Surface Rheology Research Articles

β-lactoglobulin microgel layers at the surface of aqueous solutions

The spread and adsorbed layers of β-lactoglobulin (BLG) microgel were investigated by the dilational surface rheology, atomic force microscopy and optical microscopy. It is shown that only careful purification of the BLG microgel dispersion gives a possibility to observe distinctions between the properties of spread layers of BLG nano- and micro particles on the one hand, and the properties the layers of BLG molecules on the other hand. The BLG particles do not have a thick and soft corona like poly(N-isopropylacryl) microgel. The fluctuations of the surface pressure of the BLG microgel layers at high surface compressions are a consequence of a special collapse mechanism, which has not observed earlier for the layers of both soft and rigid nano- and microparticles.

A model for bubble dynamics in a protein solution

This paper presents a model for bubble dynamics in a protein solution, including varying surface tension and dynamic adsorption/desorption of protein onto the bubble surface. We model the protein-coated bubble surface as a linear viscoelastic interface. Two cases are studied to understand the importance of the surface excess stress: (1) bubble dissolution in a protein solution due to gas diffusion; and (2) bubble response to an imposed fluctuating pressure field. In the first case study, the surface excess stress stabilizes the bubble against dissolution. Initially, the surface excess stress is negligible, and the dissolution rate is governed by the Weber number, which compares the gas inertial force and the surface tension force. As the bubble shrinks, the surface excess stress grows and eventually balances the surface tension. After that, the dissolution rate is governed by the protein desorption rate and the elasto-capillary number, which compares the surface tension and the surface dilatational elasticity. Our model predictions for the dissolution process agree with experiments before the bubble buckles. In the second case study, the surface dilatational viscosity and dilatational elasticity add resistance and stiffness to the system, respectively. Including the surface excess stress increases (or reduces) the amplitude of the bubble radius if the frequency of the imposed fluctuating pressure is greater (or less) than a critical value. These results highlight the importance of the surface rheology on the protein-coated bubble dynamics, which has applications in drug delivery and ultrasound contrast agents.

Modulation of bubble flow resistance and surface fluidity :the effect of nanoparticle packing density at gas–liquid interface

Nanoparticles (NPs) adsorbed at bubble surface have a substantial impact on gas–liquid interface properties, but how to regulate the properties and further control foam flow remaining to be elucidated. Here, the effects of nanoparticle surfactancy on surface rheology, fluidity and shear force field around bubbles were quantitatively analyzed. It was found that the adsorption of nanoparticles on the bubble surface gives rise to surface solidification, the flow velocity close to surface decreased by 76%, meanwhile the shear stress loaded on bubble surface increases sharply. Furthermore, the surface solidification degree or fluidity can be controlled by regulating the packing density of nanoparticles on bubble surface, whereby the bubble flow could be control accordingly, which greatly contribute to the application of foam.

The effect of sea salt solution erosion on cohesion, chemical and rheological properties of SBS modified asphalt

This paper aims to explore the damage mechanism of asphalt under sea salt erosion environment from the aspects of surface physics, chemistry, and rheology. To simulate the sea salt erosion environment, styrene–butadiene–styrene (SBS) modified asphalt samples were soaked with mixed salt solutions containing sodium chloride (NaCl) and sodium sulphate (Na2SO4) at six different concentrations. The effect of sea salt solution erosion on cohesion, chemical and rheological properties of SBS modified asphalt was studied through surface free energy (SFE) test, Fourier transform infrared spectroscopy (FTIR) analysis and Dynamic Shear Rheometer (DSR) test, respectively. The results indicate that the salt in the mixed salt solution migrates into the asphalt samples, resulting in the decrease of the total SFE, cohesion work. While the appearance of the new absorption peaks and the changes of peak area ratio of characteristic peaks indicate that the salt migrates into the asphalt sample, reacts with the asphalt, and leads to the aging of asphalt simultaneously. Besides, the viscous component of asphalt decreases, while the elastic component and the Superpave rutting parameter increase, indicating that elastic recovery ability and rutting resistance of the SBS modified asphalt are enhanced. Moreover, the changes of phase angle and complex modulus of rheological master curves at low frequency domain, as well as the increase of failure temperature and the Glover-Rowe parameter, indicate that the high temperature properties of asphalt are improved, while the cracking resistance is damaged. Finally, all the above indexes have linear relationships with the concentration of mixed salt solution.

