Lamellar Phase Research Articles

Dynamic surfactants drive anisotropic colloidal assembly.

Colloidal building blocks with re-configurable shapes and dynamic interactions can exhibit unusual self-assembly behaviors and pathways. In this work, we consider the phase behavior of colloids coated with surface-mobile polymer brushes that behave as "dynamic surfactants." Unlike traditional polymer-grafted colloids, we show that colloids coated with dynamic surfactants can acquire anisotropic macroscopic assemblies, even for spherical colloids with isotropic attractive interactions. We use Brownian Dynamics simulations and dynamic density functional theory to demonstrate that time-dependent reorganization of the dynamic surfactants leads to phase diagrams with anisotropic assemblies. We observed that the microscopic polymer distributions impose unique geometric constraints between colloids that control their packing into lamellar, string, and vesicle phases. Our work may help discover versatile building blocks and provide extensive design freedom for assembly out of thermodynamic equilibrium.

Effects of dilution and age on perfume release from two mixed‐surfactant systems containing hydrotropes

AbstractThis study investigates the encapsulation and controlled release of perfume within micellar systems. We explored how perfume‐surfactant interactions and micelle structure influence fragrance delivery. Two mixed‐micelle systems, one with branched‐tail and the other with linear‐tail surfactants, were subjected to varying perfume concentrations, dilution, and time. Using small‐angle neutron scattering (SANS), gas chromatography‐mass spectrometry (GC‐MS), and statistical analysis, we determined that micelle size and shape are significantly affected by perfume content and dilution. While both systems exhibited similar trends, the branched‐tail system uniquely formed a lamellar phase at higher perfume levels. Our findings reveal a strong correlation between micelle geometry and headspace perfume concentration, highlighting the role of surfactant tail structure. This research provides fundamental insights into perfume‐micelle interactions, with potential applications in materials science and active ingredient delivery.

Morphological Influence on a Nonionic Bilayer Bending Rigidity and Compression Modulus.

The mechanical properties of multilamellar vesicles and their relevance to soft matter physics and material science are of significant interest. The bending rigidity, κ, and compression modulus, B, of three-dimensional (3D) finite nonspontaneous multilamellar vesicles, formed by a nonionic surfactant, are linked to nanoscale bilayer thickness, δ, estimated via small-angle X-ray scattering, and macroscopic elastic modulus measured through small-amplitude oscillatory shear experiments. κ and B significantly differ from the same system in the two-dimensional (2D) infinite nanostructured planar lamellar phase. Particularly, κ3D was found to be much smaller than κ2D, while an opposite behavior was seen for B. The 2D-to-3D morphology transition occurs under a transient mechanical field, resulting in rheopectic behavior. κ scales quadratically with δ, consistent with bilayer membrane theories, and linearly with vesicle radius in the densely packed state. These findings have implications for understanding and designing soft interfaces due to the influence of bending rigidity on transport properties.

Effects of magnetic field heat treatment on magnetic properties and microstructure of Sm2Co17-type sintered magnets

Sm2Co17-type sintered magnets have attracted widespread attention for their excellent magnetic properties and thermal stability. The magnetic properties largely depend on the cellular structure and Cu, Fe distributions within these magnets. This paper systematically studies the effect of magnetic field heat treatment (MFHT) on the magnetic properties and microstructure of Sm2Co17-type sintered magnets. MFHT improves the room-temperature magnetic properties and remanence temperature stability of magnets but slightly deteriorates the temperature coefficient of intrinsic coercivity. A microstructure analysis shows that MFHT improves the cell boundary phase content and optimizes the cellular structure and Cu, Fe distributions of magnets. A high-density short lamellar phase, possibly induced by MFHT, provides easy diffusion paths for Cu and Fe, thereby improving the magnetic properties of magnets. Compared with conventional aging treatment, this paper proposes a promising method to improve the magnetic properties of Sm2Co17-type sintered magnets under the same heat treatment time and temperature.

