Uptake Of Solvents Research Articles

Tailoring the properties of poly(vinyl alcohol) “twin-chain” gels via sebacic acid decoration

HypothesisThe development of gels capable to adapt and act at the interface of rough surfaces is a central topic in modern science for Cultural Heritage preservation. To overcome the limitations of solvents or polymer solutions, commonly used in the restoration practice, poly(vinyl alcohol) (PVA) “twin–chain” polymer networks (TC-PNs) have been recently proposed. The properties of this new class of gels, that are the most performing gels available for Cultural Heritage preservation, are mostly unexplored. This paper investigates how chemical modifications affect gels’ structure and their rheological behavior, producing new gelled systems with enhanced and tunable properties for challenging applications, not restricted to Cultural Heritage preservation. ExperimentsIn this study, the PVA-TC-PNs structural and functional properties were changed by functionalization with sebacic acid into a new class of TC-PNs. Functionalization affects the porosity and nanostructure of the network, changing its uptake/release of fluids and favoring the uptake of organic solvents with various polarity, a crucial feature to boost the versatility of TC-PNs in practical applications. FindingsThe functionalized gels exhibited unprecedented performances during the cleaning of contemporary paintings from the Peggy Gugghenheim collection (Venice), whose restoration with traditional solvents and swabs would be difficult to avoid possible disfigurements to the painted layers. These results candidate the functionalized TC-PNs as a new, highly promising class of gels in art preservation.

표면 개질된 Halloysite 나노튜브(mHNTs)가 EPDM/NBR 나노복합체의 기계적 물성 및 팽윤 거동에 미치는 영향

Ethylene-propylene-diene monomer/acrylonitrile-butadiene rubber (EPDM/NBR)-modified halloysite nanotubes (mHNTs) nanocomposites were prepared by two-roll mixing mill and vulcanization process. The mole percent uptake of some aromatic (toluene, xylene, benzene and mesitylene), aliphatic (n-hexane, n-heptane, n-octane and n-pentane) and chlorinated (chloroform, carbon tetrachloride and dichloromethane) solvents through mHNT filled EPDM/NBR nanocomposites has been investigated. The aim of the present work is to investigate the role of the cure characteristics, mechanical properties, abrasion resistance and swelling resistance in analysing the compatibility between rubber matrix and nanotubes and the reinforcing effect of mHNT as nanofiller in the EPDM/NBR matrix. The mole percent uptake of organic solvents via membranes has been explored in detail as a function of mHNT content, type of solvent, and temperature between 23 and 60 oCelsius. The findings revealed that mHNT could reduce scorch and optimum cure time in EPDM/NBR vulcanizates, as well as play a significant role in strengthening EPDM/NBR vulcanizates. Mechanical properties and swelling resistance were investigated and were found to increase with the increase of mHNT loading. The cross-link density values indicated the improved strengthening at 8 phr mHNT filler loading. In the rubber matrix, mHNT particles form a local filler–filler network at high concentrations. As a result, the composites

Facile Preparation of Cost‐Effective Triphenylamine‐Based Nanoporous Organic Polymers for CO2, I2, and Organic Solvents Capture

AbstractSeeking cost‐effective construction of nanoporous organic polymers for CO2 and I2 capture and organic solvents adsorption remains challenging. Two triphenylamine‐based nanoporous organic polymers, ANOP‐1 and ANOP‐2, have been prepared successfully by Friedel–Crafts (F–C) hydroxyalkylation from low‐cost triphenylamine (TPA) with commercial terephthalaldehyde and isophthalaldehyde, respectively. The effect of isomers of phenyl dialdehydes on the structure of porous architecture is investigated. The as‐prepared ANOPs exhibit a moderate uptake of CO2, I2, and organic solvents because of the electron‐rich TPA unit and nanometer‐scale pore size of <2 nm. These findings demonstrate that F–C hydroxyalkylation is a cost‐effective strategy for producing large amounts of triphenylamine‐enriched, high specific BET surface area materials to develop commercial organic materials for industrial use.

A Mechanical Analysis of Chemically Stimulated Linear Shape Memory Polymer Actuation.

