Hydrophobic PDMS Surface Research Articles

Structurally Heterogeneous Amphiphilic Conetworks of Poly(vinyl imidazole) Derivatives with Potent Antimicrobial Properties and Cytocompatibility.

We report the construction of amphiphilic conetwork (APCN)-based surfaces with potent antimicrobial activity and biofilm inhibition ability. The construction strategy is based on the separation of lipophilic alkyl groups (>C6) from the cationic network to obtain good antibacterial properties. The reaction of partially alkylated poly(vinyl imidazole) with the activated halide compounds followed by coating a glass or poly(dimethylsiloxane) (PDMS) sheet leads to the formation of the APCN surface. The dangling alkyl chains, crosslinking junctions, and unreacted vinyl imidazole groups are heterogeneously distributed in the APCNs. The swelling, mechanical property, and phase morphology of the APCN films have been evaluated. Bacterial cell disrupting potency of the APCN coatings increases with increasing alkyl chain length from C6 to C18 with somewhat more of an effect on Escherichia coli as compared to Bacillus subtilis bacteria. The minimum inhibitory amount of the APCNs on glass and a hydrophobic PDMS surface is in the range of 0.02-0.04 mg/cm2 depending on the chain length of the alkyl and the degree of quaternization. The effect of the type of crosslinker for the construction of the conetwork on the antimicrobial property has been evaluated to elucidate the exclusive design of the APCNs. The APCN-based coatings provide potent biocidal activity without much negatively affecting the hemocompatibility and cytocompatibility. These APCNs provide a good model system for comparative evaluation of the biocidal property and structural effect on the biocidal activity.

Acoustic Tweezer-Modulated Biomimetic Patterned Particle-Polymer Composite for Water Vapor Harvesting.

With the recent threat of climate change and global warming, ensuring access to safe drinking water is a great challenge in many areas worldwide. Designing functional materials for capturing water from natural resources like fog and mist has become one of the key research areas to maximize the production of clean water. From this aspect, nature is a great source for designing bioinspired functional materials as some of the plant leaves and animal exoskeletons can harness water and then store it to save themselves from arid, xeric conditions. Inspired by the Stenocara beetle, we have designed a composite surface structure with periodic islands made of aluminum microparticles surrounded by poly(dimethylenesiloxane) (PDMS). An acoustic tweezer-based method was used to fabricate the bioinspired composite structures, where surface acoustic waves at specific frequencies and amplitudes are applied to align the microparticles as islands in the polymer matrix. An oxygen plasma etching step was applied to expose the microparticles on the PDMS surface. The average water harvesting efficiencies for structures made with 120 and 80 kHz acoustic frequencies and 1 hour etching time were found to be 9.41 and 8.84 g cm-2 h-1, respectively. The acoustically patterned biomimetic composite surface showed higher water harvesting efficiency compared with completely hydrophobic PDMS and hydrophilic aluminum surfaces, demonstrating the advantages of the bioinspired composite material design and acoustic-assisted manufacturing technique. The biomimetic fog water harvesting material is a promising avenue to fulfill the demand for a cost-effective, sustainable, and energy-efficient solution to safe drinking water.

Polyelectrolytes layer-by-layer surface modification of PDMS microchips for the production of simple O/W and double W/O/W emulsions: From global to localized treatment

The fabrication of stable double emulsions remains a challenge in many industrial applications and appears as a hot topic in the microfluidics field. We apply a novel approach to selectively modify the wetting properties of the walls of the micro-emulsifier by deposing successive layers of polyelectrolytes on the targeted sections of the microsystems. The PDMS surface of a microfluidic droplet generator is locally modified by a layer-by-layer polyelectrolytes assembly of poly(allylaminehydrochloride) and poly(acrylicacid). This surface functionalization is successfully performed on flat surfaces, the complete microchip constituted of two steps flow-focusing, or on localized sections of the microsystem, which led to the hydrophilization of hydrophobic PDMS surfaces. The long lasting treatment, over a month, is confirmed. Direct O/W emulsions are enabled, and more interestingly, double W/O/W emulsions of controlled size and shell thickness are formed in PDMS microchip. This work presents an interesting alternative to the other systems commonly used such as imbricated glass capillary microsystems and also other approaches of surface modifications of PDMS microchips. This layer-by-layer surface functionalization on a microsystem displays the advantage of the versatility and ease of use of the PDMS. Polycarbonate and poly(methyl methacrylate) based microfluidic devices are successfully functionalized by simply transposing the process.

