Abstract  π-A isotherms, atomic force microscopy (AFM), and sum frequency generation (SFG) vibrational spectroscopy are employed to investigate the molecular structure and lateral interactions in mixed monolayers of dioctadecyldimethylammonium chloride (DOAC) and stearyl alcohol (SA) at air/water and air/solid interfaces. To avoid possible interference between the two molecules in the SFG spectroscopic measurements, perprotonated DOAC and perdeuterated SA (dSA) were used. The thermodynamic analyses for the π-A isotherms show that DOAC is miscible with dSA. SFG observations reveal that DOAC molecules become conformationally ordered as dSA molecules are introduced into the monolayer. AFM observations demonstrate coexistence of DOAC-rich and dSA-rich domains in the mixed monolayer with ratios different from their initial composition in the subphase. The present study suggests that DOAC molecules in the mixed monolayer are condensed by mixing with dSA in which the repulsive interactions between positively charged head groups of the DOAC molecules are largely reduced along with an increase of van der Waals interactions with dSA.

Abstract  To reveal the effects of particle size distributions on flame propagation mechanism during octadecanol dust explosions clearly, the flame propagation through dust clouds with three different particle size distributions in an open space were recorded using an approach combined by high-speed photography and band-pass filter. From the direct light emission photographs and CH emission photographs, it has been demonstrated in the experiments that the flame front structures were changed as varying the particle size distributions. Flame propagated in the dust cloud with a smaller particle size was characterized by a regular shape and spatially continuous combustion zone structure, which was similar to the premixed gas explosions. On the contrary, when flame propagated through the dust cloud with a larger particle size, discrete blue luminous spots appeared surrounding the yellow luminous zone. Further increase in diameter resulted mostly in the appearance of blue spot flames and the disappearance of yellow luminous zone in the flame propagation process. Additionally, a simple mathematical model was developed to determine the critical particle size to illustrate the different flame propagation mechanisms in octadecanol dust explosions. (C) 2013 Elsevier B.V. All rights reserved.

Abstract  A valid assessment of selective aerobic degradation on organic matter (OM) and its impact on OM-based proxies is vital to produce accurate environmental reconstructions. However, most studies investigating these effects suffer from inherent environmental heterogeneities. In this study, we used surface samples collected along two meter-scale transects and one longer transect in the northeastern Arabian Sea to constrain initial OM heterogeneity, in order to evaluate selective aerobic degradation on temperature, productivity and alteration indices at the sediment-water interface. All of the studied alteration indices, the higher plant alkane index, alcohol preservation index, and diol oxidation index, demonstrated that they are sensitive indicators for changes in the oxygen regime. Several export production indices, a cholesterol-based stanol/stenol index and dinoflagellate lipid- and cyst-based ratios, showed significant (more than 20%) change only over the lateral oxygen gradients. Therefore, these compounds do not exclusively reflect surface water productivity, but are significantly altered after deposition. Two of the proxies, glycerol dibiphytanyl glycerol tetraether-based TEX86 sea surface temperature indices and indices based on phytol, phytane and pristane, did not show any trends related to oxygen. Nevertheless, unrealistic sea surface temperatures were obtained after application of the TEX86, TEX86L, and TEX86H proxies. The phytol-based ratios were likely affected by the sedimentary production of pristane. Our results demonstrate the selective impact of aerobic organic matter degradation on the lipid and palynomorph composition of surface sediments along a short lateral oxygen gradient and suggest that some of the investigated proxies may be useful tracers of changing redox conditions at the sediment-water interface.