In the present work, we study the role of programming strain (50% and 100%), end loads (0, 0.5, 1.0, and 1.5 MPa), and chemical environments (acetone, ethanol, and water) on the exploitable stroke of linear shape memory polymer (SMP) actuators made from ESTANE ETE 75DT3 (SMP-E). Dynamic mechanical thermal analysis (DMTA) shows how the uptake of solvents results in a decrease in the glass temperature of the molecular switch component of SMP-E. A novel in situ technique allows studying chemically triggered shape recovery as a function of time. It is found that the velocity of actuation decreases in the order acetone > ethanol > water, while the exploitable strokes show the inverse tendency and increases in the order water > ethanol > acetone. The results are interpreted on the basis of the underlying chemical (how solvents affect thermophysical properties) and micromechanical processes (the phenomenological spring dashpot model of Lethersich type rationalizes the behavior). The study provides initial data which can be used for micromechanical modeling of chemically triggered actuation of SMPs. The results are discussed in the light of underlying chemical and mechanical elementary processes, and areas in need of further work are highlighted.

All‐in‐One Bioinspired Multifunctional Graphene Biopolymer Foam for Simultaneous Removal of Multiple Water Pollutants

AbstractPolluted waters are complex systems with many different co‐existing contaminants that make their simultaneous removal a very challenging task. To address this problem, all‐in‐one ad/ab‐sorbent with unique combination of interfacial properties and multiple surface chemistry is developed to simultaneously and efficiently remove several pollutants including heavy metals, dyes, oils, and organic solvents. By mimicking the wetting micro‐topology of a darkling beetle with a combined hydrophilic‐hydrophobic surface, a new bioinspired adsorbent, graphene biopolymer foam (Alg‐Fe3O4‐rGO‐4S) for removal of multiple water pollutants is engineered by combining alginate (Alg) and reduced graphene oxide (rGO) functionalized with tetrathiol that is also decorated with iron oxide nanoparticles (Fe3O4). This concept is first proved by single pollutant removal, showing adsorption capacity of 789.7 ± 36 mg/g for methylene blue (MB), 107.0 ± 2.1 mg/g for Hg (II), 73.5 ± 0.7 mg/g for Cu (II), and rapid oil‐water separation with high sorption capacity (11–18 g/g). A remarkable performance for simultaneous removal of their mixtures in milli‐Q, river, and sea water is demonstrated with efficiency for MB (≈90%), Cu (II) (>99.99%) and Hg (II) (100%) and rapid (≈30 s) uptake of organic solvents and oils. The obtained results indicate a valuable potential of proposed concept for simultaneous removal of co‐existing water pollutants.

Facile synthesis of fluorine-free cellulosic paper with excellent oil and grease resistance

Fluorine-free cellulosic paper was successfully obtained by coating the glassine base paper with eco-friendly cellulosic coating, which was made from dissolving cellulose in 8 wt% NaOH/12 wt% urea aqueous solution. Then the coated paper was severally immersed into CH3COOH, Na2SO4, and H2O solution to coagulate and regenerate. Benefiting from the compact matrix and fully covered surface, the resultant cellulosic paper exhibited favorable barrier properties and mechanical performance. Notably, the paper coagulated with CH3COOH displayed the reduction in water–vapor transmission rate, air permeability, and uptake of organic solvents due to its low porosity (26.8%) and narrow pore size distribution (0.1–0.36 µm). The tensile strength and elongation at break of papers treated by CH3COOH at coating weight of 5 g/m2 were increased by 72.1% and 34.0%, respectively. In summary, the fluorine-free cellulosic paper with high oil and grease resistance is attractive for the development of high-performance materials for food packing applications. Fluorine-free paper was obtained from the glassine base paper coated with eco-friendly, non-fluorinated, and degradable cellulosic coating, then coagulated with CH3COOH, Na2SO4, and H2O solution, respectively. The resultant functional papers displayed enhanced barrier properties (oil, organic solvent, vapor, and gas) and mechanical performance.

Zwitterionic impetus on single lithium-ion conduction in solid polymer electrolyte for all-solid-state lithium-ion batteries

Single lithium-ion conducting solid polymer electrolytes (SLICSPEs) with high ionic conductivity play critical roles in pursuit of efficient and safe energy storage. Herein, we presented a universal and facile strategy towards high-performance SLICSPEs by applying representatively monomeric or polymeric zwitterions as synergistic ion dissociator and phase plasticizer for expedited single Li+ conduction in solid polymer matrix. It is manifested that the strong molecular interactions between zwitterions and SLICSPEs effectively facilitate the disintegration of Li+ from polyanionic backbone, while the impregnation of zwitterions simultaneously reduces the PEO crystallinity and increases the flexibility of EO segments, thus cooperatively promoting the Li+ mobility within the solid polymer matrix without expense of ion selectiveness. Attributed to these unique features, the as-developed SLICSPE achieved a considerable ionic conductivity of 8.39 × 10−5 S/cm at 90 °C without uptake of any organic solvents, as well as a high Li+ transference number approximately to unity, which further powered the decent cyclability and rate capability of the corresponding LiFePO4/SLICSPE/Li batteries, demonstrating a good promise in advancing the development of all-solid-state lithium ion batteries.