Mucin-Inspired Lubrication on Hydrophobic Surfaces.

In the human body, high-molecular-weight glycoproteins called mucins play a key role in protecting epithelial surfaces against pathogenic attack, controlling the passage of molecules toward the tissue and enabling boundary lubrication with very low friction coefficients. However, neither the molecular mechanisms nor the chemical motifs of those biomacromolecules involved in these fundamental processes are fully understood. Thus, identifying the key features that render biomacromolecules such as mucins outstanding boundary lubricants could set the stage for creating versatile artificial superlubricants. We here demonstrate the importance of the hydrophobic terminal peptide domains of porcine gastric mucin (MUC5AC) and human salivary mucin (MUC5B) in the processes of adsorbing to and lubricating a hydrophobic PDMS surface. Tryptic digestion of those mucins results in removal of those terminal domains, which is accompanied by a loss of lubricity as well as surface adsorption. We show that this loss can in part be compensated by attaching hydrophobic phenyl groups to the glycosylated central part of the mucin macromolecule. Furthermore, we demonstrate that the simple biopolysaccharide dextran can be functionalized with hydrophobic groups which confers efficient surface adsorption and good lubricity on PDMS to the polysaccharide.

A self-powered sensor with super-hydrophobic nanostructure surfaces for synchronous detection and electricity generation

A new kind of self-powered sensor which can synchronously detect the salinity of water solution from 0mmol/L to 1mmol/L and generate electricity is developed. The power generation of this self-powered sensor is realized by repeatedly moving water droplets down from hydrophobic PDMS surface to generate negative charges on the surface of PDMS at first and change the capacitance between two electrodes to drive the screen charges (electrons) moving back and forth between two electrodes, subsequently. The ability for droplet to change the capacitance depends on its salinity. So the self-powered sensor can successfully detect the solution's salinity. Furthermore, both the distance between two electrodes and the thickness of PDMS film can influence the change quantity of capacitance when the water droplets are same, which benefits to the improvement of self-powered sensor's detection ability. Finally, the performance of this self-powered sensor can also be optimized by improving its current signal through modulating external load.

Carbohydrate analysis on hybrid poly(dimethylsiloxane)/glass chips dynamically coated with ionic complementary peptide

A facile and efficient dynamic coating method using an ionic complementary peptide was established for high-performance separation of 8-aminopyrene-1,3,6-trisulfonic acid (APTS)-labeled carbohydrates in a hybrid poly(dimethylsiloxane) (PDMS)/glass microfluidic channel. EAK16-II with a sequence of [(Ala-Glu-Ala-Glu-Ala-Lys-Ala-Lys)2] can readily self-organize into a complete coating layer tightly adsorbed on both hydrophobic PDMS and hydrophilic glass surfaces, which efficiently suppressed nonspecific analyte adsorption and minimized electroosmotic flow (EOF). Separation conditions were systematically investigated with respect to EAK16-II concentration, running buffer, buffer pH, and field strength (Esep). Under the optimal conditions, rapid and reproducible separations of maltodextrin ladder, glycans from glucosamine capsules, tablets, and pomegranate peel extracts were achieved with over 450000 theoretical plates per meter in the hybrid PDMS/glass microchannels dynamically coated with 1.0mg/mL EAK16-II-0.05% n-dodecyl β-d-maltoside (DDM), and the relative standard deviation (RSD) values were less than 3.2% (n=4) for the migration times. The present work provides a facile and efficient means to minimize EOF and nonspecific analyte adsorption in microfluidic chips fabricated in various substrates, thereby broadening the applications of microfluidic chips in complicated biological assays.

High-performance liquid chromatography as a technique to determine protein adsorption onto hydrophilic/hydrophobic surfaces

