High Interfacial Tension Research Articles

Experimental investigations and development of mathematical model to estimate drop diameter and jet length

The key process used in nuclear industries for the management of radiotoxicity associated with spent fuel in a closed fuel cycle is solvent extraction. An understanding of hydrodynamics and mass transfer is of primary importance for the design of mass transfer equipment used in solvent extraction processes. Understanding the interfacial phenomenon and the associated hydrodynamics of the liquid drops is essential for model-based design of mass transfer devices. In this work, the phenomenon of drop formation at the tip of a nozzle submerged in quiescent immiscible liquid phase is revisited. Previously reported force balance based models and empirical correlations are analyzed. Experiments are carried out to capture the process of drop formation using high-speed imaging technique. The images are digitally processed to measure the average drop diameter. A correlation based on the force balance model is proposed to estimate drop diameter and jet length. The average drop diameter obtained from the proposed model is in good agreement with experimental data with an average error of 6.3%. The developed model is applicable in both the necking as well as jetting regime and is validated for liquid-liquid systems having low, moderate and high interfacial tension.

The utilization of Surfactant on enhanced oil recovery chemical injection to maintain energy in Indonesia

The needs of oil in the world for the transportation, industry, power plant and other fields drive us to be more consumptive in the utilization. Oil needs in Indonesia that keeps on increasing along the years is unequal with the number of oil exploration activity, which further create a scarcity on fossil energy fuel source availability. If Indonesia is unable to discover new oil sources as soon as possible, Indonesia is predicted to become oil importer in 2025. Oil production is known to be practiced through three steps which are primary recovery, secondary recovery, and tertiary recovery. At this moment, several oil wells in Indonesia have reached final stages of secondary recovery. If the production activity on these wells is continued, the recovered oil will never be able to reach optimum result and will unable to cover the production cost. Because of that, oil development and production management projects will never be able to run. The offered solution to fulfill this energy needs is by conducting tertiary recovery method known as Enhanced Oil Recovery (EOR). EOR method is known to be able to optimize oil recovery as much as 30% of total remaining reserve on an oil or gas field. One of EOR method that will be the focus in this research is chemical injection or chemical flooding, where a certain chemical compound is injected into the reservoir with an objective of reservoir physical or chemical manipulation to facilitate oil production to the surface. The material required for chemical flooding are surfactant, alkali, and polymer. On the previously conducted research at EOR Laboratory Universitas Trisakti is aimed to observe the impact of surfactant concentration on water formation salinity on phase and interfacial tension (IFT) tests to improve surfactant performance on EOR process to optimize recovery factor (RF) or oil production. Chemical ingredients used in this research are anionic surfactants which are Alpha Olein Sulfonate (AOS) and paraffin oil. The utilization of surfactant solution concentration is 0.5%, 1%, 1.5% and 2%. Meanwhile formation salinities are at 10,000 ppm, 15,000 ppm, and 20,000 ppm. The emulsion formed from the phase test is an upper phase. The factor of emulsion phase formation is high interfacial tension and the utilized surfactant basic ingredient is a petroleum based ingredient. The result of IFT measurement on surfactant solution possess a value range of 16 dyne/m to 41 dyne/m. Based on the research result and conducted analysis, the utilized AOS surfactant in this research is proven to be able to lower significant IFT of water and oil on emulsion percentage formed and stable at 18.75% on 1.5% concentration with water salinity of 15,000 ppm.

Synergistic and Competitive Adsorption of Hydrophilic Nanoparticles and Oil-Soluble Surfactants at the Oil-Water Interface.

Fundamental insights into the interplay and self-assembly of nanoparticles and surface-active agents at the liquid-liquid interface play a pivotal role in understanding the ubiquitous colloidal systems present in our natural surroundings, including foods and aquatic life, and in the industry for emulsion stabilization, drug delivery, or enhanced oil recovery. Moreover, well-controlled model systems for mixed interfacial adsorption of nanoparticles and surfactants allow unprecedented insights into nonideal or contaminated particle-stabilized emulsions. Here, we investigate such a model system composed of hydrophilic, negatively, and positively charged silica nanoparticles and the oil-soluble cationic lipid octadecyl amine with in situ synchrotron-based X-ray reflectometry, which is analyzed and discussed jointly with dynamic interfacial tensiometry. Our results indicate that negatively charged silica nanoparticles only adsorb if the oil-water interface is covered with the positively charged lipid, indicating synergistic adsorption. Conversely, the positively charged nanoparticles readily adsorb on their own, but compete with octadecyl amine and reversibly desorb with increasing concentrations of the lipid. These results further indicate that with competitive adsorption, an electrostatic exclusion zone exists around the adsorbed particles. This prevents the adsorption of lipid molecules in this area, leading to a decreased surface excess concentration of surfactants and unexpectedly high interfacial tension.

