Polymorphic phase transitions in triglycerides and their mixtures studied by SAXS/WAXS techniques: In bulk and in emulsions.

Triacylglycerols (TAGs) exhibit a monotropic polymorphism, forming three main polymorphic forms upon crystallization: α, ß' and ß. The distinct physicochemical properties of these polymorphs, such as melting temperature, subcell lattice structure, mass density, etc., significantly impact the appearance, texture, and long-term stability of a wide range products in the food and cosmetics industries. Additionally, TAGs are also of special interest in the field of controlled drug delivery and sustained release in pharmaceuticals, being a key material in the preparation of solid lipid nanoparticles. The present article outlines our current understanding of TAG phase behavior in both bulk and emulsified systems. While our primary focus are investigations involving monoacid TAGs and their mixtures, we also include illustrative examples with natural TAG oils, highlighting the knowledge transfer from simple to intricate systems. Special attention is given to recent discoveries via X-ray scattering techniques. The main factors influencing TAG polymorphism are discussed, revealing that a higher occurrence of structural defects in the TAG structure always accelerates the rate of the α â†’ ß polymorphic transformation. Diverse approaches can be employed based on the specific system: incorporating foreign molecules or solid particles into bulk TAGs, reducing drop size in dispersed systems, or using surfactants that remain fluid during TAG particle crystallization, ensuring the necessary molecular mobility for the polymorphic transformation. Furthermore, we showcase the role of TAG polymorphism on a recently discovered phenomenon: the creation of nanoparticles as small as 20 nm from initial coarse emulsions without any mechanical energy input. This analysis underscores how the broader understanding of the TAG polymorphism can be effectively applied to comprehend and control previously unexplored processes of notable practical importance.

Computational Procedure for Analysis of Crystallites in Polycrystalline Solids of Quasilinear Molecules.

In the current work, a comprehensive procedure for structural analysis of quasilinear organic molecules arranged in a polycrystalline sample generated by molecular dynamics is developed. A linear alkane, hexadecane, is used as a test case because of its interesting behavior upon cooling. Instead of a direct transition from isotropic liquid to the solid crystalline phase, this compound forms first a short-lived intermediate state known as a "rotator phase". The rotator phase and the crystalline one are distinguished by a set of structural parameters. We propose a robust methodology to evaluate the type of ordered phase obtained after a liquid-to-solid phase transition in a polycrystalline assembly. The analysis starts with the identification and separation of the individual crystallites. Then, the eigenplane of each of them is fit and the tilt angle of the molecules relative to it is computed. The average area per molecule and the distance to the nearest neighbors are estimated by a 2D Voronoi tessellation. The orientation of the molecules with respect to each other is quantified by visualization of the second molecular principal axis. The suggested procedure may be applied to different quasilinear organic compounds in the solid state and to various data compiled in a trajectory.

Computational assessment of hexadecane freezing by equilibrium atomistic molecular dynamics simulations.

HYPOTHESIS: Upon cooling, alkanes can form intermediate phases between liquid and crystal. They are called "rotator" or "plastic" phases and have long-range positional order with rotational freedom around the long molecular axis which gives them non-trivial and useful visco-plastic properties. We expect that the formation and structure of rotator phases formed in freezing alkanes can be understood much deeper by tracking the process at molecular level with atomistic molecular dynamics. SIMULATIONS: We defined an appropriate CHARMM36-based computational protocol for simulating the freezing of hexadecane, which contained a sufficiently long (500 ns) equilibrium sampling of the frozen states. We employed it to simulate successfully the freezing of bulk and interface-contacting hexadecane and to provide a pioneering clarification of the effect of surfactant on the crystallization mechanism and on the type of intermolecular ordering in the crystallites. FINDINGS: The devised computational protocol was able to reproduce the experimentally observed polycrystalline structure formed upon cooling. However, different crystallization mechanisms were established for the two types of models. Crystallites nucleate at random locations in the bulk and start growing rapidly within tens of nanoseconds. In contrast, the surfactants freeze first during the fast cooling (<1 ns), followed by rapid hexadecane freezing, with nucleation starting along the entire surfactant adsorption layer. Thereby, the hexadecane molecules form rotator phases which transition into a more stable ordered phase. This collective transition is first-time visualized directly. The developed robust computational protocol creates a foundation for future in-depth modelling and analysis of solid-state alkane-containing, incl. lipid, structures.

