Low molecular weight aromatic compounds possessing a nonflammable characteristic in fluoroalkyl end‐capped acrylic acid oligomer/silica nanocomposite matrices after calcination at 800 °C under atmospheric conditions

Fluoroalkyl end‐capped acrylic acid oligomer [R_F‐(ACA)_n‐R_F] reacted with tetraethoxysilane and silica nanoparticles in the presence of low molecular weight aromatic compounds [ Ar‐H ] such as cetylpyridinium chloride (CPC) and bisphenol AF under alkaline conditions to afford R_F‐(ACA)_n‐R_F/SiO₂ nanocomposites‐encapsulated Ar‐H in 47–94% isolated yields. These fluorinated silica nanocomposites‐encapsulated Ar‐H can exhibit no weight loss behavior corresponding to the contents of Ar‐H after calcination at 800 °C under atmospheric conditions, although fluoroalkyl end‐capped acrylic acid oligomer in the nanocomposites decomposed completely under similar conditions. UV‐vis spectra of well‐dispersed methanol solutions of R_F‐(ACA)_n‐R_F/SiO₂/CPC nanocomposites before calcination show that CPC can be encapsulated into fluorinated silica nanocomposites with encapsulated ratios: 23–43%. The fluorinated nanocomposites after calcination was found to exhibit a higher antibacterial activity related to the presence of CPC in the composites. Encapsulated bisphenol AF into R_F‐(ACA)_n‐R_F/SiO₂ nanocomposites before and after calcination at 800 °C can exhibit a good releasing ability toward methanol with released ratios: 48 and 26%, respectively. ¹H MAS NMR, HPLC analysis, and LC‐MS spectra of R_F‐(ACA)_n‐R_F/silica nanocomposites‐encapsulated bisphenol AF also showed the presence of bisphenol AF in the nanocomposites even after calcination at 800 °C under atmospheric conditions. These findings suggest that CPC and bisphenol AF can exhibit a nonflammable characteristic in the fluorinated silica nanocomposites. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Preparation and applications of novel fluoroalkyl end‐capped oligomers/polyimide/silica nanocomposites

Fluoroalkyl end‐capped acrylic acid, N,N‐dimethylacrylamide, N‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide and vinyltrimethoxysilane oligomers reacted with polyamic acid possessing trimethoxysilyl groups under alkaline conditions to yield the corresponding fluoroalkyl end‐capped oligomers/polyamic acid/silica nanocomposites. These isolated fluorinated composite powders were found to afford nanometer size‐controlled fine particles with a good dispersibility and stability in water and traditional organic solvents. We succeeded in preparing new fluoroalkyl end‐capped oligomers/polyimide/silica nanocomposites by the imidization of fluorinated polyamic acid silica nanocomposites through the stepwise heating at 110 and 270°C under air atmosphere conditions. These fluorinated polyimide/silica nanocomposites thus obtained were applied to the surface modification of glass and poly(methyl methacrylate) (PMMA) to exhibit good hydro‐ and oleo‐phobic characteristics imparted by fluoroalkyl groups in the composites on their surface. In addition, the surface morphology of the modified glass treated with these fluorinated nanocomposites were analyzed by using FE‐SEM and DFM. Copyright © 2011 John Wiley & Sons, Ltd.     

Preparation and thermal stability of fluoroalkyl end‐capped vinyltrimethoxysilane oligomeric silica/boric acid nanocomposites‐encapsulated a variety of low molecular weight organic compounds

Fluoroalkyl end‐capped vinyltrimethoxysilane oligomer [R_F‐(VM)_n‐R_F] reacted with boric acid to afford the corresponding fluorinated oligomeric silica/boric acid nanocomposite [R_F‐(VM? SiO₂)_n‐R_F/B(OH)₃] fine particles with mean diameter: 36–105 nm. The obtained R_F‐(VM? SiO₂)_n‐R_F/B(OH)₃ nanocomposites were applied to the encapsulation of low molecular weight organic compounds such as diphenylsilanediol, 1,1′‐bi‐2‐naphthol, 4,4′‐biphenol, bisphenol A, bisphenol F, bisphenol AF, biphenyl, dibenzyl, and pentaerythritol into these nanocomposite cores to provide the corresponding fluorinated oligomeric silica/boric acid nanocomposites—encapsulated these organic molecules. Interestingly, the obtained nanocomposites were found to exhibit no weight loss behavior corresponding to the contents of these guest molecules even after calcination at 800 °C, although these nanocomposites were isolated through no purification process. The R_F‐(VM? SiO₂)_n‐R_F nanocomposites—encapsulated these organic guest molecules were prepared under similar conditions. However, it was demonstrated that these nanocomposites can provide the clear weight loss corresponding to the contents of these guest molecules in the nanocomposites after calcination at 800 °C. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3835–3845     

