Ureasil-polyether hybrid film-forming materials

The objectives of this work were to study the suitability and highlight the advantages of the use of cross-linked ureasil-polyether hybrid matrices as film-forming systems. The results revealed that ureasil-polyethers are excellent film-forming systems due to specific properties, such as their biocompatibility, their cosmetic attractiveness for being able to form thin and transparent films, their short drying time to form films and their excellent bioadhesion compared to the commercial products known as strong adhesives. Rheological measurements have demonstrated the ability of these hybrid matrices to form a film in only a few seconds and Water Vapor Transmitting Rate (WVTR) showed adequate semi-occlusive properties suggesting that these films could be used as skin and wound protectors. Both the high skin bioadhesion and non-cytotoxic character seems to be improved by the presence of multiple amine groups in the hybrid molecules. © 2012 Elsevier B.V.

Elevated levels of PFOS and PFHxS in firefighters exposed to aqueous film forming foam (AFFF)

Exposure to aqueous film forming foam (AFFF) was evaluated in 149 firefighters working at AFFF training facilities in Australia by analysis of PFOS and related compounds in serum. A questionnaire was designed to capture information about basic demographic factors, lifestyle factors and potential occupational exposure (such as work history and self-reported skin contact with foam). The results showed that a number of factors were associated with PFAA serum concentrations. Blood donation was found to be linked to low PFAA levels, and the concentrations of PFOS and PFHxS were found to be positively associated with years of jobs with AFFF contact. The highest levels of PFOS and PFHxS were one order of magnitude higher compared to the general population in Australia and Canada. Study participants who had worked ten years or less had levels of PFOS that were similar to or only slightly above those of the general population. This coincides with the phase out of 3M AFFF from all training facilities in 2003, and suggests that the exposures to PFOS and PFHxS in AFFF have declined in recent years. Self-reporting of skin contact and frequency of contact were used as an index of exposure. Using this index, there was no relationship between PFOS levels and skin exposure. This index of exposure is limited as it relies on self-report and it only considers skin exposure to AFFF, and does not capture other routes of potential exposure. Possible associations between serum PFAA concentrations and five biochemical outcomes were assessed. The outcomes were serum cholesterol, triglycerides, high-density lipoproteins, low density lipoproteins, and uric acid. No statistical associations between any of these endpoints and serum PFAA concentrations were observed.

Performance of thin film carbon materials and carbon nanotubes as cold cathodes

The field emissions from three different types of carbon films are studied using a Kiethly voltage-current source-measure unit under computer control. The three types of carbon films are : 1) a-C:H:N deposited using an inductively coupled rf PECVD process, where the N content in the films can be as high as 30 at %; 2) cathodic arc deposited tetrahedral amorphous carbon with embedded regions of carbon nanotube and anion structures and 3) unoriented carbon nanotube films on a porous substrate. The films are formed by filtering a solution of nanotubes dispersed in alcohol through the pores and drying.

Rational Design, Synthesis, and Optical Properties of Film-Forming, Near-Infrared Absorbing, and Fluorescent Chiromophores with Multidonors and Large Heterocyclic Acceptors

A new series of film-forming, low-bandgap chromophores (1a,b and 2a,b) were rationally designed with aid of a computational study., and then synthesized and characterized. To realize absorption and emission above the 1000 nm wavelength, the molecular design focuses on lowering the LUMO level by fusing common heterocyclic units into a large conjugated core that acts an electron acceptor and increasing the charge transfer by attaching the multiple electron-donating groups at the appropriate positions of the acceptor core. The chromophores have bandgap levels of 1.27-0.71 eV, and accordingly absorb at 746-1003 nm and emit at 1035-1290 nm in solution. By design, the relatively high molecular weight (up to 2400 g mol(-1)) and non-coplanar structure allow these near-infrared (NIR) chromophores to be readily spin-coated as uniform thin films and doped with other organic semiconductors for potential device applications. Doping with [6,6]-phenyl-C-61 butyric acid methyl ester leads to a red shift in the absorption on]), for la and 2a. An interesting NIR electrochromism was found for 2a, with absorption being turned on at 1034 nm when electrochemically switched (at 1000 mV) from its neutral state to a radical cation state. Furthermore, a large Stokes shift (256-318 nm) is also unique for this multidonor-acceptor type of chromophore.

