Fluoroalkyl End-capped Oligomer Research Articles

Preparation and applications of novel fluoroalkyl end-capped oligomers/calcium carbonate nanocomposites

Calcium chloride reacted with sodium carbonate in the presence of a variety of self-assembled molecular aggregates formed by fluoroalkyl end-capped acrylic acid, 2-methacryloyloxyethane sulfonic acid, dimethylacrylamide, and acryloylmorpholine oligomers in aqueous solutions to afford the corresponding fluorinated oligomers/calcium carbonate composites in excellent to moderate isolated yields. These fluorinated calcium carbonate composites thus obtained were shown to have a good dispersibility not only in water but also in traditional organic media including fluorinated solvents. Dynamic light scattering measurements (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that these fluorinated composites are nanometer-size-controlled particles and well dispersed in these media. Cross-linked fluoroalkyl end-capped acrylic acid co-oligomer containing poly(oxyethylene) units was also applied to the preparation of new cross-linked fluorinated calcium carbonate nanocomposites under similar conditions. The obtained cross-linked fluorinated calcium carbonate nanocomposites were found to have an extremely higher dispersibility in aqueous and organic media including fluorinated solvents, compared to that of the corresponding fluoroalkyl end-capped oligomer nanocomposites. In particular, it was verified that these fluorinated calcium carbonate nanocomposites are applicable to the dispersion above poly(methyl methacrylate) (PMMA) film surface. Interestingly, field-emission SEM (FE-SEM) images of the cross-section of the modified PMMA films showed that calcium carbonate particles dispersed into these PMMA films could be arranged regularly above the modified film surface. More interestingly, cross-linked fluorinated oligomeric aggregates were able to provide suitable host moieties for the crystallization of calcium carbonate.

Preparation and applications of novel fluoroalkyl end-capped sulfonic acid oligomers–silica gel polymer hybrids

Fluoroalkyl end-capped 2-methacryloxyethanesulfonic acid homo-oligomer [RF–(MES)n–RF] and 2-methacryloxyethanesulfonic acid–N,N-dimethylacrylamide co-oligomers [RF–(MES)x–(DMAA)y–RF] reacted with tetraethoxysilane (TEOS) under acidic conditions to afford RF–(MES)n–RF homo-oligomer–SiO2 polymer hybrid and RF–(MES)x–(DMAA)y–RF co-oligomer–SiO2 polymer hybrid, respectively. Thermogravimetric–mass spectra showed that the thermal stability of RF–(MES)n–RF homo-oligomer–SiO2 polymer hybrid was superior to that of traditionally well-known perfluorinated ion exchange polymers such as Nafion 112 (TR). The sol solutions of the fluorinated co-oligomer–SiO2 polymer hybrid were applied to the surface modification of glass to exhibit not only a strong oleophobicity imparted by fluorine but also a good hydrophilicity on the glass surface. On the other hand, RF–(MES)x–(DMAA)y–RF co-oligomer reacted with TEOS in the presence of a variety of silica nanoparticles (mean diameters: 11–95 nm) under alkaline conditions to afford fluoroalkyl end-capped oligomers–silica nanoparticles (mean diameters: 32–173 nm) with a good dispersibility and stability in methanol. Similarly, a variety of fluorinated oligomers containing sulfo groups–silica nanoparticles were prepared by the homo- and co-oligomerizations of fluoroalkanoyl peroxides with 2-methacryloxyethane sulfonic acid (MES) and comonomers such as N,N-dimethylacrylamide (DMAA) and acryloylmorpholine (ACMO) in the presence of silica nanoparticles. Interestingly, these isolated fluorinated particle powders were found to afford nanometer size-controlled colloidal particles with a good redispersibility and stability in aqueous and organic media such as methanol. These fluorinated nanoparticles containing sulfo groups were also applied to an excellent heterogeneous catalyst for Bronsted acid-catalyzed transformations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 110–117, 2007

Preparation of novel fluoroalkyl end-capped oligomers/silica hybrid nanoparticles-encapsulation of a variety of guest molecules into fluorinated nanoparticles