Structure and Undulations of Escin Adsorption Layer at Water Surface Studied by Molecular Dynamics.

The saponin escin, extracted from horse chestnut seeds, forms adsorption layers with high viscoelasticity and low gas permeability. Upon deformation, escin adsorption layers often feature surface wrinkles with characteristic wavelength. In previous studies, we investigated the origin of this behavior and found that the substantial surface elasticity of escin layers may be related to a specific combination of short-, medium-, and long-range attractive forces, leading to tight molecular packing in the layers. In the current study, we performed atomistic molecular dynamics simulations of 441 escin molecules in a dense adsorption layer with an area per molecule of 0.49 nm2. We found that the surfactant molecules are less submerged in water and adopt a more upright position when compared to the characteristics determined in our previous simulations with much smaller molecular models. The number of neighbouring molecules and their local orientation, however, remain similar in the different-size models. To maintain their preferred mutual orientation, the escin molecules segregate into well-ordered domains and spontaneously form wrinkled layers. The same specific interactions (H-bonds, dipole-dipole attraction, and intermediate strong attraction) define the complex internal structure and the undulations of the layers. The analysis of the layer properties reveals a characteristic wrinkle wavelength related to the surface lateral dimensions, in qualitative agreement with the phenomenological description of thin elastic sheets.

Rotator phases in hexadecane emulsion drops revealed by X-ray synchrotron techniques.

HYPOTHESIS: Micrometer sized alkane-in-water emulsion drops, stabilized by appropriate long-chain surfactants, spontaneously break symmetry upon cooling and transform consecutively into series of regular shapes (Denkov et al., Nature 2015, 528, 392). Two mechanisms were proposed to explain this phenomenon of drop "self-shaping". One of these mechanisms assumes that thin layers of plastic rotator phase form at the drop surface around the freezing temperature of the oil. This mechanism has been supported by several indirect experimental findings but direct structural characterization has not been reported so far. EXPERIMENTS: We combine small- and wide-angle X-ray scattering (SAXS/WAXS) with optical microscopy and DSC measurements of self-shaping drops in emulsions. FINDINGS: In the emulsions exhibiting drop self-shaping, the scattering spectra reveal the formation of intermediate, metastable rotator phases in the alkane drops before their crystallization. In addition, shells of rotator phase were observed to form in hexadecane drops, stabilized by C16EO10 surfactant. This rotator phase melts at ca. 16.6 °C which is significantly lower than the melting temperature of crystalline hexadecane, 18 °C. The scattering results are in a very good agreement with the complementary optical observations and DSC measurements.

Correction: Spontaneous particle desorption and "Gorgon" drop formation from particle-armored oil drops upon cooling.

Correction for 'Spontaneous particle desorption and "Gorgon" drop formation from particle-armored oil drops upon cooling' by Diana Cholakova et al., Soft Matter, 2020, 16, 2480-2496, DOI: 10.1039/C9SM02354B.

Cold-Burst Method for Nanoparticle Formation with Natural Triglyceride Oils.

The preparation of nanoemulsions of triglyceride oils in water usually requires high mechanical energy and sophisticated equipment. Recently, we showed that α-to-ß (viz., gel-to-crystal) phase transition, observed with most lipid substances (triglycerides, diglycerides, phospholipids, alkanes, etc.), may cause spontaneous disintegration of microparticles of these lipids, dispersed in aqueous solutions of appropriate surfactants, into nanometer particles/drops using a simple cooling/heating cycle of the lipid dispersion (Cholakova et al. ACS Nano 2020, 14, 8594). In the current study, we show that this "cold-burst process" is observed also with natural oils of high practical interest, including coconut oil, palm kernel oil, and cocoa butter. Mean drop diameters of ca. 50-100 nm were achieved with some of the studied oils. From the results of dedicated model experiments, we conclude that intensive nanofragmentation is observed when the following requirements are met: (1) The three-phase contact angle at the solid lipid-water-air interface is below ca. 30 degrees. (2) The equilibrium surface tension of the surfactant solution is below ca. 30 mN/m, and the dynamic surface tension decreases rapidly. (3) The surfactant solution contains nonspherical surfactant micelles, e.g., ellipsoidal micelles or bigger supramolecular aggregates. (4) The three-phase contact angle measured at the contact line (frozen oil-surfactant solution-melted oil) is also relatively low. The mechanism(s) of the particle bursting process is revealed, and on this basis, the role of all of these factors is clarified and discussed. We explain all main effects observed experimentally and define guiding principles for optimization of the cold-burst process in various, practically relevant lipid-surfactant systems.