The purpose of this study is to evaluate the potential of simple high performance liquid chromatography (HPLC) setup for quantification of adsorbed proteins on various type of plane substrates with limited area (<3cm2). Protein quantification was investigated with a liquid chromatography chain equipped with a size exclusion column or a reversed-phase column. By evaluating the validation of the method according to guidelines of the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH), all the results obtained by HPLC were reliable. By simple adsorption test at the contact of hydrophilic (glass) and hydrophobic (polydimethylsiloxane: PDMS) surfaces, kinetics of adsorption were determined and amounts of adsorbed bovine serum albumin, myoglobin and lysozyme were obtained: as expected for each protein, the amount adsorbed at the plateau on glass (between 0.15μg/cm2 and 0.4μg/cm2) is lower than for hydrophobic PDMS surfaces (between 0.45μg/cm2 and 0.8μg/cm2). These results were consistent with bicinchoninic acid protein determination.According to ICH guidelines, both Reversed Phase and Size Exclusion HPLC can be validated for quantification of adsorbed protein. However, we consider the size exclusion approach more interesting in this field because additional informations can be obtained for aggregative proteins. Indeed, monomer, dimer and oligomer of bovine serum albumin (BSA) were observed in the chromatogram. On increasing the temperature, we found a decrease of peak intensity of bovine serum albumin as well as the fraction of dimer and oligomer after contact with PDMS and glass surface. As the surface can act as a denaturation parameter, these informations can have a huge impact on the elucidation of the interfacial behavior of protein and in particular for aggregation processes in pharmaceutical applications.

Microfluidic Genipin Deposition Technique for Extended Culture of Micropatterned Vascular Muscular Thin Films.

The chronic nature of vascular disease progression requires the development of experimental techniques that simulate physiologic and pathologic vascular behaviors on disease-relevant time scales. Previously, microcontact printing has been used to fabricate two-dimensional functional arterial mimics through patterning of extracellular matrix protein as guidance cues for tissue organization. Vascular muscular thin films utilized these mimics to assess functional contractility. However, the microcontact printing fabrication technique used typically incorporates hydrophobic PDMS substrates. As the tissue turns over the underlying extracellular matrix, new proteins must undergo a conformational change or denaturing in order to expose hydrophobic amino acid residues to the hydrophobic PDMS surfaces for attachment, resulting in altered matrix protein bioactivity, delamination, and death of the tissues. Here, we present a microfluidic deposition technique for patterning of the crosslinker compound genipin. Genipin serves as an intermediary between patterned tissues and PDMS substrates, allowing cells to deposit newly-synthesized extracellular matrix protein onto a more hydrophilic surface and remain attached to the PDMS substrates. We also show that extracellular matrix proteins can be patterned directly onto deposited genipin, allowing dictation of engineered tissue structure. Tissues fabricated with this technique show high fidelity in both structural alignment and contractile function of vascular smooth muscle tissue in a vascular muscular thin film model. This technique can be extended using other cell types and provides the framework for future study of chronic tissue- and organ-level functionality.

Surface Modification of Poly(dimethylsiloxane) Using Ionic Complementary Peptides to Minimize Nonspecific Protein Adsorption.

Poly(dimethylsiloxane) (PDMS) has become a widely used material for microfluidic and biological applications. However, PDMS has unacceptably high levels of nonspecific protein adsorption, which significantly lowers the performance of PDMS-based microfluidic chips. Most existing methods to reduce protein fouling of PDMS are to make the surface more hydrophilic by surface oxidization, polymer grafting, and physisorbed coatings. These methods suffer from the relatively short-term stability, the multistep complex treatment procedure, or the insufficient adsorption reduction. Herein, we developed a novel and facile modification method based on self-assembled peptides with well-tailored amino acid composition and sequence, which can also interact strongly with the PDMS surface in the same way as proteins, for suppressing the nonspecific protein fouling and improving the biocompatibility of PDMS-based microfluidic chips. We first demonstrated that an ionic complementary peptide, EAR16-II with a sequence of [(Ala-Glu-Ala-Glu-Ala-Arg-Ala-Arg)2], can readily self-assemble into an amphipathic film predominantly composed of tightly packed β-sheets on the native hydrophobic and plasma-oxidized hydrophilic PDMS surfaces upon low concentrations of carbohydrates. The self-assembled EAR16-II amphipathic film exposed its hydrophobic side to the solution and thus rendered the PDMS surface hydrophobic with water contact angles (WCAs) of around 110.0°. However, the self-assembled EAR16-II amphipathic film exhibited excellent protein-repelling and blood compatibility properties comparable to or better than those obtained with previously reported methods. A schematic model has been proposed to explain the interactions of EAR16-II with the PDMS surface and the antifouling capability of EAR16-II coatings at a molecular level. The current work will pave the way to the development of novel coating materials to address the nonspecific protein adsorption on PDMS, thereby broadening the potential uses of PDMS-based microfluidic chips in complex biological analysis.

