Perturbation of nanoscale structure of polypeptide multilayer thin films

Multilayer thin films formed by sequential deposition of oppositely charged polypeptides on a charged surface are known from previous studies to comprise a mixture of types of secondary structure. Here, study of the perturbation of polypeptide film structure by deposition of poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate) (PSS) on the film surface has revealed differences in behavior attributable to physical properties of the peptides. The methods of analysis were circular dichroism spectroscopy (CD), ultraviolet spectroscopy (UVS), and quartz crystal microbalance (QCM). Films made of poly(L-lysine) (PLL) and poly(L-glutamic acid) (PLGA) with an average charge per monomer of about 1 were substantially more susceptible to perturbation of structure than films made of designed polypeptides with an average charge per monomer of about 0.5, despite preparation under identical conditions. PLL-PLGA films showed loss or gain of material and change in secondary structure content on perturbation, whether made of high molecular mass (ca. 90 kDa) or low molecular mass (ca. 14 kDa) polymers. By contrast, films made of very low molecular mass (ca. 3.5 kDa) designed polypeptides showed little change in secondary structure content. The data suggest that the penetrability of PSS or PAH into a film and therefore film density can depend substantially on the polypeptides of which it is made and the character of intermolecular interactions.     

Temperature‐Induced Swelling and De‐swelling of Thin Poly(N‐Isopropylacrylamide) Gels in Water: Combined Acoustic and Optical Measurements

The temperature‐induced swelling and deswelling of thin layers of poly(N‐isopropylacrylamide) gels in water was measured as a function of cross‐link density and thickness. The collapse behavior was probed via an in situ combination of a quartz‐crystal microbalance (QCM) and a surface plasmon resonance (SPR) spectrometer. The shifts in the SPR coupling angle are explained in terms of decrease of the refractive index inside the film. The evanescent optical wave mostly probes the film's interior properties. The acoustic shear wave emanating from the quartz resonator, on the other hand, propagates to the outer surface of the film, unless the film is very dilute. The acoustic data are dominated by the changes in thickness, rather than in its viscosity. The combination of acoustic and optical measurements, therefore, provides complementary information on the film that can be exploited for sensing applications.     

Assembly of poly(N-isopropylacrylamide)-co-acrylic acid microgel thin films on polyelectrolyte multilayers: Effects of polyelectrolyte layer thickness, surface charge, and microgel solution pH

Temperature- and pH-sensitive poly(N-isopropylacrylamide)?Cco-acrylic acid (pNIPAm-co-AAc) microgels were deposited on glass substrates coated with polyelectrolyte multilayers composed of the polycation poly(allylamine hydrochloride) (PAH) and the polyanion poly(sodium 4-styrenesulfonate) (PSS). The microgel density and structure of the resultant films were investigated as a function of: (1) the number of PAH/PSS layers (layer thickness); (2) the charge on the outer layer of the polyelectrolyte multilayer film; and (3) the pH of microgel deposition solution. The resultant films were studied by differential interference contrast optical microscopy, atomic force microscopy, and scanning electron microscopy. It was found that the coverage of the microgels on the surface was a complex function of the pH of the deposition solution, the charge on the outer layer of the polyelectrolyte thin film and the PAH/PSS layer thickness; although it appears that microgel charge plays the biggest role in determining the resultant surface coverage.     

Oligosilsesquioxanes as versatile building blocks for the preparation of self-assembled thin films

A self-assembly approach to the preparation of nanocomposite siliceous thin films by using oligosilsesquioxanes as building blocks is presented. Poly(styrene-4-sulfonate), PSS, and octa(3-aminopropyl)silsesquioxane, NSi8, were layer-by-layer (LbL) assembled onto planar substrates and polystyrene (PS) particles, thus forming composite multilayers. We have clarified the binding properties of NSi8 to PSS by examining the pH influence on film buildup by microelectrophoresis (zeta-potential) and quartz crystal microgravimetry (QCM). The regular growth of PSS/NSi8 multilayers on planar supports was confirmed by surface plasmon resonance (SPR) spectroscopy and QCM. By applying the LbL coating procedure to spherical templates, we prepared compact, microporous hollow silica spheres by calcining PS spheres coated with (poly(allylamine hydrochloride) (PAH)/PSS)(2)/(NSi8/PSS)(n) (n varying from 3 to 12), at 750 degrees C, because of sintering of the octameric clusters (NSi8). Hollow spheres derived from coatings with n = 3 drastically altered in size (relative to the template core), depending on the size of the PS particles used. The novelty of this method for the nanofabrication of siliceous films stems from the use of well-defined and discrete building blocks, such as NSi8, leading to homogeneous organic-silica composite films as well as individual siliceous particles of variable size and shape.     