UV resistance of encapsulated low molecular weight aromatic compounds in fluoroalkyl end‐capped trimethoxyvinylsilane oligomer/silica nanocomposites

Sol–gel reactions of fluoroalkyl end‐capped trimethoxyvinylsilane oligomer in the presence of low molecular weight aromatic compounds (ArH) such as 1,1′‐bi(2‐naphthol) (BINOL) and 2‐hydroxy‐4‐methoxy benzophenone (HMB) were found to proceed smoothly under alkaline conditions at room temperature to give the corresponding fluorinated oligomeric silica nanocomposites‐encapsulated aromatic compounds (BINOL and HMB) [R_F‐(VM‐SiO₂)_n‐R_F/ArH nanocomposites]. UV light irradiation (λ_max: 254 nm) toward R_F‐(VM‐SiO₂)_n‐R_F/ArH nanocomposites showed that photodegradation of encapsulated ArH was not observed at all in the fluorinated nanocomposites cores, although the parent ArH can exhibit an effective photodegradation behavior under similar conditions. Especially, encapsulated ArH can exhibit no weight loss corresponding to the contents of the aromatic compounds in the fluorinated nanocomposites even after calcination at 800°C. Therefore, fluoroalkyl end‐capped trimethoxyvinylsilane oligomer has high potential for not only the thermal resistance but also the UV resistance fluorinated polymeric materials. Copyright © 2014 John Wiley & Sons, Ltd.     

Preparation and applications of novel cross‐linked fluoroalkyl end‐capped oligomeric nanocomposites possessing aromatic siloxane segments as core units

Fluoroalkyl end‐capped N,N‐dimethylacrylamide oligomer and N‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide oligomer were reacted with phenylene‐ and biphenylene‐bridged ethoxysilanes under alkaline conditions to yield cross‐linked fluoroalkyl end‐capped oligomeric composites possessing aromatic siloxane segments as core units. These isolated fluorinated composite powders were found to be nanometer size‐controlled fine particles with a good dispersibility and stability in water and organic solvents. Nitrogen adsorption–desorption isotherms confirmed the presence of micropores in these nanocomposites; the micropore size estimated by the HK method was 0.7–0.8 nm. Interestingly, fluorinated nanocomposites possessing a higher micropore volume ratio were found to exhibit a selective encapsulation ability of fullerene into their composite cores. These fluorinated nanocomposites were also applied to the surface modification of poly(methyl methacrylate) film, resulting in a good oleophobicity imparted by fluorine on the surface. In addition, fluorescence emission was visibly observed only from the modified PMMA film surface treated with fluorinated nanocomposites possessing biphenylene units when irradiated by light. Copyright © 2009 John Wiley & Sons, Ltd.     

Fluoroalkyl end‐capped oligomers possessing nonflammable characteristic in calcium carbonate nanocomposites