Fluoroalkyl end-capped oligomers reacted with tetraethoxysilane and silica/nanoparticles under alkaline conditions to afford fluoroalkyl end-capped oligomers/silica nanoparticles (mean diameters: 31–54 nm) with a good dispersibility and stability in organic media. Interestingly, the isolated fluorinated particle powders were found to afford nanometer size-controlled colloidal particles with a good redispersibility and stability in these media. In addition, fluoroalkyl end-capped oligomers/silica nanoparticles-encapsulated guest molecules such as stable organic radicals and ionic liquids were prepared under similar conditions. These fluorinated nanoparticles-encapsulated guest molecules were applied to a new type of surface-modification agent, and these particles were able to disperse well above the poly (methyl methacrylate) films.

Solubilization of fullerene into ionic liquids by the use of fluoroalkyl end‐capped oligomers

AbstractFluoroalkyl end‐capped oligomers were solubilized into a variety of ionic liquids such as N‐methylpyrazolium tetrafluoroborate, 3‐methylpyrazolium tetrafluoroborate and 1‐butyl‐3‐methylimidazolium hexafluorophosphate, and these fluorinated oligomers were able to reduce the surface tension of these ionic liquids. Interestingly, these fluorinated oligomers were able to solubilize fullerene into ionic liquids effectively. Fluoroalkyl end‐capped fullerene co‐oligomers, which were prepared by the oligomerizations of fluoroalkanoyl peroxides with radical polymerizable monomers such as acryloylmorpholine in the presence of fullerene, were more effective in solubilizing fullerene into ionic liquids compared to the corresponding fluoroalkyl end‐capped homo‐oligomers possessing no fullerene units. Fluoroalkyl end‐capped fullerene co‐oligomers/fullerene/ionic liquid complexes thus obtained were applied to the arrangements of fullerenes above the poly(methyl methacrylate) (PMMA) surface, and the higher fluorescent intensity of fullerene was obtained in the modified PMMA surface, although the reverse side of this modified film surface afforded an extremely weak fluorescent intensity. Copyright © 2005 John Wiley & Sons, Ltd.

Preparation of magnetic nanoparticles by the use of self-assembled fluorinated oligomeric aggregates—A new approach to the dispersion of magnetic particles on poly(methyl methacrylate) film surface

Fluoroalkyl end-capped acrylic acid oligomer-encapsulated magnetic nanoparticles were prepared by the coprecipitation of aqueous ferric and ferrous ions in the presence of the corresponding oligomers under alkaline conditions. The dynamic light scattering measurements showed that these fluorinated oligomer magnetic nanoparticles were encapsulated in the self-assemblies of fluoroalkyl end-capped oligomers. Fluoroalkyl end-capped oligomer-encapsulated magnetic nanoparticles thus obtained were applied to the dispersion of magnetic particles on the poly(methyl methacrylate) film surface to exhibit not only the surface active property imparted by fluorine but also magnetic behavior toward a permanent magnet.

DISSOLUTION OF CARBON NANOTUBES IN WATER AND ORGANIC MEDIA WITH A VARIETY OF FLUOROALKYL END-CAPPED OLIGOMERS

Dissolution of single-wall carbon nanotube (SW-CNT) in water and organic media was studied by the use of fluoroalkyl end-capped acrylic acid oligomers [RF‒(ACA)n‒RF], N,N-dimethylacrylamide oligomers [RF‒(DMAA)n‒RF], acryloyl-morpholine oligomers [RF‒(ACMO)n‒RF], and N-(1,1-dimethyl-3-oxobutyl) acrylamide oligomers [RF‒(DOBAA)n‒RF]. Among these fluorinated oligomers, it was demonstrated that RF‒(ACMO)n‒RF; RF˭CF(CF3)OC6F13] oligomer is more effective for the dissolution of SW-CNT in both aqueous and organic media. Additionally, it was demonstrated that RF‒(DOBAA)n‒RF oligomer is a convenient tool for the arrangement of SW-CNT on PMMA surface.