Layer-by-layer assembled microgel films with high loading capacity: reversible loading and release of dyes and nanoparticles

Multilayer films containing microgels of chemically cross-linked poly(allylamine hydrochloride) (PAH) and dextran (named PAH-D) were fabricated by layer-by-layer deposition of PAH-D and poly(styrene sulfonate) (PSS). The successful fabrication of PAH-D/PSS multilayer films was verified by quartz crystal microbalance measurements and cross-sectional scanning electron microscopy. The as-prepared PAH-D/PSS multilayer films can reversibly load and release negatively charged dyes such as methyl orange (MO) and fluorescein sodium and mercaptoacetic acid-stabilized CdTe nanoparticles. The loading capacity of the film for MO can be as large as approximately 3.0 microg/cm2 per bilayer, which corresponds to a MO density of 0.75 g/cm3 in the film. The high loading capacity of the PAH-D/PSS films originates from the cross-linked film structure with sufficient binding groups of protonated amine groups, as well as their high swelling capability by solvent. The loaded material can be released slowly when immersing the films in 0.9% normal saline. Meanwhile, the PAH-D/PSS multilayer films could deposit directly on either hydrophilic or hydrophobic substrates such as quartz, polytetrafluoroethylene, polystyrene, poly(ethylene terephthalate), and polypropylene. The microgel films of PAH-D/PSS are expected to be widely useful as matrixes for loading functional guest materials and even for controlled release.     

Effect of introduced charge in cellulose gels on surface interactions and the adsorption of highly charged cationic polyelectrolytes

The interaction between cellulose surfaces in aqueous solution has been measured using colloidal probe microscopy. Cellulose thin films with varying charge through carboxyl group substitution were used in this study with the surface forces fit to DLVO theory. It was found that the surface potential increased, as expected, with increasing carboxyl substitution. Furthermore, for a given degree of substitution, the surface potential increased as a function of increasing pH. At low pH, the surface forces interaction were attractive and could be fit to the non-retarded Hamaker equation using a constant of 3 x 10(-21) J. At pH greater than 5, the force interactions were monotonically repulsive, regardless of the ionic strength of the solution for all charge densities of the cellulose thin films. The adsorption of polyDADMAC to these charged cellulose films was also investigated using the quartz crystal microbalance. It was found that for the low charge film, a low surface excess of PDADMAC was sensed and that the adsorbed conformation was essentially flat. However for the higher charged cellulose film, a spontaneous de-swelling was observed resulting in no possibility of quantitatively determining the sensed mass using QCM.     

Study of film structure and adsorption kinetics of polyelectrolyte multilayer films: effect of pH and polymer concentration

The alternate adsorption of polycation poly(allylamine hydrochloride)(PAH) and the sodium salt of the polymeric dye poly(1-[ p-(3'-carboxy-4'-hydroxyphenylazo)benzenesulfonamido]-1,2-ethandiyl)(PCBS) on quartz crystals coated with silica was studied to understand the structural properties and adsorption kinetics of these films using a combination of quartz crystal microbalance with dissipation monitoring (QCM-D), absorbance, and ellipsometry measurements. In-situ deposition of the polycation PAH on QCM crystals was monitored, followed by rinsing with water and then deposition of the polyanion PCBS. The effects of polymer concentration and pH on film structure, composition and adsorption kinetics were probed. The polymers were adsorbed at neutral pH conditions and at elevated pH conditions where PAH was essentially uncharged to obtain much thicker films. The change in the resonant frequency, Deltaf, of the QCM-D showed a linear decrease with the number of bilayers, a finding consistent with absorbance and ellipsometric thickness measurements which showed linear growth of film thickness. By using the Delta f ratios of PCBS to PAH, the molar ratios of repeat units of PCBS to PAH in the bilayer films as determined by QCM-D were approximately 1:1 at polyelectrolyte concentrations 5-10 mM repeat unit, indicating complete dissociation of the ionic groups. The frequency and dissipation data from the QCM-D experiments were analyzed with the Voigt model to estimate the thickness of the hydrated films which were then compared with thicknesses of dry films measured by ellipsometry. This led to estimates of the water content of the films to be approximately 45 wt %. In addition to the QCM-D, some films were also characterized by a QCM which measures only the first harmonic without dissipation monitoring. For the deposition conditions studied, the deposited mass values measured by the QCM's first harmonic were similar to the results obtained using higher harmonics from QCM-D, indicating that the self-assembled polyelectrolyte films were rigid.     