Charge‐Induced Structural Changes of Confined Copolymer Hydrogels for Controlled Surface Morphology, Rheological Response, Adhesion, and Friction

AbstractThe ability to modulate polyacrylamide hydrogel surface morphology, rheological properties, adhesion and frictional response is demonstrated by combining acrylic acid copolymerization and network confinement via grafting to a surface. Specifically, atomic force microscopy imaging reveals both micellar and lamellar microphase separations in grafted copolymer hydrogels. Bulk characterization is conducted to reveal the mechanisms underlying microstructural changes and ordering of the polymer network, supporting that they stem from the balance between hydrogen bonding in the substrate‐grafted hydrogels, electrostatic interactions, and a decrease in osmotically active charges. The morphological modulation has direct impacts on the spatial distribution of surface stiffness and adhesion. Furthermore, lateral force measurements show that the microphase separations lead to speed and load‐dependent lubrication regimes as well as spatial variation of friction. A proof of concept via salt screening demonstrates the dynamic control of surface morphology and adhesion. This work advances the knowledge necessary to design complex hydrogel interfaces that enable spatial and dynamic control of surface morphology and thereby of friction and adhesion through modulation of hydrogel composition and surface confinement, which is of significance for applications in biomedical devices, soft tissue design, soft robotics, and other engineered tribosystems.

Instabilities of a shear-thinning fluid falling over an undulating porous layer

We investigate the stability of a fluid film with power-law rheology flowing down a porous nonplanar incline with periodic undulations. A model is implemented which accounts for filtration flow through the substrate. A reduction in dimensionality in the model is achieved by exploiting the assumed thinness of the liquid film relative to the wavelength of the bottom undulations. A steady flow is obtained and its linear stability determined through the application of Floquet–Bloch theory. A nonlinear stability analysis is also carried out by calculating the evolution of the perturbed steady flow by means of numerical simulations. • An investigation of instability of film flow down an uneven porous incline. • A power-law rheological model is implemented. • Film flow is coupled with the filtration flow through the porous medium. • Combined effects of surface tension, rheology and properties of substrate determined.

Continuum and Molecular Dynamics Studies of the Hydrodynamics of Colloids Straddling a Fluid Interface

Colloid-sized particles (10 nm–10 μm in characteristic size) adsorb onto fluid interfaces, where they minimize their interfacial energy by straddling the surface, immersing themselves partly in each phase bounding the interface. The energy minimum achieved by relocation to the surface can be orders of magnitude greater than the thermal energy, effectively trapping the particles into monolayers, allowing them freedom only to translate and rotate along the surface. Particles adsorbed at interfaces are models for the understanding of the dynamics and assembly of particles in two dimensions and have broad technological applications, importantly in foam and emulsion science and in the bottom-up fabrication of new materials based on their monolayer assemblies. In this review, the hydrodynamics of the colloid motion along the surface is examined from both continuum and molecular dynamics frameworks. The interfacial energies of adsorbed particles is discussed first, followed by the hydrodynamics, starting with isolated particles followed by pairwise and multiple particle interactions. The effect of particle shape is emphasized, and the role played by the immersion depth and the surface rheology is discussed; experiments illustrating the applicability of the hydrodynamic studies are also examined.

High-performance sulphate-free cleansers: Surface activity, foaming and rheology.