Designer Core-Shell Nanoparticles as Polymer Foam Cell Nucleating Agents: The Impact of Molecularly Engineered Interfaces.

The interface between nucleating agents and polymers plays a pivotal role in heterogeneous cell nucleation in polymer foaming. We describe how interfacial engineering of nucleating particles by polymer shells impacts cell nucleation efficiency in CO2 blown polymer foams. Core–shell nanoparticles (NPs) with a 80 nm silica core and various polymer shells including polystyrene (PS), poly(dimethylsiloxane) (PDMS), poly(methyl methacrylate) (PMMA), and poly(acrylonitrile) (PAN) are prepared and used as heterogeneous nucleation agents to obtain CO2 blown PMMA and PS micro- and nanocellular foams. Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy are employed to confirm the successful synthesis of core–shell NPs. The cell size and cell density are determined by scanning electron microscopy. Silica NPs grafted with a thin PDMS shell layer exhibit the highest nucleation efficiency values, followed by PAN. The nucleation efficiency of PS- and PMMA-grafted NPs are comparable with the untreated particles and are significantly lower when compared to PDMS and PAN shells. Molecular dynamics simulations (MDS) are employed to better understand CO2 absorption and nucleation, in particular to study the impact of interfacial properties and CO2-philicity. The MDS results show that the incompatibility between particle shell layers and the polymer matrix results in immiscibility at the interface area, which leads to a local accumulation of CO2 at the interfaces. Elevated CO2 concentrations at the interfaces combined with the high interfacial tension (caused by the immiscibility) induce an energetically favorable cell nucleation process. These findings emphasize the importance of interfacial effects on cell nucleation and provide guidance for designing new, highly efficient nucleation agents in nanocellular polymer foaming.

Introduction to the Study of Mechanical Properties of Terpolymer PP/EPDM Mixtures

Thermoplastic elastomers (TPEs), based in PP (Polypropylene) / EPDM (Ethylene Propylene Diene Monomer) have as purpose improving PP resistance and impact, aiming to a more comprehensive use in automotive market, among edifications, construction and packaging sectors, due to their recyclability properties. PP is a commodity, with a high melting point, high mechanical resistance and low density, posing a balance between physical and mechanical properties; in addition, it shows an easy processing, at low cost. In order to minimize this deficiency, EPDM, an impact modifier, can be used. Nevertheless, most of polymeric blends are incompatible and immiscible, i.e., show a mutual and limited solubility and in most of cases, a high interfacial tension. However, there is a relatively low interfacial tension (force which acts on transformation of a continuous structure in a dispersion) between PP and EPDM (approximately 0.3 mN.m-1), reducing the rate of breakup and facilitating the build-up of a continuous structure. This work aims to the study of compatibility of PP and EPDM blends and variation of mechanical properties, emphasizing that many properties of thermoplastic elastomers can be processed according with conventional thermoplastics methods: herein, PP/EPDM blends, 90/10, 80/20, 70/30 and 50/50 were characterized according to: Mechanical essays, Differential Scanning Calorimetry, Thermogravimetric Analyses, Melt Flow Index, Izod Impact Strength and Dynamic mechanical Analyses.

