Collective and self-diffusion coefficients in an ionic critical mixture: 3-methylpyridine+water+NaBr

The dynamics of concentration fluctuations of three critical samples of the 3-methylpyridine (3MP)+water+NaBr system have been measured by photon correlation spectroscopy. The collective-diffusion coefficient D shows the usual Ising behavior near the critical temperature T(c). However, as |T-T(c)| increases, the dynamic correlation length calculated from D, xi, takes values higher than the correlation length of the critical fluctuations calculated from static light scattering, xi(s). At the largest |T-T(c)| measured, xi approaches the value, xi(0,d) approximately equal to 1.13 nm, while the amplitude of xi(s) is xi(0,s)=0.38 nm. Pulsed-gradient NMR spectroscopy points out the existence of two dynamic contributions. One of them is consistent with the existence of molecular entities of hydrodynamic radius 0.31 nm, while the other one indicates the existence of aggregates rich in 3MP of radius 1.16 nm. The existence of the aggregates may explain the apparent anomalous behavior of the dynamic light scattering experiments for this system far from the critical point.     

Small-angle X-ray scattering and rheological characterization of aqueous lignosulfonate solutions

Lignosulfonate is a colloidal polyelectrolyte widely used as a dispersant in various industrial applications and produced during chemical pulping of wood chips. Here we present a systematic small-angle X-ray scattering (SAXS) and rheological study of fractionated lignosulfonate (mass weighted molar mass M w 18 000 g/mol) dissolved in water and 0.2 M NaCl. The concentration range varied from semidilute to concentrated regime. SAXS intensity of all solutions followed the Porod law at all concentrations, which is a clear indication of a compact shape of the lignosulfonate particle. In water, below 10 mass % lignosulfonate, the average interparticle distance obtained from SAXS patterns relates to concentration via a power law with exponent -0.28. Deviation of the power law exponent from ideal -0.33 and a linear decrease in volume fraction normalized Porod constant as a function of concentration are taken as indications of self-association of lignosulfonate. In saline solutions at high lignosulfonate mass fractions the average distance between lignosulfonate particles was longer and the average particle size was larger than those in aqueous solutions. The intrinsic viscosity in saline solution also was larger than that in aqueous solution. Lignosulfonate solutions showed Newtonian viscosity, except at very high concentrations. The variation of the relative zero-shear viscosity eta(0),r) with concentration was interpreted with the Krieger-Dougherty equation. An oblate spheroid shape with an axial ratio of 3.5 describes the average shape of the lignosulfonate particles in saline solutions based on SAXS intensities, the size distribution obtained using gel permeation chromatography, and rheological characterization. The largest dimension of the particles was about 8 nm. SAXS and rheology studies as a function of temperature reveal indications of temperature-dependent self-association.     

Microstructure and structural transition in microemulsions stabilized by aldonamide-type surfactants

Significant efforts were undertaken to characterize the microstructure and structural properties of water-in-oil (w/o), oil-in-water (o/w), and bicontinuous (bc) microemulsions composed of N-alkyl-N-methylgluconamides (n-alkyl = n-C(12)H(25), n-C(14)H(29), n-C(16)H(33)) and n-alcohols (ethanol, n-propanol, n-butanol) or iso-alcohols (iso-propanol, iso-butanol) as cosurfactants, as well as iso-octane and water. The internal structure of so created four-component system was elucidated by means of an analysis of isotropic area magnitudes in phase diagrams and conductivity measurements. Dynamic light scattering (DLS) measurements provided the microemulsion size and polydispersity. Polarity and viscosity of microemulsion microenvironment were acquired by means of electron paramagnetic resonance (EPR), UV-vis absorption spectroscopy (in the case of w/o droplets), and steady-state fluorescence (SSF) (in the case of o/w droplets). The results show that both the surfactant and the cosurfactant types affect the shape and extent of microemulsions. The size of droplets depends strongly on the type of examined microemulsion and the type of cosurfactant (linear or brunched) but is almost independent of the length of the surfactant alkyl chain. The size of microemulsion droplets ranges from 8.1 to 22.6 nm and from 3.7 to 14.3 nm respectively, for o/w and o/w microemulsions, making them good candidates for both template-based reactions and household components solubilizing media.     

