Bubble Contact Angle Research Articles

Hydration and chain entanglement determines the optimum thickness of poly(HEMA-co-PEG₁₀MA) brushes for effective resistance to settlement and adhesion of marine fouling organisms.

Understanding how surface physicochemical properties influence the settlement and adhesion of marine fouling organisms is important for the development of effective and environmentally benign marine antifouling coatings. We demonstrate that the thickness of random poly(HEMA-co-PEG10MA) copolymer brushes affect antifouling behavior. Films of thicknesses ranging from 50 to 1000 Å were prepared via surface-initiated atom-transfer radical polymerization and characterized using infrared spectroscopy, ellipsometry, atomic force microscopy and contact angle measurements. The fouling resistance of these films was investigated by protein adsorption, attachment of the marine bacterium Cobetia marina, settlement and strength of attachment tests of zoospores of the marine alga Ulva linza and static immersion field tests. These assays show that the polymer film thickness influenced the antifouling performance, in that there is an optimum thickness range, 200-400 Å (dry thickness), where fouling of all types, as well as algal spore adhesion, was lower. Field test results also showed lower fouling within the same thickness range after 2 weeks of immersion. Studies by quartz crystal microbalance with dissipation and underwater captive bubble contact angle measurements show a strong correlation between lower fouling and higher hydration, viscosity and surface energy of the poly(HEMA-co-PEG10MA) brushes at thicknesses around 200-400 Å. We hypothesize that the reduced antifouling performance is caused by a lower hydration capacity of the polymer for thinner films, and that entanglement and crowding in the film reduces the conformational freedom, hydration capacity and fouling resistance for thicker films.

Contact angle of sapphire melt and bubble generation on crucible material

Contact angles of sapphire melt on tungsten (W), tungsten–molybdenum alloy (W–Mo), and molybdenum (Mo) test pieces were observed. The contact angles were 30.1±3.8°, 27.5±4.2°, and 23.5±3.2° for W, W–Mo, and Mo, respectively. Bubbles were generated only in the sapphire melt on W test piece. The contact angle of bubbles on W test piece was 31.2±4.9°. Because of the large contact angle of sapphire melt, bubbles were generated in the sapphire crystal grown in W crucible. The contact angles of water and formamide were also measured at room temperature in order to calculate the specific surface free energy (SSFE). The contact angles of water were 60.0±4.2°, 56.7±4.9°, and 50.2±4.9° on W, W–Mo, and Mo, respectively. The contact angles of formamide were 44.9±3.0°, 40.7±2.9°, and 37.7±4.0° on W, W–Mo, and Mo, respectively. The SSFEs were calculated as 46.3±3.0, 48.8±2.5, and 52.5±2.0mN/m for W, W–Mo, and Mo, respectively.

Electrowetting of soap bubbles

A proof-of-concept demonstration of the electrowetting-on-dielectric of a sessile soap bubble is reported here. The bubbles are generated using a commercial soap bubble mixture—the surfaces are composed of highly doped, commercial silicon wafers covered with nanometer thick films of Teflon®. Voltages less than 40 V are sufficient to observe the modification of the bubble shape and the apparent bubble contact angle. Such observations open the way to inter alia the possibility of bubble-transport, as opposed to droplet-transport, in fluidic microsystems (e.g., laboratory-on-a-chip)—the potential gains in terms of volume, speed, and surface/volume ratio are non-negligible.

Surface Microdynamics Phase Transition and Internal Structure of High-Density, Ultrathin PHEMA-b-PNIPAM Diblock Copolymer Brushes on Silicone Rubber