Abstract  In order to obtain a novel prescription to treat scald, a new ointment was assessed. The ointment was made of pepsin soluble collagen (PSC), Bletilla striata polysaccharide (CBSP), lentinan, 1-octadecanol, dodecyl sodium sulfate, white vaseline, methyl hydroxybenzoate, propyl hydroxybenzoate, propylene glycol and distilled water. Experiment involving mice with their biochemical assays was used to evaluate the suitability of the ointment. The ointment which include by 1.5 g PSC, 1.5 g CBSP, 1.5 g lentinan, 20 g 1-octadecanol, 1.46 g dodecyl sodium sulfate, 23 g white vaseline, 0.025 g methyl hydroxybenzoate, 0.015 g propyl hydroxybenzoate, 11 g propylene glycol, and 40 g distilled water is optimal ointment. The scar outcomes rate all reach 100.00% in ointment group and model group. However, the ointment group of scar outcomes rate is higher than model group in the tenth day. The ointment 1, 2 and 3 group can significantly improve the activity of superoxide dismutase, increase the content of monoamine oxidase and reduce the content of malondialdehyde. The ointment had no influence on the body mass, the relative organ mass, blood hematology and serum biochemical indices of the mice. The results of the study indicated that the ointment can be used to treat scalds on mouse, increase the rate of the scar outcome and promote scald heal.

Abstract  Aerobic oxidation of a thin film of octadecanol at 105 degrees C and ambient pressures to its corresponding carbonyl derivatives (a mixture of aldehyde and carboxylic acid) was for the first time performed over a flat-model (i.e. two-dimensional), silicon wafer-supported metallic silver catalyst. The experimental set-up was extraordinary simple. An open-to-the-atmosphere glass beaker was used as reactor. Just enough octadecanol was placed on the silicon-supported catalytic surface to cover it with a thin film when melted. Reaction progress was monitored by ATR-FTIR analyses to identify the appearance of octadecanal and octadecanoic acid carbonyl stretching peaks at 1730 and 1710 cm(-1) respectively. The successful demonstration of this simple approach in studying catalysed small-molecule condensed organic reactions opens a new avenue towards simplified catalytic mechanistic studies of such processes. The catalyst was prepared by spin coating silver nitrate on a flat silicon wafer with (100) surface orientation, pretreated to have 4-5 silanol (-Si-OH) groups per nm(2). Reduction by hydrogen at 350 degrees C afforded metallic silver particles on the two-dimensional support at a nominal surface concentration of ca. 21-23 silver atoms/nm(2). XPS differentiation between the catalyst precursor, AgNO3. and the metallic silver catalytic surface required use of the Auger MNN kinetic energies. TEM studies of the active catalyst showed no serious aggregation of metallic Ag particles occurred during reduction. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  Purpose: To ascertain the influence of paraffin, white soft paraffin and pre-hydrated white soft paraffin on the viscosity of a cream formulated with a corticosteroid. Methods: The formulations were prepared via homogenization with variable velocity in the range 3300 4000 rpm. Individual series of preparations contained the same proportion of macrogol cetostearyl alcohol, cetyl alcohol, stearyl alcohol, sorbitan stearate, propylene glycol, metyl parahydroxybenzoate, propyl parahydroxybenzoate and water. The semi-solid preparations were assessed by viscometric and microscopic methods. Results: The viscosity of the samples measured ranged from 13050 to 15660 mPas. The particles in dispersed phase sized from 15 to 90 mu m. Within the multiple emulsion, the continuous phase included fine particles with diameter < 5 mu m. Change of the liquid paraffin used from Ondina 934 to Vara 600P significantly decreased the viscosity of the formulation. Several phases within the formulations were distinguished microscopically. Increased viscosity was observed in formulations with increasing proportion of white soft paraffin. Conclusion: Both the ratio of liquid paraffin to white soft paraffin, as well as the initial hydration of white soft paraffin influenced the viscosity of the cream as well as the diameter of particles in the dispersed phase.

Abstract  In the present work some stability studies on Supported Liquid Membranes (SLMs) to be used for chiral separations were realized. In particular, primary aim was to determine how a modification of the support surface influences the SLM stability. First, the procedure for support modification was optimised, making a screening of various compounds (sulphuric acid, nitric acid, chromic acid, sodium dodecyl sulphate (SDS), glycerol, oleic alcohol, propylene glycol (PPG), bovine serum albumin (BSA)) and testing their performance by means of contact angle measurements. Next, a second screening was realized by permeation tests in a stirred cell. Finally, to compare the stability of modified with unmodified support in a process of interest for chemical and/or biochemical industries, some permeation tests for resolution of DNB-DL-Leucine were realized in a re-circulation system. Results showed a better surface hydrophilization of chemically modified support and better stability of the sulphonated support. However, in operating conditions a little high stability of the unmodified support was obtained.