Lubrication theory of drag on a scanning probe in structured water, near a hydrophilic surface

The drag is evaluated, in lubrication theory, on a parabolic-cylindrical tip moving parallel to a flat sample, in water, close enough that the presumed nanometer-thick, structured-water, "interphase" coatings of both it and the sample overlap. Assuming coatings of width, w, and of viscosity, eta, much larger than bulk water's, the friction force is predicted to equal -2pietacRphi(D/2w), where R is the tip's radius of curvature, c is its speed, D is the tip-sample separation, and Phi is a universal function whose value only differs noticeably from ln(2w/D) for D < w.     

Nanorheology of dioctyl phthalate confined between surfaces coated with long alkyl chains

To shed light on the mechanism related to the high viscosity of a precipitated calcium carbonate (PCC) dispersion in dioctyl phthalate (DOP), the viscosity of DOP in a nanometer space was investigated using the shear resonance measurement. We used mica surfaces modified with dioctadecyldimethylammonium bromide (DODA) as a model of a PCC surface which bears long alkyl chains and bare mica surfaces as a reference. We found that a resonance peak for DOP of high water content (1164 ppm) confined between the DODA-modified surfaces gradually decreased upon approach from a distance of 320.6 nm and disappeared at ca. 57 nm. This indicated that the viscosity of DOP increased with decreasing distance, and a highly ordered state appeared at a large separation of 57 nm. This highly ordered state, however, cannot be observed for DOP of low water content (469 ppm) confined between the DODA-modified surfaces. The resonance peak for DOP of high water content (1164 ppm) between bare mica surfaces gradually decreased upon approach from a distance of 358.4 nm and disappeared at 10.7 nm, which is much shorter than the value for the DODA-modified surfaces. These results could be correlated with the high macroscopic viscosity of a dispersion of PCC coated with long alkyl chains in DOP. We propose the interpenetration of the long alkyl chains and the hydrogen-bonding network of DOP molecules mediated by water molecules as a plausible model for interpreting the high viscosity of coated PCC dispersions.     

Paclitaxel loaded poly (DL lactic acid co castor oil) 60:40 with poloxamer‐F68 rod shape cylindrical nanoparticle preparation and in vitro cytotoxicity studies

This research presents a thin‐film hydration‐solvent evaporation method to formulate the paclitaxel loaded poly (DL lactic acid co castor oil) 4:6 with poloxamer‐F68 cylindrical shape nanoparticles. The particles were less than 250 nanometers (nm) in size, with an average width of 60 nm and an average length of 100 nm. The percent yield, encapsulation efficiency (EE), and percent drug loading (DL) were detected. This approach produces drug loading values between 5% and 20% w/w. X‐ray powder diffraction (XRD) identified the physicochemical properties of nanoparticles differential scanning calorimetry (DSC) and Fourier‐transform infrared spectroscopy (FTIR). The investigation shows that the drug is molecularly dispersed in polymers or given in an amorphous or semicrystalline state. Horizontal water bath shaker technology considered the in vitro release of PTX loaded nanoparticles under sink conditions. Poly (DL lactic acid co castor oil) 4:6 nanoparticles exhibited a sustained release analysis. At the end of 30 hours, the percent cumulative drug release from the formulations was between 74.52% and 92.87% for F1 and F4. In vitro cytotoxicity assays indicate that PTX having p (DLLA:CO60:40) nanoparticles have a higher cytotoxic effect on MCF‐7/ADR.     

Thermostable biocatalytic films of enzymes and polylysine on electrodes and nanoparticles in microemulsions

Microemulsions of oil, water and surfactant were evaluated as media for biocatalysis at high temperatures employing films of polylysine (PLL) and the enzymes horseradish peroxidase (HRP), soybean peroxidase (SBP) and the protein myoglobin (Mb). PLL was covalently linked to oxidized pyrolytic graphite electrodes or carboxylated 500 nm diameter silica nanoparticles, then cross-linked by amidization to HRP, SBP and Mb. The resulting film systems were stable at 90 degrees C for >12 h in microemulsions. Characterization of the microemulsions by conductivity, viscosity and probe diffusion coefficients suggested that these media have bicontinuous microstructures from 25 to 90 degrees C. UV circular dichroism and visible spectroscopy confirmed that the enzymes retained near-native conformation in the films at temperatures as high as 90 degrees C. Oxidation of o-methoxyphenol to 3,3'-dimethoxy-4,4'-biphenoquinone by enzyme-PLL films on silica nanoparticles gave yields 3-5-fold larger in microemulsions at 90 degrees C compared to the same reaction at 25 degrees C. The best yields were in CTAB microemulsions and were 3-fold larger than in buffers at 90 degrees C.     