A cost-effective two-step method for enhancing the hydrophilicity of PDMS surfaces

Poly(dimethylsiloxane) (PDMS) is commonly used for fabricating micro- and nanofluidic devices due to its low cost and ease of fabrication. The major disadvantage to using PDMS for these applications is its hydrophobic properties. The current methods that enhance the hydrophilicity of elastomers used for micro- and nanofluidic applications are intricate and cost-inefficient. This contribution demonstrates how the hydrophobic PDMS surface can be chemically modified in 5 minutes using a two-step silanization method in an oxygen-saturated environment to provide a highly stable hydrophilic surface for irreversible PDMS to PDMS bonding and PDMS to borosilicate glass bonding. The surface wettabilities of the modified and pristine PDMS were characterized over a wide range of time using static contact angle measurements. The modified PDMS surfaces exhibit enhanced stable hydrophilicity with a contact angle of 87° for 5 days. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectra of the modified and pristine PDMS surfaces confirmed the presence of hydroxyl groups of water molecules in the modified PDMS at 3150 cm−1 in addition to the characteristic peaks of pristine PDMS. This reliable silane beaker chemistry-based method allows easy bonding of the PDMS surfaces for liquid containment and irreversible bonding to borosilicate glass. This approach can effectively be adapted for enhancing the hydrophilicity of PDMS, which ensure relevance for current and future micro- and nanofluidic applications.

Micropatterning of Cells on Electron-Irradiated Poly(dimethylsiloxane) Surface

In this study, a facile route to fabricate micropatterns of cells is presented on the basis of electron irradiation of poly(dimethylsiloxane) (PDMS). PDMS films were irradiated with electron beams through a pattern mask with micrometer-sized grids. After irradiation, the changes in the chemical composition, morphology, and wettability of the PDMS surface were investigated by using an X-ray photoelectron spectrometer, an atomic force microscope, and a contact anglometer. The results of the surface analysis revealed that the hydrophobic PDMS surface was changed into a hydrophilic one by the electron irradiation. Furthermore, on the basis of cell culturing on the selectively-irradiated PDMS, cells such as NIH3T3 and L929 were selectively adhered to and proliferated on the irradiated regions of the PDMS surface, resulting in the micropatterns of the cells on the PDMS surface.

Cell adhesion on phase-separated surface of block copolymer composed of poly(2-methacryloyloxyethyl phosphorylcholine) and poly(dimethylsiloxane)

We investigated the morphological effect of phase-separated block copolymer surfaces composed of poly(2-methacryloyloxyethyl phosphorylcholine (MPC)) (PMPC) and poly(dimethylsiloxane) (PDMS) on protein adsorption and cell adhesion behavior. We observed three different types of phase-separated surface morphologies by TEM and AFM. The elemental composition of phosphorus on the surface increases with the PMPC composition. Furthermore, the polymer surface formed by a block copolymer-containing a higher MPC unit composition shows a slightly lower static water contact angle. This result indicates that the elemental surface ratio of the surface depends on the MPC composition in the block copolymer. Protein adsorption tests revealed that only hydrophobic PDMS domains showed selective protein adsorption. Cell adhesion tests revealed that the number of adhered cells increased with increasing hydrophobic PDMS domain size of block copolymers in serum-containing media. In contrast, no cells adhered onto block copolymer surfaces in serum-free media, whereas a large amount of adhered cells were observed on the hydrophobic PDMS surface. This result indicates that segregated hydrophobic domains on a biocompatible PMPC surface strongly affect serum protein adsorption, thereby promoting considerable cell adhesion, although the surface is hydrophilic. Thus, both the composition of MPC units and the segregated hydrophobic surface morphology are important considerations in biomaterial surface design.

Remote Atmospheric Pressure DC Glow Discharge Treatment for Adhesion Improvement of PDMS

AbstractIn this paper, a remote DC glow discharge at atmospheric pressure is employed for surface modification of PDMS aimed at improvement of its adhesive properties. The effects of the discharge on the surface properties of PDMS are probed using contact angle measurements, XPS and T‐peel tests. Results show that the DC glow discharge transforms the initially hydrophobic PDMS surface into a hydrophilic one due to the incorporation of silanol groups at the expense of methyl groups. Moreover, T‐peel tests confirm that the remote DC glow plasma is able to remarkably enhance the adhesion between two PDMS layers, but only when both layers are plasma‐treated.