Jumping liquid metal droplets controlled electrochemically

Jumping droplets are interesting because of their applications in energy harvesting, heat transfer, anti-icing surfaces, and displays. Typically, droplets “jump” from a surface when two or more drops coalesce. Here, we demonstrate an approach to get a single droplet of liquid metal (eutectic gallium indium) to jump by using electrochemistry in a solution of 1M NaOH. Applying a positive potential to the metal (∼1 V relative to the open circuit potential) drives electrochemical surface oxidation that lowers the interfacial tension from ∼450 mN/m to ∼0 mN/m. In the low interfacial tension state, the droplet flattens due to gravity. Rapid switching to a negative potential (relative to the open circuit potential) reduces the surface oxide, returning the deformed droplet to a state of high interfacial tension. This rapid change in interfacial tension in the flattened state generates excess surface energy, which drives the droplet to return to a spherical shape with enough momentum that the liquid droplet jumps. This work is unique because (1) the jumping is controlled and tuned electrically, (2) the approach works with a single droplet, (3) it does not require a superhydrophobic surface, which is typically used to prevent droplets from adhering to the substrate, (4) the drops jump through a viscous medium rather than air, and (5) the potential energy obtained by the jumping drops is one order of magnitude higher than previous approaches. Yet, a limitation of this approach relative to conventional jumping drops is the need for electrolyte and a source of electricity to enable jumping. Herein, we characterize and optimize the jumping height (∼6 mm for a 3.6 mm diameter drop) by changing the reductive and oxidative potential and time.

Spectrophotometric Determination of Ca2+ and Ca-Complex Formation Constants: Application to Chemical Enhanced Oil Recovery.

Chemicals such as anionic surfactants and polymers often contain groups that complex divalent ions such as Ca2+. The formation of divalent ion complexes can decrease emulsifying or viscosifying power and lead to adsorption or precipitation. This is particularly relevant in chemical enhanced oil recovery, where high viscosities and low interfacial tensions are required for mobility control and the formation of oil–water microemulsions, respectively. In this work, we use a Ca2+-sensitive dye to determine the Ca2+ concentration and Ca-complex formation constants in solutions containing complexing agents. This method can be used to rapidly screen the affinity of different chemicals to form Ca-complexes in low-salinity solutions. The complex formation constants can be implemented into chemical flooding simulators to investigate the interplay with mineral dissolution and cation exchange and model adsorption processes.

Numerical modelling of the effect of wettability, interfacial tension and temperature on oil recovery at pore-scale level

A numerical investigation into the effect of wettability and temperature on oil recovery with a hot water injection at different temperatures is reported in this paper. The computational domain is a two-dimensional porous medium (reservoir) maintained at a fixed temperature with pore spaces of varying sizes and interconnected pore-throats. ANSYS-Fluent VOF (volume of fluid) model was used to simulate the two-phase transport through the reservoir with hot water injections at varying temperatures (20, 40 and 60 °C) and wettability contact angles of 45°, 90° and 150°. In addition, an investigation was conducted on the effect of combined interfacial tension and matrix wettability on oil recovery process at low and high interfacial tension of 0.025 N/m and 0.045 N/m respectively for the three different wettability contact angles.The results showed that, the displacement behaviour of water and oil-wet system is affected significantly by the contact angle with a profound effect on the oil recovery factor. In the water-wet case (with the water wetting the matrix wall and the oil phase surrounded by water), relatively more oil is displaced from the domain thereby improving the oil recovery factor. The water-wetter system resulted in about 35–45% oil recovery than the oil-wet system, with the unrecovered oil mainly adhering to the wall region of the pore bodies for oil-wet system. For the intermediate wet case, initial fluid distribution is seen to have a more significant effect on the displacement behaviour than the contact angles. In conclusion, by altering the wettability from oil-wet to water-wet condition, the oil recovery rate is improved. The results from this study are consistent with the experimental and numerical studies in literature and it will further enhance the understanding of the phenomenon that is critical to the mechanism of recovery such as surfactant and polymer flooding process.

Viscosity decrease by interfacial slippage between immiscible polymers

AbstractThe rheological behavior under pressure‐driven shear flow was studied using binary blends with a sea‐island structure. The addition of a low‐viscosity dispersion having a high interfacial tension with the continuous phase greatly reduces the shear viscosity, for example, the addition of atactic polystyrene (PS) with a low viscosity to isotactic polypropylene (PP) and the addition of PP with a low viscosity to PS. The interfacial slippage occurs because of the poor adhesive strength with the enlarged interfacial area and is responsible for the viscosity decrease. When the dispersion has a similar viscosity to the continuous phase, the viscosity decrease is barely detected. This is because the deformation of dispersed droplets is restricted, which creates a small interfacial area. The interfacial tension between the continuous and dispersed phases plays a crucial role on the shear viscosity. In the case of PP, the addition of linear low‐density polyethylene with a relatively low interfacial tension to PP has almost no impact on the shear viscosity. This is despite the polyethylene having a low viscosity.