THE EFFECT OF FILM-FORMING CONDITIONS FOR TAPCUPC LANGMUIR-BLODGETT-FILMS ON MORPHOLOGY AND PROPERTIES

The dependence of morphology and properties on film-forming conditions is described for the symmetrically substituted copper tetra-4-(2, 4-di-t-amylphenoxy) phthalocyanine (tapCuPc) Langmuir-Blodgett (LB) films. The effects of LB film-forming conditions (such as the surface pressure, pH value and the concentrations of spreading solutions) on film quality were studied with the help of a UV-visible spectrophotometer and a transmission electron microscope. Transmission electron microscopy photographs of the surface morphology of tapCuPc LB films show that a smooth and homogeneous surface structure can be obtained under optimum film-forming conditions.

The influence of commercial film-forming polymers on reducing salt spray injury in evergreen oak (Quercus ilex L.) and laurel (Prunus laurocerasus L.)

A field trial was undertaken to determine the influence of four commercially available film-forming polymers (Bond [alkyl phenyl hydroxyl polyoxyethylene], Newman Crop Spray 11E™ [paraffinic oil], Nu-Film P [poly-1-p menthene], and Spray Gard [di-1-p menthene]) on reducing salt spray injury on two woody species, evergreen oak (Quercus ilex L.) and laurel (Prunus laurocerasus L.). Irrespective of species, the film-forming polymers Nu-Film-P and Spay Gard did not provide any significant degree of protection against salt spray damage irrespective of concentration (1% or 2%) applied as measured by leaf chlorophyll concentrations, photosynthetic efficiency, visual leaf necrosis, foliar sodium and chloride content, and growth (height, leaf area). The film-forming polymer Newman Crop Spray 11E™ provided only 1-week protection against salt spray injury. The film-forming polymer Bond provided a significant (P < 0.05) degree of protection against salt spray injury 3 months after application as manifest by higher leaf chlorophyll content, photosynthetic efficiency, height and leaf area, and lower visual leaf necrosis and foliar Na and Cl content compared with nontreated controls. In conclusion, results indicate that application of a suitable film-forming polymer can provide a significant degree of protection of up to 3 months against salt spray injury in evergreen oak and laurel. Results also indicate that when applied at 1% or 2% solutions, no problems associated with phytotoxicity and rapid degradation on the leaf surface exist.

Evaluation of film forming polymers to control apple scab (Venturia inaequalis (Cooke) G. Wint.) under laboratory and field conditions

A detached leaf bioassay was used to determine the influence of several film forming polymers and a conventional triazole fungicide on apple scab (Venturia inaequalis (Cooke) G. Wint.) development under laboratory in vitro conditions, supported by two field trials using established apple cv. Golden Delicious to further assess the efficacy of foliar applied film forming polymers as scab protectant compounds. All film forming polymers used in this investigation (Bond, Designer, Nu-Film P, Spray Gard, Moisturin, Companion PCT12) inhibited germination of conidia, subsequent formation of appressoria and reduced leaf scab severity using a detached leaf bioassay. Regardless of treatment, there were no obvious trends in the percentage of conidia with one to four appressoria 5 days after inoculation. The synthetic fungicide penconazole resulted in the greatest levels of germination inhibition, appressorium development and least leaf scab severity. Under field conditions, scab severity on leaves and fruit of apple cv. Golden Delicious treated with a film forming polymer (Bond, Spray Gard, Moisturin) was less than on untreated controls. However, greatest protection in both field trials was provided by the synthetic fungicide penconazole. Higher chlorophyll fluorescence Fv/Fm emissions in polymer and penconazole treated trees indicated less damage to the leaf photosynthetic system as a result of fungal invasion. In addition, higher SPAD values as measures of leaf chlorophyll content were recorded in polymer and penconazole treated trees. Application of a film forming polymer or penconazole resulted in a higher apple yield per tree at harvest in both the 2005 and 2006 field trials compared to untreated controls. Results suggest application of an appropriate film forming polymer may provide a useful addition to existing methods of apple scab management. (C) 2008 Elsevier Ltd. All rights reserved.

Film-forming polymers containing in the main-chain dibenzo crown ethers with aliphatic (C-10-C-16), aliphatic-aromatic, or oxyindole spacers