New single lithium ion conducting polymer electrolyte derived from delocalized tetrazolate bonding to polyurethane

In this work, a new class of single Li-ion conducting polyelectrolytes (SLICPs) were skillfully synthesized from highly delocalized lithium tetrazolate, polyethylene glycols (PEGs) and diisocyanates. The chemical composition of SLICPs was confirmed by FT-IR, NMR and XPS, and the physical and electrochemical properties were investigated with XRD, SEM, DSC, TG, EIS, LSV, etc. The results showed that the related properties could be tailored using various diisocyanates and PEGs, and the SLICPs comprising PEG1000 exhibited higher ionic conductivities and Li+ transference number. It was noted that the conductivity of SLICP prepared from isophorone diisocyanate, lithium tetrazolate and PEG 1000 (IPULi-1000) could be close to 1 × 10−4 S cm−1 at 80 °C without uptake of any organic solvents. Besides, the polymer electrolytes could endure an oxidation potential up to 4.2 V (vs. Li+/Li), and the stable cycle (more than 200 cycles for Li/Li symmetric cell at 30 °C) indicated that the developed SLICPs were compatible with lithium electrode. Hence, the developed SLICPs were promising solid polymer electrolytes materials for Lithium batteries.

Fabrication, rheological analysis, and in vitro characterization of in situ chemically cross‐linkable thermogels as controlled and prolonged drug depot for localized and systemic delivery

5‐Fluorouracil (5‐FU) is widely used against many types of solid cancer in clinics. However, because of its limitations such as short half‐life, poor oral absorption and rapid clearance by dihydropyrimidine dehydrogenase have limited its applications. In current study, new in situ chemically grafted thermogels for prolonged drug release are formed on the basis of poloxamer 407 (PF127) and carboxymethyl chitosan (CMCS) using glutaraldehyde as cross‐linking agent. The phase transition from sol to gel state at body temperature was confirmed by tube titling, rheological analysis, and optical transmittance determinations. Swelling and drug release experiments conducted at various pH and temperature demonstrated that developed formulations are thermoresponsive with maximum swelling and release below critical gelation temperature (CGT) (pH 7.4, 25°C). Cells growth inhibition study confirmed the biocompatibility of thermogels against L929 cell lines. Methyl thiazolyl tetrazolium (MTT) assay confirmed that 5‐FU–loaded thermogels have the potential to cause cells death against HeLa and MCF‐7 cancer lines. The IC50 values calculated for pure 5‐FU solution (27 ± 0.81 μg/mL for HeLa and 24 ± 0.58 μg/mL for MCF‐7) were found higher in comparison with 5‐FU–loaded thermogels, against HeLa (17 ± 0.39 μg/mL) and MCF‐7 (14 ± 0.67 μg/mL). Fourier transform infrared (FTIR) confirmed the new structure formation and chemical grafting between PF127 and CMCS. Thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses proved the phase transition around physiologic temperature range, while scanning electron microscopy (SEM) analysis displayed the presence of connected pores in the cross section of thermogels facilitating the uptake of solvents and drug particles. Altogether, results concluded that developed chemically grafted thermogels can be used in vivo for prolonged drug release after subcutaneous administration.

QCM detection of molecule-nanoparticle interactions for ligand shells of varying morphology.