Effect of oil type and β-carotene incorporation on the properties of gelatin nanoparticle-stabilized pickering emulsions

The type of oil used and the introduction of bioactive compounds could strongly influence the microstructure and physicochemical properties of Pickering emulsions, which have yet to be fully understood. Herein, oil-in-water (O/W) Pickering emulsions were stabilized by autofluorescent gelatin nanoparticles with either corn oil or medium chain triglyceride (MCT) oil as references for commonly studied edible oils. The microstructure of the emulsions with changes in nanoparticle concentration, oil fraction (Φ), and oil type was investigated with confocal laser scanning microscopy (CLSM). An increase in nanoparticle concentration resulted in an increased thickness of the adsorption layers and number of droplets. Increasing Φ helped to form compact gel-like emulsions and improve the oxidation stability of the emulsions. The high oil-water interfacial tension and surface-active long-chain fatty acids of corn oil caused sparse packing droplet interfaces. Hence, corn oil emulsions were generally less stable than MCT oil emulsions, which was further demonstrated through studies of water holding capacity (WHC), long-term storage stability, and rheology. Furthermore, the incorporation of β-carotene had negative effects on the formation and stability of the emulsions, especially for corn oil emulsions. The findings in this work may have important implications for exploiting Pickering emulsion formulations in real food products.

Temperature-sensitive soft microgels at interfaces: air-water versus oil-water.

The formation of smart emulsions or foams whose stability can be controlled on-demand by switching external parameters is of great interest for basic research and applications. An emerging group of smart stabilizers are microgels, which are nano- and micro-sized, three-dimensional polymer networks that are swollen by a good solvent. In the last decades, the influence of various external stimuli on the two-dimensional phase behavior of microgels at air- and oil-water interfaces has been studied. However, the impact of the top-phase itself has been barely considered. Here, we present data that directly address the influence of the top-phase on the microgel properties at interfaces. The dimensions of pNIPAM microgels are measured after deposition from two interfaces, i.e., air- and decane-water. While the total in-plane size of the microgel increases with increasing interfacial tension, the portions or fractions of the microgels situated in the aqueous phase are not affected. We correlate the area microgels occupy to the surface tensions of the interfaces, which allows to estimate an elastic modulus. In comparison to nanoindentation measurements, we observe a larger elastic modulus for the microgels. By combining compression, deposition, and visualization, we show that the two-dimensional phase behavior of the microgel monolayers is not altered, although the microgels have a larger total in-plane size at higher interfacial tension.

Microstructural Rearrangements and Their Rheological Signature in Coarsening of Cocontinuous Polymer Blends

Domains of cocontinuous polymer blends coarsen during annealing. In general, coarsening undergoes two regimes: linear growth followed by slower nonlinear growth. While the linear regime is well understood by several theories, the number of studies on the nonlinear regime is scarce and often inconclusive. Herein, we examine the entire spectrum of the coarsening of cocontinuous polymer blends using an in situ high-temperature confocal rheology technique. By linking 4-dimensional microscopic details (time evolution of three-dimensional microscopic details) with the rheological properties, we demonstrate that the transition to the nonlinear regime is associated with the onset of droplet formation during the coarsening of these blends. Such transitions and morphological changes occurred only in the blends with high interfacial tension to zero-shear viscosity ratio (Γ/η₀). This phenomenon provides a framework for comprehensive model development. By analyzing the data from the literature, we propose that there exists a critical Γ/η₀ ratio beyond which the system undergoes such transitions.

Dynamic Contact Angle Reformulates Pore-Scale Fluid-Fluid Displacement at Ultralow Interfacial Tension

Summary Surfactant flooding is an effective enhanced oil recovery method in which the oil/water interfacial tension (IFT) is reduced to ultralow values (<0.01 mN/m). The microscopic fluid-fluid displacement has been extensively studied at high IFT (>10 mN/m). However, the microscopic displacement dynamics can be significantly different when the IFT is ultralow because the dynamic contact angle increases with the increase of the capillary number. In this study, surfactant flooding was performed and visualized in micromodels to investigate the dynamics of multiphase displacement at ultralow IFT. Although the micromodels used were strongly water-wet, the displacements of oil by surfactant solutions at ultralow IFT appeared as drainage. Furthermore, a macroscopic oil film was left behind on the surface, which indicates that a contact line instability occurred during displacements. The shape of the oil/water meniscus was determined by the balance between viscous forces and capillary forces. The meniscus can be significantly distorted by viscous forces at ultralow IFT. Therefore, the water-wet micromodel exhibits an oil-wet behavior at ultralow IFT, and the displacements of oil by surfactant solutions at ultralow IFT manifested as drainage rather than imbibition. The flow behavior is further complicated by the spontaneous formation of microemulsion during displacement. The microemulsion is mainly formed from the residual oil. The formation of a microemulsion bank made the surfactant solution discontinuous, with transport in the form of droplets in the microemulsion bank and displacement front. The novelty of this work is to reveal the effects of dynamic contact angle on the ultralow IFT displacement.