Inhomogeneous deformation behavior and recrystallization mechanism of Mg-Gd-Y-Zn-Zr alloy containing only intragranular lamellar LPSO phase

Inhomogeneous plastic deformation and recrystallization behavior of Mg-Gd-Y-Zn-Zr alloy containing only intragranular lamellar long-period stacking ordered (LPSO) phase were investigated by isothermal compression experiments at the temperatures of 350–450 °C, and the strain rates of 0.001 ∼ 10 s−1. Results showed that Mg-Gd-Y-Zn-Zr alloys with varying degrees of bimodal structures were obtained after compression. The lamellar LPSO phase directions in residual coarse grains were aligned in the radial direction (RD). Dynamic recrystallization (DRX) grains induced at grain boundaries, kinked bands, and lamellar shearing regions during compression synergistically promoted coarse grain refinement. Moreover, the condition of high temperature and medium strain rate (450 °C-0.1 s−1) contributed to the uniform extension of "mantle layers" of fine DRX grains. In contrast, the condition of medium temperature and high strain rate (400 °C-10 s−1) could accelerate the deflection of CD-directed (compression direction) LPSO lamellae and the formation of local high-energy regions, facilitating the generation of recrystallization band. In addition, a high strain rate (400 °C-10 s−1) is more conducive to the formation of a heavily bimodal structure than a high temperature (450 °C-0.1 s−1). Only a larger spacing of LPSO lamellae (∼1.4 μm) could meet the spatial requirements of recrystallization. Further analysis revealed that the continuous dynamic recrystallization (CDRX) mechanism characterized by the expansion of "mantle layers" and nucleation along kinked boundaries and lamellar shearing regions was the primary grain refinement mechanism. The discontinuous dynamic recrystallization (DDRX) mechanism only exhibited a limited role due to the inhibition of the highly dense lamellar LPSO phase on grain boundaries bulging. After compression, the orientation of residual coarse grains gradually deviated toward the CD. While the recrystallization with limited proportion and random orientation cannot significantly weaken the basal texture.

Identifying Topological Defects in Lamellar Phases through Contour Analysis of Complex Wave Fields

Identifying Topological Defects in Lamellar Phases through Contour Analysis of Complex Wave Fields

Tailoring lyotropic liquid crystals for skin barrier penetration: Exploring composition and structure–function relationships

Lyotropic liquid crystals (LLCs) have garnered attention as a promising nanocarrier delivery system for enhancing skin permeation owing to their unique structural properties, such as improved drug loading and controlled drug release and versatility. LLCs are greatly explored for topical drug delivery owing to their strong bio-adhesive nature and structural similarity to the biological membranes when applied topically, which improves skin retention and permeation of the drugs. This review explores the functionality of structural design, especially the optimization of micellar systems, hexagonal and lamellar phases, and bicontinuous cubic and sponge phases, to achieve efficient skin permeation of therapeutic loaded LLCs. Furthermore, customization of surfactant to achieve skin compatibility and permeation is explored along with incorporating molecular modifications, functionalization, and the influence of surfactant hydrophilic–lipophilic balance. Additionally, the review illuminates the impact of LLCs curvature and the engineering of ordered and disordered phases for optimal drug release. Emerging advanced techniques such as surface modification with various ligands, stimuli-responsive LLCs for on-demand drug release, and combination therapies with multifunctional LLCs for synergistic effects that can promote targeted and site-specific drug delivery have also been discussed. The detailed findings have been discussed in this review with appropriate case studies. Challenges and future perspectives in designing and formulating LLCs for skin permeation are addressed to ignite future research. The knowledge and advancements presented in this review pave the way for developing next-generation LLCs-based systems, enabling enhanced permeation through the skin and opening new possibilities in the treatment of various dermatological conditions.

The Effect of Mixtures and Additives on Dissolving Surfactant Lamellar Phases.

Understanding the dissolution process of surfactant solutions is important in formulating product design processes. The main goal of this study is to gain further insights into how additives and mixtures affect surfactant dissolution processes. To achieve this goal, dissipative particle dynamic simulations were used. Lamellar phases at 80% volume of surfactant were initially equilibrated with water. After reaching an equilibrium state, the dissolution simulations were carried out for different surfactant mixtures. To track the dissolution process, different metrics were used, including visual analysis, local concentration analysis, diffusion, and cluster size calculations. Results show that by having a mixture of surfactants, the diffusion of the micelles is not affected only by the size of the micelles as in pure surfactant systems, but there is also an effect due to the composition of the micelles. When oil is added to a surfactant system, the system acts like a longer chain surfactant system, but only when the chain of oil becomes sufficiently long.