Stimuli-responsive ultrathin diblock copolymer brushes (DCBs) composed of poly(2-hydroxyethyl methacrylate) (PHEMA) as bottom block and poly(N-isopropylacrylamide) (PNIPAM) as top block on the surface of silicone rubber (SR) were examined as high-throughput platforms to trace the thermally induced phase transition mechanisms in water. A high grafting density DCB was precisely prepared from SiOx substrate via surface-initiated atom transfer radical polymerization (SI-ATRP). Surface modification studies with different initiator concentrations were performed to optimize their attachment, producing surfaces with dense covalently attached initiator monolayers with up to 2.8 initiators/nm2. Changes in the physicochemical properties according to each step of surface modification were investigated using in situ analysis with the sample both in a liquid environment and on layer in dry state. The temperature-dependent contact angle of the air bubbles underneath the high-density DCB (0.53 chains/nm2) gradually increased up to around 24 °C in water with increasing temperature and then decreased up to around 30 °C, followed by a rapid decrease at LCST of PNIPAM top block, approximately 32 °C. To obtain a thorough understanding of the microdomain orientation in DCB, the structure of SR/PHEMA-b-PNIPAM brush was investigated by μ-focused grazing incidence small-angle X-ray scattering (μ-GISAXS). Upon exposure to higher temperature conditions (above the LCST of PNIPAM top block), the film showed a “matrix-island” structure, in which the PNIPAM nanodomains were distributed over the highly packed PHEMA bottom block. The thermally induced evolution mechanism of various interactions in PHEMA-b-PNIPAM DCB and water mixtures during the heating–cooling cycles was investigated by means of temperature-dependent FTIR in combination with a two-dimensional correlation (2Dcos) technique. Both conventional IR spectrum and 2Dcos had figured out the volume phase transition temperature for PNIPAM top block and PHEMA bottom block to be about 33 and 33.5 °C, respectively, close to the results obtained from turbidity measurements [Sun et al. Soft Matter2013, 9, 1807; Weaver et al. Macromolecules2004, 37, 2395] on the same bulk polymers.

Wetting of soap bubbles on hydrophilic, hydrophobic, and superhydrophobic surfaces

Wetting of sessile bubbles on various wetting surfaces (solid and liquid) has been studied. A model is presented for the apparent contact angle of a sessile bubble based on a modified Young's equation––the experimental results agree with the model. Wetting a hydrophilic surface results in a bubble contact angle of 90° whereas using a superhydrophobic surface one observes 134°. For hydrophilic surfaces, the bubble angle diminishes with bubble radius whereas on a superhydrophobic surface, the bubble angle increases. The size of the plateau borders governs the bubble contact angle, depending on the wetting of the surface.

Impact of characteristic membrane parameters on the transfer rate of ammonia in membrane contactor application

Membrane contactors are a promising approach for ammonia removal from waste streams. The objective of this research was to evaluate the potential of common membrane parameters (bubble point, breakthrough pressure, airflow, pore size, contact angle and thickness) to predict the free ammonia mass transfer coefficient of hydrophobic membranes. 22 flat sheet membranes from different manufacturers and of various compositions were included in this study. Their main characteristics as well as the corresponding mass transfer coefficients were determined and statistically analyzed.Mass transfer coefficients between 0.04×10−3 and 24.59×10−3m/h were obtained. Using multilinear regression, the relative impact of each parameter on the mass transfer was identified. The developed statistical models successfully explain up to 63.2% of the observed variation. The parameters bubble point, airflow and pore size which are related to the void space of the membrane, as well as membrane thickness, determining the transport length, showed the strongest impact. In the simplest version a statistically significant model, explaining 55.3% of the variation, was obtained using only bubble point and thickness.Obtained results can facilitate the design of suitable membranes with improved ammonia transfer and assist researchers or practitioners to choose appropriate membranes for screening tests.

STIMULI RESPONSIVE MORPHOLOGICAL CHANGES OF PNIPA POLYMER BRUSHES SYNTHESIZED ON SILICON SUBSTRATE

High-density polymer brushes were grown from the silicon surface by atom transfer radical polymerization of Poly(N-isopropylacrylamide) (PNIPA) at different polymerization conditions. PNIPA brushes were prepared using Copper (I) Chloride/tris(2-(dimetylamino)ethyl)amine (Me6TREN) as a catalytic system in DMSO at 20°C. Free polymer formed during the brush formation was characterized by gel permeation chromatography. The grafting densities up to 0.52 chains/nm2 were obtained. The layer thickness of polymer brush increases with the increase of conversion of the monomer conversion as well as polymerization time. Atomic force microscopy and air bubble contact angle under pH solution were employed to study the surface morphology, reversible conformational changes of and stimulus-response behavior. PNIPA brushes exhibited a different nanomorphology after treatment with different pH solution. It also revealed a unique reversible wetting behavior with pH. The reversible properties of the PNIPA brushes can be used to regulate the adsorption of the sulfonated PS nanoparticles.