Nanoparticles (NP) have widespread applications from sensing to drug delivery where much behavior is determined by the nature of the surface and the resulting intermolecular interactions with the local environment. Ligand mixtures enable continuously tunable behavior where both the composition and morphology influence molecular interactions. Mixed ligand shells form multiple morphologies ranging from Janus to patchy and stripe-like with varying domain dimensions. Solvent-NP interactions are generally measured by solubility measures alone. Here we develop a quartz crystal microbalance (QCM) approach to more broadly quantify molecule-NP interactions via vapor phase uptake into solid NP-films independent from solvation constraints. The composition and morphology of mixed ligand shells were found to exhibit pronounced non-monotonic behavior that deviated from continuum thermodynamics, highlighting the influence of ligand morphology upon absorption/adsorption. Alkyl and perfluorinated thiols were used as a model case with constant core-size distribution. The ligand morphology was determined by 19F NMR. Molecule uptake into NPs was measured with five benzene derivatives with varied degree of fluorination. For the cases examined, QCM measurements revealed enhanced uptake for patchy morphologies and suppressed uptake for stripe-like morphologies. These results contrast with insights from solubility measures alone where QCM sometimes identified significant molecular uptake of poor solvents. This QCM method thus provides new insights to molecule-NP interactions independent of the solvation shell.

A 4-fold interpenetrated diamondoid metal-organic framework with large channels exhibiting solvent sorption properties and high iodine capture

The characterisation of a 4-fold interpenetrated diamondoid metal-organic framework (MOF) {[Ni4(44pba)8]·sol}n, (1) (44pba = 4-(4-pyridyl)benzoate) is reported. The compound was prepared from Ni(II) and 44pba under solvothermal conditions. When activated to give 1d, the compound absorbs a wide range of solvents which is accompanied by a visible colour change. Sorption of water triggers an irreversible phase transformation, while adsorption of methanol, ethanol, benzene, dimethylformamide and cyclohexanone does not affect the structural integrity of the framework as revealed by powder X-ray diffraction studies. Apart from ethanol, the uptake of polar protic solvents gave rise to an increase in the energy difference between the asymmetric and symmetric carboxylate stretches as confirmed by infrared studies. We attributed this to a change in the binding mode of the carboxylates from chelating to monodentate. The activated phase (1d) was found to absorb high levels of iodine into its channels in comparison to other reported MOFs. This is due to the high porosity of the network compound in which aromatic walls allow for the interaction of iodine molecules with the framework walls.

Characterization of clay filled poly (butylene terephthalate) nanocomposites prepared by solution blending

Kaolin clay/poly (butylene terephthalate) (clay/PBT) composites films were prepared by solution casting technique. The scanning electron microscope (SEM) study showed that clay particles were well dispersed and embedded within the PBT matrix. The TGA thermograms showed that the thermal stability of PBT matrix was slightly improved by the incorporation of clay into the polymer matrix. The polarized optical microscopy (POM) study presented that the size of spherulites of PBT was decreased by the incorporation of clay into matrix, which might be due to nucleation effect of kaolin clay. The tensile strength and modulii of PBT polymer matrix were also significantly improved by the addition of clay polymer matrix. The solvent uptake study showed that the uptake of various solvents by clay/PBT nanocomposite were lower than neat PBT.

Transport properties of coconut shell powder (CSP)-reinforced natural rubber composites in aromatic solvents

The solvent swelling characteristics of natural rubber composites containing both untreated and alkali-treated coconut shell powder (CSP) were investigated in three, aromatic organic solvents (benzene, toluene, and xylene) by conventional weight-gain experiments. The effects of fiber loading, chemical treatment, and filler particle size on solvent sorption were analyzed. Transport parameters such as diffusion coefficient, sorption coefficient, and permeation coefficient have been calculated in terms of CSP content, particle size, nature of solvent, and temperature. All the NR–CSP composites were found to decrease with the uptake of aromatic solvents than NR, but the effect was more significant in the case of alkali-treated CSP composites. The estimated Arrhenius activation energy (E D) for the processes of sorption, diffusion, and permeation were discussed. The thermodynamic parameters of the sorption process were also evaluated. The mode of transport in all cases was evaluated.

Transport studies of peanut shell powder reinforced natural rubber composites in aromatic solvents

AbstractThis article investigates the transport behavior of three aromatic organic solvents, viz. benzene, toluene, and xylene in natural rubber (NR) composite membranes containing peanut shell powder (PSP) as filler at different temperatures by conventional weight‐gain experiments. PSP used in compounding the NR was processed in two particle sizes. The solvent swelling characteristics of NR composites containing both untreated and alkali‐treated fillers were investigated. The computed sorption characteristics were discussed in terms of PSP content, particle size, nature of solvent, and temperature. All the NR‐PSP composites were found to decrease with the uptake of aromatic solvents than NR, but the effect was more significant in the case of alkali‐treated PSP composites. Furthermore, the uptake of solvent decreased with decrease in penetrant size. The estimated Arrhenius activation energies (ED) for the processes of sorption, diffusion, and permeation showed that ED was generally highest in xylene at the filler contents investigated. The thermodynamic parameters of the sorption process were also evaluated. The relationship between the transport behavior and the morphology of the system was examined. The mechanism of diffusion is found to be close to Fickian trend in toluene and xylene and Fickian trend in benzene. Comparison between theoretical and experimental diffusion results was made to understand the mechanism of diffusion. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