Fluorescence ratiometry and fluorescence lifetime imaging: using a single molecular sensor for dual mode imaging of cellular viscosity

Intracellular viscosity strongly influences transportation of mass and signal, interactions between the biomacromolecules, and diffusion of reactive metabolites in live cells. Fluorescent molecular rotors are recently developed reagents used to determine the viscosity in solutions or biological fluid. Due to the complexity of live cells, it is important to carry out the viscosity determinations in multimode for high reliability and accuracy. The first molecular rotor (RY3) capable of dual mode fluorescence imaging (ratiometry imaging and fluorescence lifetime imaging) of intracellular viscosity is reported. RY3 is a pentamethine cyanine dye substituted at the central (meso-) position with an aldehyde group (CHO). In nonviscous media, rotation of the CHO group gives rise to internal conversion by a nonradiative process. The restraining of rotation in viscous or low-temperature media results in strong fluorescence (6-fold increase) and lengthens the fluorescence lifetime (from 200 to 1450 ps). The specially designed molecular sensor has two absorption maxima (λ(abs) 400 and 613 nm in ethanol) and two emission maxima (in blue, λ(em) 456 nm and red, 650 nm in ethanol). However it is only the red emission which is markedly sensitive to viscosity or temperature changes, providing a ratiometric response (12-fold) as well as a large pseudo-Stokes shift (250 nm). A mechanism is proposed, based on quantum chemical calculations and (1)H NMR spectra at low-temperature. Inside cells the viscosity changes, showing some regional differences, can be clearly observed by both ratiometry imaging and fluorescence lifetime imaging (FLIM). Although living cells are complex the correlation observed between the two imaging procedures offers the possibility of previously unavailable reliability and accuracy when determining intracellular viscosity.     

Counterion associative behavior with flexible polyelectrolytes

At low ionic strength, organic counterions dress a flexible charged polymer as measured directly by small-angle neutron scattering and neutron spin-echo spectroscopy. This dressed state, quantified by the concentration dependence of the static correlation length, illustrates the polymer-counterion coupled nature on the nanometer length scale. The counterions, made visible by selective hydrogen and deuterium labeling, undress from the polymeric template by addition of sodium chloride. The addition of this electrolyte leads to two effects: increased Debye electrostatic screening and decoupled organic counterion-polymer correlations. Neutron spin-echo spectroscopy measures a slowing down of the effective diffusion coefficient of the labeled counterions at the length scale of 8 nm, the static correlation length, indicating the nanosecond counterion dynamics mimics the polymer. These experiments, performed with semidilute solutions of tetramethylammonium poly(styrene sulfonate) [(h-TMA(+)) d-PSS], apply to relevant biopolymers including single and double stranded DNA and unfolded proteins, which undergo orchestrated dynamics of counterions and chain segments to fold, unfold, and assemble.     

导电玻璃上室温沉积钛膜及TiO2纳米管阵列的制备与表征

在掺氟的杂nO2(FTO)导电玻璃衬底上采用射频磁控溅射的方法室温沉积纯Ti薄膜, 以NH4F/甘油为电解液, 经电化学阳极氧化得到结构有序、微米级的TiO2纳米管阵列/FTO复合结构, 并通过场发射扫描电子显微镜(FESEM)、X射线衍射(XRD)以及光电化学的方法对纳米管阵列进行了表征. 研究表明, 在氩气气压为0.5 Pa, 功率为150 W, 时间为0.5 h条件下在导电玻璃上室温沉积获得钛膜的结构为晶带T型组织, 表面均匀性好且致密度较高; 在电压为30 V下, 随着阳极氧化时间从1 h延长至3 h, 纳米管的管径从50 nm增加到75 nm, 纳米管的长度从750 nm增至1100 nm后减至800 nm, 管壁由平滑变为波纹状; 随氧化电压的升高, 纳米管管径逐渐增大, 而表面覆盖物逐渐减少, 可通过在稀的HF溶液(0.05%(w, 质量分数))中超声清洗去除; 此外, 瞬态光电流测试表明结晶的电极表现出更好的光电转换性能, 紫外光照射下能促进TiO2光生载流子有效分离, 在热处理温度为450 ℃时, 具有较高的光电化学性能.     