In-situ surface wettability parameters of submerged in brackish water surfaces derived from captive bubble contact angle studies as indicators of surface condition level

The characterization of wetting properties (by contact angles) of several undersea artificial (glass plates,) and natural (stones, sand layers, soft-bottom structures, aquatic macrophytes, sediments, and seafloor communities) solid substrata in the Baltic Sea brackish water (Gulf of Gdansk). The studies were performed under laboratory and field conditions using a novel captive bubble air-pipette computer microscope system. A set of the surface wettability parameters: the apparent surface free energy γSV, adhesive layer film pressure Π, work of adhesion WA, and work of spreading WS were determined to quantify the wetting properties of model substrata using the contact angle hysteresis (CAH) approach. The useful technique to measure in situ the contact angle giving reproducible and accurate values of CA turned out to be a captive bubble method, for fully hydrated interfacial layers of highly hydrophilic and porous nature met at seabed (Rodrigues-Valverde et al., 2002). CA measurements revealed mostly hydrophilic nature of the studied solid material (CA<90°) where the presence of adsorbed organic matter layer or crude oil film covering lead to surface hydrophobization (CA↑, γSV ↓,WA↓, WS more negative). The adhesion of biofouling was correlated both with CAH and the dispersive interaction term γSVd of the total γSV. Monitoring of the artificial substrata of the hydrophilic nature with a CA technique can be used to observe the development of the organisms community i.e., microfouling, and to carry out a comprehensive study of surfaces of the submerged macrophytes (Potamogeton lucens in particular). Since aquatic macrophytes can act as bio-indicators of water chemistry their surface wettability may reflect plant surface erosion and organic matter accumulation state being of particular value in biological assessment of ecosystems status.

Modeling of ionic diffusivity in non-saturated cement-based materials using lattice Boltzmann method

The ionic diffusivity in non-saturated cement-based materials is quantitatively studied using lattice Boltzmann method. The Shan–Chen multi-phase lattice Boltzmann model modified by incorporating the Carnahan–Starling equation of state into the model is used to simulate the equilibrium distribution of water and gas phases with density ratio as high as 775 in the three-dimensional microstructure of cement paste at various degrees of water saturation. The lattice Boltzmann diffusion model is subsequently applied to simulate the diffusion process of the ionic species through the partially saturated cement paste. Before the application of the modified Shan–Chen model, the benchmark tests including bubble test and contact angle test are carried out to validate it. It is shown that the ionic diffusivity is greatly influenced by the degree of water saturation. The simulated relative ionic diffusivity as a function degree of water saturation is in good agreement with the experimental data obtained from literature. In addition, the effect of w/c ratio on the ionic diffusivity through cement paste under non-saturated conditions is investigated. It indicates that there is a significant difference between the relative diffusivity for cement paste with w/c ratios of 0.4 and 0.5 over the whole range of water saturation degree. However, the difference of relative diffusivity for cement paste with w/c ratios of 0.5 and 0.6 is not obvious.

Flow Visualization, Critical Heat Flux Enhancement, and Transient Characteristics in Pool Boiling Using Nanofluids

Abstract This paper presents the experimental outcome of a study of the pool boiling heat transfer characteristics of alumina and CuO nanofluid in distilled water using a 0.19 mm diameter NiCr wire. A series of experiments were conducted in order to visualize the flow, critical heat flux (CHF) enhancement, and transient characteristics of nanofluid. The boiling phenomenon was visualized using a 0.1 g/l concentration of alumina nanofluid. The average bubble diameter was measured and was found to increase with increased heat flux. The average bubble contact angle decreased from 69° during the initial stages of boiling to 33° at CHF. Massive vapour bubbles were observed on the test heater surface near the CHF, inducing vapour blankets and forming hot/dry spots. The increase in the CHF could be well explained by the hot/dry spot theory. Pool boiling experiments conducted using low volume concentrations of CuO-water nanofluid at atmospheric pressure in distilled water showed an increase in the CHF by 30 % at a 0.3 g/l concentration. The transient behaviour of nanofluid, examined by exposing the heater surface at a constant heat flux of 700 kW/m2, indicated CHF enhancement of 5.21 % to 6.77 % for the two time durations. Based on the experimental investigations, it was concluded that the CHF enhancement is due to nanoparticle coating, which changes the thickness of the surface as a function of time and surface wettability and corroborates the hot/dry spot theory.