The main objective of this paper is to analyse the composition of a sulphate-free binary or ternary surfactant system with alkyl olefin sulfonate (AOS), alkyl polyglucoside (APG) and lauryl hydroxysultaine (Sultaine). The composition was optimized by observing critical parameters such as surface activity and rheological properties while varying the concentration of APG in a ternary system, varying the ratio of AOS and Sultaine in a binary system and studying the effect of sodium chloride addition. The experimental results can provide an alternative, sulphate-free surfactant system to replace the common system containing sodium laureth sulfate (SLES) and cocamidopropyl betaine (CapB), without compromising on the parameters previously mentioned. A DuNouy Ring was utilized on a tensiometer to measure the surface tension of the samples. To observe foaming abilities of samples, a visual foaming study was conducted and recorded by taking pictures. A TA instruments mechanical rheometer was used to measure the viscosity. Studying the effect of APG concentration on surface tension illustrated that as APG concentration decreases, surface tension decreases as well. The minimum surface tension was found to be 26.587 for 7.5wt.% AOS and 7.5wt.% Sultaine. When the ratio between AOS and Sultaine changed, the 1:1system produced the lowest surface tension value again. As the concentration of AOS decreased in the ratio, the surface tension increased. When the ratio was held constant, and APG was introduced into the system, the systems containing APG had higher surface tension values compared with the systems with the same ratios but did not have APG added. As the concentration of salt increased, the surface tension decreased for AOS, increased for the binary mixture and had no effect on Sultaine. Foaming has a direct correlation with surface tension so a decrease in surface tension led to better foaming abilities; therefore, the 1:1 ratio of AOS:Sultaine had the best foaming qualities. The AOS/Sultaine system exhibited Maxwellian behaviour, suggesting the presence of worm-like micellar structures. As the concentration of APG increased, the viscosity decreased and at a concentration of 2.5wt.% AOS, 5wt.% APG and 7.5wt.% Sultaine, the system changed from shear thinning non-Newtonian fluid to Newtonian. Varying the ratio of AOS:Sultaine in the binary system, showed as the ratio changed, the viscosity decreased, and at a ratio of 1:3 AOS:Sultaine, the system was primarily Newtonian. As the ratio remained constant and APG was added, the viscosity continued to decrease and the 1:3 ratio was completely Newtonian. The addition of salt had no effect on the viscosity of Sultaine, but the viscosity of AOS increased at a salt concentration of 2wt.%. The binary mixture saw as the concentration of salt increased, the viscosity profile decreased, even though the system remained non-Newtonian and shear thinning. The surface activity and rheological study of the sulfate-free surfactant systems unveil a strong synergistic interaction between AOS and Sultaine specifically at a ratio of 1:1 resulting in high surface activity and corresponding good foaming and formation of entangled wormlike micelles resulting in excellent viscosity build in the system. If introducing a biobased surfactant into this system is desired without completely compromising the performance properties, the ternary surfactant system 4.5wt.% AOS, 3wt.% APG and 7.5wt.% Sultaine should be considered optimal. Any further addition of APG or changing the ratio results in detrimental reductions of all performance controlling physio-chemical parameters.

Interfacial Behavior of Particle-Laden Bubbles under Asymmetric Shear Flow.

The behavior of moving bubbles has mostly been studied in an axisymmetric flow field. To extend the knowledge to practical conditions, we investigate the interfacial and hydrodynamic properties of bubbles under asymmetric shear forces. Experiments are performed with a buoyant bubble at the tip of a capillary placed in a defined shear flow in the presence of surfactants, nanoparticles, and glass beads. The response of the interface to the surrounding asymmetric flow is measured under successive reduction of the surface area. Profile analysis tensiometry is utilized to investigate the dynamic surface tension and the surface rheology of the surfactant- and nanoparticle-laden interfaces. Microscopic particle image and tracking velocimetry are used to study the bulk flow and the interfacial mobility of the buoyant bubble. According to our results, the rotational component of the shear flow provokes an interfacial flow, which redistributes the adsorbed surfactants and particles at the interface. In the presence of NPSCs, a contiguous network of particles forms at the interface through densification of surface structures. We show that this interconnected nanoparticle network eventually stops the interfacial flow and decreases the mobility of the glass beads at the interface. The immobilization of the interface is characterized by a dimensionless number, defined as the ratio of the interfacial elasticity to bulk shear forces. This number provides an estimate of the interfacial forces required to impose interfacial immobility at a defined flow field. Our findings can serve as a basis to formulate boundary conditions for refined modeling and to predict the hydrodynamics of bubbles and droplets.

PH effects on the molecular structure and charging state of β-Escin biosurfactants at the air-water interface

Saponins like β-escin exhibit an unusually high surface activity paired with a remarkable surface rheology which makes them as biosurfactants highly interesting for applications in soft matter colloids and at interfaces. We have applied vibrational sum-frequency generation (SFG) to study β-escin adsorption layers at the air-water interface as a function of electrolyte pH and compare the results from SFG spectroscopy to complementary experiments that have addressed the surface tension and the surface dilational rheology. SFG spectra of β-escin modified air-water interfaces demonstrate that the SFG intensity of OH stretching vibrations from interfacial water molecules is a function of pH and dramatically increases when the pH is increased from acidic to basic conditions and reaches a plateau at a solution pH of > 6. These changes are attributable to the interfacial charging state and to the deprotonation of the carboxylic acid group of β-escin. Thus, the change in OH intensity provides qualitative information on the degree of protonation of this group at the air-water interface. At pH < 4 the air-water interface is dominated by the charge neutral form of β-escin, while at pH > 6 its carboxylic acid group is fully deprotonated and, consequently, the interface is highly charged. These observations are corroborated by the change in equilibrium surface tension which is qualitatively similar to the change in OH intensity as seen in the SFG spectra. Further, once the surface layer is charge neutral, the surface elasticity drastically increases. This can be attributed to a change in prevailing intermolecular interactions that change from dominating repulsive electrostatic interactions at high pH, to dominating attractive interactions, such as hydrophobic and dispersive interactions, as well as, hydrogen bonding at low pH values. In addition to the clear changes in OH intensity from interfacial H2O, the SFG spectra exhibit drastic changes in the CH bands from interfacial β-escin which we relate to differences in the net molecular orientation. This orientation change is driven by tighter packing of β-escin adsorption layers when the β-escin moiety is in its charge neutral form (pH < 4).