Revealing the Origin of the Specificity of Calcium and Sodium Cations Binding to Adsorption Monolayers of Two Anionic Surfactants.

The studied anionic surfactants linear alkyl benzene sulfonate (LAS) and sodium lauryl ether sulfate (SLES) are widely used key ingredients in many home and personal care products. These two surfactants are known to react very differently with multivalent counterions, including Ca2+. This is explained by a stronger interaction of the calcium cation with the LAS molecules, compared to SLES. The molecular origin of this difference in the interactions remains unclear. In the current study, we conduct classical atomistic molecular dynamics simulations to compare the ion interactions with the adsorption layers of these two surfactants, formed at the vacuum-water interface. Trajectories of 150 ns are generated to characterize the adsorption layer structure and the binding of Na+ and Ca2+ ions. We found that both surfactants behave similarly in the presence of Na+ ions. However, when Ca2+ is added, Na+ ions are completely displaced from the surface with adsorbed LAS molecules, while this displacement occurs only partially for SLES. The simulations show that the preference of Ca2+ to the LAS molecules is due to a strong specific attraction with the sulfonate head-group, besides the electrostatic one. This specific attraction involves significant reduction of the hydration shells of the interacting calcium cation and sulfonate group, which couple directly and form surface clusters of LAS molecules, coordinated around the adsorbed Ca2+ ions. In contrast, SLES molecules do not exhibit such specific interaction because the hydration shell around the sulfate anion is more stable, due to the extra oxygen atom in the sulfate group, thus precluding substantial dehydration and direct coupling with any of the cations studied.

Nanopore and Nanoparticle Formation with Lipids Undergoing Polymorphic Phase Transitions.

We describe several unexpected phenomena, caused by a solid-solid phase transition (gel-to-crystal) typical for all main classes of lipid substances: phospholipids, triglycerides, diglycerides, alkanes, etc. We discovered that this transition leads to spontaneous formation of a network of nanopores, spreading across the entire lipid structure. These nanopores are spontaneously impregnated (flooded) by water when appropriate surfactants are present, thus fracturing the lipid structure at a nanoscale. As a result, spontaneous disintegration of the lipid into nanoparticles or formation of double emulsions is observed, just by cooling and heating of an initial coarse lipid-in-water dispersion around the lipid melting temperature. The process of nanoparticle formation is effective even after incorporation of medical drugs of high load, up to 50% in the lipid phase. The role of the main governing factors is clarified, the procedure is optimized, and the possibility for its scaling-up to industrially relevant amounts is demonstrated.

Spontaneous particle desorption and "Gorgon" drop formation from particle-armored oil drops upon cooling.

We study how the phenomenon of drop "self-shaping" (Denkov et al., Nature, 528, 2015, 392), in which oily emulsion drops undergo a spontaneous series of shape transformations upon emulsion cooling, is affected by the presence of adsorbed solid particles, like those used in Pickering emulsion stabilization. Experiments with several types of latex particles, and with added surfactant of low concentration to enable drop self-shaping, revealed several new unexpected phenomena: (1) adsorbed latex particles rearranged into regular hexagonal lattices upon freezing of the surfactant adsorption layer. (2) Spontaneous particle desorption from the drop surface was observed at a certain temperature - a remarkable phenomenon, as the solid particles are known to irreversibly adsorb on fluid interfaces. (3) Very strongly adhered particles to drop surfaces acted as a template to enable the formation of tens to hundreds of semi-liquid fibres, growing outwards from the drop surface, thus creating a shape resembling the Gorgon head from Greek mythology. Mechanistic explanations of all observed phenomena are provided using our understanding of the rotator phase formation on the surface of the cooled drops. The surface rotator phase creates positive line tension at the contact line formed between the particle surface and the fluid interface, which causes the particle ejection from the drop surface.

Origin of the extremely high elasticity of bulk emulsions, stabilized by Yucca Schidigera saponins.