Synthesis and Applications of Novel Fluoroalkyl End-capped Oligomers/Silica Gel Polymer Hybrids

Fluoroalkyl end-capped N,N-dimethylacrylamide and acryloylmorpholine oligomers were polymerized with hydrolysis and condensation of tetraethoxysilane (TEOS) to afford homogeneous fluoroalkyl end-capped oligomers and silica gel polymer hybrids, respectively. In particular, the sol solutions of fluorinated oligomers/TEOS polymer hybrids were applied to surface modifications of glass with not only a strong oleophobicity but also good hydrophilicity.

Synthesis and properties of novel fluoroalkyl end-capped oligomers having adamantane units in the main chains via a radical process

Fluoroalkanoyl peroxides were reacted with adamantane in the presence of radical polymerizable monomers such as acrylic acid, acryloylmorpholine, and N,N-dimethylacrylamide to afford fluoroalkyl end-capped oligomers having adamantane units in the main chains via a radical process under very mild conditions. Thermal stability of these new fluorinated adamantane co-oligomers thus obtained became higher than that of the corresponding fluorinated homo-oligomers having no adamantane units. Interestingly, these fluorinated adamantane co-oligomers exhibited good solubility in traditional organic solvents such as methanol, ethanol, tetrahydrofuran, chloroform, benzene, dimethylsulfoxide and N,N-dimethylformamide including water, although the parent adamantane exhibited no solubility in water, methanol and dimethylsulfoxide. Furthermore, these adamantane co-oligomers were able to reduce the surface tension effectively to form the nanometer size-controlled self-assembled fluorinated molecular aggregates. Copyright © 2005 John Wiley & Sons, Ltd.

Synthesis and antibacterial activity of novel fluoroalkyl end-capped oligomers containing ammonium segments: application to new fluorinated gelling materials with antibacterial activity

New fluoroalkyl end-capped 2-aminoethyl methacrylate hydrochloride (AEM) co-oligomers containing triol or tetraol segments were prepared by reaction of fluoroalkanoyl peroxides with AEM and the corresponding triol or tetraol monomer under very mild conditions. Fluoroalkyl end-capped AEM co-oligomers thus obtained had no solubility in water and DMSO. However, these co-oligomers could cause gelation in these solvents under non-crosslinked conditions, although the corresponding AEM homo-oligomers had good solubility in these solvents, and were able to reduce the surface tension of water quite effectively. Interestingly, fluoroalkyl end-capped AEM co-oligomers exhibited as extremely high antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa as the corresponding fluorinated AEM homo-oligomers. In addition, fluoroalkyl end-capped AEM co-oligomer gels are applicable to new fluorinated gelling polymer electrolytes, and these cationic gels containing lithium ions exhibited a considerably high ionic conductivity of the level of 10−3 S cm−1 at room temperature.

Surface modification of glass by oligomeric fluoroalkylating agents having oxime-blocked isocyanate groups

A new type of oligomeric fluoroalkylating agent with oxime-blocked isocyanate groups was synthesized and the modification of a glass surface using this oligomer was studied. Based on contact angle measurements, the surface free energy of the modified glass was calculated. The results show that the glass surface was effectively fluoroalkylated, the surface free energy was lowered enough and the glass surface became both water- and oil-repellent. The longer the chain length of the fluoroalkyl group (R f) is, the lower is the surface free energy of the modified glass. There existed a good relationship between the surface free energy and the F 1s /Si 2 p peak area ratio measured by XPS. The surface free energies decreased with an increase of this peak area ratio and above a ratio of 2, they became constant. The effects of modification by fluoroalkyl end-capped oligomers having oxime-blocked isocyanate groups and fluoroalkyl end-capped silanes were interpreted in terms of the structure of the modified layer, i.e. in terms of the monolayer interphase and network interphase models, respectively.

