Synthesis of fluoroalkyl end‐capped preoligomers containing succinimidyl segments—Application to novel fluorinated oligomers possessing surface antibacterial activity

Fluoroalkyl end‐capped N‐acryloxysuccinimide (ASuI) cooligomers were prepared under very mild conditions by the cooligomerizations of fluoroalkanoyl peroxides with ASuI and comonomers such as N,N‐dimethylacrylamide (DMAA) and acryloylmorpholine (ACMO). These fluorinated ASuI cooligomers thus obtained were in general easily soluble in water and common organic solvents. These fluorinated ASuI cooligomers were also able to reduce the surface tension of water quite effectively to around 20 mN/m with a clear break point resembling a critical micelle concentration (CMC), although the corresponding nonfluorinated ASuI cooligomers were not effective for reducing the surface tension of water. Fluorinated ASuI cooligomers were applicable to new fluorinated precooligomers, and these precooligomers could react with several amino compounds such as aniline, cytosine, and cyclohexylamine to afford fluorinated cooligomer‐bound aromatic and cyclohexyl segments under mild conditions. Of particular interest, these fluorinated precooligomers were able to react with low molecular weight biocides such as sulfathiazole (STZ) and 3‐amino‐5‐hydroxypyrazole (AHP) to give the corresponding fluorinated cooligomers containing antibacterial segments under similar conditions. These cooligomers were shown to have not only a good oleophobicity imparted by fluorine but also surface antibacterial activity against Staphylococcus aureus. Therefore, our present fluorinated cooligomers containing antibacterial segments are suggested to have high potential for new fluorinated functional materials through their surface active property and surface antibacterial activity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3874–3880, 2004     

Synthesis and applications of silicone oil–soluble fluoroalkyl end‐capped cooligomers

Fluoroalkyl end‐capped cooligomers containing polydimethylsiloxane and polyoxyethylene segments were prepared under very mild conditions by the cooligomerizations of fluoroalkanoyl peroxides with methacrylate monomers containing the corresponding segments and comonomers such as dimethylacrylamide and acryloylmorpholine. These obtained fluorinated cooligomers exhibited amphipathic characteristics and became soluble in water and common organic solvents. In particular interest, fluoroalkyl end‐capped cooligomers containing polyoxyethylene units were soluble not only in poly(methylphenylsiloxane) (silicone oil) but also in water, including common organic solvents except for hexane. Additionally, these fluorinated cooligomers were able to reduce the surface tension of water and m‐xylene quite effectively, to around 15 and 20 mN/m levels, respectively. In these fluorinated cooligomers, fluoroalkyl end‐capped acryloylmorpholine cooligomers containing polyoxyethylene segments were applicable as a novel emulsifying agent against water and silicone oil. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1467–1476, 2005     

Unexpected formation of N-methylfulleropyrrolidines by the reaction of fullerene and gossypol and their bioactivity

Reaction of fullerene, sarcosine and gossypol through the Prato reaction resulted in some unexpected N-methylfulleropyrrolidines. These fulleropyrrolidines were fully characterized via rigorous structure determination through multiple spectral experiments, which included 1D, 2D NMR, FT-IR, MS and X-ray crystallography. During the reaction, gossypol decomposed into benzaldehyde which was successfully detected as a new intermediate through GC-MS. In an in vitro assay of NO radical induced apoptosis in 3T3L1 cells, N-methylfulleropyrrolidine (2) and N-methyl-2,2-dimethylfulleropyrrolidine (3) showed dose dependent and stronger radical scavenging activities than the parent fullerene.     

A molecular dynamics study of the Gibbs free energy of solvation of fullerene particles in octanol and water

The Gibbs free energy of solvation (ΔG^solv) for C₆₀, and six other idealized, non-functionalized, fullerene particles of differing size and shape has been determined in octanol and water solvents from molecular dynamics simulations using thermodynamic integration. In particular, we have studied Buckminster fullerene (C₆₀) and open and capped carbon nanotubes of different aspect ratios and solvent accessible surface areas. Knowledge of the ΔG^solv of a molecule in octanol and water can be used to understand the partitioning of the molecule between organic and aqueous phases and is one of several parameters used to model the fate of chemicals in the natural environment. The simulations were performed at ambient conditions, i.e., a temperature of 25 °C and a pressure of 1 bar. The fullerene molecules are all found to have a very high ΔG^solv in water, and a very low ΔG^solv in octanol, suggesting a strong preference for the organic phase. From a comparison of the results for capped and uncapped carbon nanotubes we found that the uncapped tubes exhibit significantly higher ΔG^solv than capped tubes. Furthermore, for capped carbon nanotubes, hydrophobic/organophilic shifts are observed with increasing excluded volume and solvent accessible surface area.     

