Preparation of Novel Fluoroalkyl End-Capped Trimethoxyvinylsilane Oligomeric Nanoparticle-Encapsulated Binaphthol: Encapsulated Binaphthol Remaining Thermally Stable Even at 800 °C

Abstract

Novel cross-linked fluoroalkyl end-capped trimethoxyvinylsilane oligomeric nanoparticles [RF–(VM-SiO2)n–RF]-encapsulated 1,1′-bi(2-naphthol) (BINOL) were prepared by the hydrolysis of fluoroalkyl end-capped trimethoxyvinylsilane oligomer in the presence of BINOL under alkaline conditions. RF–(VM-SiO2)n–RF-encapsulated BINOL nanocomposite thus obtained afforded no weight loss corresponding to the presence of BINOL in the composite at 800 °C. Interestingly, RF–(VM-SiO2)n–RF/BINOL nanocomposite did not show absorption peaks before calcination however this nanocomposite was found to exhibit similar absorption and fluorescence peaks to those of the parent BINOL after calcination at 800 °C. More interestingly, RF–(VM-SiO2)n–RF/BINOL nanocomposite after calcination exhibited a releasing characteristic into methanol although before calcination this nanocomposite showed no such characteristic at all. In particular, FT-IR spectra of the released molecules showed typical bands related to both the parent BINOL and silica gel, indicating that the released guest molecules should be thermally stable even at 800 °C through the architecture of rigid BINOL-containing silica gel matrices.

Fluoroalkyl end-capped vinyltrimethoxysilane oligomer/anatase titanium oxide nanocomposites possessing photocatalytic activity even after calcination at 1000°C

“…Especially, the size of the composites after calcination except for Run 4 in Table 1 was found to be smaller than before calcination. This finding would be due to the flammable characteristic of R F -(VM) n -R F oligomer in TiO 2 nanocomposites after calcination, because it has been already reported that R F -(VM) n -R F oligomer can exhibit a flammable characteristic in silica gel matrices after calcination at 800°C [10].…”

Preparation and photocatalytic activity of fluoroalkyl end-capped vinyltrimethoxysilane oligomer/anatase titanium oxide nanocomposite-encapsulated low molecular weight aromatic compounds

“…R F -(VM-SiO 2 ) n -R F nanoparticles, which were prepared by the sol-gel reaction of R F -(VM) n -R F oligomer under alkaline conditions, markedly dropped around 420°C and decomposed gradually, reaching 63 % around 800°C, of whose weight loss corresponds to the flammable organic moieties in R F -(VM-SiO 2 ) n -R F nanoparticles (see Fig. 2) [23]. R F -(VM-SiO 2 ) n -R F /an-TiO 2 nanocomposites, which were prepared according to Scheme 1, afforded a clear weight loss (18 %) at 800°C, indicating that the contents of titanium oxide nanoparticles in the composites is estimated to be 45 %.…”

Preparation of ionic liquid/silica nanocomposites possessing no weight loss characteristic after calcination at 800 °C

“…Similarly, ammonium-type and imidazolium-type ionic liquids such as TEON-TFSI, TBMN-TFSI, and EMI-TFSI were able to afford no weight loss behavior toward the corresponding ionic liquid/SiO 2 nanocomposites even after calcinaton at 800°C. Previously, we reported that fluoroalkyl end-capped oligomers possessing amido protons or sulfo groups can suffer the sol-gel reactions with TEOS and silica nanoparticles in the presence of aqueous ammonia to afford the corresponding oligomer/ silica nanocomposites possessing no weight loss behavior even after calcination at 800°C [20][21][22][23][24][25][26][27][28]. Especially, these fluorinated oligomers can afford the smooth dehydrofluorination of amido protons or sulfonic acid protons with fluorines in oligomers catalyzed by ammonia and silica nanoparticles to afford ammonium hexafluorosilicate during the sol-gel process [20][21][22][23][24][25][26][27][28].…”

“…Previously, we reported that fluoroalkyl end-capped oligomers possessing amido protons or sulfo groups can suffer the sol-gel reactions with TEOS and silica nanoparticles in the presence of aqueous ammonia to afford the corresponding oligomer/ silica nanocomposites possessing no weight loss behavior even after calcination at 800°C [20][21][22][23][24][25][26][27][28]. Especially, these fluorinated oligomers can afford the smooth dehydrofluorination of amido protons or sulfonic acid protons with fluorines in oligomers catalyzed by ammonia and silica nanoparticles to afford ammonium hexafluorosilicate during the sol-gel process [20][21][22][23][24][25][26][27][28]. The surface of these smoothly encapsulated fluorinated oligomer into silica gel nanomatrices through the effective hydrogen bonding interactions between the amido protons or sulfonic acid protons in oligomers and fluorines in ammonium hexafluorosilicate could possess an extraordinarily high oxidation resistance to exhibit a nonflammable characteristic during the calcination process at 800°C [20][21][22][23][24][25][26][27][28].…”

“…Especially, these fluorinated oligomers can afford the smooth dehydrofluorination of amido protons or sulfonic acid protons with fluorines in oligomers catalyzed by ammonia and silica nanoparticles to afford ammonium hexafluorosilicate during the sol-gel process [20][21][22][23][24][25][26][27][28]. The surface of these smoothly encapsulated fluorinated oligomer into silica gel nanomatrices through the effective hydrogen bonding interactions between the amido protons or sulfonic acid protons in oligomers and fluorines in ammonium hexafluorosilicate could possess an extraordinarily high oxidation resistance to exhibit a nonflammable characteristic during the calcination process at 800°C [20][21][22][23][24][25][26][27][28]. Therefore, no weight loss behavior of these ammonium-and imidazolium-type ionic liquid/silica nanocomposites would be due to the formation of ammonium hexafluorosilicate, which could be obtained by the dehydrofluorination between ammonium protons or 1-ethyl-3-methylimidazolium protons with fluorines in the corresponding counter anions catalyzed by ammonia in the presence of silica nanoparticles as a co-catalyst during the sol-gel process.…”