Novel, linear, soluble, high-molecular-weight, film-forming polymers and copolymers in which main-chain crown ether units alternate with aliphatic (C-10-C-16) units have been obtained for the first time from aromatic electrophilic substitution reactions of crown ethers by aliphatic dicarboxylic acids followed by reduction of the carbonyl groups. The crown ether unit is dibenzo-18-crown-6, dibenzo-21-crown-7, dibenzo-24-crown-8, or dibenzo-30-crown-10; the aliphatic spacer is derived from a dicarboxylic acid (sebacic, 1,12-dodecanedicarboxylic, hexadecanedioic or 1,4-phenylenediacetic acids). The reactions were performed at 35 degrees C in a mixture of methanesulfonic acid (MSA) with phosphorus pentoxide, 12:1 (w/w), (Eaton's reagent). The carbonyl groups in the polyketones obtained were completely reduced to methylene linkages by treatment at room temperature with triethylsilane in a mixture of trifluoroacetic acid and dichloromethane. Polymers containing in the main chain crown ethers alternating with oxyindole fragments were prepared by one-pot condensation of crown ethers with isatin in a medium of Eaton's reagent. A possible reaction mechanism is suggested. According to IR and NMR analyses, the polyacylation reactions lead to the formation of isomeric (syn/anti-substituted) crown ether units in the main chain. The polymers obtained were soluble in the common organic solvents, and flexible transparent films could be cast from the solutions. DSC and X-ray studies of the polymers with "symmetrical" crown ethers reveal the presence of the endotherms corresponding to the supramolecular assemblies.

Film forming solutions based on gelatin and poly(vinyl alcohol) blends: Thermal and rheological characterizations

The objective of this work was to study the theological and thermal properties of film forming solutions (FFS) based on blends of gelatin and poly(vinyl alcohol) (PVA). The effect of the PVA concentration and plasticizer presence on the flow behavior, and viscoelastic and thermal properties of FFS was studied by steady-shear flow and oscillatory experiments, and also, by microcalorimetry. The FB presented Newtonian behavior at 30 degrees C, and the viscosity was not affected neither by the PVA concentration nor by the plasticizer. All FFS presented a phase transition during tests applying temperature scanning. It was verified that the PVA affected the viscoelastic properties of FFS by dilution of gelatin. This behavior was confirmed by microcalorimetric analysis. The behaviors of the storage (G`) and loss (G ``) moduli as a function of frequency of FFS obtained at 5 degrees C were typical of physical gels; with the G` higher than the G ``. The strength of the gels was affected by the PVA concentration. (C) 2009 Elsevier Ltd. All rights reserved.

Anti-erosive properties of solutions containing fluoride and different film-forming agents

Objectives: To evaluate the anti-erosive potential of solutions containing sodium fluoride (NaF, 225 ppm F) and different film-forming agents.Methods: In Phase 1, hydroxyapatite crystals were pre-treated with solutions containing NaF (F), linear sodium polyphosphate (LPP), sodium pyrophosphate tetrabasic (PP), sodium tripolyphosphate (STP), sodium caseinate (SC), bovine serum albumin (BSA), stannous chloride (Sn) and some combinations thereof. Deionized water was the control (C). The pH-stat method was used to evaluate hydroxyapatite dissolution. In Phase 2, the most effective solutions were tested in two independent experiments. Both consisted of an erosion-remineralization cycling model using enamel and dentine specimens with three solution treatments per day. In Phase 2a, the challenge was performed with 0.3% citric acid (pH = 3.8). In Phase 2b, 1% citric acid (pH = 2.4) was used. Hard tissue surface loss was determined profilometrically. Data were analyzed with two-way ANOVA and Tukey tests.Results: In Phase 1, F, LPP, Sn and some of their combinations caused the greatest reduction in hydroxyapatite dissolution. In Phase 2a, C showed the highest enamel loss, followed by LPP. There were no differences between all other groups. In Phase 2b: (F + LPP + Sn) < (F + LPP) = (F + Sn) < (F) = (LPP + Sn) < (LPP) < (Sn) < C. For dentine, in both experiments, only the fluoride-containing groups showed lower surface loss than C, except for LPP + Sn in 2a.Conclusions: F, Sn, LPP reduced enamel erosion, this effect was enhanced by their combination under highly erosive conditions. For dentine, the F-containing groups showed similar protective effect.Clinical significance: The addition of LPP and/or Sn can improve the fluoride solution protection against erosion of enamel but not of dentine. (C) 2015 Elsevier Ltd. All rights reserved.

