Hydrophilic Film Research Articles

Reusable Self-Powered Electrochromic Sensor Patch Based on Enzymatic Biofuel Cells for On-Site Visualized Monitoring of Lactic Acid.

Wearable sensors have broad application potential in motion assessment, health monitoring, and medical diagnosis. However, relying on a specialized instrument for power supply and signal reading makes sensors unsuitable for on-site detection. To solve this problem, a reusable self-powered electrochromic sensor patch based on enzymatic biofuel cells were constructed to realize the on-site visualized monitoring. In this design, hydrophilic agarose hydrogel and SiO2 hydrophobic film were used to control the collection and elimination of sweat. Lactic acid (LA) served not only as a model analyte, but also as a fuel to convert chemical energy into electrical energy. The generated electrons further reduced the Prussian blue (PB) to Prussian white (PW), accompanied by visible color changes. It could achieve semiquantitative detection by reading color changes with the naked eye or quantitative detection by the output blue value and current signals. In order to reduce costs, the PB color was restored by applying voltage, causing the electrode to change from a faded state to a blue colored state again, thus, achieving the repeated use of the sensor patch. This work established a proof-of-concept for the design of a reusable self-powered electrochromic sensor patch that could provide innovative inspiration for the formation of a general visualized wearable patch.

Achieving Color-Tunable and Stable Luminescent Hydrophilic Phosphorescent Films in the Presence of Cucurbit[8]uril for Advanced Anti-counterfeiting

Achieving Color-Tunable and Stable Luminescent Hydrophilic Phosphorescent Films in the Presence of Cucurbit[8]uril for Advanced Anti-counterfeiting

Solid dispersions as effective curcumin vehicles to obtain k-carrageenan functional films for olive oil preservation

Synthetic packaging materials offer cost efficiency and performance but pose environmental risks. This study explores sustainable alternatives by developing k-carrageenan (KC) films functionalized with curcumin, using solid dispersions (SDs) to improve curcumin's compatibility, addressing the challenge of incorporating hydrophobic functionalities into hydrophilic film matrices. Films with varying curcumin content (1–20 wt%; KC1-KC20) were compared to a base film without curcumin (KC0) regarding water solubility, vapor permeability, water contact angle, and tensile properties. Compared to KC0, KC10 (10 % curcumin-SDs) exhibited improved water resistance, with solubility decreasing from 82.89 % to 77.18 %, while maintaining vapor permeability (2.96 × 10−10 g·m/s·m2·Pa). KC10 demonstrated enhanced tensile properties, with a 12.51 % increase in tensile modulus (241.47 MPa), a 3.86 % increase in stress at break (3.50 MPa), and a 4.42 % increase in strain at break (2.36 %). Furthermore, it exhibited potent antioxidant activity without releasing curcumin into a simulated fatty medium (non-migratory active protection mechanism), effectively preserving olive oil by limiting lipid oxidation to a peroxide value (PV) of 14 mEq. O2/kg oil, compared to 20 mEq. O2/kg oil in unprotected samples under accelerated conditions. It demonstrated significant antimicrobial activity with bacterial reductions of 95.4 % (Escherichia coli) and 90.6 % (Listeria monocytogenes), surpassing KC0. In conclusion, k-carrageenan films functionalized with curcumin SDs are promising and sustainable alternatives to synthetic packaging materials.

Starch-based films with incorporated apple peel and chokeberry polyphenols

The aim was to prepare biodegradable starch-based films with active substances, and to examine the influence of temperature (80, 90, 99 °C), plasticizer (glycerol 1, 2, 4 %), and incorporation of phenolic compounds form apple peel and chokeberry on the properties of the films. The hygroscopic nature of glycerol affected the film properties. With the increase in glycerol content the water content, water solubility, and water vapor permeability of films significantly increased, while the swelling degree and hardness significantly decreased (p<0.05). Temperature did not have a significant influence on film properties. Phenolic compounds from apple peel and chokeberry increased the water solubility of films, and the loss of weight in water, in some cases significantly (p<0.05). The increase in hydrophilicity of films after the addition of phenolic compounds could be suggested, which affected the higher solubility and weight loss in the water. However, phenolic compounds decreased the swelling degree of films, in some cases significantly (p<0.05). The denser structure of films with the addition of phenolic compounds can be suggested, which caused the swelling degree to decrease. All films were biodegradable in water (the weight loss 18-38 %). The properties of starch-based films need to be studied and adjusted further for packing foods.

