Preparation of novel cross-linked fluoroalkyl end-capped adamantane cooligomer/copper nanocomposites

Copper(II) oxide reacted with hydrazine in the presence of fluoroalkyl end-capped oxime-blocked isocyanato cooligomer containing adamantyl segments at 90 °C for 30 min in ethylene glycol, and the deprotecting reaction of the cooligomer in the resulting product at 120 °C for 15 min was found to afford the colloidal red-brown colored cross-linked fluorinated cooligomer/Cu nanocomposites, which were stabilized by fluoroalkyl end-capped cooligomer containing benzotriazole segments. On the other hand, the corresponding cross-linked fluorinated cooligomer possessing no adamantyl segments could not afford the copper nanocomposites under similar conditions. Dynamic light scattering measurements and TEM photography of these cross-linked fluorinated cooligomer/Cu composites showed that these composites are nanometer size-controlled very fine nanoparticles. These fluorinated Cu nanocomposites have a good dispersibility and stability in mixed solvents of ethylene glycol and methanol for two weeks under air atmosphere conditions. In addition, these fluorinated Cu nanocomposite powders have been found to be stable for more than three months.     

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.     

Synthesis and application of novel fluoroalkyl end-capped cooligomers having adamantane as a pendant group

Fluoroalkyl end-capped cooligomers having adamantane as a pendant group [R_F-(Ad-HAc) _x –(Co-M) _y -R_F] were prepared by the reactions of fluoroalkanoyl peroxide with 3-hydroxy-1-adamantylacrylate (Ad-HAc) and comonomers (Co-M) such as acrylic acid (ACA), N,N-dimethylacrylamide (DMAA), and acryloylmorpholine (ACMO) under mild conditions. Thermogravimetric analyses (TGA) showed that thermal stability of R_F-(Ad-HAc) _x –(Co-M) _y -R_F was superior to that of the corresponding fluoroalkyl end-capped cooligomers having adamantane in the main chains [R_F-(Ad) _x –(Co-M) _y -R_F] and the fluoroalkyl end-capped homooligomers possessing no adamantyl segments [R_F-(M) _n -R_F]. It is interesting to note that fluoroalkyl end-capped Ad-Hac–DMAA cooligomer [R_F-(Ad-HAc) _x –(DMAA) _y -R_F] was found to form the nanometer size-controlled cooligomeric aggregates which consist of around 16 fluorinated cooligomeric molecules in methanol/water mixed solvents. Furthermore, these fluorinated cooligomeric aggregate could occupy around 320 ADMDD [5-(2-adamantylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione] molecules as guest molecules per aggregate core, although ADMDD could not be encapsulated into the R_F-(Ad) _x –(Co-M) _y -R_F cooligomeric and R_F-(M) _n -R_F homooligomeric aggregate cores under similar conditions.     

Preparation and properties of novel cross-linked fluoroalkyl end-capped cooligomeric nanoparticles possessing double decker-type aromatic silsesquioxane segments as core units

Cross-linked fluoroalkyl end-capped cooligomers possessing double decker-type aromatic silsesquioxane segments as core units [R_F-(Ar-SiSQ) _x -(Co-M) _y -R_F] were prepared under mild conditions by the cooligomerizations of fluoroalkanoyl peroxide with the corresponding aromatic silsesquioxane possessing bifunctional vinyl groups (Ar-SiSQ) and comonomers (Co-M) such as acryloylmorpholine (ACMO), N,N-dimethylacrylamide (DMAA) and N-(1,1-dimethyl-3-oxobutyl)acrylamide (DOBAA). Interestingly, these cross-linked fluorinated cooligomers thus obtained were found to form the nanometer size-controlled nanoparticles with a good dispersibility in a variety of solvents including fluorinated aliphatic solvents. These fluorinated cooligomeric nanoparticles were demonstrated to have red-shifted fluorescent emissions related to the presence of aromatic silsesquioxane segments, compared with that of parent aromatic silsesquioxane, indicating that each aromatic moiety in these nanoparticles can interact effectively with each other through the π–π stacking between the aromatic moieties to afford the red-shifted fluorescent emissions. These fluorinated nanoparticles were also applied to the surface modification of poly(methyl methacrylate) (PMMA) to exhibit not only a good oleophobicity imparted by fluorine but also a fluorescent emission behavior related to aromatic silsesquioxane segments in nanoparticles on the modified PMMA surface. More interestingly, cross-linked R_F-(Ar-SiSQ) _x -(DOBAA) _y -R_F cooligomeric nanoparticles interacted with fluorescein to give the corresponding fluorinated cooligomeric particles/fluorescein nanocomposites in methanol. These fluorinated fluorescein nanocomposites were found to afford an extraordinarily enhanced light absorption (λ _max = 441 nm), compared with that of fluoroalkyl end-capped DOBAA oligomer [R_F-(DOBAA) _n -R_F] possessing no aromatic silsesquioxane segments.     