Calcium chloride reacted with sodium carbonate in the presence of a variety of fluoroalkyl end‐capped oligomers such as fluoroalkyl end‐capped acrylic acid oligomer (R_F‐[ACA]_n‐R_F), 2‐methacryloyloxyethanesulfonic acid oligomer (R_F‐[MES]_n‐R_F), N,N‐dimethylacrylamide oligomer (R_F‐[DMAA]_n‐R_F) and acryloylmorpholine oligomer (R_F‐[ACMO]_n‐R_F) to afford the corresponding fluorinated oligomers/calcium carbonate composites. Each fluorinated oligomer/calcium carbonate composite thus obtained is nanometer size‐controlled very fine particles (25–114 nm) possessing a good dispersibility and stability in a variety of solvents including water. Thermal stability of these fluorinated calcium carbonate nanocomposites was studied by thermogravimetic analyses measurements. Fluorinated oligomes, in which the theoretical oligomer content in the composites is 19%, were able to give no weight loss corresponding to the content of oligomer in each case even after calcination at 800 °C. On the other hand, a slight weight loss corresponding to the contents of oligomers in the composites after calcination at 800 °C was observed in R_F‐(MES)_n‐R_F/, R_F‐(DMAA)_n‐R_F/ and R_F‐(ACMO)_n‐R_F/calcium carbonate nanocomposites, in which the theoretical contents of the oligomers were 36–53%, although R_F‐(ACA)_n‐R_F/calcium carbonate nanocomposites gave a clear weight loss corresponding to the contents of oligomer under similar conditions. Fluorinated oligomers/calcium carbonate nanocomposites possessing no weight loss at 800 °C were applied to the surface modification of poly(methyl methacrylate) (PMMA) to exhibit a good oleophobicity imparted by fluorines on the surfaces. Interestingly, these fluorinated calcium carbonate nanocomposites after calcination at 800 °C were found to exhibit the similar oleophobic characteristic on the modified PMMA surfaces as well as that of the nanocomposites before calcination. Copyright © 2013 John Wiley & Sons, Ltd.     

Preparation of colloidal stable fluoroalkyl end‐capped oligomer/silver nanocomposites––application to the surface modification of traditional organic polymers with these nanocomposites

A variety of fluoroalkyl end‐capped oligomers/silver nanocomposites were prepared by the reactions of silver ions with poly(methylhydrosiloxane) in the presence of fluoroalkyl end‐capped N,N‐dimethylacrylamide oligomer, N‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide oligomer, N,N‐dimethylacrylamide cooligomer containing poly(dimethylsiloxane) segments in organic media such as toluene and 1,2‐ dichloroethane. These fluorinated oligomers/silver nanocomposites thus obtained were found to exhibit clear plasmon absorption bands around 420 nm related to the formation of silver nanoparticles. In particular, these composites could display narrow plasmon absorptions around 420 nm in toluene by the addition of trioctylamine (TOA). On the other hand, the corresponding non‐fluorinated N‐(1,1‐ dimethyl‐3‐oxobutyl)acrylamide oligomer was not able to afford such a plasmon absorption under similar conditions. These fluorinated oligomers/silver nanocomposites in organic media have been found to be stable for more than 10 days. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements showed that silver nanoparticles could be effectively encapsulated into fluorinated oligomeric aggregate cores to afford colloidal stable fluorinated oligomers/silver nanocomposites. Fluorinated oligomers/silver nanocomposites were also applied to the surface modification of traditional organic polymers such as polystyrene (PSt) and poly(methyl methacrylate) (PMMA) to exhibit not only a good oleophobicity imparted by fluorine but also a higher surface antibacterial activity related to the silver nanoparticles on their surface. Copyright © 2007 John Wiley & Sons, Ltd.     

A fluoroalkyl end-capped <Emphasis Type="Italic">N</Emphasis>-(1,1-dimethyl-3-oxobutyl)acrylamide oligomer/silica gel nanocomposite with no weight loss even at 800 °C equal to an original silica gel

Fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomer [R_F-(DOBAA)_n-R_F]/silica gel nanocomposite, which was prepared by reaction of the corresponding fluorinated oligomer with tetraethoxysilane and silica gel nanoparticles under alkaline conditions, exhibited no weight loss even at 800 °C equal to the original silica gel, although the corresponding parent R_F-(DOBAA)_n-R_F oligomer was completely degraded at 600 °C. Thermogravimetric analyses/mass spectra of fluorinated nanocomposite showed that this nanocomposite decomposed around 280 °C to afford CO₂ and H₂O as the major evolved gaseous products including some minor fluoro- and hydrocarbons. X-ray photoelectron spectroscopy analyses also showed that the contents of C, F, and Si atoms in R_F-(DOBAA)_n-R_F/SiO₂ nanocomposite after the calcination at 800 °C were similar to those before the calcination. These findings suggest that the evolved gaseous products should be encapsulated quantitatively into nanometer-size-controlled silica matrices to give the fluorinated silica gel nanocomposite with no weight loss even at 800 °C equal to the original silica gel.