Cellulose nanofibres and cellulose nanowhiskers based natural rubber composites: Diffusion, sorption, and permeation of aromatic organic solvents

AbstractThis article investigates the transport behavior of three aromatic organic solvents, viz. benzene, toluene, and p‐xylene in natural rubber nanocomposite membranes containing cellulose nanofibres (CNFs) and cellulose nanowhiskers (CNWs) isolated from bamboo pulp. The solvent molecules act as molecular probes to study the diffusion, sorption, and permeation through the nanocomposites, and provide information on the nanocomposite structure and matrix–filler interactions. Both the nanocelluloses were found to decrease the uptake of aromatic solvents in nanocomposite membranes, but the effect was more significant in the case on nanofibers compared to nanowhiskers. Furthermore, the uptake decreased with increased penetrant size; being the highest for benzene and the lowest for p‐xylene. Transport parameters such as diffusion coefficient, sorption coefficient, and permeation coefficient have been calculated. Comparison of the experimental values of equilibrium solvent uptake with the predicted values indicated that both the nanocelluloses have restricted the molecular mobility at the interphase and thereby decreased the transport of solvents through the materials; being more significant for nanofibers. The results showed that both the used cellulosic nanomaterials act as functional additives capable of manipulating and tailoring the transport of organic solvents through elastomeric membranes, even at concentrations as low as 2.5 wt %. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Thermodynamic considerations of solvent/enhancer uptake into a model membrane

The aim of this study was to conduct a thermodynamic analysis of the uptake of solvents into a model membrane as a precursor to skin transport studies. The investigation was designed so that the methodology may be applied to analyse data produced from measurement of the uptake of enhancers into skin. The uptake of a series of alcohols into polydimethylsiloxane (silicone) membranes in the temperature range 5–45 °C was examined. A thermodynamic analysis of the data was performed to provide fundamental insight into the uptake process. A simple structure activity relationship was found to exist for the uptake of alcohols with a carbon chain length greater than four, with additional methylene groups exponentially decreasing the equilibrium uptake. Two separate straight lines were observed in the van’t Hoff plot for the equilibrium solvent uptake above and below 16 °C. The two separate straight lines in the van’t Hoff plot suggest a change in the mechanism of solvent uptake and solvent structure in the membrane above and below 16 °C. This is likely to have implications for the effect of the solvents on the partitioning of drugs into the membrane and will be used to provide insight into dynamic measurements of the effect of temperature on the transport of drug molecules in the same vehicles, across the membrane. The analysis described here should provide a useful methodology for investigating the uptake of solvents into model membranes.

ATR-FTIR spectroscopy and spectroscopic imaging of solvent and permeant diffusion across model membranes

The uptake and diffusion of solvents across polymer membranes is important in controlled drug delivery, effects on drug uptake into, for example, infusion bags and containers, as well as transport across protective clothing. Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy has been used to monitor the effects of different solvents on the diffusion of a model compound, 4-cyanophenol (CNP) across silicone membrane and on the equilibrium concentration of CNP obtained in the membrane following diffusion. ATR-FTIR spectroscopic imaging of membrane diffusion was used to gain an understanding of when the boundary conditions applied to Fick’s second law, used to model the diffusion of permeants across the silicone membrane do not hold. The imaging experiments indicated that when the solvent was not taken up appreciably into the membrane, the presence of discrete solvent pools between the ATR crystal and the silicone membrane can affect the diffusion profile of the permeant. This effect is more significant if the permeant has a high solubility in the solvent. In contrast, solvents that are taken up into the membrane to a greater extent, or those where the solubility of the permeant in the vehicle is relatively low, were found to show a good fit to the diffusion model. As such these systems allow the ATR-FTIR spectroscopic approach to give mechanistic insight into how the particular solvents enhance permeation. The solubility of CNP in the solvent and the uptake of the solvent into the membrane were found to be important influences on the equilibrium concentration of the permeant obtained in the membrane following diffusion. In general, solvents which were taken up to a significant extent into the membrane and which caused the membrane to swell increased the diffusion coefficient of the permeant in the membrane though other factors such as solvent viscosity may also be important.