Abstract  Systematically synthetic zinc 3-hydroxymethyl-131-oxo-chlorins esterified by different linear alcohols (methanol, 1-propanol, 1-hexanol, 1-dodecanol and 1-octadecanol) at the 17-propionate were self-assembled in the presence of cetyltrimethylammonium bromide in an aqueous solution. These zinc chlorins exhibited red-shifted Qy absorption bands and circular dichroism (CD) signals in the corresponding Qy region after incubation for 17h, indicating that the zinc chlorins formed self-aggregates like those in natural chlorosomes of green photosynthetic bacteria. Visible absorption and CD spectra of self-aggregates of the zinc chlorins depended on the length of their esterifying alcohols. Zinc chlorins esterified by shorter alcohols gave larger changes in their visible absorption and CD spectra after incubation above 40 degrees C, whereas zinc chlorins esterified by longer alcohols afforded smaller changes. These results indicate that hydrophobic interaction among esterifying chains of chlorin molecules as well as that between the esterifying chains and peripheral surfactants or lipids play an important role in the stability of chlorosomal self-aggregates.

Abstract  Breflate is a water soluble prodrug developed to facilitate parenteral administration of the investigational antineoplastic agent brefeldin A (BFA). Previously, using analytical methods based upon reversed-phase high performance liquid chromatography (HPLC) with low wavelength UV detection or gas chromatography (GC) with electron capture detection following derivatization with heptafluorobutyrylimidazole, it was demonstrated that breflate undergoes rapid and efficient conversion to BFA following bolus i.v. injection in mice and dogs. However, plasma concentrations of the drug and prodrug achieved during the administration of nontoxic doses of breflate to beagle dogs as a 72 h continuous i.v. infusion were undetectable (< 0.1 microgram ml-1) by these methods. The sensitivity and specificity required for therapeutic drug level monitoring were achieved by GC with selected-ion mass spectrometry (MS) detection. Breflate, BFA and 1-eicosanol, the latter added to the sample as an internal standard (IS), were extracted from plasma into tert-butyl methyl ether (TBME) and esterified with trifluoroacetic anhydride. Methanol was added to the reaction mixture to effect the convenient removal of excess reagent as the volatile methyl ester during evaporation of the solvent. The residual material was analyzed directly upon reconstitution by capillary GC with automated splitless injection. Electron-ionization (70 eV) MS detection was performed by sequentially scanning ions at m/z 58, 202 and 325. The lowest concentration of either analyte quantified with acceptable reproducibility, as defined by an inter-day R.S.D. of about 20%, was near 10 ng ml-1 in plasma using a sample volume of 100 microliters. The assay has proven to be sufficiently sensitive, specific and reproducible for the routine analysis of pharmacokinetic specimens acquired during IND (investigational new drug)-directed toxicology studies in dogs.

Abstract  Scanning tunneling microscopy (STM) images of 1-docosanol, 1-docosanethiol, didocosyl disulfide, and 1-chlorooctadecane on graphite are compared. The images of the 1-docosanethiol and didocosyl disulfide show bright spots which are attributed to the positions of the S-H and S-S functional groups. The STM images of the 1-docosanol and 1- chlorooctadecane do not show such bright spots. The fact that both the S-H and S-S groups appear bright in the STM images indicates that the presence of an S atom on graphite results in a higher tunneling current when the tip scans over it compared to the tunneling current over a C, O, or Cl atom. The different behavior of the S atoms compared to the O, C, and Cl atoms is discussed in terms of the interactions between these atoms and the underlying graphite substrate. The persistent brightness of S atoms in the images of molecular adsorbates suggests that sulfur may serve as a useful ''chromophore'' for molecules imaged by STM.

