The synthesis of poly(VDF-ter-TFMA-ter-HFP) terpolymers (where VDF, TFMA, and HFP stand for vinylidene fluoride, R-trifluoromethacrylic acid, and hexafluoropropylene, respectively) and their blends with silica filler for preparing original fluorocomposites are presented. First, the radical terpolymerization of VDF, TFMA, and HFP by iodine transfer polymerization without any surfactant was investigated in the presence of 1,6-diiodoperfluorohexane as the chain transfer agent. TFMA monomer was well incorporated, and the terpolymers were obtained in good yields (>65%). The microstructures of the produced terpolymers were characterized by 1 H and 19 F NMR spectroscopy to assess the amounts of each comonomer, the molecular weights, and the nature of the end groups of the copolymers. Molar percentages of VDF, TFMA, and HFP were in the 45-80, 12-53, and 1-8 ranges, respectively, whereas the molecular weights of the resulting terpolymers were ca. 5400-12 600 g 3 mol -1 . End groups were VDF-I only with a high amount of CH 2 CF 2 -I. Then, these poly(VDF-ter-TFMA-ter-HFP) terpolymers were involved in the preparation of the fluorinated polymers/silica nanocomposites by sol-gel reactions in the presence of tetraethoxysilane and silica nanoparticles under alkaline and acidic conditions, respectively. Interestingly, poly(VDF-ter-TFMA-ter-HFP) terpolymer/silica nanocomposites, which were prepared under alkaline conditions, showed exceptional thermal properties because they were found to exhibit almost no weight loss up to 800 °C.

Fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomer [R F -(DOBAA) n -R F ] in silica nanocomposite can exhibit a nonflammability, even after calcination at 800 1C, through the formation of ammonium hexafluorosilicate during nanocomposite reactions. In contrast, the lack of formation of ammonium hexafluorosilicate during the usual composite reactions affords a flammable behavior for the R F -(DOBAA) n -R F oligomer in silica nanocomposite. Ammonium hexafluorosilicate is formed as a result of the dehydrofluorination of amido protons [-C(¼O)NH-] in R F -(DOBAA) n -R F oligomer, with fluorine atoms in the oligomers catalyzed by both ammonia and silica nanoparticles in the composite reactions. In contrast, the lack of dehydrofluorination in the nanocomposite reaction under acidic conditions affords the usual flammable behavior for the oligomer.

We succeeded in observing the similar solid‐state NMR spectra (1H‐magic‐angle spinning NMR spectra) of fluoroalkyl end‐capped N‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide oligomer [RF‐(DOBAA)n‐RF]/silica gel nanocomposite before and even after calcinations at 800°C. This finding suggests that RF‐(DOBAA)n‐RF oligomer in RF‐(DOBAA)n‐RF/silica gel nanocomposite can afford a nonflammable characteristic to exhibit no weight loss behavior even at 800°C under atmospheric conditions. In addition, we had good oleo‐ and hydrophobic characteristics on the modified glass surface treated with RF‐(DOBAA)n‐RF/silica gel nanocomposite even after calcination at 800°C as well as those before calcinations. Especially, RF‐(DOBAA)n‐RF/silica gel nanocomposite‐encapsulated cetylpyridinium chloride (CPC) possessing no weight loss characteristic even at 800°C exhibited a clear UV–vis absorption band around 260 nm related to the presence of CPC before and even after calcinations at 800°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

A variety of fluoroalkyl end‐capped N‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide oligomer [RF‐(DOBAA)n‐ RF]/silica nanocomposites, in which the oligomer contents are 18–96%, were prepared by reactions of the corresponding fluorinated oligomer with tetraethoxysilane and silica nanoparticles under alkaline conditions. Each fluorinated oligomer/silica composite thus obtained is nanometer size‐controlled very fine particles (22–68 nm) possessing a good dispersibility and stability in a variety of solvents including water. Interestingly, the weight loss of RF‐(DOBAA)n‐RF/silica nanocomposites, in which the oligomer contents are 18–72%, were not observed at all even at 800°C, as well as the original silica nanoparticles, although the corresponding sub‐micrometer size‐controlled RF‐ (DOBAA)n‐RF/silica composites (particle size: 359 nm) decomposed completely at 800°C to afford the weight loss in proportion to the content of RF‐(DOBAA)n‐RF oligomer in composites. On the other hand, a slight weight loss of RF‐(DOBAA)n‐RF/silica nanocomposites, in which the oligomer contents are 75–94%, was observed at 800°C compared to that of the original silica nanoparticles. Copyright © 2008 John Wiley & Sons, Ltd.

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