Nanotribology, standard friction, and bulk rheology properties compared for a Brij microemulsion

A microemulsion consisting of Brij 96, glycerol (co-surfactant), oil, and water was compared as concerns deformations in a surface forces apparatus whose surface where rendered hydrophobic by coating with a monolayer of condensed OTE (octadecyltriethoxysilane), as concerns tribology of the conventional kind during sliding between hydrophobic PDMS surfaces, and as concerns bulk rheology. In the bulk, light scattering characterization showed swollen spherical micelles with a 13 nm diameter. When squeezed to form thinner films than this, the effective viscosity measured rose by orders of magnitude. It appears that thin films in the range of thickness 13 to 7 nm are comprised of deformed micelles and that confinement to thinner films expels micelles with concomitant even more drastic structural deformation of the remaining micelles, until the thinnest films retain only adsorbed surfactant. Tentatively, this may explain why the friction response then became similar to that of surfactant itself [M. Graca, J.H.H. Bongaerts, J.R. Stokes, S. Granick, J. Colloid Interface Sci. 315 (2007) 662]. These measurements are considered to be the first comparison of microemulsion rheology in the bulk and in nanometer-thick films.

Viscous Boundary Lubrication of Hydrophobic Surfaces by Mucin

The lubricating behavior of the weakly charged short-side-chain glycoprotein mucin "Orthana" (Mw=0.55 MDa) has been investigated between hydrophobic and hydrophilic PDMS substrates using soft-contact tribometry. It was found that mucin facilitates lubrication between hydrophobic PDMS surfaces, leading to a 10-fold reduction in boundary friction coefficient for rough surfaces. The presence of mucin also results in a shift of the mixed lubrication regime to lower entrainment speeds. The observed boundary lubrication behavior of mucin was found to depend on the bulk concentration, and we linked this to the structure and dynamics of the adsorbed mucin films, which are assessed using optical waveguide light spectroscopy. We observe a composite structure of the adsorbed mucin layer, with its internal structure governed by entanglement. The film thickness of this adsorbed layer increases with concentration, while the boundary friction coefficient for rough surfaces was found to be inversely proportional to the thickness of the adsorbed film. This link between lubrication and structure of the film is consistent with a viscous boundary lubrication mechanism, i.e., a thicker adsorbed film, at a given sliding speed, results in a lower local shear rate and, hence, in a lower local shear stress. The estimated local viscosities of the adsorbed layer, derived from the friction measurements and the polymer layer density, are in agreement with each other.

Deoxyribonucleic acid modified poly(dimethylsiloxane) microfluidic channels for the enhancement of microchip electrophoresis

In this paper, deoxyribonucleic acid (DNA) was employed to construct a functional film on the PDMS microfluidic channel surface and apply to perform electrophoresis coupled with electrochemical detection. The functional film was formed by sequentially immobilizing chitosan and DNA to the PDMS microfluidic channel surface using the layer-by-layer assembly. The polysaccharide backbone of chitosan can be strongly adsorbed onto the hydrophobic PDMS surface through electrostatic interaction in the acidic media, meanwhile, chitosan contains one protonatable functional moiety resulting in a strong electrostatic interactions between the surface amine group of chitosan and the charged phosphate backbone of DNA at low pH, which generates a hydrophilic microchannel surface and reveals perfect resistance to nonspecific adsorption of analytes. Aminophenol isomers ( p-, o-, and m-aminophenol) served as a separation model to evaluate the effect of the functional PDMS microfluidic chips. The results clearly showed that these analytes were efficiently separated within 60 s in a 3.7 cm long separation channel and successfully detected on the modified microchip coupled with in-channel amperometric detection mode at a single carbon fiber electrode. The theoretical plate numbers were 74,021, 92,658 and 60,552 N m −1 at the separation voltage of 900 V with the detection limits of 1.6, 4.7 and 2.5 μM (S/N = 3) for p-, o-, and m-aminophenol, respectively. In addition, this report offered an effective means for preparing hydrophilic and biocompatible PDMS microchannel surface, which would facilitate the use of microfluidic devices for more widespread applications.

Adsorption Properties of Poly(l-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) at a Hydrophobic Interface: Influence of Tribological Stress, pH, Salt Concentration, and Polymer Molecular Weight