Dicarboxy-telechelic cooligomers with sequence structure tunable light absorption

Alternating cooligomers of 5 pyrrole (P) and thiophene (T) units with a PTPTP sequence and carboxylic telechelic groups in α,α′-position are supposed to provide a low band gap and might be incorporated into degradable polymers. In this study we explored whether such new α,α′-ester linked π-conjugated alternating electron rich PTPTP cooligomers of defined size could be created following a Stille coupling synthesis pathway. The obtained cooligomers displayed in the absorption spectra λ_max between 341 and 379 nm in solution and between 346 and 410 nm in the solid state, which could be tuned by the substitution with donor type alkyl and alkoxy functions. A strong red shift of the absorption bands into the IR region of the spectrum with absorption maxima between 550 and 650 nm and further to 850 and 1000 nm could be obtained when additional charges by deprotonation or oxidation were introduced. The prepared semi conducting materials could be applied potentially as dyes for photoacoustic imaging or in sensors for oxidation monitoring.     

Transport of Small Molecules through Polyphenylene Oxide Membranes Modified by Fullerene

Abstract

Homogeneous membranes based on fullerene‐polyphenylene oxide compositions containing up to 2 wt% fullerene C₆₀ were prepared. The effect of fullerene addition on PPO transport properties was studied in gas separation and pervaporation processes. Permeability coefficients of H₂, O₂, N₂, CH₄, and CO₂ were measured; a correlation between gas transport properties and membrane free volume was established. Pervaporation properties were studied for the system with ethyl acetate synthesis reaction: quaternary system ethanol—acetic acid—water—ethyl acetate and some constituent binary and ternary mixtures. Pervaporation in binary systems, ethanol–water and ethyl acetate–water was considered with the use of the data on sorption capacities and interaction parameters. In pervaporation of a quaternary reacting mixture, the permeate containing essentially ethyl acetate was obtained. Results show that membranes with fullerene additives exhibit improved transport properties.     

Synthesis and characterization of C60‐based composites of amphiphilic N‐vinylpyrrolidone/triethylene glycol dimethacrylate copolymers

It was found that under mixing of aqueous solutions of copolymers and toluene solutions of C₆₀ two types of polymer composites can be produced with different matrix structure, the fullerene content and an aggregation degree. The dimethacrylate enriched macromolecules migrate to toluene and the VP units enriched copolymer chains remain in water to form copolymer micelles and their aggregates in these media that solubilize and encapsulate the fullerene. The structure and properties of obtained polymer composites were studied by GPC with dual detection (RI and MALLS), FT‐IR, WAXS and SAXS methods. It is shown that in a composite based on N‐vinylpyrrolidone copolymer isolated from toluene the fullerene form larger particles, compare to that isolated from water. According to SAXS, the fullerene particles in a solid copolymer are organized in spherical objects with fine coil‐like structure. The stability of the composites in water, ethanol, and chloroform was shown to depend on the original polymer matrix structure and on copolymer/fullerene ratio. POLYM. COMPOS., 35:1362–1371, 2014. © 2013 Society of Plastics Engineers     