Abstract  A new derivatization procedure to increase the sensitivity of electrospray ionization mass spectrometry (ESI-MS) to non-ethoxylated and ethoxylated alcohols was investigated. The analytes were oxidized with chromium(VI) oxide and the resulting carboxylic and ethoxy-carboxylic acids were isolated by extraction with ethyl acetate; the extracts were alkalinized and infused into the ESI-MS system working in the negative-ion mode. The yields of the combined oxidation-extraction were ca. 100% for non-ethoxylated fatty alcohols dissolved in acetone and they decreased moderately in samples containing increasing amounts of water (e.g., a 75% yield was obtained with 50% water). Ethoxylated alcohols with more than two ethylene oxide units resulted in yields of ca. 60%. Low limits of detection (LODs) were obtained when the procedure was applied to the analysis of body-care products and cosmetics containing fatty alcohols, e.g., in a varicose-vein cream, the LODs were 25 microg cetyl alcohol and 7.5 microg stearyl alcohol (detected as palmitic acid and stearic acid, respectively) per gram of sample. High molecular mass alcohols were also detected in seawater after pre-concentration by solid-phase extraction. Thus, the proposed method is particularly valuable for use in industrial samples having complex matrices and in environmental samples and it is competitive with other methods for the analysis of trace amounts of fatty alcohols.

Abstract  Continuous butanol/isopropanol fermentation with immobilized Clostridium isopropylicum was performed in a downflow column reactor using molasses as the substrate. In order to prevent product inhibition and at the same time obtain high concentration of the products, the column reactor was coupled with a pervaporation module using a supported liquid membrane. The liquid membrane was prepared with oleyl alcohol nontoxic to the microorganism. In comparison with the continuous fermentation without product removal, the specific butanol production rate was 2 times higher. The butanol concentration in the permeate was 230 kg/m(3), which was about 50 times higher than that in the culture broth. A numerical investigation suggested a further increase in the productivity by improving the module construction.

Abstract  Emulsion copolymerization of vinyl chloride with vinyl acetate comonomer was performed. Potassium persulfate, a mixture of stearyl alcohol and sodium lauryl sulfate, was used and reactions were performed at 55 degrees C in a pressurized reactor. By sampling during the reaction in different intervals copolymer composition was investigated using FTIR and NMR spectroscopy. The results showed that the partitioning of vinyl acetate in the copolymerization in general follows the Mayo-Lewis copolymerization equation with some discrepancy. This was attributed to the gaseous nature of vinyl chloride monomer and the differences between polymerization in heterogeneous and homogeneous systems. Both FT - IR and NMR spectroscopy showed two peaks in vinyl acetate content of copolymer beyond 65% conversion which was attributed to the elimination of vinyl chloride droplets in the media and replacing them with vinyl acetate monomer. The first increase is related to the consumption of vinyl chloride droplets and the second is related to the consumption of gaseous vinyl chloride; in both instances vinyl acetate governs the polymerization.

Abstract  Experiments concerning the effect of shear flow on the turbidity of a colloidal dispersion close to its gas-liquid critical point are described. Theory predicts that in the mean-field region, the turbidity of the sheared syst em relative to that of the quiescent dispersion is a function of a single dimensionless group lambda that is proportional to gamma xi(-4) (gamma is the shear rate and xi(-1) is the correlation length of the quiescent dispersion at the given temperature). Experiments are found to be in accordance with this scaling behavior. Moreover, the experiments confirm the theoretically predicted lambda dependence. As a model colloidal system, we used spherical silica particles coated with stearyl alcohol. When dissolved in benzene, these colloidal particles attract each other, due to the fact that benzene is a marginal solvent for the stearyl coating. These attractions give rise to a gas-liquid critical point.