Calla lily-inspired 3D evaporator: A dual interface design for enhanced solar water evaporation

Due to the exponential growth of the global population, groundwater resources have long been insufficient to meet the escalating demand for potable water. In recent years, interfacial solar stream generation (ISSG) technology has emerged as a pivotal approach in generating clean water. The paramount performance factors of solar thermal evaporators encompass their exceptional light absorption capacity, efficient water transport, and effective thermal management. Among these factors, the 3D interface evaporator stands out due to its inherent advantages and ingenious structural design that enhances overall performance. In this study, the structure of calla lilies was used as inspiration, we propose a novel design featuring a 3D inverted conical double-sided evaporator (3D-ASIE) which effectively traps sunlight within its core, thereby augmenting light absorption capabilities while simultaneously forming a dual-evaporation interface. The inverted conical structure comprises two cellulose/TiN aerogel films with superior light absorption and heat insulation properties along with a polytetrafluoroethylene (PTFE) hydrophilic film that is skillfully bent and assembled together. To ensure continuous water supply during evaporation, the tail end of the hydrophilic membrane is immersed in water. During interfacial evaporation process, activation of the outer photothermal layer of our 3D-ASIE facilitates steam diffusion along both inner and outer surfaces of the inverted cone structure concurrently resulting in an impressive dual-evaporative effect. Under sunlight intensity level at 1 kW m−2, our 3D-ASIE exhibits remarkable performance with an evaporation flux reaching up to 2.97 kg m−2 h−1 alongside an efficiency as high as 94.7 %, thus demonstrating immense potential for large-scale solar desalination applications.

Enhancing Starch Film Properties Using Bacterial Nanocellulose-Stabilized Pickering Emulsions.

This study aimed to address issues related to hydrophilicity, barrier properties, and mechanical performance in starch-based films by incorporating Pickering emulsions stabilized with nano-fibrillated bacterial cellulose (BC). Emulsions were added to the film-forming suspension at varying concentrations (1.0%, 2.5%, 5.0%, and 7.5% v/v) for comparison. The films were evaluated using water vapor permeability (WVP), contact angle, Fourier Transform Infrared Spectroscopy (FTIR), and tensile tests. The results showed a significant reduction in film hydrophilicity, with the contact angle increasing from 49.7° ± 1.5 to 71.0° ± 1.4, and improved water vapor barrier properties, with WVP decreasing from 0.085 ± 0.04 to 0.016 ± 0.01 g·mm/h·m2·kPa. FTIR analysis confirmed the successful incorporation of the emulsion into the starch matrix. Among the tested concentrations, 2.5% provided an optimal balance, increasing hydrophobicity while maintaining mechanical strength. These findings demonstrate that Pickering emulsions are an effective strategy for enhancing the functional properties of starch films.

Thioether-Functionalized Cellulose for the Fabrication of Oxidation-Responsive Biomaterial Coatings and Films.

Biomaterial coatings and films can prevent premature failure and enhance the performance of chronically implanted medical devices. However, current hydrophilic polymer coatings and films have significant drawbacks, including swelling and delamination. To address these issues, hydroxyethyl cellulose is modified with thioether groups to generate an oxidation-responsive polymer, HECMTP. HECMTP readily dissolves in green solvents and can be fabricated as coatings or films with tunable thicknesses. HECMTP coatings effectively scavenge hydrogen peroxide, resulting in the conversion of thioether groups to sulfoxide groups on the polymer chain. Oxidation-driven, hydrophobic-to-hydrophilic transitions that are isolated to the surface of HECMTP coatings under physiologically relevant conditions increase wettability, decrease stiffness, and reduce protein adsorption to generate a non-fouling interface with minimal coating delamination or swelling. HECMTP can be used in diverse optical applications and permits oxidation-responsive, controlled drug release. HECMTP films are non-resorbable in vivo and evoke minimal foreign body responses. These results highlight the versatility of HECMTP and support its incorporation into chronically implanted medical devices.