Fabrication and characterization of fullerene-Nafion composite membranes

Fullerene-Nafion composite membranes have been fabricated through a new solution casting for the first time. The fullerenes used for the composites included C₆₀ and polyhydroxy fullerene (PHF), C₆₀(OH)_n (n ∼ 12). The dispersion of the fullerene in the composite membrane was much more refined with smaller agglomeration particles, relative to the previously prepared fullerene-Nafion composites in which the fullerene was introduced through doping. The miscibility of the hydrophobic fullerene, C₆₀, in the Nafion matrix was further improved by a new fullerene dispersant, poly[tri(ethylene oxide)benzyl]fullerene, C₆₀[CH₂C₆H₄(OCH₂CH₂O)₃OCH₃]_n (n ∼ 5), synthesized in this work. The solution-cast fullerene composites also demonstrated a significant improvement in the physical stability relative to the fullerene-doped Nafion composites through a better integration of the fullerene into the Nafion matrix. Furthermore, increased loadings of the fullerene in Nafion were made possible through the new solution-casting method, compared to the previous doping method. The water characteristics in the fullerene composites have been examined by TGA and ¹H pulse NMR measurements. The interactions between the fullerene and the Nafion have been studied through ATR FT-IR and molecular dynamics simulations which suggested PHF resides primarily in the hydrophobic domain of Nafion when the loading was low. The voltammetric measurements also have shown that the fullerene composites have the reduced limiting current density, compared to Nafion membranes without fullerenes.     

Aggregation of biodegradable amphiphilic poly(succinimide-co-N-propyl aspartamide) and poly(N-dodecyl aspartamide-co-N-propyl aspartamide) in aqueous medium and its preliminary drug-released properties

Two series of biodegradable amphiphilic copolymers, poly(succinimide-co-N-propyl aspartamide) (PSI-PA) and poly(N-dodecyl aspartamide-co-N-propyl aspartamide) (PDDA-PA) were synthesized by partial and total aminolysis of polysuccinimide (PSI), respectively. PSI-PA copolymers could self-aggregate in water directly under ultrasonication at room temperature. Differing from PSI-PA copolymers, the aggregates of PDDA-PA need to add PDDA-PA DMF solution into an excessive amount of water. The aggregative properties of PSI-PA and PDDA-PA copolymers have been investigated by dynamic light scattering (DLS) and surface tension measurements. Hydrophilicity of these two copolymers was attributed to the N-propyl aspartamide segments. Due to the stiff structure, succinimide segments preferred to form irregular hydrophobic microdomains, and some aggregates of PSI-PA are bimodal size distribution in water medium, while the more flexible PDDA-PA copolymer chains preferred to form monodispersed spherical aggregates. Elevated temperature could reduce the aggregate size of both PSI-PA and PDDA-PA copolymers due to the breaking of the hydrogen bonding and the releasing of the bonded water molecules. PSI-PA copolymers were surface active, while the surface tension of PDDA-PA copolymers was independent on concentration. The drug-loaded aggregates of PSI-PA also have been prepared and the preliminary release properties have been studied in vitro.     

Adsorption of N,N′-dimethylthiourea at a mercury/aqueous solution of NaClO4 interface; dependence on the supporting electrolyte concentration

Adsorption of N,N′-dimethylthiourea (DMTU) on mercury electrode from 0.1, 1 and 5 M NaClO₄ was studied as the function of electrode charge density and adsorbate bulk concentration. In the study, the experimental data obtained from the measurements of differential capacity of double layer were used, the measurements of zero charge potential and surface tension at the zero charge potential. In each system studied the values of the relative surface excess increase with an increase of the concentration of N,N′-dimethylthiourea and NaClO₄. The adsorption parameters were obtained from the Frumkin, virial and modified Flory-Huggins isotherms. It was found that the values of free adsorption energy, interactions constants and integral capacity depends on the supporting electrolyte concentration. The strength of the surface bond formed between N,N′-dimethylthiourea and the electrode surface and the influence of water present on the electrode surface in the obtained results of calculations were discussed.     

A temperature-responsive carbon black nanoparticle prepared by surface-induced reversible addition-fragmentation chain transfer polymerization

A reversible addition-fragmentation chain transfer (RAFT) agent, 2-{[(dodecylsulfanyl)carbonothioyl]sulfanyl}propanoic acid (DSCTSP), was immobilized on the hydroxyl-functionalized carbon black (CB) surface via a direct condensation reaction, producing CB-DSCTSP. Then, RAFT polymerizations were carried out on carbon black surface using the CB-DSCTSP as a chain transfer agent. Poly(N-isopropylacrylamide) (PNIPAAm) chains were grown from the carbon black surface by a surface-induced reversible addition-fragmentation chain transfer (SI-RAFT) polymerization. FT-IR, ¹H NMR, TGA, TEM, and dynamic light scattering were used to characterize the carbon black grafted with poly(N-isopropylacrylamide) (CB-g-PNIPAAm). Dispersion experiment showed that CB-g-PNIPAAm had a good solubility in water. ¹H NMR, AFM and dynamic light scattering measurements showed that CB-g-PNIPAAm behaved a reversible temperature-responsive property in water.     