Scaling behavior of delayed demixing, rheology, and microstructure of emulsions flocculated by depletion and bridging

This paper describes an experimental comparison of microstructure, rheology, and demixing of bridging- and depletion-flocculated oil-in-water emulsions. Confocal scanning laser microscopy imaging showed that bridging-flocculated emulsions were heterogeneous over larger length scales than depletion-flocculated emulsions. As a consequence, G' as determined from diffusing wave spectroscopy (DWS) corresponded well with G' as measured macroscopically for the depletion-flocculated emulsions, but this correspondence was not found for the bridging-flocculated emulsions. The heterogeneity of bridging-flocculated emulsions was confirmed by DWS-echo measurements, indicating that their structure breaks up into large fragments upon oscillatory shear deformation larger than 1%. Depletion- and bridging-flocculated emulsions showed a different scaling of the storage modulus with the volume fraction of oil and a difference in percolation threshold volume fraction. These differences will be discussed on the basis of the two types of droplet-droplet interactions studied. Gravity-induced demixing occurred in both emulsions, but the demixing processes differed. After preparation of bridging-flocculated emulsions, serum immediately starts to separate, whereas depletion-flocculated systems at polysaccharide concentrations in the overlap regime usually showed a delay time before demixing. The delay time was found to scale with the network permeability, B; the viscosity, eta, of the aqueous phase; and the density difference between oil and water, Deltarho, as tdelay approximately B(-1)etaDeltarho(-1). The results are in line with the mechanism proposed by Starrs et al. (J. Phys.: Condens. Matter 2002, 14, 2485-2505), where erosion of the droplet network leads to widening of the channels within the droplet networks, facilitating drainage of liquid.     

Abnormal viscosity increment observed for an ionic liquid by dissolving lithium chloride

The effect of adding an inorganic salt, lithium chloride, and water on the viscosity of an ionic liquid, 1-n-butyl-3-methylimidazolium chloride (BmimCl), was investigated by shear stress measurements with a rheometer. The shear rate dependence of the viscosity showed shear thinning behavior, which implies that some structure should exist in the liquid and the structure should change at high shear rates. Addition of LiCl enhances the viscosity of BmimCl. The logarithmic value of zero-shear viscosity, eta(0), of BmimCl increases linearly and largely with increasing added salt content. The increasing rate of the viscosity by addition of LiCl was about 10 times larger than that for an aqueous solution of LiCl. When water is added into BmimCl, viscosity decreased. The increasing rate of the viscosity by addition of LiCl for BmimCl with about 5 wt % of water was almost the same as that for BmimCl without addition of water.     

Ion-induced multiply reentrant liquid-liquid transitions and the nature of criticality in ethanol-water mixture

We report a quite unusual feature of four liquid-liquid reentrant transitions in ethanol (E)+water (W)+ammonium sulfate mixture by meticulous tuning of the ammonium sulfate concentration in a narrow range, as a function of temperature, at atmospheric pressure. Detailed exploration of the intricate phase behavior in terms of E/W sections shows that the range of triple reentrance shrinks with increasing E/W. The behavior of osmotic susceptibility is investigated by light scattering, near the critical point, in the one-phase region by varying the temperature at fixed concentration of the components, in a particular E/W section. The critical exponent of susceptibility (gamma) and correlation length (nu) are observed to have Fisher renormalized Ising values [Phys. Rev. 176, 237 (1968)], with gamma(r)=1.41 and nu(r)=0.718. The effective susceptibility exponent, gamma(eff), exhibits a sharp, nonmonotonic crossover from Ising to mean-field critical behavior, which is completed outside the critical regime. The amplitude of the correlation length, xi(o)(=21.2+/-0.4 A), deduced from light scattering experiment, is an order of magnitude larger than the typical values in usual aqueous electrolyte systems. This value of xi(o) is further verified from small-angle x-ray scattering (SAXS) experiments and found to be consistent. SAXS experiments on the critical sample reveal the presence of long-ranged intermolecular correlations, leading to supramolecular structuring, at a temperature far away from the critical point. These results convincingly demonstrate that the finite length scale arising due to the structuring competes with the diverging correlation length of critical concentration fluctuations, which influences the nonasymptotic critical behavior in this aqueous electrolyte system. The sulphate ions play a dominant role in both structuring and the complex phase behavior.     