We found experimentally that the elasticity of sunflower oil-in-water emulsions (SFO-in-W) stabilized by Yucca Schidigera Roezl saponin extract, is by >50 times higher as compared to the elasticity of common emulsions. We revealed that strong specific interactions between the phytosterols from the non-purified oil and the saponins from the Yucca extract lead to the formation of nanostructured adsorption layers which are responsible for the very high elasticity of the oil-water interface and of the respective bulk emulsions. Remarkably, this extra high emulsion elasticity inhibits the emulsion syneresis even at 65 vol% of the oil drops - these emulsions remain homogeneous and stable even after 30 days of shelf-storage. These results demonstrate that the combination of saponin and phytosterols is a powerful new approach to structure oil-in-water emulsions with potential applications for formulating healthier functional food.

Role of interfacial elasticity for the rheological properties of saponin-stabilized emulsions.

HYPOTHESIS: Saponins are natural surfactants which can provide highly viscoelastic interfaces. This property can be used to quantify precisely the effect of interfacial dilatational elasticity on the various rheological properties of bulk emulsions. EXPERIMENTS: We measured the interfacial dilatational elasticity of adsorption layers from four saponins (Quillaja, Escin, Berry, Tea) adsorbed on hexadecane-water and sunflower oil-water interfaces. In parallel, the rheological properties under steady and oscillatory shear deformations were measured for bulk emulsions, stabilized by the same saponins (oil volume fraction between 75 and 85%). FINDINGS: Quillaja saponin and Berry saponin formed solid adsorption layers (shells) on the SFO-water interface. As a consequence, the respective emulsions contained non-spherical drops. For the other systems, the interfacial elasticities varied between 2 mN/m and 500 mN/m. We found that this interfacial elasticity has very significant impact on the emulsion shear elasticity, moderate effect on the dynamic yield stress, and no effect on the viscous stress of the respective steadily sheared emulsions. The last conclusion is not trivial, because the dilatational surface viscoelasticity is known to have strong impact on the viscous stress of steadily sheared foams. Mechanistic explanations of all observed effects are described.

Structure of Dense Adsorption Layers of Escin at the Air-Water Interface Studied by Molecular Dynamics Simulations.

Saponins are natural surfactants with high surface activity and unique surface properties. Escin is a triterpenoid saponin which has unusually high surface viscoelasticity [Golemanov et al. Soft Matter 2013, 9, 5738] and low permittivity to molecular gas diffusion of its adsorption layers. In our previous study [Tsibranska et al. Langmuir 2017, 33, 8330], we investigated the molecular origin of this unconventional behavior and found that escin molecules rapidly assemble in a compact and stable surface cluster. This behavior was explained with long-range attraction between the hydrophobic aglycones combined with intermediate dipole-dipole attraction and strong short-range hydrogen bonds between the sugar residues in the adsorbed escin molecules. In this study, we performed atomistic molecular simulations of escin molecules in dense adsorption layers with two different areas per molecule. The results show that the surfactant molecules in these systems are much less submerged in water and adopt a more upright position compared to the dilute layers studied previously. A significant number of trapped water molecules are located around the hydrophilic groups placed above the water equimolecular surface to solvate them in the dense layer. To maintain the preferred orientation of the escin molecules with respect to the interface, the most compact adsorption layer acquires a significant spontaneous curvature. The substantial elasticity of the neutral escin layers, as in our previous study, is explained with the presence of a specific interaction, which is intermediate between hydrogen bonding and dipole-dipole attraction (populated lengths in the range 0.16 to >0.35 nm), supplemented by substantial flexibility of the surfactant heads, optimal curvature of the interface, and significant normal displacement of the molecules to allow their tight surface packing. The simulations reveal long-range order within the layers, which signifies the role of the collective behavior of the saponin molecules in such dense adsorption layers.

Rotator phases in alkane systems: In bulk, surface layers and micro/nano-confinements.