Hydrophilic Separator Stables CO2-to-C2H4 Conversion at Low Cell Voltage with Non-Noble Metal Anode

Electrochemical carbon dioxide (CO2) reduction (ECR) is a promising approach for enabling the conversion of greenhouse gas CO2 into valuable products with electricity from renewable sources to achieve net-zero CO2 emission. ECR simultaneously reduces carbon emissions and dependence on fossil-based fuels and chemicals. Membrane electrode assemblies (MEAs), which often comprise an anion exchange membrane (AEM) and a precious iridium oxide (IrOx)-based anode, have been extensively studied in the last few years. However, challenges such as salt precipitation on cathodic gas diffusion electrodes (GDEs), high cell voltage and the need to use noble metal anodes have hindered ECR's practical applications. Herein, we introduce a new design of MEA cells using a low-cost hydrophilic film separator and a Nickel (Ni) foam instead of AEM and IrOx, respectively. Hydrophilic separator material with high water permeability lowers the full-cell voltage and eliminates the salt accumulation on the GDE in both alkaline and neutral-pH conditions. Using copper-sputtered polytetrafluoroethylene (Cu/PTFE) as cathodes, we demonstrated a stable conversion of CO2 to ethylene (C2H4) at current densities over 100 mA/cm2. In neutral-pH anolyte, the average C2H4 FE was sustained at around 50% for more than 200 hours with a cell voltage of 3.1 V at the current density of 110 mA/cm2. Under alkaline conditions, this system showed 500 hours of stability of CO2-to-C2H4 conversion: the C2H4 FE was maintained above 60% with the cell voltage of only 2.2 V at 110 mA/cm2 current density. Our research provides a solution for achieving stable ECR operation at a relatively high current density using Earth-abundant materials. This work opens opportunities for energy-efficient and stable CO2 conversion without needing expensive and rare elements, which are crucial for practical applications.

Naked-eye detection of Legionella pneumophila using smart fluorogenic polymers prepared as hydrophilic films, coatings, and electrospun nanofibers

Legionella pneumophila is a significant public health threat, responsible for severe diseases such as Legionnaires’ disease. Traditional detection methods are often labour-intensive, time-consuming, and require sophisticated equipment. This study introduces smart fluorogenic polymeric materials for the naked-eye detection of L. pneumophila via protease activity. These materials, prepared as hydrophilic films, cellulose-coated linear copolymers, and electrospun nanofibers, operate on an OFF/ON FRET system, emitting fluorescence under UV light upon interaction with L. pneumophila proteases. Characterisation confirmed the successful immobilisation of the peptide substrate and its response to proteases. The sensors showed moderate to high sensitivity and specificity, with detection limits of 2.91 × 105, 3.64 × 10⁵, and 4.04 × 105 CFUs/mL for the film, copolymer, and nanofiber formats, respectively. Cross-reactivity tests identified only Pseudomonas aeruginosa as an interferent. This novel approach offers rapid, simple, and cost-effective L. pneumophila detection with visible results under UV light, suitable for clinical and environmental samples. It highlights the potential for broader pathogen detection applications.

Synthesis, characterization, and optical sensing of hydrophilic anodic alumina films

Herein, the anodization of 2.6 μm Al-0.2 at. % Cu (Al-0.2Cu) films on TiN/p-type Si substrate were performed using common acidic mediums at different ranges of anodization voltage (Va) to produce porous anodic alumina (PAA) nanostructures with high porosity. The anodization of Al-0.2Cu in 1 M H2SO4 at Va range of 10–30 V produced a higher oxide thickness, and hence, a higher volume expansion factor, compared to the anodization in 0.75 M H3PO4 at Va range of 100–140 V. The increase in Va, as expected, increases the inter-pore distance, pore size, and porosity of the PAA and improves the anodization rate. The optical sensing performance of the synthesized PAA under different conditions was investigated. The maximum surface wettability was attained for PAA anodized in 1 M H2SO4 at 20 and 30 V. Moreover, the Vickers hardness (HV) of PAA was improved by forming a thin alumina layer on the Al-0.2Cu surface, and the anodized Al-0.2Cu in 0.3 M C2H2O4 revealed the highest HV compared to other acids. The synthesized PAA was tested as an optical sensor for some liquids by monitoring the refractive index. The synthesized PAA structure demonstrated a sensitivity of 180 nm/RIU. The anodization of Al-0.2Cu films using a one-step anodization process in different acidic mediums, and the resulting multifunctional properties (improved hardness, tunable wettability, and competitive sensitivity) existing a novel and potentially impactful approach.