pH sensor based on polyaniline and aniline–anthranilic acid copolymer films using quartz crystal microbalance and electronic absorption spectroscopy

The pH sensitivity based on conducting polyaniline (PANI) and copolymer of aniline and o‐anthranilic acid (AA) films were studied using quartz crystal microbalance (QCM) technique and UV–Vis spectroscopy. The sensor was constructed from these polymer films coated on the electrode of the QCM. The resonant frequency changes as a function of pH in the range of 2–12 were measured. These changes are quantitative indication of the degree of dedoping or redoping of the polymer films upon the subsequent exposure of the electrode to 0.25 M sulfuric acid and different pH solutions. There are two linear regressions between the frequency change and pH with two different and opposite slopes in the regions from 2 to 9 and 9 to 12. The pH sensitivity of the copolymer film was found to be less than using the PANI film. Thin films of PANI and copolymer, which were chemically polymerized in a sulfuric acid solution, were deposited onto the inner walls of the quartz cuvettes. The UV–Vis absorption spectra of these films were measured in different pH solutions. Relations between the maximum absorption and its wavelength versus pH were constructed. The copolymer film shows some advantages over the PANI film. The difference between the PANI and copolymer films as pH sensors using the QCM and electronic absorption extends from the determination of pK_a for both films. Copyright © 2008 John Wiley & Sons, Ltd.     

Influence of solvent quality on the growth of polyelectrolyte multilayers

The effect of solvent conditions on the growth of polyelectrolyte (PE) multilayer films comprising poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate sodium salt) (PSS) on planar substrates was investigated by means of surface plasmon resonance spectroscopy (SPRS), quartz crystal microbalance (QCM), and atomic force microscopy techniques. The solvent quality was varied by the addition of ethanol to the PE solutions used for deposition of the layers, thus tuning the relative strength of electrostatic and secondary intermolecular and intramolecular interactions. Experiments were performed with PE solutions both without added electrolyte and containing 0.5 M NaCl. Decreasing the solvent quality (i.e., increasing the amount of ethanol in the adsorption solution) resulted in a marked increase of both the multilayer film thickness and mass loading, as determined from the SPRS spectra and QCM frequency shifts, respectively. With the solution composition approaching the precipitation point, thick PAH/PSS films were formed due to the screening of the electrostatic intra- and interchain repulsions and enhanced hydrophobic interactions between the polyelectrolyte chains. However, the films formed from water/ethanol mixtures remained stable upon subsequent exposure to water or salt-containing solutions: no significant film desorption occurred after up to 24 h of exposure to water or 0.5 M NaCl solutions. In addition, the effect of postdeposition exposure to water/ethanol mixtures was investigated for PE multilayers assembled from aqueous solutions. In this case, the optical thickness of the films was determined during exposure to water/ethanol mixtures, and instead of swelling, the polyelectrolyte films collapse to the surface as a result of the unfavorable segment-solvent interactions.     

Spun films of perylene diimide derivative for the detection of organic vapors with host–guest principle

The optical characterization and chemical vapor sensing properties of 1,7-dibromo-N,N′-(bicyclohexyl)-3,4:9,10-perylene diimide thin film against to organic vapors were discussed in this study by using spin coating, UV–Vis spectroscopy, atomic force microscopy, surface plasmon resonance (SPR) and Quartz Crystal Microbalance (QCM) techniques. The perylene diimide thin films were fabricated with a refractive index values from 1.55 to 1.60 and thicknesses in the range between 15.80 and 26.32 nm using different spin speeds from 1000 to 5000 rpm. In this study, perylene diimide thin film sensor was exposed to dichloromethane, chloroform, carbon tetrachloride, tetrahydrofuran and ethyl acetate vapors by using both SPR and QCM techniques. Also, the swelling behaviors of the perylene diimide thin films prepared at different spin speeds were investigated with respect to dichloromethane vapor at the room temperature by using SPR data. Diffusion coefficients were found to be 11.34?×?10^?17 (1000 rpm), 2.56?×?10^?17 (3000 rpm) and 0.38?×?10^?17 cm² s^?1 (5000 rpm) for dichloromethane vapor by using the Fick’s law of diffusion. It might be proposed that perylene diimide thin film optical chemical sensor element has a good sensitivity and selectivity for the dichloromethane vapor at room temperature.     