Synthesis and properties of novel fluoroalkyl end-capped oligomers containing phosphorus segments

New fluoroalkyl end-capped oligomers containing pendant phosphoric acid groups wereprepared by the reactions of the corresponding monomer with fluoroalkanoyl peroxides. It was demonstrated that not only strong aggregations of fluoroalkyl segments but also hydrogen bonding could interact synergistically to form the highly viscoelastic fluids (gel-like fluids) in aqueous solutions of these new fluoroalkyl end-capped oligomers containing pendant phosphoric acid groups. Furthermore, these oligomers were able to reduce the surface tension of water effectively to exhibit a clear breakpoint resembling a CMC, and the modified stainless-steel surface treated with these oligomers was shown to possess an excellent property imparted by fluorine. More interestingly, these oligomers were found to be potent and selective inhibitors against HIV-1 replication in vitro. New fluoroalkyl end-capped phosphonic acid and phosphonate oligomers were also prepared by the reactions of the corresponding phosphonic acid and phosphonate monomers, respectively, by the use of fluoroalkanoyl peroxides. These new fluoroalkyl end-capped phosphonic acid and phosphonate oligomers were found to have a higher solubility in not only water but also in common organic solvents than that of the corresponding fluorinated oligomers containing pendant phosphoric acid groups, and these new oligomers were able to reduce the surface tension of these solvents quite effectively. Thus, these oligomers are expected to develop as new fluorinated oligosurfactants. Moreover, the modified poly(methyl methacrylate) surface treated with these phosphonate oligomers was clarified to exhibit a good oil-repellency imparted by fluorine. In addition, fluoroalkyl end-capped phosphonate homo- and cooligomers were found to form monomolecular films at the air–water interface. Therefore, these fluorinated oligomers are suggested to have high potential for new functional materials through not only their excellent properties imparted by both fluorine and phosphorus, but also through their biological properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 228–245, 2001

Novel Fluorinated Oligo-Surfactants Imparted by the Aggregation of Fluoroalkyl Segments

Fluoroalkanoyl peroxide was found useful for the synthesis of fluoroalkyl end-capped oligomers having COOH, SO3H, O=C-NR1R2, OH, betaine segments, phosphorous segments and blocked-isocyanato segments. The fluoroalkyl end-capped oligomers were generally soluble not only in water but common organic solvents as well. These oligomers were highly surface active, showing very low surface tensions and clear break points, as in the case of low molecular weight fluorinated surfactants. Self-organization thus occurs to form molecular aggregates. Based on light scattering studies, fluoroalkyl end-capped oligomers having COOH formed ellipsoidal micelles. Fluoroalkyl end-capped oligomers with hydroxy or betaine segments gave rise to gelation owing to hydrophobic interaction of end-capped fluoroalkyl segments in addition to the hydrogen bonding and/or the ionic interaction of betaine segments. Moreover, as some examples of interesting properties of fluoroalkyl end-capped acrylamide type oligomers, the unique binding power of Ca2+ or Cr3+, selective recognition of organic color material having -NH2 or -NMe2 groups such as methylene blue and/or luminol, and the immobilization of cytochrome c are discussed. These features may be due to molecular aggregates produced by the interaction between end-capped fluoroalkyls.

Water Repellent and Antibacterial Modification of Cellulose using Fluoroalkyl End-Capped Oligomers.

Surface modification of cellulose to give an antibacterial property as well as water- and oil-repellency was studied using fluoroalkyl end-capped oligomeric allylammonium hydrochloride, allylammonium hydrochloride-fluorosilane combined system, and fluorosilanes having tributylphosphonium segments. (1) In the case of modification with oligomeric allylammonium hydrochloride alone, oil-repellency increased in spite of low water-repellency. After immersion in water for 1h, modification effects were missing, which indicated the low water-durability of modification. (2) By combining allylammonium hydrochloride oligomer and fluorosilanes, modified cellulose surface exhibited high water- and oil-repellency. Modification effects were maintained even after immersion in water for 24h. Based on the ESCA analysis, it is suggested that allylammonium hydrochloride oligomer would be kept in the siloxane network on the cellulose surface. (3) Modification with fluorosilanes having tributylphosphonium segments could also change cellulose surface to highly water- and oil-repellent. Modified surface showed good microbiostasis activity against Staphylococcus aureus.