Association behaviors of poly(<Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone)-grafted fullerenes in aqueous solution

Poly(N-vinylpyrrolidone) (PVP)-grafted fullerenes (PVP-C₆₀ and PVP-C₇₀) were synthesized by iniferter polymerization in order to fabricate water-soluble fullerene containing micelles. PVP-C₆₀ formed micelles with hydrodynamic diameters ranging from 15 to 33 nm. The solubilization of fullerene molecules into the core of the PVP-C₆₀ micelles was also found to control the size of the micelles. By increasing the amount of added fullerene, we gradually increased the micelle size before drastically increasing it to that of 200 nm in hydrodynamic diameter. The drastic change occurred at a critical value of the added C₆₀/PVP monomer ratio, almost independently of the molecular weight of PVP.     

Theoretical phase diagram calculation and membrane morphology evaluation for water/solvent/polyethersulfone systems

Theoretical ternary phase diagrams with very good agreement with experimental cloud point data were constructed for water/N,N-dimethylacetamide (DMAc)/polyethersulfone (PES) and water/N-methyl-2-pyrrolidone (NMP)/polyethersulfone systems. Theoretical phase diagrams were determined based on the extended Flory-Huggins theory of polymer solutions. To construct the theoretical phase diagrams, all binary interaction parameters were determined accurately and thoroughly revisited. Also, the structures of membranes prepared of these systems by phase separation process were investigated. The morphological studies showed that in spite of better miscibility between water and DMAc compared to water and NMP, channel-like structures were observed in membranes prepared of water/NMP/PES systems but tear-like structures with more spongy areas were observed in membranes prepared of water/DMAc/PES system. According to the constructed theoretical ternary phase diagrams of these systems, these unexpected observations were attributed to the higher concentration of polymer in the polymer-rich phase of water/DMAc/PES system, which causes an early vitrification in this system which suppresses the growth of macrovoids.     

N-1-alkylitaconamic acids-co-styrene copolymers. Surface characterization

A serie of six N-1-alkylitaconamic acids-co-styrene copolymers with alkyl groups varying in side chain length from 3 to 12 was used in this study. The surface behaviour of the copolymers has been studied as function of the side chain length. Contact angle data for two of these copolymer surfaces were obtained in water and several liquids. From this information the surface energy was determined. Differences in the wettability of N-1-alkylitaconamic acid-co-styrene are found. The results are discussed in terms of hydrophobic and polar effect of the copolymers. Results on spread monolayers characteristics of these copolymers on water surfaces are also reported. Surface pressure-area (π-A) isotherms on a pure water subphase exhibit a transition region depending on the length of the alkyl side chain of the itaconamic acid moiety. It was also analyzed the phase transition in the monolayer at the air/water interface by brewster angle microscopy (BAM). Molecular mechanics approach was used to obtain predictions about the local interaction energies between segments. It was possible to conclude that the local interaction energies of propyl and decyl derivatives are quite similar while the hexyl derivative has higher interaction energy. The analysis of the coulombic energies together with the dispersion van der Waals energies (VDW) would be indicative, in first approximation, that carbonyl groups are more exposed in the case of propyl than in the other copolymers studied.     

Quinone–amine polymers. VI. Syntheses and solubilities of several cooligomers (paqs) produced by reacting two diamines with p-benzoquinone

The solubilities of some polyamine–;quinone oligomers (PAQs) derived from various diamines were found to be incredibly low. Ethylene-diamine–p-benzoquinone products were insoluble in all 34 solvents used in assessing solubilities of polymers. Syntheses of copolymers/cooligomers of an amine yielding insoluble product with another that produces highly soluble amine were attempted. The increase in the solubilities of these copolymers/cooligomers as well as their appearances suggest that it is possible to produce PAQs from two different diamines.     