Film stability during postassembly morphological changes in polyelectrolyte multilayers due to acid and base exposure

The mechanism of the transition from a continuous morphology to a porous morphology within polyelectrolyte multilayers (PEMs) of linear poly(ethylene imine) (LPEI) and poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) and PAA assembled by the layer-by-layer (LbL) technique is examined. These morphological changes were created by both acidic and basic postassembly treatments. Basic postassembly treatment is shown to create different types of porosity than acidic postassembly treatment. The morphological variation from the introduction of porosity to the collapse of these porous structures and the dissolution of films under postassembly treatments was observed by AFM, optical microscopy, quartz crystal microbalance (QCM), and SEM. These morphological transitions which are a result of structural rearrangement of weak polyelectrolytes due to pH changes are closely related to the neutralization of the polycations and the ionization of polyanions. Results obtained from FTIR spectroscopy and QCM confirm that polyelectrolytes are being selectively or partially released from the polyelectrolyte multilayers thin films (PEMs) in response to the pH treatment as a function of exposure time. In conclusion, here new information is presented about the structural reorganization found in a number of weak polyelectrolyte systems. This information will be useful in designing functional materials based on polyelectrolytes.     

Moisture absorption and absorption kinetics in polyelectrolyte films: influence of film thickness

Specular X-ray reflectivity (XR) and quartz crystal microbalance (QCM) measurements were used to determine the absorption of water into thin poly(4-ammonium styrenesulfonic acid) films from saturated vapor at 25 degrees C. The effect of film thickness on the absorption kinetics and overall absorption was investigated in the range of thickness from (3 to 200) nm. The equilibrium swelling of all the films irrespective of film thickness was (0.57+/-0.03) volume fraction. Although the equilibrium absorption is independent ofthickness, the absorption rate substantially decreases for film thickness < 100 nm. For the thinnest film (3 nm), there is a 5 orders of magnitude decrease in the diffusion coefficient for water.     

Effect of chain length and charge density on the construction of polyelectrolyte multilayers on colloidal particles

Two combinations of sodium poly(4-styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) of different chain length and charge density are employed to construct multilayer films. The polyelectrolytes are assembled layer-by-layer on colloidal particles in the absence of salt. We have investigated the formation and electrical characteristics of the films by using electric light scattering technique. The results show that the film thickness is independent of the chain length when fully charged PAH (at pH 4.6) is combined with fully charged PSS. When the films are prepared with less charged PAH (at pH 6.7) and fully charged PSS, lower thickness is found for the film with shorter polymer chains. In all cases, the thickness increment realized on addition of the polymer with lower molar concentration is partially lost on exposure to the solution with higher concentration of the oppositely charged partner. When the film growth is regular (at equal molar concentrations of the fully charged polyelectrolytes), the ratio of PSS to PAH charge, estimated from the electro-optical effect values, exceeds 1. The electro-optical effect is also higher for the films ending with PSS when fully charged PSS is combined with less charged PAH (at pH 6.7). This reveals the key role of the charge in the last-adsorbed layer for the electro-optical behavior of the whole film.     

Surface-confined photopolymerization of pH-responsive acrylamide/acrylate brushes on polymer thin films

Dynamic acrylamide/acrylate polymeric brushes were synthesized at gold-plated quartz crystal surfaces. The crystals were initially coated with polystyrene-type thin films, derivatized with photolabile iniferter groups, and subsequently subjected to photoinitiated polymerization in acrylamide/acrylate monomer feeds. This surface-confined polymerization method enabled direct photocontrol over the polymerization, as followed by increased frequency responses of the crystal oscillations in a quartz crystal microbalance (QCM). The produced polymer layers were also found to be highly sensitive to external acid/base stimuli. Large oscillation frequency shifts were detected when the brushes were exposed to buffer solutions of different pH. The dynamic behavior of the resulting polymeric brushes was evaluated, and the extent of expansion and contraction of the films was monitored by the QCM setup in situ in real time. The resulting responses were rapid, and the effects were fully reversible. Low pH resulted in full contractions of the films, whereas higher pH yielded maximal expansion in order to minimize repulsion around the charged acrylate centers. The surfaces also proved to be very robust because the responsiveness was reproducible over many cycles of repeated expansion and contraction. Using ellipsometry, copolymer layers were estimated to be approximately 220 nm in a collapsed state and approximately 340 nm in the expanded state, effectively increasing the thickness of the film by 55%.     