Simple-by-design approach for production of stabilizer-free cubosomes from phosphatidylglycerol and docosahexaenoic acid monoacylglycerol

Docosahexaenoic acid monoacylglycerol represents a promising lipid constituent in the development of drug nanocarriers owing to its amphiphilicity and the beneficial health effects of this docosahexaenoic acid precursor in various disorders including cancer and inflammatory diseases. Here, we describe the formation and characterization of simple-by-design and stabilizer-free lamellar and non-lamellar crystalline nanoparticles (vesicles and cubosomes, respectively) from binary mixtures of docosahexaenoic acid monoacylglycerol and phosphatidylglycerol, which is a ubiquitous amphiphilic component present in biological systems. At the physiological temperature of 37 °C, these single amphiphilic components tend to exhibit inverse hexagonal and lamellar liquid crystalline phases, respectively, on exposure to excess water. They can also be combined and dispersed in excess water by employing a high-energy emulsification method (by means of ultrasonication) to produce through an electrostatic stabilization mechanism colloidally stable nanodispersions. A colloidal transformation from vesicles to cubosomes was detected with increasing MAG-DHA content. Through use of synchrotron small-angle X-ray scattering, cryo-transmission electron microscopy, and nanoparticle tracking analysis, we report on the structural and morphological features, and size characteristics of these nanodispersions. Depending on the lipid composition, their internal liquid crystalline architectures were spanning from a lamellar (Lα) phase to biphasic features of coexisting inverse bicontinuous (Q2) cubic Pn3m and Im3m phases. Thus, a direct colloidal vesicle-cubosome transformation was detected by augmenting the concentration of docosahexaenoic acid monoacylglycerol. The produced cubosomes were thermally stable within the investigated temperature range of 5–60 °C. Collectively, our findings contribute to understanding of the imperative steps for production of stabilizer-free cubosomes from biocompatible lipids through a simple-by-design approach. We also discuss the potential therapeutic use and future implications for development of next-generation of multifunctional vesicles and cubosomes for co-delivery of docosahexaenoic acid and drugs in treatment of diseases.

Disclosing Topographical and Chemical Patterns in Confined Films of High-Molecular-Weight Block Copolymers under Controlled Solvothermal Annealing.

The microphase separation of high-molecular-weight block copolymers into nanostructured films is strongly dependent on the surface fields. Both, the chain mobility and the effective interaction parameters can lead to deviations from the bulk morphologies in the structures adjacent to the substrate. Resolving frustrated morphologies with domain period L0 above 100 nm is an experimental challenge. Here, solvothermal annealing was used to assess the contribution of elevated temperatures of the vapor Tv and of the substrate Ts on the evolution of the microphase-separated structures in thin films symmetric of polystyrene-b-poly(2vinylpyridine) block copolymer (PS-PVP) with L0 about 120 nm. Pronounced topographic mesh-like and stripe patterns develop on a time scale of min and are attributed to the perforated lamella (PL) and up-standing lamella phases. By setting Tv/Ts combinations it is possible to tune the sizes of the resulting PL patterns by almost 10%. Resolving chemical periodicity using selective metallization of the structures revealed multiplication of the topographic stripes, i.e., complex segregation of the component within the topographic pattern, presumably as a result of morphological phase transition from initial non-equilibrium spherical morphology. Reported results reveal approaches to tune the topographical and chemical periodicity of microphase separation of high-molecular-weight block copolymers under strong confinement, which is essential for exploiting these structures as functional templates.

Montmorillonite restricts free fatty acid liberation and alters self-assembled structures formed during in vitro lipid digestion

The global rise in obesity necessitates innovative weight loss strategies. Naturally occurring smectite clays, such as montmorillonite (MMT), offer promise due to their unique properties that interfere with free fatty acid (FFA) liberation, reducing systemic uptake. However, the mechanisms of MMT-FFA interactions and their implications for weight management are undefined. This study investigates these interactions by adding MMT (10 % w/w) to in vitro lipolysis media containing medium chain triglycerides (MCTs), and monitoring FFA liberation using pH-stat titration. Nanoparticle tracking analysis (NTA) and synchrotron-based small-angle X-ray scattering (sSAXS) observed time-dependent structural changes, while electron microscopy examined clay morphology during digestion. A 35 % reduction in FFA liberation occurred after 25 min of digestion with MCT + MMT, with digestion kinetics following a biphasic model driven by calcium soap formation. NTA revealed a 17-fold decrease in vesicular structures with MCT + MMT, and sSAXS highlighted a rapid lamellar phase evolution linked to calcium soap formation. This acceleration is attributed to MMT's adsorption to unionized FFAs via hydrogen bonding, supported by TEM images showing a decrease in d-spacing, indicating FFA intercalation is not the main adsorption mechanism. These findings highlight MMT's potential as a novel intervention for reducing dietary lipid absorption in obesity and metabolic diseases.