Medium- and long-chain alkanes and their mixtures possess a remarkable physical property - they form intermediate structured phases between their isotropic liquid phase and their fully ordered crystal phase. These intermediate phases are called "rotator phases" or "plastic phases" (soft solids) because the incorporated alkane molecules possess a long-range positional order while preserving certain mobility to rotate, which results in complex visco-plastic rheological behaviour. The current article presents a brief overview of our current understanding of the main phenomena involved in the formation of rotator phases from single alkanes and their mixtures. In bulk, five rotator phases with different structures were identified and studied in detail. Along with the thermodynamically stable rotator phases, metastable and transient (short living) rotator phases were observed. Bulk rotator phases provided important information about several interfacial phenomena of high scientific interest, such as the energy of crystal nucleation, entropy and enthalpy of alkane freezing, interfacial energy between a crystal and its melt, etc. In alkane mixtures, the region of existence of rotator phases increases significantly, reflecting the disturbed packing of different molecules. All these phenomena are very important in the context of alkane applications as lubricants, in cosmetics, as phase-change materials for energy storage, etc. Significant expansion of the domain of rotator phases was observed also in confinements - in the pores of solid materials impregnated with alkanes, in polymeric microcapsules containing alkanes, and in micrometer sized emulsion droplets. The rotator phases were invoked to explain the mechanisms of two recently discovered phenomena in cooled alkane-in-water emulsions - the spontaneous "self-shaping" and the spontaneous "self-bursting" (fragmentation) of emulsion drops. The so-called "α-phases" formed by fatty acids and alcohols, and the "gel phase" formed in phospholipid and soap systems exhibit structural characteristics similar to those in the alkane rotator phases. The subtle connections between all these diverse systems are outlined, providing a unified outlook of the main phenomena related to the formation of such soft solid materials. The occurrence of alkane rotator phases in natural materials and in several technological applications is also reviewed to illustrate the general importance of these unique materials and the related phenomena.

Multilayer Formation in Self-Shaping Emulsion Droplets.

In several recent studies, we showed that micrometer-sized oil-in-water emulsion droplets from alkanes, alkenes, alcohols, triglycerides, or mixtures of these components can spontaneously "self-shape" upon cooling into various regular shapes, such as regular polyhedrons, platelets, rods, and fibers ( Denkov , N. , Nature 2015 , 528 , 392 ; Cholakova , D. , Adv. Colloid Interface Sci. 2016 , 235 , 90 ). These drop-shape transformations were explained by assuming that intermediate plastic rotator phase, composed of ordered multilayers of oily molecules, is formed beneath the drop surface around the oil-freezing temperature. An alternative explanation was proposed ( Guttman , S. , Proc. Natl. Acad. Sci. USA 2016 113 , 493 ; Guttman , S. , Langmuir 2017 , 33 , 1305 ), which is based on the assumption that the oil-water interfacial tension decreases to very low values upon emulsion cooling. Here, we present new results, obtained by differential scanning calorimetry (DSC), which quantify the enthalpy effects accompanying the drop-shape transformations. Using optical microscopy, we related the peaks in the DSC thermograms to the specific changes in the drop shape. Furthermore, from the enthalpies measured by DSC, we determined the fraction of the intermediate phase involved in the processes of drop deformation. The obtained results support the explanation that the drop-shape transformations are intimately related to the formation of ordered multilayers of alkane molecules with thickness varying between several and dozens of layers of alkane molecules, depending on the specific system. The new results provide the basis for a rational approach to the mechanistic explanation and to the fine control of this fascinating and industrially relevant phenomenon.

Effect of Surfactant-Bile Interactions on the Solubility of Hydrophobic Drugs in Biorelevant Dissolution Media.

Biorelevant dissolution media (BDM) methods are commonly employed to investigate the oral absorption of poorly water-soluble drugs. Despite the significant progress in this area, the effect of commonly employed pharmaceutical excipients, such as surfactants, on the solubility of drugs in BDM has not been characterized in detail. The aim of this study is to clarify the impact of surfactant-bile interactions on drug solubility by using a set of 12 surfactants, 3 model hydrophobic drugs (fenofibrate, danazol, and progesterone) and two types of BDM (porcine bile extract and sodium taurodeoxycholate). Drug precipitation and sharp nonlinear decrease in the solubility of all studied drugs is observed when drug-loaded ionic surfactant micelles are introduced in solutions of both BDM, whereas the drugs remain solubilized in the mixtures of nonionic polysorbate surfactants + BDM. One-dimensional and diffusion-ordered 1H NMR spectroscopy show that mixed bile salt + surfactant micelles with low drug solubilization capacity are formed for the ionic surfactants. On the other hand, separate surfactant-rich and bile salt-rich micelles coexist in the nonionic polysorbate surfactant + bile salt mixtures, explaining the better drug solubility in these systems. The nonionic alcohol ethoxylate surfactants show intermediate behavior. The large dependence of the drug solubility on surfactant-bile interactions (in which the drug molecules do not play a major role per se) highlights how the complex interplay between excipients and bile salts can significantly change one of the key parameters which governs the oral absorption of poorly water-soluble drugs, viz. the drug solubility in the intestinal fluids.