Assembly of multilayer films from polyelectrolytes containing weak and strong acid moieties

Multilayer films were assembled from a copolymer containing both weakly and strongly charged pendant groups, poly(4-styrenesulfonic acid-co-maleic acid) (PSSMA), deposited in alternation with poly(allylamine hydrochloride) (PAH). The strongly charged groups (styrene sulfonate, SS) are expected to form electrostatic linkages (to enhance film stability), while the weakly charged groups (maleic acid, MA) can alter multilayer film properties because they are responsive to external pH changes. In this study, we varied several assembly conditions such as pH, SS/MA ratio in PSSMA, and the ionic strength of the polyelectrolyte solutions. The multilayer films were also treated by immersion into pH 2 and 11 solutions after assembly. Quartz crystal microgravimetry and UV-visible spectrophotometry showed that the thickness of PSSMA/PAH multilayers decreases with increasing assembly pH regardless of whether salt was present in the polyelectrolyte solutions. When no salt was added, the multilayers are thinner, smoother, and grow less regularly. Atomic force microscopy images indicate that the presence of salt in polyelectrolyte solutions results in rougher surface morphologies, and this effect is especially significant in multilayers assembled at pH 2 and pH 11. When both polyelectrolytes are adsorbed at conditions where they are highly charged, salt was necessary to promote regular multilayer growth. Fourier transform infrared spectroscopy studies show that the carboxylic acids in the multilayers are essentially ionized when assembled from different pHs in 0.5 M sodium chloride solutions, whereas some carboxylic acids remain protonated in the multilayers assembled from solutions with no added salt. This resulted in different pH stability regimes when the multilayers were exposed to different pH solutions, post assembly.     

Direct surface force measurements of polyelectrolyte multilayer films containing nanocrystalline cellulose

Polyelectrolyte multilayer films containing nanocrystalline cellulose (NCC) and poly(allylamine hydrochloride) (PAH) make up a new class of nanostructured composite with applications ranging from coatings to biomedical devices. Moreover, these materials are amenable to surface force studies using colloid-probe atomic force microscopy (CP-AFM). For electrostatically assembled films with either NCC or PAH as the outermost layer, surface morphology was investigated by AFM and wettability was examined by contact angle measurements. By varying the surrounding ionic strength and pH, the relative contributions from electrostatic, van der Waals, steric, and polymer bridging interactions were evaluated. The ionic cross-linking in these films rendered them stable under all solution conditions studied although swelling at low pH and high ionic strength was inferred. The underlying polymer layer in the multilayered film was found to dictate the dominant surface forces when polymer migration and chain extension were facilitated. The precontact normal forces between a silica probe and an NCC-capped multilayer film were monotonically repulsive at pH values where the material surfaces were similarly and fully charged. In contrast, at pH 3.5, the anionic surfaces were weakly charged but the underlying layer of cationic PAH was fully charged and attractive forces dominated due to polymer bridging from extended PAH chains. The interaction with an anionic carboxylic acid probe showed similar behavior to the silica probe; however, for a cationic amine probe with an anionic NCC-capped film, electrostatic double-layer attraction at low pH, and electrostatic double-layer repulsion at high pH, were observed. Finally, the effect of the capping layer was studied with an anionic probe, which indicated that NCC-capped films exhibited purely repulsive forces which were larger in magnitude than the combination of electrostatic double-layer attraction and steric repulsion, measured for PAH-capped films. Wherever possible, DLVO theory was used to fit the measured surface forces and apparent surface potentials and surface charge densities were calculated.     