Solvent Dependent Friction Force Response of Polystyrene Brushes Prepared by Surface Initiated Polymerization

Polystyrene (PS) brushes were prepared on oxide passivated silicon by the surface initiated polymerization (SIP) technique. From an AIBN-type free radical initiator, which was silanized and immobilized on silicon wafers, styrene brushes were directly polymerized and grafted from the surface. The formation of the initiator monolayer and, subsequently, the polymer brush on the surface were monitored by X-ray photoelectron spectroscopy (XPS) and ellipsometry. Friction force measurements were performed by atomic force microscopy (AFM), using a 5 microm SiO2 colloidal sphere tip and under systematically varied solvent environments (nonpolar to polar), to demonstrate the dependence of brush lubricity on solvation. The relative uptake of solvents in the PS brush was determined by quartz crystal microbalance (QCM), and it correlates well with friction data. It is surmised that, in poor solvent environments, the polymer brush exists in a collapsed conformation, giving rise to the higher observed friction response.

Cover Picture: Vapor Sorption and Electrical Response of Au‐Nanoparticle– Dendrimer Composites (Adv. Funct. Mater. 6/2007)

AbstractThe cover shows chemiresistors and mass‐sensitive vapor sensors coated with Au‐nanoparticle/dendrimer composites. The Au nanoparticles provide the film with electrical conductivity and the dendrimers control the chemical selectivity, as reported by Nadjedja Krasteva and co‐workers on p. 881. Analyte sorption follows a combined Henry–Langmuir model, and measurements reveal that sorption‐induced increase in film resistance scales linearly with the concentration of analyte sorbed in the film. The background shows a silicon wafer with lithographically defined microelectrode structures for chemiresistor fabrication.Films comprising Au nanoparticles and polyphenylene dendrimers (first and second generation) are deposited onto transducer substrates via layer‐by‐layer self‐assembly and characterized by atomic force microscopy and X‐ray photoelectron spectroscopy. Their sorption behavior is studied by measuring the uptake of solvents from the vapor phase with quartz crystal microbalances (QCMs). The resistance of the films is simultaneously monitored. Both sensor types, QCMs and chemiresistors, give qualitatively very similar response isotherms that are consistent with a combination of Henry‐ and Langmuir‐type sorption processes. The sorption‐induced increase in relative differential resistance scales linearly with the amount of analyte accumulated in the films. This result is in general agreement with an activated tunneling process for charge transport, if little swelling and only small changes in the permittivity of the film occur during analyte sorption (a first‐order approximation). The relative sensitivity of the films to different solvents decreases in the order toluene ≈ tetrachloroethylene > 1‐propanol ≫ water. Films containing the larger second‐generation dendrimers show higher sensitivity than films containing first‐generation dendrimers.

Uptake of aromatic solvents by polyethylene films

AbstractThe sorption properties of the solvents benzene, toluene, and xylene in polyethylene films at 40, 60, and 80°C were investigated. The diffusion coefficient increased with an increase in the sorption temperature for the solvents and was highest for xylene and least for benzene. The inability of xylene to show a definite order of the diffusion coefficients at the investigated temperatures was attributed to the presence of two methyl side groups in the molecule. The solubilities of the solvents in polyethylene increased with an increase in the sorption temperature, and the following order of the solubilities could be observed: xylene > toluene > benzene. The permeabilities of the solvents in polyethylene depended on the sorption temperature, and the following order of the permeabilities was observed: xylene > toluene > benzene. The calculated activation energies of sorption in polyethylene films were all positive; benzene had the highest energy of sorption, and xylene had the lowest. The calculated enthalpies of sorption (ΔHS) were also positive for the three solvents and were in the following order: xylene > toluene > benzene. The calculated entropies of sorption (ΔS) were negative for the solvents and showed trends similar to the variation of ΔHS among the solvents. The change in the Gibbs free energies of sorption (ΔGS), evaluated with the expression ΔGS = ΔHS − TΔS (where T is the Kelvin temperature), were all positive, and this was an indication of the nonspontaneity of the solubility of polyethylene in the aromatic solvents at 313 K. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3849–3854, 2007