Investigation of surface properties of quince seed extract as a novel polymeric surfactant

In recent years, there is a growing trend from both academia and the industry towards the use of “clean-labeled” ingredients obtained from renewable resources. Proteins and polysaccharides, in particular, are becoming increasingly popular as alternatives to already well-established synthetic surfactants. Quince seeds are a relatively novel hydrocolloid source that has recently raised interest among researchers due to their strong surface activity and viscosity-enhancing properties. This study investigates quince seed extract's surface properties (dynamic surface tension and dilatational surface rheology) and how they differ with varying concentrations (between 0.01% and 1%), pH's (3, 7, 9, and 11), and ionic strengths (0.1, 0.3, 0.5 M NaCl). By QSE addition alone, equilibrium surface tension could be lowered to ∼36 mN/m, which is lower than the lowest ST that can be achieved with many other surface active biopolymers. Critical aggregation concentration (CAC) was identified as 0.165% w/v, meaning a relatively low extract concentration was sufficient to provide complete surface coverage. Dynamic surface tension curves revealed almost instantaneous polymer adsorption for concentrations over 0.01% w/v, which demonstrates the strong potential of the gum as a foaming agent. As solution pHs get further from the isoelectric point of QSE proteins, the rate of adsorption of QSE molecules onto the interface and the equilibrium surface pressures increased. Surface properties were also significantly affected by the ionic strength of the medium, with eq. STs decreasing with increasing QSE concentration. pH and ionic strength induced conformational changes in the interfacial layer and also led to local minima and maxima in dilatational elastic and loss modulus within ranges studied. Considering these findings, QSE is a very promising natural alternative to other polymeric surfactants and stabilizers currently used in the food, cosmetic and pharmaceutical industries.

Development of a Computational Fluid Dynamics Compositional Wellbore Simulator for Modeling of Asphaltene Deposition

The asphaltene problem is a two-step process: (1) asphaltene precipitation, as predicted by the thermodynamic model, and (2) asphaltene deposition, the amount of which is estimated by the kinetic model. Asphaltene precipitation is a prerequisite but not a sufficient condition for deposition. Deposition is dependent on other factors such as surface properties, phase behavior, rheology, and flow patterns. As a result, in addition to understanding thermodynamic and kinetic models, it is critical to also understand flow models. In fact, multiphase flow modeling is at the core of simulation, and it must be coupled with thermodynamic and kinetic models. Numerous studies on modeling asphaltene deposition on pipe walls have been performed theoretically and experimentally, but a comprehensive theory to properly understand this phenomenon has not yet been presented. In thermodynamic modeling, the perturbed chain statistical associating fluid theory (PC-SAFT) equation of state is used to predict the asphaltene phase behavior. In this study, we show that the proposed PC-SAFT model is more accurate than the solid model used in commercial software. Unlike prior research that neglected flow patterns or used empirical relations to model multiphase flow, this study simulates multiphase flow using separate momentum equations for each phase. Among the existing kinetic models, the Kurup model has been used to predict the asphaltene deposition profile in the wellbore due to its greater compatibility for computational fluid dynamics application. The results of the proposed model show good agreement with field case data of asphaltene deposition thicknesses along the wellbore tubing.

Stability of Foams in Vacuum Drying Processes. Effects of Interactions between Sugars, Proteins, and Surfactants on Foam Stability and Dried Foam Properties.