Principles of quartz crystal microbalance/heat conduction calorimetry: Measurement of the sorption enthalpy of hydrogen in palladium

A sensitive new measurement technology is described which combines calorimetry, gravimetry, and rheology applied to chemical reactions in thin films: quartz crystal microbalance/heat conduction calorimetry (QCM/HCC). The quartz crystal microbalance/heat conduction calorimeters constructed so far simultaneously measure heat generation, mass uptake or release, and viscoelastic property changes in the same, sub-milligram solid film sample when gases interact with the film in an isothermal surrounding. It is possible to measure the energetics of formation of a single layer of adsorbed molecules on a gold surface with this technique. The principles of operation of both the mass and the heat flow sensor are described, and one implementation of the combined sensor and apparatus and its electronics is presented. Methods for calibration and the preparation of thin sample films are summarized. As an illustrative example, the determination of the sorption enthalpy of hydrogen in a 25 °C palladium film of 140 nm thickness is discussed in detail. Other examples of the operation of the QCM/HCC are tabulated.     

Microgel-based etalon coated quartz crystal microbalances for detecting solution pH: The effect of Au overlayer thickness

Poly (N-isopropylacrylamide)-co-acrylic acid (pNIPAm-co-AAc) microgels were “painted” on the Au electrode of a quartz crystal microbalance (QCM). Another Au layer (overlayer) was subsequently deposited on the microgel layer. This structure is known as a microgel-based etalon. These devices have been shown to exhibit optical properties (i.e., color) that depend on solution pH and temperature, among other things. Previously, we measured QCM frequency shifts that are a result of solution pH changes; the frequency shifts are a direct result of the pH dependent solvation state of the microgels that make up the etalon. In fact, the shifts observed for the etalons were much greater in magnitude than just a microgel layer immobilized on the QCM crystal without the Au overlayer. We reasoned that the Au overlayer lead to an enhancement of the observed frequency change due to its mass. In this submission we investigate how the Au overlayer thickness (mass) affects the observed sensitivity to solution pH. We found that the change in QCM resonant frequency depended dramatically on the mass of the Au overlayer.     

Organic vapor sensing properties and characterization of α-naphthylmethacrylate LB thin films

Determination of organic vapor sensing properties of α-Naphthylmethacrylate (α-NMA) monomer based Langmuir-Blodgett (LB) thin films was aimed in this study. LB thin film fabrication was performed on quartz glass and quartz crystal substrates in order to investigate the characterization and organic vapor properties of α-NMA materials by using UV-Visible, Atomic Force Microscopy (AFM) and Quartz Crystal Microbalance (QCM) techniques. π-A isotherm graph was taken and a suitable surface pressure value were primarily determined as 13?mN m^?1 for successful α-NMA LB thin film fabrication. Transfer ratio value was found to be ≥ 0.93 for quartz glass and quartz crystal substrates. The typical frequency shift per layer was obtained as 16.93?Hz/layer and the deposited mass onto a quartz crystal was calculated as 271.30?ng/layer (1.02?ng mm^?2). The sensing responses of α-NMA LB films against dichloromethane, chloroform, toluene and m-xylene were measured by QCM system. Dichloromethane created the maximum shift in the resonance frequency than other organic vapors used in this study. Results exhibited that α-NMA LB thin films were potential candidates for organic vapor sensing applications, especially high sensitive detection of dichloromethane at room temperature.     

Determining the effects of vapor sorption in polymers with the quartz crystal microbalance/heat conduction calorimeter

The quartz crystal microbalance/heat conduction calorimeter (QCM/HCC) is a versatile instrument coupling both gravimetric and calorimetric techniques. The QCM/HCC is used to probe vapor sorption in thin films. Three parameters are measured simultaneously as a thin film undergoes vapor sorption, namely: mass changes in the film (±10 ng), corresponding thermal effects upon vapor sorption (±100 nW), and motional resistance (±0.5Ω) changes within the film. A range of film thicknesses (0.75 to 8.5 μm) of the polymer, Tecoflex? are cast on QCMs and the interaction of each film with ethanol and water is determined. From the direct calorimetric measurements, sorption enthalpies (Δ_sorptionH kJ/mol) are determined for the film–vapor interactions. Sorption isotherms are then analyzed for each film. The isotherms shown here generally display a linear Henry's Law dissolution relationship between the vapor pressure and the amount of vapor sorbed into the film. Motional resistance data provides a window to view viscoelastic effects of the polymer films upon vapor sorption. Motional resistance data are compared for ethanol sorption in a relatively thin (0.75 μm) and thicker (8.5 μm) Tecoflex? film. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3893–3906, 2004