Fluorinated Amphiphilic Polymers and Their Blends for Fouling-Release Applications: The Benefits of a Triblock Copolymer Surface

Surface active triblock copolymers (SABC) with mixed polyethylene glycol (PEG) and two different semifluorinated alcohol side chains, one longer than the other, were blended with a soft thermoplastic elastomer (TPE), polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS). The surface composition of these blends was probed by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The surface reconstruction of the coatings in water was monitored qualitatively by dynamic water contact angles in air as well as air bubble contact angle measurements in water. By blending the SABC with SEBS, we minimize the amount of the SABC used while achieving a surface that is not greatly different in composition from the pure SABC. The 15 wt % blends of the SABC with long fluoroalkyl side chains showed a composition close to that of the pure SABC while the SABC with shorter perfluoroakyl side chains did not. These differences in surface composition were reflected in the fouling-release performance of the blends for the algae, Ulva and Navicula.

Wettability determination by contact angle measurements: hvbB coal–water system with injection of synthetic flue gas and CO 2

Geological sequestration of pure carbon dioxide (CO 2) in coal is one of the methods to sequester CO 2. In addition, injection of CO 2 or flue gas into coal enhances coal bed methane production (ECBM). The success of this combined process depends strongly on the wetting behavior of the coal, which is function of coal rank, ash content, heterogeneity of the coal surface, pressure, temperature and composition of the gas. The wetting behavior can be evaluated from the contact angle of a gas bubble, CO 2 or flue gas, on a coal surface. In this study, contact angles of a synthetic flue gas, i.e. a 80/20 (mol%) N 2/CO 2 mixture, and pure CO 2 on a Warndt Luisenthal (WL) coal have been determined using a modified pendant drop cell in a pressure range from atmospheric to 16 MPa and a constant temperature of 318 K. It was found that the contact angles of flue gas on WL coal were generally smaller than those of CO 2. The contact angle of CO 2 changes from water-wet to gas-wet by increasing pressure above 8.5 MPa while the one for the flue gas changes from water-wet to intermediate-wet by increasing pressure above 10 MPa.

Spreading of triple line and dynamics of bubble growth inside nanoparticle dispersions on top of a substrate plate

This work investigates the feasibility of engineering surface wettability by using different nanoparticles. As an illustration, detailed formation of gas bubbles on top of a stainless steel substrate plate in a quiescent pool of aqueous gold and alumina nanofluids is studied. The presence of nanoparticles is shown to be able to modify the dynamics of triple line and bubble growth significantly. An early pinning of the bubble triple line is observed and a larger bubble contact angle is found for bubbles growing in a gold nanofluid, whereas an opposite phenomenon is observed for bubbles growing in an alumina nanofluid compared to those of pure water. Other bubble parameters such as departure volume, bubble frequency, and waiting time of bubble formation are also affected by the presence of nanoparticles. The variation of solid surface tensions due to the existence of nanoparticles and the resultant force at the triple line should be responsible for such differences. Such results illustrate the big potential of nanoparticle in engineering surface wettability of a solid–liquid–gas system.

Fluorine-free mixed amphiphilic polymers based on PDMS and PEG side chains for fouling release applications

Fluorine-free mixed amphiphilic block copolymers with mixtures of short side groups of polydimethyl siloxane (PDMS) and polyethylene glycol (PEG) were synthesized and studied for their ability to influence the surface properties and control the adhesion of marine organisms to coated surfaces. The settlement (attachment) and strength of adhesion of two different marine algae, the green seaweed Ulva and the diatom Navicula, were evaluated against the surfaces. It is known that hydrophobic coatings based on polydimethyl siloxane elastomers (PDMSe) are prone to protein adsorption and accumulation of strongly adherent diatom slimes, in contrast to PEG-based hydrophilic surfaces that inhibit protein adsorption and moderate only weak adhesion of diatoms. By incorporating both PDMS and PEG side chains into the polymers, the effect of incorporating both polar and non-polar groups on fouling-release could be studied. The dry surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). The ability of these mixed amphiphilic polymers to reconstruct in water was examined using underwater bubble contact angle and dynamic water contact angle experiments. To understand more about surface reconstruction behavior, protein adsorption experiments were carried out with fluorescein isothiocyanate-labeled bovine serum albumin (BSA-FITC) on both dry and pre-soaked surfaces.