Surface modification and patterning of polymer thin films by plasma and adsorption behavior of proteins

The surface wettability property of hydrophobic polystyrene (PS) and hydrophilic polyethylene glycol (PEG) thin films subjected to modification by direct current plasma glow discharge is studied. The polymer films exhibited change of surface wettability on exposure to air, nitrogen, oxygen or argon plasmas. In PS films a swift modification to hydrophilic surface and subsequent steady recovery following first order kinetics are observed. The rate of modification and recovery are adjustable by adjusting the plasma ambient and parameters, and additional wet-chemical treatment using ionic solutions. In PEG films the hydrophobic wettability evolve with ageing following the first order kinetics, and is stable for long period on exposure to air ambient. Moreover, a vapor deposition like process is possible using the PEG films as source to deposit self-assembled molecular layers with hydrophobic wettability on other surfaces. Using surface modification or molecular deposition processes, the fabrication of wettability patterns in the surface of PS and PEG films, and on other surfaces by vapor transport using PEG films, and also the possibility to produce gradient wettability patterns are demonstrated. Moreover, the adsorption behavior of immuno-specific system of proteins on surface modified hydrophilic PS films is studied.

Copper Polypropylene Metal Plastic Composite Copper Foil: Future-Proof Anode Current Collector Solution for Lithium-Ion Batteries with High Energy Density.

Composite copper foil is considered to be the future-proof anode current collector solution for lithium-ion batteries (LIBs) with high energy density, for its light weight and low cost. Polypropylene (PP) film is widely used as the support layer of composite copper foil current collectors (CCs) due to its excellent mechanical properties and chemical stability. However, the interface adhesion between the PP layer and the copper layer is weak, due to the significant difference in surface energy. In this study, we prepared a hydrophilic PP film by air plasma treatment. After magnetron sputtering and electroplating, the composite copper foil (PP@Cu-1) with strong adhesion was then successfully prepared. In the T-peel test, for PP@Cu-1, the pull required to separate PP from the copper layer is approximately 7 times that of PP@Cu-0. The PP@Cu-1 composite copper foil exhibits excellent electrochemical properties when applied to LIBs. As an anode CC material, it could be a favorable competitor to conventional commercial Bare Cu and holds broad prospects for application in high-energy-density LIBs.

Small-Molecule Mixed Ionic-Electronic Conductors for Efficient N-Type Electrochemical Transistors: Structure-Function Correlations.

The fundamental challenge in electron-transporting organic mixed ionic-electronic conductors (OMIECs) is simultaneous optimization of electron and ion transport. Beginning from Y6-type/U-shaped non-fullerene solar cell acceptors, we systematically synthesize and characterize molecular structures that address the aforementioned challenge, progressively introducing increasing numbers of oligoethyleneglycol (OEG; g) sidechains from 1 g to 3 g, affording OMIECs 1gY, 2gY, and 3gY, respectively. The crystal structure of 1gY preserves key structural features of the Yn series: a U-shaped/planar core, close π-π molecular stacking, and interlocked acceptor groups. Versus inactive Y6 and Y11, all of the new glycolated compounds exhibit mixed ion-electron transport in both conventional organic electrochemical transistor (cOECT) and vertical OECT (vOECT) architectures. Notably, 3gY with the highest OEG density achieves a high transconductance of 16.5 mS, an on/off current ratio of ~106, and a turn-on/off response time of 94.7/5.7 ms in vOECTs. Systematic optoelectronic, electrochemical, architectural, and crystallographic analysis explains the superior 3gY-based OECT performance in terms of denser ngY OEG content, increased crystallite dimensions with decreased long-range crystalline order, and enhanced film hydrophilicity which facilitates ion transport and efficient redox processes. Finally, we demonstrate an efficient small-molecule-based complementary inverter using 3gY vOECTs, showcasing the bioelectronic applicability of these new small-molecule OMIECs.