Association of methanol and water in ionic liquids elucidated by infrared spectroscopy using two-dimensional correlation and multivariate curve resolution

Water and methanol associations in ionic liquids (ILs) have been studied by means of FTIR spectroscopy. Spectra at different concentrations of water or methanol in ILs were obtained by means of on-line dilution using a flow injection analysis system. Spectral features in the OH stretching region revealed that most of the water and methanol molecules tended to be isolated from each other and to interact with the anion of the IL via H bonding. By means of two-dimensional correlation spectroscopy, the formation of methanol and water dimers was also detected. Multivariate curve resolution was used to recover pure spectra and concentration profiles of the different species. Methanol dimers form at concentrations higher than 0.8% (w/w) in the three studied ILs, 1-ethyl-3-methylimidazolium tetrafluoroborate (emimBF4), 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4), and 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6). Self-association of water molecules takes place in emimBF4 and bmimBF4 at a molar ratio similar to that of methanol molecules; however, water dimers cannot be detected in bmimPF6, the most hydrophobic IL studied. No evidence was found that bigger water clusters are formed in these ILs at the studied cosolvent concentrations.     

The use of NIR as a multi-parametric in situ monitoring technique in filamentous fermentation systems

The use of Fourier transform near infrared (FT-NIR) spectroscopy for simultaneous determination of multiple properties in an active pharmaceutical ingredient (API) fermentation process is described, together with procedures for developing accurate NIR calibrations with a performance independent of scale and the specific bioreactor used. Measurements were made in situ, by insertion of transflection probes into pilot and industrial bioreactors providing direct contact with the fermentation culture media. The ultimate goal was to establish methods for real time process monitoring aimed at enhanced process supervision, fault detection diagnosis and control of bioreactors. The in situ acquired spectra were related to lab results of samples taken from the reactors during the course of the manufacturing process. Suitable spectral wavenumber regions were selected and calibration models based on partial least squares (PLS) were developed. The root mean square errors of prediction for API content, viscosity, nitrogen source and carbon source concentration were all within acceptable ranges as compared to the off-line lab measurements, respectively, 0.03% (w/w), 150 cp, 0.01% (w/w), and 0.4% (w/w).     

Free volume in glassy poly(arylene ether ketone)s

Amorphous polyarylene ether ketones were examined in the glassy state by positron annihilation lifetime spectroscopy (PALS) and in the melt by standard rheological techniques. Specimens were well-characterized fractions of two isomeric structures. PALS clearly shows that the polymer with meta linkages in its backbone contains larger voids (> 0.25 nm radius). Thus despite their similar bulk densities, the two materials must pack very differently on a local scale. On the other hand, the free volumes inferred from the WLF treatment of melt viscosity data are practically identical in both materials ca. 4% at T_g. The comparison between techniques sheds some light on the distribution of free volume. © 1992 John Wiley & Sons, Inc.     

Optically transparent hydrogels from an auxin-amino-acid conjugate super hydrogelator and its interactions with an entrapped dye

Low-molecular-weight organic hydrogelators (LMHGs) that can rigidify water into soft materials are desirable in various applications. Herein, we report the excellent hydrogelating properties of a simple synthetic auxin-amino-acid conjugate, naphthalene-1-acetamide of L-phenylalanine (1-NapF, M(w)=333.38?Da), which gelated water even at 0.025?wt?%, thereby making it the most-efficient LMHG known. Optically transparent gels that exhibited negligible scattering in the range 350-900?nm were obtained. A large shift from the theoretical pK(a) value of the gelator was observed. The dependence of the minimum gelator concentration (MGC) and the gel-melting temperatures on the pH value indicated the importance of H-bonding between the carboxylate groups on adjacent phenylalanine molecules in the gelator assembly. FTIR spectroscopy of the xerogels showed a β-sheet-like assembly of the gelator. Variable-temperature (1)H?NMR spectroscopy demonstrated that π stacking of the aromatic residues was also partly involved in the gelator assembly. TEM of the xerogel showed the presence of a dense network of thin, high-aspect-ratio fibrillar assemblies with diameters of about 5?nm and lengths that exceeded a few microns. Rheology studies showed the formation of stable gels. The entrapment of water-soluble dyes afforded extremely fluorescent gels that involved the formation of J-aggregates by the dye within gel. A strong induced-CD band established that the RhoB molecules were interacting closely with the chiral gelator aggregates. H-bonding and electrostatic interactions, rather than intercalation, seemed to be involved in RhoB binding. The addition of chaotropic reagents, as well as increasing the pH value, disassembled the gel and promoted the release of the entrapped dye with zero-order kinetics.     