Synthesis and Antibacterial Activity of Novel Amido-Amine-Based Cationic Gemini Surfactants

A series of novel cationic gemini surfactants were synthesized from corresponding amido-amines in a single step reaction. The amido-amines were obtained from long chain carboxylic acids and 3-N,N-dimethylamino-1-propyl-amine with excellent isolated yield (up to 95 %). All the synthesized quaternary ammonium compounds (QACs) were further investigated for surface active properties. The critical micelle concentration (CMC) and the effectiveness of surface tension reduction were determined. The surface tension measurements of newly synthesized gemini surfactants showed good water solubility, and low CMC values, had great efficiency in lowering the surface tension and a strong adsorption at the air/water interface than the corresponding monomeric surfactants. Further, the antibacterial activity of the synthesized QACs against both Gram-positive and Gram-negative bacteria was also investigated.     

Copolymers of N-alkylacrylamides and styrene as new thermosensitive materials

New thermosensitive copolymers were obtained by copolymerization of styrene with N-methylacrylamide, N-ethylacrylamide or N,N-dimethylacrylamide. The turbidity measurements showed that these polymers can undergo a thermally induced phase transition at various temperatures, depending on their chemical composition, molecular weight and concentration in water. Fluorescence measurements indicated the occurrence of aggregation through hydrophobic interactions even below the lower critical solution temperature. The enthalpy and cooperativity of phase transition determined by microcalorimetry were strongly dependent on the chemical structure of the N-alkylacrylamide comonomer.     

Composite membranes from polyacrylonitrile with poly(N,N-dimethylaminoethyl methacrylate)-grafted silica nanoparticles as additives

Polyacrylonitrile (PAN)-based composite membranes were prepared by immersion precipitation method by using poly(N,N-dimethylaminoethyl methacrylate)-grafted silica (PDMAEMA@SiO₂) nanoparticles as hydrophilic additives. The molecular weight of PDMAEMA were controlled by the surface initiated atom transfer radical polymerization of N,N-dimethylaminoethyl methacrylate on SiO₂ nanoparticles. The synthesized nanoparticles have a typical core–shell structure as characterized in detail by FT-IR, TEM, DLS and GPC. The prepared PAN-based composite membranes have higher porosity and water permeation flux than those of the pure PAN membranes. They also show high rejection (⩾90%) to bovine serum albumin and high flux recovery ratio (⩾90%) to water permeation. These improved performances are attributed to the good hydrophilicity of PDMAEMA@SiO₂ nanoparticles. The results suggest that PDMAEMA@SiO₂ nanoparticles are suitable for the property optimization of PAN-based composite membranes.     

In situ monitoring of sorption and drying of polymer films and coatings: self-referencing, nearly temperature-independent fluorescence sensors

Sorption and drying processes were monitored in situ in polymer films by a fluorescence rotor probe, 4-tricyanovinyl-[N-(2-hydroxyethyl)-N-ethyl]aniline (TC1), a solvatochromatic fluorescence probe, 4-(N,N-dimethylamino)-4′-nitrostilbene (DANS), and pyrene. Taking advantage of an intensity ratio to monitor sorption, these fluorescence probes were found to serve as self-referencing sensors of water sorption in polyvinylacetate, with DANS being the most sensitive followed by TC1 and pyrene. Additionally, the shapes of the emission spectra (and thus intensity ratios) for TC1 and DANS were independent of temperature over a range of reasonable expected use temperatures. Covalent attachment of these fluorescence dyes was shown to enable the determination of sorbate levels within particular layers of multilayer films or coatings. Finally, these probes were also shown to provide sensitivity to desorption or drying of both water and organic sorbates.     

Synthesis,Surface Activities and Toluene Solubilization by Amine-oxide Gemini Surfactants

A series of amine-oxide gemini surfactants featuring amide groups [N, N’-dimethyl-N, N’-bis(2-alkylamideethyl)-ethylenediamine oxide (alkyl = C₁₁H₂₃, C₁₃H₂₇, C₁₅H₃₁, C₁₇H₃₅)] have been synthesized via a three-step synthetic route, and their chemical structures were confirmed by mass spectra, FTIR and ¹H-NMR spectra. The surface activities of these compounds have been measured. The results show that these synthesized amine-oxide gemini surfactants reduced the surface tension of water to a minimum value of approximately 26.91 mN m^?1 at a concentration of 2.92 × 10^?5mol L^?1. Furthermore, their critical micelle concentration (CMC) values and solubilization of toluene decrease with an increase of the hydrophobic chain length from 12 to 18. Isoelectric point measurements revealed that their pI values range from 4.0 to 10.5.