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.     

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.     

Architectures of novel fluorinated block copolymers fuelled by a poor radical polymerizable characteristic of 1,3‐divinyltetramethyldisiloxane

Fluoroalkanoyl peroxide was reacted with 1,3‐divinyltetramethyldisiloxane under very mild conditions to afford the fluoroalkyl end‐capped vinylsilane oligomer containing vinyldimethylsiloxane segments. This fluoroalkyl end‐capped vinylsilane oligomer was applied to the preparation of novel fluorinated block copolymers by the copolymerizations with traditional radical polymerizable monomers. It was demonstrated that these fluorinated block copolymers thus obtained can form the dendritic‐type unimolecular micelles in aqueous solutions, and these fluorinated block copolymers were able to provide suitable host moieties to interact with fullerenes as guest molecules. Copyright © 2006 John Wiley & Sons, Ltd.     

Nano‐hydroxyapatite Surfaces Grafted with Electroactive Aniline Tetramers for Bone‐Tissue Engineering

An electroactive amino/carboxyl‐capped aniline tetramer (AT) is covalently grafted to the surface of hydroxyapatite (HA) nanoparticles to generate novel electroactive HA‐AT nanoparticles. The amount of AT ranges from 16.5 to 34.0 wt% and is characterized by thermogravimetric analysis (TGA). The HA‐AT nanoparticles are characterized by Fourier transform IR (FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction, and scanning electron microscopy (SEM). For the excellent electroactivity of HA‐AT, the mixture of HA‐AT and PLA shows much better adhesion ability and proliferation ability than that of HA and a PLA matrix. At a 15 wt% AT grafting amount, the matrix shows the best biocompatibility.

     

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.     

Gold Nanoparticles Functionalized by a Dextran‐Based pH‐ and Temperature‐Sensitive Polymer

A dextran‐based dual‐sensitive polymer is employed to endow gold nanoparticles with stability and pH‐ and temperature‐sensitivity. The dual‐sensitive polymer is prepared by RAFT polymerization of N‐isopropylacrylamide from trithiocarbonate groups linked to dextran and succinoylation of dextran after polymerization. The functionalized nanoparticles show excellent stability under various conditions and can be stored in powder‐form. UV and DLS measurements confirm that the temperature‐induced optical changes and aggregation behaviors of the particles are strongly dependent on pH.

     

Preparation of novel cross-linked fluoroalkyl end-capped cooligomeric nanoparticles–encapsulated cytochrome c in water and ionic liquids

Cross-linked fluoroalkyl end-capped acrylic acid cooligomer containing poly(oxyethylene) units can form the nanometer size-controlled fine particles in aqueous solutions, and these cross-linked nanoparticles interact with cytochrome c (Cyto-c) to afford the corresponding cooligomeric nanoparticles–encapsulated Cyto-c effectively. Interestingly, we can easily isolate the fluorinated nanoparticles–encapsulated Cyto-c powder by the simple centrifugal separation of the corresponding aqueous solutions. The cross-linked fluorinated cooligomer also enables an effective transfer of Cyto-c from aqueous solution to ionic liquids such as 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide to afford the immobilized Cyto-c with the corresponding fluorinated cooligomer in quantitatively immobilized ratio (～100%). The immobilized Cyto-c exhibited a good dispersibility in the parent ionic liquid to afford the nanometer size-controlled fluorinated particles–encapsulated Cyto-c. Similarly, the cross-linked fluorinated cooligomer in ionic liquids such as 3-methylpyrazolium tetrafluoroborate (3MP-BF4) interacted with Cyto-c to afford the corresponding nanoparticles–encapsulated Cyto-c in quantitatively encapsulated ratio (～100%). These cross-linked fluorinated nanoparticles–encapsulated Cyto-c in water and ionic liquids were applied to the oxidation of guaiacol with hydrogen peroxide, and an extremely higher catalytic activity for this oxidation was observed in the ionic liquid (3MP-BF4).     