Abstract  Rosewood tree has high adaptability to environment and tolerance to water stress, and a long history of utilization and plantation in many countries. However, researches on Rosewood were mostly focused on the biomass analyses and utilizations of its wood, and lacked those to analyze the chemical components of extractives of Rosewood leaves, which was very important to recover and utilize the polluting waste Rosewood leaves. Therefore, the chemical components of benzene/ethanol extractives of Rosewood leaves were analyzed by method of GC/MS in order to identify top value-added bioactive components from waste leaves of Rosewood tree. The analytical result showed that the main components of benzene/ethanol extractives of freeze-dried Rosewood leaves by GC/MS analysis were identified 16 constituent (16 peaks) as: Ethanol, 2-butoxy- (40.36%), 2-O-Methyl-D-mannopyranosa (18.22 %), Hydrazine, 1,1-dipropyl- (6.09%), 1-Docosanol (5.59%), 1-Eicosanol (5.28%), Oxirane, hexadecyl- (3.63%), trans-2,4,5-Trimethoxy-center dot beta center dot-methyl- (3.50%), Bicyclo[3.1.1]heptane, 2,6,6-trimethyl- (2.53%), 9,12,15-Octadecatrienoic acid, methyl- (2.43%), Tetratetracontane (2.31%), Hexadecane, 1-(ethenyloxy)- (2.27%), Cholan-24-oic acid, 7,12-bis(acetyloxy)-3-ethoxy-, methyl ester, (3.alpha.,5.beta.)- (2.10%), Hexatriacontane (2.02%), Phytol (1.76%), Octadecane, 1-chloro (1.08%), etc. As the first report here, our result by GC/MS showed that the benzene-methanol extractive of freeze-dried Rosewood leaves can be developed into top value-added materials of medicines, biofuel, and industrial solvents.

Abstract  A method for varying the supersaturation in a turbulent mixing CNC has been used to examine heterogeneous nucleation of different compounds (working fluid) on various nuclei's compositions. Supersaturation was controlled by changing the vapor pressure of working fluid in nozzle flow, which was accomplished by saturating only a predetermined fraction of the flow while the keeping the total flow and temperature constant. This approach allows the partial pressure of the working fluid to be varied while maintaining a constant flow structure and temperature field. Experimental results characterizing the initial stages of heterogeneous nucleation are presented for NaCl, KCl, AgCl, and Ag particles. Heterogeneous nucleation was examined at various pressures of dibutylphthalate, octadecane, octadecanol, and octadecanoic acid. For octadecanoic acid as the working fluid, the size distribution of the grown particles is unimodal with the size increasing with increasing pressure of the working fluid. For the other working fluids, the initial size distribution splits into a bimodal distribution with one mode approximately the same as the initial distribution and a larger sized mode that grows with increasing pressure of the condensing vapor. For NaCl and octadecane and octadecanol, the initial unimodal size distribution splits into a trimodal size distribution.

Abstract  We developed an oil/water-type tacrolimus (FK506) cream formulation as an alternative to Protopic ointment for atopic dermatitis treatment. We determined the effects of solvents used in topical preparations on FK506 solubility and stability, and evaluated FK506 transdermal absorption into rat skin from solutions, emulsions, and creams. Screening indicated that diethyl sebacate (DES), isopropyl myristate (IPM), propylene glycol (PG), and oleyl alcohol (OA) were adequate FK506 solvents. When FK506 solutions prepared using these solvents were transdermally administered, AUC(0-24) values for DES and IPM were higher than or similar to that for 0.1% Protopic ointment. The AUC(0-24) values for PG and OA were low, so these solvents did not enhance absorption. The residual ratios of FK506 in DES and IPM solutions after incubation at 70 degrees C for 9 d were 95.6% and 88.6%, respectively, so DES and IPM were chosen for emulsion preparation. When the emulsions were transdermally administered, the IPM emulsion AUC(0-24) values increased 4.6-fold; DES emulsions did not show high transdermal absorption, but showed sustained characteristics. A cream formulation prepared by mixture of IPM and DES also showed high absorption and transdermal absorption increased with increasing IPM ratio. We developed an FK506 cream formulation with a controllable transdermal absorption rate by manipulating the IPM: DES ratio. (C) 2014 Elsevier B.V. All rights reserved.