The hypothesis was that saccharides mediate interactions between surface-active components and that this will have an impact on foam decay during the drying process. Static light scattering was performed to determine changes in interactions between the foam stabilizer on a molecular level. Furthermore, pendant drop and oscillating drop measurements were performed to examine the surface tension and surface rheology. Foams were dried in conventional dryers as well as microwave-supported vacuum dryers. Final foam properties were determined. It was shown that the addition of sugars, often added as protective substances for sensitive organic molecules, resulted in lower repulsion between different types of surface-active components, namely polysorbate 80 and β-lactoglobulin (β-lg). Differences in impact of the types of sugars and between different types of surfactant, protein, and small molecules were observed influencing the foam decay behavior. The interfacial properties of polysorbate 80 and β-lg were influenced by the type of the used sugars. The surface elasticity of protein stabilized surfaces was higher compared to that of polysorbate stabilized systems. Protein stabilized systems remained more stable compared to polysorbate systems, which was also affected by the used saccharide. Overall, a correlation between molecular interactions and foam decay behavior was found.

Examination of interfacial properties of quince seed extract on a sunflower oil-water interface

Seeds of the plant quince are a natural hydrocolloid source whose extract has shown promising results in stabilizing emulsions. The study aims to discover how quince seed extract's interfacial properties (dynamic surface tension and dilatational surface rheology) on an oil–water interface change with varying concentrations (between 0.01% and 1%), pH's (3, 7, and 11), and ionic strengths (0.1, 0.3, 0.5 M NaCl). The lowest concentration that yielded a statistically significant drop in interfacial was found as 0.02 % w/v. QSE dropped interfacial tension down to 16 mN/m at the highest concentration examined (1% w/v). Critical aggregation concentration (CAC) was identified as 0.23 % w/v, which is relatively low compared to hydrocolloids of similar nature. In the end, QSE was demonstrated to be an effective emulsion stabilizer and possesses some unique properties that help it distinguish itself from other macromolecular emulsifiers commonly employed in the food, chemical, and pharmaceutical industries.

A pH-Responsive Foam Formulated with PAA/Gemini 12-2-12 Complexes

In the search for responsive complexes with potential applications in the formulation of smart dispersed systems such as foams, we hypothesized that a pH-responsive system could be formulated with polyacrylic acid (PAA) mixed with a cationic surfactant, Gemini 12-2-12 (G12). We studied PAA-G12 complexes at liquid–air interfaces by equilibrium and dynamic surface tension, surface rheology, and X-ray reflectometry (XRR). We found that complexes adsorb at the interfaces synergistically, lowering the equilibrium surface tension at surfactant concentrations well below the critical micelle concentration (cmc) of the surfactant. We studied the stability of foams formulated with the complexes as a function of pH. The foams respond reversibly to pH changes: at pH 3.5, they are very stable; at pH &gt; 6, the complexes do not form foams at all. The data presented here demonstrate that foam formation and its pH responsiveness are due to interfacial dynamics.

PH-switchable wormlike micelles with high viscoelasticity formed by pseudo-oligomeric surfactants

A pH-switchable wormlike micellar system with high viscoelasticity was prepared by mixing N-(3-(dimethylamino) propyl) stearamide (SAM) and phthalic acid (PA) at the molar ratio of 2:1. By simple in situ neutralization reaction, SAM and PA could dynamically combine to fabricate a pseudo-oligomeric surfactant without additional inorganic salts. Through the results of surface activity, rheology and Small-angle X-ray scattering (SAXS), it was found that the pseudo-oligomeric surfactant was readily to form viscoelastic wormlike micelles and showed remarkable thickening ability. The maximum zero shear viscosity (η0) was up to 9.4 × 103 Pa·s, which was higher than most of wormlike micelles formed by the conventional covalently linked oligomeric counterparts. The viscoelastic fluid formed by the pseudo-oligomeric surfactant was highly sensitive to pH, whose viscosity could be decreased to 0.001 Pa·s instantly by adding a small amount of acid or alkali.

A numerical method for the simulation of viscoelastic fluid surfaces

Viscoelastic surface rheology plays an important role in multiphase systems. A typical example is the actin cortex which surrounds most animal cells. It shows elastic properties for short time scales and behaves viscous for longer time scales. Hence, realistic simulations of cell shape dynamics require a model capturing the entire elastic to viscous spectrum. However, currently there are no numerical methods to simulate deforming viscoelastic surfaces. Thus models for the cell cortex, or other viscoelastic surfaces, are usually based on assumptions or simplifications which limit their applicability. In this paper we develop a first numerical approach for simulation of deforming viscoelastic surfaces. To this end, we derive the surface equivalent of the upper convected Maxwell model using the GENERIC formulation of nonequilibrium thermodynamics. The model distinguishes between shear dynamics and dilatational surface dynamics. The viscoelastic surface is embedded in a viscous fluid modelled by the Navier-Stokes equation. Both systems are solved using Finite Elements. The fluid and surface are combined using an Arbitrary Lagrange-Eulerian (ALE) Method that conserves the surface grid spacing during rotations and translations of the surface. We verify this numerical implementation against analytic solutions and find good agreement. To demonstrate its potential we simulate the experimentally observed tumbling and tank-treading of vesicles in shear flow. We also supply a phase-diagram to demonstrate the influence of the viscoelastic parameters on the behaviour of a vesicle in shear flow. Finally, we explore cytokinesis as a future application of the numerical method by simulating the start of cytokinesis using a spatially dependent function for the surface tension.