Low temperature conversion (LTC) of castor seeds—A study of the oil fraction (pyrolysis oil)

The low temperature conversion (LTC) process applied to a castor seed sample at 380 °C produced pyrolysis oil (50%, w/w), pyrolytic char (29%, w/w), water (13%, w/w) and gas (8%, w/w) fractions. The oil fraction was subjected to analysis of by FTIR, ¹H NMR, ¹³C NMR, GCMS and physical–chemical analysis such as sulfur content, distillation, density, flash-point, kinematic viscosity, Ramsbottom carbon residue, ash content, corrosivity to copper, water content and sediment, cold filter plugging point, and gross calorific value.     

Formulation and physicochemical characterization of imwitor 308 based self microemulsifying drug delivery systems

Self Microemulsifying Drug Delivery Systems (SMEDDS) are a novel alternative to the conventional transdermal delivery systems. SMEDDS are water-free systems, made up of oils and surfactants that can readily form a microemulsion upon dilution within an aqueous medium. Before SMEDDS can be used as a drug delivery system it is necessary to investigate the internal microstructure of the resulting microemulsion. Novel Imwitor 308 based SMEDDS were prepared and investigated. Phase behaviour of the comprising components was investigated through the construction of pseudoternary phase diagrams. The formed systems were characterized using visual inspection, measurement of electrical conductivity, viscosity and droplet size. Amongst the pseudoternary systems investigated, IPM/Cremophor EL (50% w/w)/Imwitor (50% w/w) and Myritol 318/Tween 85 (64% w/w)/ Transcutol P (20% w/w)/Imwitor (16% w/w) possessed the largest microemulsion area. Electrical conductivity and viscosity studies depict structural transitions from w/o microemulsion to bicontinuous or o/w microemulsion around 20-35% water. This was further supported by the droplet size and Fourier transform (FT)-IR measurements. The FT-IR data suggests that below the percolation threshold (ψ(C)) the water molecules are mainly bounded to the surfactant head group (bound water). Above this value, water molecule move to the outer phase of the microemulsion mainly interacting with each other though hydrogen bounding (free water). It was also found that pseudoternary systems with water content of less than 30% were stable at 32°C. Such systems may form stable microemulsion upon contact with the skin. Absorption of water may also result in a supersaturated solution with enhanced transdermal flux.     

Hydration and dewetting near fluorinated superhydrophobic plates

The water dynamics near nanoscale fluorinated (CF(3)(CF(2))(7)(CH(2))(2)SiH(3)) monolayers (plates) as well as possible dewetting transitions in-between two such plates have been studied with molecular dynamics simulations in this paper. A "weak water depletion" is found near the single fluorinated surface, with an average water density in the first solvation shells 6-8% lower than its hydrogenated counterpart. The fluorinated molecules are also found to be water impermeable, consistent with experimental findings. More surprisingly, a dewetting transition is found in the interplate region with a critical distance D(c) of 10 A (3-4 water diameters) for double plates with 8 x 8 molecules each (plate size approximately 4 nm x 4 nm). This transition, although occurring on a microscopic length scale, is reminiscent of a first-order phase transition from liquid to vapor. The unusual superhydrophobicity of fluorocarbons is found to be related to their larger size (or surface area) as compared to hydrocarbons, which "dilutes" their physical interactions with water. The water-plate interaction profile shows that the fluorinated carbons have a 10-12% weaker water-plate interaction than their hydrogenated counterparts in the nearest solvation shell, even though the fluorocarbons do have a stronger electrostatic interaction with water due to their larger partial charges. However, the van der Waals interactions dominate the water-plate interaction within the nearest shell, with up to 90% contributions to the total interaction energy, and fluorocarbons have a noticeably weaker (by 10-15%) van der Waals interaction with water in the nearest shell than do hydrocarbons. Both the slightly weaker water-plate interaction and larger surface area contribute to the stronger dewetting transition in the current fluorinated carbon plates.