Abstract  The effects of various vehicles on percutaneous absorption of ketoprofen in a solution formulation and in a pressure-sensitive adhesive (PSA) matrix were evaluated. The permeation rate of ketoprofen across hairless mouse skin was evaluated using a flow-through diffusion cell system at 37 degrees C. The solubility of ketoprofen was determined using the equilibrium solubility method. Among tested vehicles, octanol, ethanol, and propylene glycol (PG)/oleyl alcohol (OA) mixture showed the highest flux of 30 mu g/cm(2) per h from 5 mg/ml solution. However, it was not possible to demonstrate any correlation between the solubility of ketoprofen and its permeation rate, indicating change in the barrier property of the skin and/or carrier mechanism by vehicles used. When the effects of various vehicles on the percutaneous absorption of ketoprofen from acrylic PSA matrix were evaluated, oleic acid showed a slightly higher flux of 2 mu g/cm(2) per h than all other solvents tested. As the concentration of ketoprofen in acrylic PSA matrix increased from 6.3 to 16.7%, the permeation rate also increased almost linearly. The permeation rate of ketoprofen from polyisobutylene (PIB)-type PSA matrix was more than three times higher than that from acrylic PSA matrix. (C) 1998 Elsevier Science B.V. All rights reserved.

Abstract  In this study, the integrated in situ extraction-gas stripping process was coupled with continuous ABE fermentation using immobilized Clostridium acetobutylicum. At the same time, oleyl alcohol was cocurrently flowed into the packed bed reactor with the fresh medium and then recycled back to the packed bed reactor after removing butanol in the stripper. A high glucose consumption of 52 g/L and a high butanol productivity of 11 g/L/h were achieved, resulting in a high butanol yield of 0.21 g-butanol/g-glucose. This can be attributed to both the high bacterial activity for solvent production as well as a threefold increase in the bacterial density inside the packed bed reactor. Also reported is that 64 % of the butanol produced can be recovered by the integrated in situ extraction-gas stripping process. A high butanol productivity and a high glucose consumption were simultaneously achieved.

Abstract  PURPOSE: Microemulsion (ME) systems allow for the microscopic co-incorporation of aqueous and organic phase liquids. In this study, the phase diagrams of four novel ME systems were characterized.

METHODS: Water and IPM composed the aqueous and organic phases respectively, whereas Tween 80 served as a nonionic surfactant. Transdermal enhancers such as n-methyl pyrrolidone (NMP) and oleyl alcohol were incorporated into all systems without disruption of the stable emulsion.

RESULTS: A comparison of a W/O ME with an O/W ME of the same system for lidocaine delivery indicated that the O/W ME provides significantly greater flux (p < 0.025). The water phase was found to be a crucial component for flux of hydrophobic drugs (lidocaine free base, estradiol) as well as hydrophilic drugs (lidocaine HCl, diltiazem HCl). Furthermore, the simultaneous delivery of both a hydrophilic drug and a hydrophobic drug from the ME system is indistinguishable from either drug alone. Enhancement of drug permeability from the O/W ME system was 17-fold for lidocaine free base, 30-fold for lidocaine HCl, 58-fold for estradiol, and 520-fold for diltiazem HCl.

CONCLUSIONS: The novel microemulsion systems in this study potentially offers many beneficial characteristics for transdermal drug delivery.

Abstract  Sodium hyaluronate (HYA) warrants attention as a material for inhalation due to its (i) therapeutic potential, (ii) utility as a formulation excipient or drug carrier, and (iii) ability to target lung inflammation and cancer. This study aimed to overcome formulation and manufacturing impediments to engineer biocompatible spray-dried HYA powders for inhalation. Novel methodology was developed to produce HYA microparticles by spray drying. Different types of surfactant were included in the formulation to improve powder respirability, which was evaluated in vitro using cascade impactors. The individual formulation components and formulated products were evaluated for their biocompatibility with A549 respiratory epithelial cells. The inclusion of stearyl surfactants, 5% w/v, produced the most respirable HYA-powders; FPF 59.0-66.3%. A trend to marginally higher respirability was observed for powders containing stearylamine>stearyl alcohol>cetostearyl alcohol. Pure HYA was biocompatible with A549 cells at all concentrations measured, but the biocompatibility of the stearyl surfactants (based on lethal concentration 50%; LC50) in the MTT assay ranked stearyl alcohol>cetostearyl alcohol>stearylamine with LC50 of 24.7, 13.2 and 1.8μg/mL, respectively. We report the first respirable HYA powders produced by spray-drying. A lead formulation containing 5% stearyl alcohol was identified for further studies aimed at translating the proposed benefits of inhaled HYA into safe and clinically effective HYA products.