Peptidoglycans modulating the interaction of a bactericide compound with lipids at the air-water interface

A known monoterpene, named γ-terpineol, was incorporated in mixed Langmuir monolayers composed of dipalmitoyl-phosphoethanolamine (DPPE) and peptidoglycans as a model of microbial membranes. Surface pressure and surface potential isotherms, dynamical surface rheology, Brewster angle microscopy (BAM), and infrared spectroscopy were employed to characterize the compound-membrane interactions. The compound expanded the monolayers denoting repulsive interactions. At 30 mN/m, the monolayer presented lower viscoelastic and in-plane elasticity parameters and an increased all-trans/gauche conformers ratio for the alkyl chains, confirming molecular order. The morphology of the monolayer was analyzed by BAM, which revealed a heterogeneous distribution of γ-terpineol along the mixed monolayer, which tends to segregate. In conclusion, the compound changes the thermodynamic, electric, rheological, morphological, and structural properties of the peptidoglycan-DPPE monolayer, which may be essential to understand, at the molecular level, the action of bioactives in selected membrane models.

Evolution of adsorbed layers of asphaltenes at oil-water interfaces: A novel experimental protocol

Hypothesis: Asphaltenes can form rigid interfacial films surrounding water droplets rendering water separation from crude oil sluggish. Therefore, the quantitative characterization of such complex film formation is of great importance. As the adsorbed layers of asphaltene illustrate crumpling under compression at certain conditions, the evolution process from soft to rigid states of the film can be evaluated considering standard deviations from Young-Laplace shape fitting. ExperimentalIn this study, novel experimental protocols are introduced to investigate the evolution of adsorbed asphaltene layer to a film of aggregates at model oil/water interface by means of dynamic interfacial tension (IFT) and dilational surface rheology measurements. In particular, the surface elasticity and standard deviation from the Young-Laplace shape fitting (YL-SD) are introduced as important indicators for the transformation of a regular asphaltene adsorbed layer to a film of aggregates. Different parameters affecting the film formation and stability, such as aging time, asphaltene concentration, and history of interfacial dynamics, are discussed and linked to emulsion stability.Findings: It is shown for the first time that the standard deviation of drop profile fitting from the Young-Laplace equation can be used as a rigorous parameter to reveal the properties of the interfacial asphaltene film, which cannot be recognized by regular IFT measurements. Via this novel technique, it is revealed that the transformation of an asphaltene adsorbed layer to a rigid film depends not only on the asphaltene concentration but also on the aging time and the interfacial area perturbations. The results of this new method are supported by measurements of the dilational surface elasticity, which is known as an important parameter for the characterization of complex adsorbed layers, and further verified by an emulsion stability analysis.

Effect of Diethylene Glycol on the Inkjet Printability of Reactive Dye Solution for Cotton Fabrics.

Digital inkjet printing technology plays an increasingly important role in textile printing. The printing printability of reactive dye inks is the key to improving the quality of printed fabrics. In this study, an eco-friendly and simple method to improve the inkjet printability of reactive dye solutions was proposed. The influence of diethylene glycol on the surface tension, rheology, and dye molecule aggregation properties for three reactive dye solutions was investigated. The jetting performance of dye solutions was explored by observing droplet formation. Moreover, the color performance of printed cotton fabrics, including reactive dye solution penetration, colorimetric values, and color strength, was evaluated. Addition of diethylene glycol could change the aggregation of dye molecules by hydrophobic forces and hydrogen bonds. Diethylene glycol could inhibit formation of satellite droplets by changing the viscosity and surface tension of solutions, which made the pattern printed on cotton fabrics show regular edge sharpness. Furthermore, the dye solutions containing 10% DEG not only satisfied various properties of reactive dye inks but also had the highest color strength and the deepest and brightest colors.