Contact Angle of Bubble with an Immersed-in-Water Particle of Different Materials

Advancing and relaxed contact angles of different materials in the air bubble/distilled water/solid particle system were determined utilizing flotation experiments performed in a single-bubble Hallimond microflotation cell, appropriate equations based on the balance of forces taking part in the flotation process, and a cell constant representing flotation hydrodynamics.

Preparation of thermo-responsive polypropylene membranes via surface entrapment of poly(N-isopropylacrylamide)-containing macromolecules

Thermo-responsive polypropylene (PP) microfiltration membranes have been fabricated via surface entrapment of poly(N-isopropylacrylamide) (PNIPAAm)-containing homopolymer and block copolymers. A previously developed approach based on using solutions of the polymeric modifier in a solvent which swells the base membrane polymer had been used, and conditions have been varied. One block copolymer of PNIPAAm with polybutylacrylate (PBA) had been selected as best suited modifier. Models related to the underlying deswelling/entrapment process which leads to fixation of the modifier have been considered. For PP membrane, characterization of pore size distribution in dry state revealed a significant decrease of pore size as a consequence of the entrapment modification. Surface properties have been analysed by ATR-FTIR spectroscopy and water contact angle measurements, which confirmed the presence of modifier and a strong improvement of surface and pore wettability. The thermo-sensitive properties of either outer surface and inner pore wall of modified PP membranes have been verified by temperature-dependence of captive bubble contact angle and water permeability, respectively, both due to hydratation/dehydratation and volume phase transition of PNIPAAm around the lower critical solution temperature (LCST) of the block copolymer PBA- b-PNIPAAm which was around 31–32 °C. The effects of protein desorption from the modified membrane where bovine serum albumin (BSA) had been previously adsorbed were studied by measuring water flux upon manipulating water temperature during water filtration cum washing. In addition, non-porous PP plates had been modified using the same procedure and all the surface characterization results showed similar modification efficiency and surface properties as for porous PP membranes, confirming the dominating role of entrapment of the amphiphilic functional macromolecules into the PP surface layer instead of simple deposition onto the surface.

The role of mineral surface chemistry in modified dextrin adsorption

The adsorption of two modified dextrins (phenyl succinate dextrin – PS Dextrin; styrene oxide dextrin – SO Dextrin) on four different mineral surfaces has been studied using X-ray photoelectron spectroscopy (XPS), in situ atomic force microscopy (AFM) imaging, and captive bubble contact angle measurements. The four surfaces include highly orientated pyrolytic graphite (HOPG), freshly cleaved synthetic sphalerite (ZnS), and two surfaces produced through surface reactions of sphalerite: one oxidized in alkaline solution (pH 9, 1h immersion); and one subjected to metal ion exchange between copper and zinc (i.e. copper activation: exposed to 1×10−3M CuSO4 solution for 1h). XPS measurements indicate that the different sphalerite surfaces contain varying amounts of sulfur, zinc, oxygen, and copper, producing substrates for polymer adsorption with a range of possible binding sites. AFM imaging has shown that the two polymers adsorb to a similar extent on HOPG, and that the two polymers display very different propensities for adsorption on the three sphalerite surface types, with freshly cleaved sphalerite encouraging the least adsorption, and copper activated and oxidized sphalerite encouraging significantly more adsorption. Contact angle measurements of the four surfaces indicate that synthetic sphalerite has a low contact angle upon fracture, and that oxidation on the timescale of one hour substantially alters the hydrophobicity. HOPG and copper-activated sphalerite were the most hydrophobic, as expected due to the carbon and di/poly-sulfide rich surfaces of the two samples, respectively. SO Dextrin is seen to have a significant impact on the wettability of HOPG and the surface reacted sphalerite samples, highlighting the difficulty in selectively separating sphalerite from carbonaceous unwanted minerals in flotation. PS Dextrin has the least effect on the hydrophobicity of the reacted sphalerite surfaces, whilst still significantly increasing the wettability of graphite, and thus has more potential for use as a polymer depressant in this separation.