Description of Thermochromic Offset Prints Morphologies Depending on Printing Substrate

In this study, the influence of physio-chemical properties of four printing substrates, fibrous papers (filter, bulky, recycled), and polymer film (synthetic paper) on the size of the thermochromic (TC) prints microcapsules was investigated. Results indicate that interaction between thermochromic ink and printing substrate determine the print morphology, i.e., porosity and roughness of printing substrate affect dimensions of TC microcapsules of resulting prints, while ink adhesion affects dimensional changes during heating–cooling cycle. Atomic force microscopy (AFM) analysis showed that microcapsules of the prints, on the surface of the smoothest synthetic paper, possess the smallest diameter and height, while, on the most porous and the most roughened surface of F paper, the microcapsules of the prints possess the highest diameter and height. By increasing the temperature to 40 °C, the biggest changes in the shape of the microcapsules (increase in height and decrease in diameter) were obtained using the surface of the hydrophilic filter paper. While using the recycled paper surface, the situation is opposite; the height and diameter of the microcapsules are reduced, and the microcapsules penetrate deeper into the paper structure (due to optimum adhesion). On the bulky paper surfaces, which are more hydrophobic than recycled paper (higher interfacial tension), the increase of temperature does not cause any significant changes in the shape and position of the microcapsules. The same behavior is observed using hydrophobic non-porous synthetic paper.

Light Diffraction in Magnetic Emulsions with High Interfacial Tension

Specific features of small-angle light scattering by aqueous magnetic emulsions under the action of a magnetic field and a hydrodynamic field of a rotating fluid have been investigated. It has been shown that the experimentally observed diffraction lines that have no pronounced maxima and minima are due to diffraction on an irregular system of droplet chains arising in the magnetic field. Under the combined action of the magnetic and hydrodynamic fields, a rotation of a diffraction line is observed. This phenomenon has been interpreted using the known models of orientation of extended particles having complex shapes. It has been shown that the experimental nonlinear dependence of the rotation angle of a droplet chain on the angular rate of fluid rotation may be explained by S-shaped deformations of a chain.

Uncertainty quantification of shale capillary desaturation curves for surfactant EOR in shale through fracturing fluids using predictive modeling

Surfactant is often added into hydraulic fracturing fluids for shale reservoirs because it can minimize formation damage. The surfactant is also known for its EOR potential for sandstone/ carbonate reservoirs. Given both benefits, some previous papers studied the feasibility of surfactant EOR for shale reservoirs. Evaluation of surfactant EOR potentials requires accurate capillary desaturation curves (CDCs) of the shale rocks because CDCs determine how easily the surfactant will recover the residual oil saturation and improve the relative permeabilities.However, there is currently no experimental CDC data of shale rocks because of the difficulty in the experiment. This study builds a validated predictive model to quantify the effect of the CDC uncertainty on EOR. The objective is to numerically assess how the CDCs uncertainty affects the feasibility of surfactant EOR in shale reservoirs using Monte Carlo simulation of 100,000 possible CDCs. This paper also performs sensitivity analysis on the surfactant’s wettability alteration direction and its alteration extent and target interfacial tension value. Our model reveals that surfactants can offer optimum EOR potentials in shale reservoirs if they strongly alter the shale’s wettability to water-wet while maintaining a high interfacial tension. However, even when using such optimum surfactants, there are still some possibilities of decreasing the ultimate oil recovery because of the CDC uncertainty. Lastly, this study quantitatively presents the degree of the risks.