Mechanisms of drying of skin forming materials

The literature relating to evaporation from single droplets of pure liquids, and to the drying of droplets containing solids and of droplet sprays has been reviewed. The heat and mass transfer rates for a single droplet suspended from a nozzle were studied within a 42mm I.D. horizontal wind tunnel designed to supply hot dry air, to simulate conditions encountered in a practical spray dryer. A novel rotating glass nozzle was developed to facilitate direct measurements of droplet weight and core temperature. This design minimised heat conduction through the nozzle. Revised correlations were obtained for heat and mass transfer coefficients, for evaporation from pure water droplets suspended from a rotating nozzle. Nu = 2.0 + 0.27 (l/B)°-18Re°-5Pr°-83 Sh = 2.0 + 0.575 ((T0-T.)/Tomfc) -o.o4Reo.5 ^0.33 Experimental drying studies were carried out on single droplets of different types of skin-forming materials, namely, custard, gelatin, skim milk and fructose at air temperatures ranging from 19°C to 198°C. Dried crusts were recovered and examined by Scanning Electron Microscopy. Skin-forming materials were classified into three types according to the mechanisms of skin formation. In the first type (typified by droplets of custard and starch) skin formed due to gelatinisation at high temperatures. Increasing the drying temperature resulted in increased crust resistance to mass transfer due to increased granule swelling and the crust resistance was completely transferred to a skin resistance at drying temperatures > 150°C. In the second type e.g. gelatin droplets the skin formed immediately drying had taken place at any drying temperature. At drying temperature > 60° C a more resistant skin was formed. In the third type (typified by droplets of skim milk and fructose) the skin appeared on the droplet surface at a certain stage of the drying process under any drying conditions. As the drying temperature was increased the resistance of the skin to mass transfer increased. The drying rate history of any material depended upon the nature of the skin formed which, in turn, depended upon the drying conditions. A mathematical model was proposed for the drying of the first type of skin-forming material. This was based on the assumption that, once all the granules gelatinised at the gelatinisation temperature, a skin appeared instantaneously on the droplet surface. The experimentally-observed times at which the skin appeared on the droplets surfaces were in excellent agreement with those predicted from the model. The work should assist in understanding the fundamentals of paniculate drying processes, particularly when skin-formation occurs and may be a crucial factor in volatiles retention.

Photorefractive performance of a novel multifunctional inorganic-organic hybridized nanocomposite sensitized by CdS nanoparticles

A novel multifunctional inorganic-organic photorefractive (PR) poly(N-vinyl)-3-[p-nitrophenylazolcarbazolyl-CdS nanocomposites with different molar ratios of US to poly(N-vinyl)-3-[p-nitrophenylazo]carbazolyl (PVNPAK) were synthesized via a postazo-coupling reaction and chemically hybridized approach, respectively. The nanocomposites are highly soluble and could be obtained as film-forming materials with appreciably high molecular weights and low glass transition temperature (T,) due to the flexible spacers. The PVNPAK matrix possesses a highest-occupied molecular orbital value of about -5.36 eV determined from cyclic voltammetry. Second harmonic generation (SHG) could be observed in PVNPAK film without any poling procedure and 4.7 pm/V of effective second-order nonlinear optical susceptibility is obtained. The US particles as photosensitizers had a nanoscale size in PVNPAK adopting transmission electron microscopy. The improvement of interface quality between US and polymer matrix is responsible for efficient photoinduced charge generation efficiency in the nanocomposites. An asymmetric optical energy exchange between two beams on the polymer composites PVNPAK-CdS/ECZ has been found even without an external field in two-beam coupling (TBC) experiment, and the TBC gain and diffraction efficiency of 14.26 cm(-1) and 3.4% for PVNPAK-5-CdS/ECZ, 16.43 cm(-1) and 4.4% for PVNPAK-15-CdS/ECZ were measured at a 647.1 nm wavelength, respectively.

Effects of sensing temperature on the NO2-sensing properties of octa-iso-pentyloxymetallonaphthalocyanine spin-coated films

A kind of 1,6,10,15,19,24,28,33-octa-iso-pentyloxy-2,3-metallonaphthalocyanines complexes MNc(iso-PeO)(8) (M = Co, Cu, Pd) are used as spincoating film-forming materials. The surface morphologies of the films prepared were studied first. These films were then used for the experiments of NO2 sensing. The effects of sensing temperature as well as the NO concentration on the sensing properties were studied. The experimental results showed that the three MNc(iso-PeO)(8) films were uniform, smooth and dense. Due to the different metal ions (M) on the center of naphthalocyanine, the CoNc(iso-PeO)(8) film had a higher film resistance and response-recovery rate in the NO2 sensing experiments. On the contrary, the response to NO2 of the PdNc(iso-PeO)(8) and CuNc(iso-PeO)(8) films were superior to that of CoNc(iso-PeO)(8). By varying the sensing temperature, it was found that the elevation of sensing temperature could improve the sensing response, recovery ratio, and sensitivity of the sensing films. At high concentrations of NO2, the response time became shorter. (c) 2007 Elsevier B.V. All rights reserved.