Highly Extensible Bio‐Nanocomposite Fibers

Here, we show that a poly(ethylene oxide) polymer can be physically cross‐linked with silicate nanoparticles (Laponite) to yield highly extensible, bio‐nanocomposite fibers that, upon pulling, stretch to extreme lengths and crystallize polymer chains. We find that both, nanometer structures and mechanical properties of the fibers respond to mechanical deformation by exhibiting strain‐induced crystallization and high elongation. We explore the structural characteristics using X‐ray scattering and the mechanical properties of the dried fibers made from hydrogels in order to determine feasibility for eventual biomedical use and to map out directions for further materials development.

     

Characterization of Chlorine‐, Amine‐ and Acrylate‐Functionalized TEMPO‐Capped and Bis‐TEMPO‐Capped Polystyrenes Using MALDI‐TOF MS

Chlorine‐functionalized TEMPO‐capped polystyrenes were investigated using the matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) technique. Amine‐ and acrylate‐functionalized agents and bifunctional TEMPO‐capped polystyrene were also analyzed to demonstrate the applicability of this method. Using this technique allowed to analyze the conversion of the chlorine function to an acrylate function, which was previously difficult to detect with other methods.

MALDI‐TOF mass spectrum of a polystyrene described in this article, as obtained with DHB as the matrix.     

Synthesis and applications of novel fluoroalkyl end‐capped cooligomers containing diphenylacetylene segments: a new approach to the surface arrangement of diphenylacetylene segments on the traditional organic polymer

Fluoroalkyl end‐capped cooligomers containing diphenylacetylene segments [R_F‐(DPMA)_x‐(Co‐M)_y‐R_F] were prepared by reaction of fluoroalkanoyl peroxide with 4‐(phenylethynyl)phenyl methacrylate (DPMA) and radical polymerizable comonomers such as N,N‐dimethylacrylamide (DMAA) and acryloylmorpholine (ACMO) under very mild conditions. Fluorinated cooligomers containing diphenylacetylene segments thus obtained exhibited a good solubility in a variety of organic solvents. These fluorinated cooligomers were also applied to the surface modification of traditional organic polymers such as poly(methyl methacrylate) (PMMA) to exhibit not only a good surface active property imparted by fluorine but also a fluorescent characteristic related to diphenylacetylene segments on their surface. In addition, these fluorinated cooligomers could form the nanometer size‐controlled fluorinated molecular aggregates in chloroform. Interestingly, some benzenes and biphenyl (BP) derivatives could interact with these fluorinated oligomeric aggregates as guest molecules, and in particular 2‐chloro‐5‐nitrobenzotrifluoride (CNB) was most effective for enhancing the fluorescent intensity of these guest molecules. Copyright © 2009 John Wiley & Sons, Ltd.     

Novel Water‐Soluble Shape‐Regulatable Luminescent Nanoparticles by Non‐Covalently Bonded Self‐Assembly

Summary: Novel non‐covalently connected water‐soluble nanoparticles that contain poly(fluorene‐co‐phenylene) with hydroxy‐capped alkoxy side chains (PF3BOH) and poly(acrylic acid) (PAA) have been obtained and characterized. With different proportions of PF3BOH and PAA, the shape and size of the nanoparticles can be regulated. The nanoparticles are quite stable in water with no precipitate being observed after weeks. Transmission electron microscopy and dynamic laser light scattering are used to confirm the morphology of the PF3BOH/PAA nanoparticles. Their optical properties have been investigated and show similar optoelectronic properties to a PF3BOH solid film although they do not undergo aggregation.

TEM images of the nanoparticles obtained upon varying the PAA/PF3BOH content.     

Preparation and applications of novel amphiphilic fluoroalkyl end‐capped oligomers‐clay nanocomposites

Nonionic‐type amphiphilic fluoroalkyl end‐capped acryloylmorpholine and N,N‐dimethylacrylamide homooligomers were found to be new convenient intercalating agents for the achievement of an enlarged basal spacing of the clay layers to afford fluorinated oligomers‐clay nanocomposites. These novel fluoroalkyl end‐capped oligomers‐clay nanocomposites were found to exhibit good dispersibility and stability in aqueous and organic media, and were applied to the surface modification of traditional organic polymeric materials such as poly(methyl methacrylate). Copyright © 2006 John Wiley & Sons, Ltd.     

