate ◽  
Condensation Polymerization ◽  
Acid Base ◽  
Nucleophilic Reaction ◽  
Sol Gel Process ◽  
Acidic Conditions ◽  
Adsorption Desorption ◽  
Meso Scale

Porous silica was prepared through TEOS sol-gel process catalyzed by acid-base joint catalyst, and the process was monitored by React IRTM. Based on the measurements, mechanism of TEOS hydrolyzation and succedent condensation polymerization was inferred. Under acidic conditions, H+ attacks –OR group of TEOS firstly, then the electronegative Cl- can attack Si4+ and make TEOS be hydrolyzed. When basic catalyst was added, the reaction will be accelerated. The promotion effect of base is attributed to the direct nucleophilic reaction mechanism and the smaller size of OH-, which can attack Si more easily. Thirdly, silanol, generated from TEOS hydrolyzation, attract Si-OR or other Si-OH around; thereby resulting rapid dehydration or de-alcohol reaction. So the condensation polymerization rate is elevated, and Si-O-Si bond comes into being. Lastly, cross-linking reaction among Si-O-Si bonds forms the particle like conglomeration. The porous silica was characterized by SEM and N2 adsorption-desorption technique. It was shown that the silica had large specific surface area, 818.5 m2/g, and relatively narrow distribution of pore size in meso-scale. Futhermore, the mesopores were nonuniform in shape and arrangement.

Glass transition and thermal softening of poly(phenylsilsesquioxane) particles prepared using two-step acid–base catalyzed sol–gel process

2008 ◽  
Vol 354 (2-9) ◽  
pp. 700-704 ◽  
Author(s):  
Kenji Takahashi ◽  
Kiyoharu Tadanaga ◽  
Akitoshi Hayashi ◽  
Atsunori Matsuda ◽  
Masahiro Tatsumisago
Keyword(s):  
Glass Transition ◽  
Sol Gel ◽  
Thermal Softening ◽  
Acid Base ◽  
Sol Gel Process

Preparation and Characterization of Polyaminophenylsilsesquioxane Particles by Two-step Acid–Base-catalyzed Sol–Gel Process

2007 ◽  
Vol 36 (2) ◽  
pp. 324-325 ◽  
Author(s):  
Kenji Takahashi ◽  
Kiyoharu Tadanaga ◽  
Akitoshi Hayashi ◽  
Masahiro Tatsumisago
Keyword(s):  
Sol Gel ◽  
Acid Base ◽  
Sol Gel Process

Effect of Different Reaction Solvents on the Hydrophobic and Structural Properties of Silica Cryogels

2010 ◽  
Vol 663-665 ◽  
pp. 1238-1241
Author(s):  
Li Fen Su ◽  
Lei Miao ◽  
Sakae Tanemura ◽  
Gang Xu
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Freeze Drying ◽  
Sol Gel ◽  
Base Catalysis ◽  
Molar Ratio ◽  
Nitrogen Absorption ◽  
Acid Base ◽  
Sol Gel Process

The experimental results on the microstructural and physical properties of the TEOS-based silica cryogels have been reported. The cryogels were produced by two-step sol-gel process followed by vacuum freeze drying. The wet gels were synthesized via acid-base catalysis using tetraethoxysilane (TEOS) as a silica precursor, the different solvents containing ethanol (EtOH), methanol (MeOH) and tert-butanol (TBA), the molar ratio of TEOS / solvent were varied from 1:6 to 1:13. Further, the microstructure and specific surface area of the cryogels were analysed by Scanning Electron Microscopy (SEM) and nitrogen absorption/desorption isotherms. The hydrophobicity of the cryogels was studied by contact angle. It was found that the highest specific surface area (1040.17 m2 / g) was obtained with the solvent of MeOH. The lowest density (0.074 g/cm3) was acquired with the solvent of EtOH.

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