Abstract  The interactions between colloidal particles immersed in solutions of a nonadsorbing polymer are of interest in a variety of applications such as paint and ink formulations and mineral processing, In this Letter we report the use of an atomic force microscope to study the interaction forces between a silica particle (of radius 3.8 mu m) and a planar silica surface, both bearing a terminally grafted n-octadecyl alcohol sheath (SiO2-C-18), mediated by cyclohexane solutions of poly(dimethyl siloxane) (PDMS). The experimental results are consistent with theories of the depletion interaction between hard, chemically inert surfaces in the presence of free (nonadsorbing) polymer in solution. The length of the measured (attractive) interaction was commensurate with the radius of gyration of the PDMS sample used, and the magnitude of the force increased with increasing polymer concentration. As the surfaces closely approached each other, a short-range steric interaction was observed as the opposing octadecyl chains came into contact, and this interaction was independent of the free polymer concentration. (C) 1995 Academic Press, Inc.

Abstract  Biodegradable thermoplastic oligomers have potential as biomaterials for tissue augmentation and drug-delivery applications. One means of obtaining such a biomaterial is through the ring-opening polymerization of E-caprolactone using an alcohol initiator. In this paper we continue to examine the influence of the structure of the initiator used on the thermal and rheological properties of oligo(epsilon-caprolactone). Specifically, primary and secondary pentanol, and cis- and trans-pentenol were studied as initiators in the preparation of oligomers of constant molecular weight. In agreement with previous work. the secondary conformer yielded higher inch viscosities, lower degrees of crystallinity and lower glass transition temperatures. The cis conformer produced the lowest melt viscosity: however. the activation energy for flow was hi-her than obtained previously with oleyl alcohol. This result was attributed to the alkane chain lengths on either side of the cis double bond in the initiator. The order of melt viscosity increased with initiator conformer as follows: cis, trans, primary and secondary. The results were explained in terms of oligomer chain flexibility in the melt.

Abstract  End functionalized poly(propylene oxide)s with n-alkyl endgroups are synthesized by anionic ring opening polymerization of propylene oxide (PO) in bulk employing controlled microwave heating in sealed vessels. Different alcohols ranging from n-butanol to n-octadecanol are used as initiator and 2-10 propylene oxide units are added on average. A continuous decrease of internal pressure during the sealed vessel experiment reflects the consumption of PO monomer and the completion of the reaction is confirmed by a drop of the internal pressure to zero. The products are characterized by size exclusion chromatography (SEC), liquid chromatography at critical conditions (LCCC) and liquid adsorption chromatography (LAC). SEC with coupled density and refractive index (RI) detection provides information on the chemical composition along the molar mass distribution. LCCC allows a separation of the individual polymer homologous series according to their end groups. In LAC, the alkyl terminated chains elute later than the non-functional chains and can be separated to the baseline according to the number of repeat units. (c) 2007 Elsevier Ltd. All rights reserved.

Abstract  In this work, fatty acid and its derivatives were adopted as lubricity additives for low sulfur diesel. Tribological evaluation obtained from the High-Frequency Reciprocating Rig (HFRR) apparatus showed that the lubricating performance of the additives increased in the following order: stearic acid>glycol monopalmitate>stearyl alcohol>ethyl palmitate>cetyl ethyl ether. The adsorption behavior of the additives on Fe (110) surface and Fe2O3 (001) surface was investigated by molecular dynamics (MD) simulations to verify their lubricity performance. The results suggested that adsorption energies of the additives on Fe (110) surface are determined by the van der Waals forces, while adsorptions on Fe2O3 (001) surface are significantly attributed to the electrostatic attractive forces. Higher values of adsorption energy of the additives on Fe2O3 (001) surface indicate that the additive has more efficient lubricity enhancing properties.