Small‐Molecule Mixed Ionic‐Electronic Conductors for Efficient N‐Type Electrochemical Transistors: Structure‐Function Correlations

The fundamental challenge in electron‐transporting organic mixed ionic‐electronic conductors (OMIECs) is simultaneous optimization of electron and ion transport. Beginning from Y6‐type/U‐shaped non‐fullerene solar cell acceptors, we systematically synthesize and characterize molecular structures that address the aforementioned challenge, progressively introducing increasing numbers of oligoethyleneglycol (OEG; g) sidechains from 1g to 3g, affording OMIECs 1gY, 2gY, and 3gY, respectively. The crystal structure of 1gY preserves key structural features of the Yn series: a U‐shaped/planar core, close π‐π molecular stacking, and interlocked acceptor groups. Versus inactive Y6 and Y11, all of the new glycolated compounds exhibit mixed ion‐electron transport in both conventional organic electrochemical transistor (cOECT) and vertical OECT (vOECT) architectures. Notably, 3gY with the highest OEG density achieves a high normalized transconductance of 25.29 S cm‐1, an on/off current ratio of ~106, and a turn‐on/off response time of 94.7/5.7 ms in vOECTs. Systematic optoelectronic, electrochemical, architectural, and crystallographic analysis explains the superior 3gY‐based OECT performance in terms of denser ngY OEG content, increased crystallite dimensions with decreased long‐range crystalline order, and enhanced film hydrophilicity which facilitates ion transport and efficient redox processes. Finally, we demonstrate an efficient small‐molecule‐based complementary inverter using 3gY vOECTs, showcasing the bioelectronic applicability of these new small‐molecule OMIECs.

A wearable exhaled breath condensate (EBC) collector with controllable condensation microfluidics and a branched hydrophilic film

In previous research, exhaled breath condensate (EBC) analysis has emerged as a promising noninvasive method for assessing human health, potentially increasing patient testing acceptance. However, current EBC collection devices require cooling equipment for temperature reduction, leading to issues such as increased size, increased energy consumption, and a lack of real-time collection capability. In this study, an EBC collector was developed that integrates controllable condensation microfluidics with a biomimetic water-collecting film. Microfluids induce an endothermic reaction by rapidly dissolving water and NH4NO3 within the chamber, reducing the surface temperature to 3.5 °C. When positioned inside a mask, exhaled air undergoes condensation and collection on the branched biomimetic film. Human tests were conducted to analyze caffeine and nicotine in the collected EBC samples using LC–MS, demonstrating the device’s advantages in terms of power-free operation, wearable design, and rapid sample collection for metabolite detection.

Using a Carbon Quantum Dot Suspension as a New Solvent for Clear Hydrophobic Surface Coating on Hydrophilic PVA Films.

Polyvinyl alcohol (PVA) is a popular material used in the packaging industry. However, it is vulnerable to moisture, which can affect its performance and durability. Introducing hydrophobic substances, such as tetraethyl orthosilicate (TEOS) and hexadecyltrimethoxysilane (HDTMS), on the top layer of PVA can help maintain the excellent properties of PVA under high-humidity conditions. The low compatibility of hydrophobic materials with the hydrophilic layers allows them to aggregate more easily. To overcome these issues, we focused on the effects of particle size when increasing the coating suspension's dispersibility. A carbon quantum dot (CQD) suspension is an appropriate novel solvent for hydrophobic TEOS/HDTMS coating suspensions because its particles are small and light and exhibit good dispersibility. The CQD suspension formed a smooth hydrophobic coating on the TEOS/HDTMS materials. Furthermore, the uniformly coated PVA with the CQD suspension exhibited a water contact angle of 110°. The water droplets remained intact without being absorbed, confirming the effectiveness of the surface coating facilitated by CQDs. These results suggested that CQDs improved the dispersibility and enhanced the coating quality of TEOS/HDTMS on PVA. Enhancing the hydrophobicity of PVA is ideal for applications in packaging and other fields.

Octadecylamine modified gelatin-based biodegradable packaging film with good water repellency and improved moisture service reliability

Industrial gelatin is a good candidate for fabricating biodegradable packaging film, but the strong hydrophilicity of gelatin-based film lowers its moisture service reliability. Herein, we demonstrated a low surface energy water repellency surface design combined with covalent cross-linking for decreasing the water absorption and improving the moisture service reliability. Biodegradable octadecylamine (ODA) was chosen as the low surface energy providing material to fabricate the water repellency surface through a dehydration condensation reaction between the amine groups of ODA and gelatin chains via tetra-hydroxymethyl phosphonium chloride (THPC) in an aqueous phase. THPC also was employed as the cross-linking agent to form covalent bonding between the gelatin chains. The results determined that ODA modification and covalent cross-linking endowed the gelatin-based film with good water repellency and improved moisture service reliability. But high dose of ODA would result in phase separation and mechanical strength loss of the fabricated film. Additionally, ODA modification did not change the biodegradability of gelatin-based film, all the modified films were completely biodegradable in natural soil. Considering the sustainable modification process and abundant raw materials, the proposed strategy facilitates the effective utilization of low value industrial gelatin and provides a facile way for gelatin-based film as biodegradable packaging film.