Randomised controlled study comparing comfort-related outcomes between two rigid gas permeable (RGP) lenses with different sessile drop contact angles

To compare comfort-related outcomes when wearing rigid gas permeable (RGP) contact lenses made of two different materials and using two cleaning regimes. In a double-masked lens material cross-over study, subjects (n = 28 who completed the study) were refitted with new lenses made from (A) Boston XO material in one eye and made from (B) ONSI-56 material in the other eye. The lenses made from materials A and B were worn on the right eye and the left eye following the pattern AB-BA-AB (or vice versa) during the first, second, and third 5 week trial periods respectively. Miraflow cleaner (1st and 2nd period) was replaced by Boston Advance cleaner in the 3rd period. Comfort-related outcomes were assessed by a numerical rating scale (NRS) after each period. Subjects rated six comfort-related factors: satisfaction, sharpness of vision, end of day comfort, maximum comfortable wearing time, maximum wearing time and foreign body feeling. Additionally we obtained subjects' preferences for type of lens and lens cleaner during an exit interview. The sessile drop method was used to measure static contact angles. The mean of the contact angle measured for the Boston XO material was 93.3° and for the ONSI-56 material was 75.8 °. Mean 'end of the day comfort', 'satisfaction' and 'lens feeling' scores reached statistical significance (anova periods 1, 2 and 3, p's: 0.005, 0.028, 0.046, n = 23) with marginal differences in favour of those eyes that had worn lenses made of the ONSI-56 material (differences in mean scores on a 1-10 NRS never exceeded 0.7, 0.5 and 0.2 points in periods 1, 2, 3 respectively). At the exit interview 60% of the subjects (n = 17) were not able to express a preference for wearing either of the lenses, while 29% reported some preference for lenses made of the ONSI-56 material (n = 8) and 11% for wearing lenses made of the Boston XO material (n = 3) within one or more periods. The differences in comfort-related outcomes between contact lenses made from two different materials, with sessile contact angles that differed by 17.5°, were small. Although some observed comfort differences reached statistical significance, none of these differences were sufficiently large to support a clinically significant difference in comfort between the two materials. We recommend that both the sessile drop and the captive bubble contact angles, measured according to current standards, are made available to practitioners.

Precise Synthesis and Physicochemical Properties of High-Density Polymer Brushes designed with Poly(N-isopropylacrylamide)

A high-density polymer brush of poly(N-isopropylacrylamide) (PNIPA) was precisely prepared following carefully selected procedures, which included selecting the underlying substrate, preparing its surface, and grafting PNIPA on the substrate. As a result, the graft density and the dried thickness of the brush reached more than 0.5 chains/nm2 and 200 nm, respectively, for the best combination of each procedure. This high-density polymer brush showed gradual collapse with increasing temperature in water, which must be attributed to both the low swelling and the low shrinking abilities of the brush that result from the physically constrained state of the polymers. The contact angle of the air bubbles underneath the high-density polymer brush also gradually decreased up to around 25 °C in water with increasing temperature, which indicates that the hydrophilicity of the surface decreases as it does in typical PNIPA-grafted membranes and gels. Starting at the lower critical solution temperature of free PNIPA in...

Reduction of Surface Hydrophobicity Using a Stimulus-Responsive Polysaccharide

The adsorption of carboxymethyl cellulose (CMC) onto a hydrophobic self-assembled monolayer has been characterized using the quartz crystal microbalance (with dissipation monitoring, QCM-D). Adsorption was studied as a function of initial solution conditions. CMC adsorbs to a greater extent at high ionic strength (10(-1) M KCl as opposed to 10(-2) M KCl) or low pH (3 as opposed to 9). The solution conditions that yielded the lowest initial adsorbed amount (10(-2) M KCl, pH 9) were used as a reference to investigate the response of the adsorbed layer to a switch in solution conditions after adsorption (i.e., to higher ionic strength (10(-1) M KCl) or lower pH (pH 3)). The adsorbed layer released significant amounts of hydration water after each solution switch, as determined by the QCM-D measurements. This expulsion of hydration water was fully reversible. For the two solution switches, reducing the solution pH resulted in a more pronounced change in the amount of hydration water within the adsorbed CMC, accompanied by a distinct conformational change, as determined from a QCM D-f plot. In addition to studying adsorption using QCM-D, the effect of adsorbed CMC on surface hydrophobicity has been investigated using captive bubble contact angle measurements. The effect of the polymer on the contact angle of the surface was seen to be greatest when adsorbed at low pH or at higher ionic strength. CMC was also seen to have a significantly enhanced ability to reduce the surface hydrophobicity after both the ionic strength and pH switches, lowering the advancing water contact angle by 6 and 23° and the receding water contact angle by 10 and 40° for the ionic strength and pH switches, respectively. As with the change in hydration water content, the change in the contact angle of the polymer-coated surface following the solution switches was reversible.