The adsorption properties of a graft copolymer of poly(ethylene glycol) (PEG) with a polycationic backbone, namely, poly( l-lysine)- graft-poly(ethylene glycol) (PLL- g-PEG), onto nonpolar, hydrophobic PDMS surfaces from aqueous solution and the lubrication properties of the self-mated sliding contacts of PDMS surfaces modified with PLL- g-PEG have been investigated. Whereas PLL- g-PEG is spontaneously attracted to negatively charged surfaces as a result of the polycationic PLL backbone, the collective interaction of (CH 2) 4 hydrocarbon moieties on the lysine units in the PLL backbone with nonpolar, hydrophobic surfaces also enables the adsorption of PLL- g-PEG onto hydrophobic surfaces such as PDMS. The adsorption and lubrication properties of PLL- g-PEG have been investigated by varying the aqueous solution parameters, such as pH (2, 7, and 12) and KCl concentration (0, 0.01, 0.1, and 1 M) as well as the length of the PLL backbone of the copolymer (20 vs 375 kDa). In the absence of tribological stress, the adsorption of PLL- g-PEG onto PDMS surfaces was mainly governed by the KCl concentration, whereas the role of pH or the molecular weight of the copolymer was of relatively minor importance; for all pH values, the adsorbed mass decreased with increasing KCl concentration. Under tribological stress, however, a clear dependence of the lubrication properties of PLL- g-PEG on all of the studied parameters, including pH, KCl concentration, and backbone molecular weight, was observed. The adsorption strength of PLL- g-PEG on PDMS surfaces, rather than the adsorbed mass itself, appeared to be the most critical parameter in determining the lubrication properties.

Direct patterning of quantum dots on structured PDMS surface

Semiconductor quantum dots are currently the most attractive research areas due to its variety of applications, especially in the field of life science. The present work deals with direct patterning of quantum dots (CdSe) using a modified hydrophobic–hydrophilic PDMS surface. The hydrophilic monomer was stamped on a hydrophobic PDMS to generate pattern of hydrophobic–hydrophilic PDMS surface. Fluorescent microscopy shows the selective deposition of quantum dots onto the hydrophobic PDMS surface.

Plasma based Ar+ beam assisted poly(dimethylsiloxane) surface modification

Plasma based Ar+ beam performed in RF (13.56MHz) low-pressure (200mTorr) glow discharge (at 100W, 1200W and 2500W) with a serial capacitance was employed for surface modification of poly(dimethylsiloxane) (PDMS) aimed at improvement of its interactions with living cells. The presence of a serial capacitance ensures arise of an ion-flow inside the plasma volume directed toward the treated sample and the vary of the discharge power ensures varied density of the ion-flow.XPS analysis was performed to study the changes in the surface chemical composition of the modified samples and the corresponding changes in the surface energy were monitored by contact angle measurements.We found that plasma based Ar+ beam transforms the initially hydrophobic PDMS surface into a hydrophilic one mainly due to a raising of the polar component of the surface tension, this effect being most probably due to an enrichment of the modified surface layer with permanent dipoles of a [SiOx]-based network and elimination of the original methyl groups. The initial adhesion of human fibroblast cells was studied on the described above plasma based Ar+ beam modified and acrylic acid (AA) grafted or not fibronectin (FN) pre-coated or bare surfaces.The cell response seems to be related with the peculiar structure and wettability of the modified PDMS surface layer after plasma based Ar+ beam treatment followed or not by AA grafting.

Coadsorption of Sodium Dodecyl Sulfate with Hydrophobically Modified Nonionic Cellulose Polymers. 2. Role of Surface Selectivity in Adsorption Hysteresis

We studied the reversibility of coadsorption from mixtures of the anionic surfactant sodium dodecyl sulfate with either hydroxypropyl cellulose (HPC) or hydrophobically modified hydroxyethyl cellulose (hmHEC) using optical reflectometry. The coadsorption to nonselective hydrophobic poly(dimethylsiloxane) (PDMS) surfaces was compared with coadsorption to negatively charged silica surfaces that were selective for polymer adsorption. The surface selectivity determines the reversibility of coadsorption with respect to changes in the solution sodium dodecyl sulfate (SDS) concentration. On the selective silica surface, an adsorbed layer becomes kinetically trapped in path-dependent states because SDS is electrostatically repelled from the negatively charged surface and is therefore unable to solubilize the polymer/surface contacts. On the nonselective PDMS surface, coadsorption in the HPC/SDS system is reversible, and although some irreversibility persists in the hmHEC/SDS system, the severity of the kinetic trapping effect is greatly reduced compared with that of the same system on silica. The decreased kinetic trapping effects are attributed to surfactant adsorption to the hydrophobic PDMS surface. Finally, a streaming current technique was used to measure the electrokinetic thickness of kinetically trapped polymer layers that were formed on silica by coadsorption with SDS, followed by rinsing with SDS-free polymer solution. The layer thickness was history-dependent: despite prolonged exposure to a constant concentration polymer solution, the adsorbed layer thickness depended on the SDS concentration that existed during the initial coadsorption stage.