Boosting photocatalytic stability: hydrophilic Sr-doped ZnO thin films prepared via the SILAR method for enhanced performance over multiple cycles

This study deals with the synthesis and characterization of Sr-doped ZnO thin films with different concentrations (1, 3, 5, and 7 wt%) using the SILAR method (Successive Ionic Layer Adsorption and Reaction). The main objective is to evaluate the effectiveness of the films as photocatalysts for the degradation of methylene blue under natural sunlight conditions. X-ray diffraction analysis confirms the polycrystalline nature of the films, with the crystallite size increasing with increasing Sr doping along the (100) plane. Morphological changes on the film surfaces are revealed by scanning electron microscopy and correlate with the increasing Sr content. Energy dispersive x-ray spectroscopy (EDX) confirms that there are no impurities in all films. 3D surface topography shows that higher Sr doping leads to an increase in average roughness and root mean square (Rq) values. Measurements of the water droplet contact angle (WDCA) indicate the hydrophilicity of the surface. Optical analysis shows that the absorption capacity of the films increases with Sr doping and shifts slightly towards longer wavelengths. Additionally, the band gap energy (Eg) shows a linear increment with higher Sr dopant concentrations. The unique contribution of this work lies in the careful investigation of the photocatalytic degradation of methylene blue using Sr-doped ZnO films as photocatalysts under natural sunlight. In particular, the films doped with 5 wt% Sr show exceptional performance, achieving degradation rates of 94.82%, 94.61%, and 93.48% for the first, second, and third cycles, respectively. The novelty of these results lies in the successful synthesis of Sr-doped ZnO thin films by SILAR, the comprehensive characterization of their properties and the remarkable photocatalytic efficiency observed under real sunlight conditions. This work provides valuable insights into the potential application of these unique films for the efficient degradation of methylene blue, thus contributing to the further development of environmentally friendly photocatalytic materials.

Fish-Mimicking Hydrophilic and Hygroscopic Transparent Films with Long-Lasting Anti-Oil Adhesion and Its Application to PET Bottles

With the recent ban on the production and use of long-chain perfluorinated compounds, the development of alternative approaches to prepare liquid-repellent surfaces that avoids the use of such compounds has become an urgent issue. We have succeeded in the development of fish-mimicking hydrophilic transparent hydrogel-based films with long-lasting anti-oil adhesion properties. Such films could be prepared by simply mixing poly(vinylpyrrolidone) (PVP), nanoclay particles (NCPs), and a waterborne aminosilane (AOS) using an integral blend (IB) method. When submerged in water, these films displayed underwater superoleophobicity (advancing and receding contact angles (CAs) of diiodomethane were ~171°/~163°) with low CA hysteresis (less than 8°), because the hydrophilic nature of the films promoted the formation of a thin layer of adsorbed water on the topmost film surfaces, similar to fish scales. Furthermore, when our films were coated onto the inside of poly(ethylene terephthalate) (PET) bottles and pre-wetted using 80 °C hot water vapors, these film surfaces could effectively repel various oils and were able to maintain their oil-repellent properties for more than 5 weeks. These water-driven, non-perfluorinated transparent hydrogel-based films are expected to increase recycling of PET bottles for oils that are generally incinerated or landfilled.

Thermodynamic water adsorption analysis of biodegradable films based on corn starch-chitosan added with triblock copolymers

Adding triblock copolymers to hydrophilic films is an option to improve the functional properties and water resistance under high equilibrium relative humidity (RHeq) environments. Sorption isotherms of corn starch-chitosan based films added with triblock copolymers (L64 and P123) measured at 4, 20, and 36 °C were fitted using the Guggenheim-Anderson-De Boer equation. Thermodynamic analysis allowed allocating the minimum integral entropy value between 0.09 and 0.50 of water activity. The compensation enthalpy-entropy showed that the entropy driven the process at low water activities (0.10–∼0.33) and the enthalpy driven the water sorption at high water activities (∼0.33–∼0.90).