Mechanisms and Control of Self-Emulsification upon Freezing and Melting of Dispersed Alkane Drops.

Emulsification requires drop breakage and creation of a large interfacial area between immiscible liquid phases. Usually, high-shear or high-pressure emulsification devices that generate heat and increase the emulsion temperature are used to obtain emulsions with micrometer and submicrometer droplets. Recently, we reported a new, efficient procedure of self-emulsification (Tcholakova et al. Nat. Commun. 2017, 8, 15012), which consists of one to several cycles of freezing and melting of predispersed alkane drops in a coarse oil-in-water emulsion. Within these freeze-thaw cycles of the dispersed drops, the latter burst spontaneously into hundreds and thousands of smaller droplets without using any mechanical agitation. Here, we clarify the main factors and mechanisms, which drive this self-emulsification process, by exploring systematically the effects of the oil and surfactant types, the cooling rate, and the initial drop size. We show that the typical size of the droplets, generated by this method, is controlled by the size of the structural domains formed in the cooling-freezing stage of the procedure. Depending on the leading mechanism, these could be the diameter of the fibers formed upon drop self-shaping or the size of the crystal domains formed at the moment of drop-freezing. Generally, surfactant tails that are 0-2 carbon atoms longer than the oil molecules are most appropriate to observe efficient self-emulsification. The specific requirements for the realization of different mechanisms are clarified and discussed. The relative efficiencies of the three different mechanisms, as a function of the droplet size and cooling procedure, are compared in controlled experiments to provide guidance for understanding and further optimization and scale-up of this self-emulsification process.

Self-Assembly of Escin Molecules at the Air-Water Interface as Studied by Molecular Dynamics.

Escin belongs to a large class of natural biosurfactants, called saponins, that are present in more than 500 plant species. Saponins are applied in the pharmaceutical, cosmetics, and food and beverage industries due to their variously expressed bioactivity and surface activity. In particular, escin adsorption layers at the air-water interface exhibit an unusually high surface elastic modulus (>1100 mN/m) and a high surface viscosity (ca. 130 N·s/m). The molecular origin of these unusual surface rheological properties is still unclear. We performed classical atomistic dynamics simulations of adsorbed neutral and ionized escin molecules to clarify their orientation and interactions on the water surface. The orientation and position of the escin molecules with respect to the interface, the intermolecular interactions, and the kinetics of molecular aggregation into surface clusters are characterized in detail. Significant differences in the behavior of the neutral and the charged escin molecules are observed. The neutral escin rapidly assembles in a compact and stable surface cluster. This process is explained by the action of long-range attraction between the hydrophobic aglycones, combined with intermediate dipole-dipole attraction and short-range hydrogen bonds between the sugar residues in escin molecules. The same interactions are expected to control the viscoelastic properties of escin adsorption layers.

"Self-Shaping" of Multicomponent Drops.

In our recent study we showed that single-component emulsion drops, stabilized by proper surfactants, can spontaneously break symmetry and transform into various polygonal shapes during cooling [ Denkov Nature 2015 , 528 , 392 - 395 ]. This process involves the formation of a plastic rotator phase of self-assembled oil molecules beneath the drop surface. The plastic phase spontaneously forms a frame of plastic rods at the oil drop perimeter which supports the polygonal shapes. However, most of the common substances used in industry appear as mixtures of molecules rather than pure substances. Here we present a systematic study of the ability of multicomponent emulsion drops to deform upon cooling. The observed trends can be summarized as follows: (1) The general drop-shape evolution for multicomponent drops during cooling is the same as with single-component drops; however, some additional shapes are observed. (2) Preservation of the particle shape upon freezing is possible for alkane mixtures with chain length difference Δn ≤ 4; for greater Δn, phase separation within the droplet is observed. (3) Multicomponent particles prepared from alkanes with Δn ≤ 4 plastify upon cooling due to the formation of a bulk rotator phase within the particles. (4) If a compound, which cannot induce self-shaping when pure, is mixed with a certain amount of a compound which induces self-shaping, then drops prepared from this mixture can also self-shape upon cooling. (5) Self-emulsification phenomena are also observed for multicomponent drops. In addition to the three recently reported mechanisms of self-emulsification [ Tcholakova Nat. Commun. 2017 , ( 8 ), 15012 ], a new (fourth) mechanism is observed upon freezing for alkane mixtures with Δn > 4. It involves disintegration of the particles due to a phase separation of alkanes upon freezing.