Rheology of water-in-water emulsions: Caseinate-pectin and caseinate-alginate systems

Conventional models developed for oil-water emulsions do not fit viscosity of caseinate-pectin and caseinate-alginate water-in-water emulsions, which is always lower than predicted, except for high viscosities of disperse phase. These models do not consider strong deformations, prevented by the high interfacial tension of oil-water interphases. The ultra-low interfacial tension of water-in-water emulsions facilitates the creation of interphase and very elongated droplets. Capron model considers interfacial tension, fitting results when the dispersed phase is the most viscous, but, for other cases, lower experimental values are obtained related to the shear-induced stratification. Even values below the stratification model are observed for some samples, related to the influence of the interphase in the viscosity of the emulsion. A model that takes into account the presence of a relatively thick interphase poor in both polymers is proposed. Intermediate structures between highly elongated and stratified fluids, with influence of interphase viscosity could explain results.

Effect of spontaneous emulsification on oil recovery in tight oil-wet reservoirs

Surfactants improve oil recovery from tight oil-wet formations through wettability alteration and interfacial tension (IFT) reduction. The popular perspective believes that wettability alteration induced capillary-driven spontaneous imbibition is the major mechanism of Enhanced Oil Recovery (EOR) in tight oil reservoirs. Therefore, surfactant with functions of wettability alteration while guarding a relatively high IFT should be chosen as the best candidate. However, ultra-low IFT may change the phase behavior and flow-pattern within the porous media to improve the oil recovery through emulsification.Therefore, in this paper, we investigated the effect of spontaneous emulsifying surfactants on the oil recovery from tight sandstones through spontaneous imbibition experiments and the results are compared with that of regular surfactants The results manifested that the spontaneous-emulsifying surfactants with ultra-low IFT can improve oil recovery from oil-wet cores, and the performance surpassed that of regular surfactants through wettability alteration. It is because a spontaneous-emulsifying surfactant is capable of accelerating the oil dispersion and reducing the residual oil saturation by emulsifying the oil phase. Partly, it diffuses out from the porous media in the form of the microemulsion, and partly small oil droplets with ultra-low IFT may coalesce into larger ones so that it is easy for them to deform and to be produced by buoyancy. Therefore, comparing with the traditional viscous flow, the change of the flow pattern due to the addition of spontaneous-emulsifying surfactants further enhanced the recovery in term of producing rate and final recovery factor.

Measurement of liquid/liquid interfacial tension with water on liquid paraffin by the floating drop method

A floating drop method has the potential of high accurate interfacial tension measurement for liquid-liquid. In order to clarify its validity, the verification of the method should be carried out based on the liquid-liquid system where its interfacial tension is available. We measured the interfacial tension between water and liquid paraffin via a floating drop method by observing a clear submerged profile of heavier water droplet floating on lighter liquid paraffin. We then investigated the effect of the droplet size on the interfacial tension. Large droplets were found to improve the accuracy of the measured values, as demonstrated by a simulation based on the Laplace equation. The measured interfacial tension was 50.5 mN/m, which reasonably agrees with the values reported in the literature. We conclude that the floating drop method with a heavy droplet on a light liquid is effective for measuring the interfacial tension.

Formulation of polyphthalaldehyde microcapsules for immediate UV-light triggered release

Triggered release from responsive drug reservoirs activated by remote stimuli is desired in a range of fields. Critical bottlenecks are cost-efficient formulation avenues applicable for industrial scale-up, viable triggers and immediate release rather than continuous release upon activation. UV-sensitive microcapsules based on self-immolating polymers in combination with thin shells and morphological weak spots should allow for immediate triggered release. Polyphthalaldehyde-based microcapsules were prepared using several variations of the internal phase separation route. In addition, a fluorescence microscopy method was developed to study both the microcapsule morphology and the triggered release in-situ. The microcapsule formation was driven by the surface activity of the stabilizer, effectively lowering the high polymer-water interfacial tension, which is in sharp contrast to conventional encapsulation systems. Contrary to previous findings, a core–shell morphology was obtained via slow emulsion-to-suspension transformation. Rapid transformation captured intermediate inverted core–shell structures. The capsules were highly sensitive to both acid- and UV-mediated triggers, leading to an unzipping and rupturing of the shell that released the core content. Poly(methacrylic acid)-stabilized microcapsules displayed immediate UV-triggered release provided by their stimuli-sensitive blueberry morphology. Both capsules in aqueous and dry environment started to lose their core content after less than one minute of UV light exposure.