Vesicles Formed by Oligostyrene‐block‐Oligoaniline‐block‐Oligostyrene Triblock Oligomer

Novel π‐conjugated coil–rod–coil triblock oligomers containing optoelectronic active oligoaniline segments were synthesized. The block oligomer can self‐assemble into diverse aggregating morphologies including spherical micelles and thin‐layer vesicles in THF, which is found associated with the removing of the protecting groups of oligoaniline segments. A possible mechanism was proposed to explain the self‐assembly behavior changes in which chain conformation variation of the aniline segments initiated from deprotection of the nitrogen atoms is pointed to be the key factor that dominates the transition process.

     

Synthesis of novel fluoroalkyl end‐capped oligomers/silica gel polymer hybrids possessing antibacterial activity

New fluoroalkyl end‐capped oligomers/silica gel polymer hybrids‐low‐molecular weight biocide (hibitane) composites were prepared by the reactions of tetraethoxysilane (TEOS) with fluoroalkyl end‐capped N‐(1,1‐dimethyl‐3‐oxobutyl)acrylamide oligomer, N,N‐dimethylacrylamide oligomers, and acrylic acid oligomers in methanol under acidic conditions at room temperature. The presence of hibitane in the composites was clarified by the use of elementary analyses of nitrogen in fluorinated acrylic acid oligomer composite and thermogravimetric analysis (TGA) of these fluorinated composites. Thermal stability of fluorinated composites thus obtained were found to increase significantly compared to those of the parent fluorinated oligomers. Thermal stability of fluorinated N,N‐dimethylacrylamide oligomer, acrylic acid oligomer/silica gel polymers hybrid‐hibitane composites decreased compared to those of the corresponding fluorinated oligomers/silica gel polymer hybrids; however, the thermal stability of fluorinated N‐(1,1‐dimethyl‐3‐oxobutylacryl)amide oligomer/silica gel polymer hybrid‐hibitane composite increased significantly compared to that of the corresponding fluorinated oligomer hybrid. The sol methanol solutions of these fluorinated composites were applied to the surface modification of glass to exhibit not only a strong oleophobicity imparted by end‐capped fluoroalkyl groups in oligomers but also a good hydrophilicity on the glass surface. Fluorinated oligomers/silica gel polymer hybrids‐hibitane composites were found to exhibit high anti‐bacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus. Therefore, these fluorinated hibitane composites are suggested to have high potential for new attractive functional materials through not only their excellent surface active property imparted by fluorine and their thermal stability but also through their anti‐bacterial activity. Copyright © 2005 John Wiley & Sons, Ltd.     

Cross‐Linked Conjugated Polymers for Achieving Patterned Three‐Color and Blue Polymer Light‐Emitting Diodes with Multi‐Layer Structures

Reactions between the ethylene groups in the backbone of conjugated polymers under UV illumination and heat treatment result in the cross‐linking of the main polymer chains. The cross‐linking leads to two simultaneous results in the polymer: excellent solvent resistance and increased bandgap. Using this reaction, three‐color polymer light‐emitting diodes (PLEDs) with a multi‐layer structure can be easily realized by a dry photo‐pattern in an active‐gas‐free environment. Multi‐layer blue devices with dramatically enhanced efficiency can also be achieved conveniently.

     

Alkyne‐Linked Poly(1,8‐carbazole)s: A Novel Class of Conjugated Carbazole Polymers

Novel conjugated carbazole polymers based on the alkyne‐linked 1,8‐carbazole structure are synthesized in high yield by the Sonogashira cross‐coupling reaction and acetylenic oxidative coupling reaction. The polymers are thermally stable and highly soluble in common organic solvents such as CHCl₃, CH₂Cl₂, and THF. As compared to ethynylene‐linked polymer, the butadiynylene‐linked polymer display a bathochromic shift in the absorption maximum and end absorption position. In addition, the fluorescence behaviors in CH₂Cl₂ are almost identical for both polymers. Electrochemical measurements indicate that the ethynylene‐linked polymer possesses a lower first oxidation potential than the butadiynylene‐linked one.