Phase behavior and rheology of the sucrose laurate/sorbitan mono-laurate (Span 20)/water pseudo-ternary system

In order to develop a lamellar liquid crystal system consisting of temperature-insensitive and mild non-ionic surfactants, we construct the phase diagram of sucrose laurate (L1695)/sorbitan monolaurate (Span 20)/water pseudo-ternary systems at 25 ℃ based on the direct visual inspection and polarized microscopy. In contrast to the phase diagrams of polyoxyethylene alkyl ethers and co-surfactant mixtures reported in relevant studies, the single-phase region of the liquid crystalline phase in sucrose laurate (L1695)/sorbitan monolaurate (Span 20)/water pseudo-ternary systems is shown to be narrower. Moreover, the liquid crystal phase behaviors of the sucrose laurate/sorbitan mono-laurate (Span 20)/water pseudo-ternary systems are examined in depth applying cryo-SEM, X-ray scattering measurements, rheological test and low field NMR experiments. In the abovementioned aqueous systems with a L1695 to Span 20 mass ratio (between 53.9: 46.1 and 43.3:56.7), sucrose mono-laurate combines with a certain number of sorbitan monolaurate molecules to form a single lamellar liquid crystalline phase. Furthermore, the present experimental results as well as their analysis could give the quantitative playground for the interaction between sugar-based surfactants in aqueous system, which has rarely been investigated compared with the phase behavior of polyoxyethylene alkyl ethers in aqueous solution.

The Sphingosine and Phytosphingosine Ceramide Ratio in Lipid Models Forming the Short Periodicity Phase: An Experimental and Molecular Simulation Study.

The lipids located in the outermost layer of the skin, the stratum corneum (SC), play a crucial role in maintaining the skin barrier function. The primary components of the SC lipid matrix are ceramides (CERs), cholesterol (CHOL), and free fatty acids (FFAs). They form two crystalline lamellar phases: the long periodicity phase (LPP) and the short periodicity phase (SPP). In inflammatory skin conditions like atopic dermatitis and psoriasis, there are changes in the SC CER composition, such as an increased concentration of a sphingosine-based CER (CER NS) and a reduced concentration of a phytosphingosine-based CER (CER NP). In the present study, a lipid model was created exclusively forming the SPP, to examine whether alterations in the CER NS:CER NP molar ratio would affect the lipid organization. Experimental data were combined with molecular dynamics simulations of lipid models containing CER NS:CER NP at ratios of 1:2 (mimicking a healthy SC ratio) and 2:1 (observed in inflammatory skin diseases), mixed with CHOL and lignoceric acid as the FFA. The experimental findings show that the acyl chains of CER NS and CER NP and the FFA are in close proximity within the SPP unit cell, indicating that CER NS and CER NP adopt a linear conformation, similarly as observed for the LPP. Both the experiments and simulations indicate that the lamellar organization is the same for the two CER NS:CER NP ratios while the SPP NS:NP 1:2 model had a slightly denser hydrogen bonding network than the SPP NS:NP 2:1 model. The simulations show that this might be attributed to intermolecular hydrogen bonding with the additional hydroxide group on the headgroup of CER NP compared with CER NS.

Microstructure and mechanical properties of Tip/GWZ723 composites adjusted by Tip/Mg laminate structure

In this work, the spherical Tip was introduced into Mg-7Gd-2Y–3Zn (GWZ723) alloy, the Tip/Mg laminar-like configuration was constructed by hot extrusion. The layers quantity and interlayer spacing were adjusted by Tip content. The effects of Tip/Mg laminar-like structure parameters on the microstructure, mechanical properties, work hardening and fracture behavior of Tip/GWZ723 composites were investigated. The results indicate that after extrusion, the Tip elongates along the extrusion direction (ED) and form Tip/Mg laminar-like configuration with the matrix. The Tip aspect ratio increases with the Tip content increases, resulting in a pronounced Tip/Mg laminar-like configuration. The addition of Tip promotes DRX, refines the grain size and promotes the precipitation of the lamellar 14H LPSO phase. The Tip/Mg laminar-like configuration induces the accumulation of high-density dislocations at the interface, thereby contributing to hetero-deformation induced (HDI) hardening, which improves the work hardening rate and dynamic recovery rate. With increasing of Tip content, the HDI hardening effect becomes more pronounced. The Tip/Mg laminar-like configuration facilitates strain redistribution, alleviates stress concentration, impacts crack initiation and inhibits crack propagation, enhancing the plasticity of the Tip/GWZ723 composites. At a Tip content of 15 vol%, the 15 vol%Tip/GWZ723 composite exhibits YS of 439 MPa, UTS of 477 MPa and EL of 3.3 %.

First Order Alignment Transition in an Interfaced Active Nematic Fluid.

We investigate experimentally the dynamic phase transition of a two-dimensional active nematic layer interfaced with a passive liquid crystal. Under a temperature ramp that leads to the transition of the passive liquid into a highly anisotropic lamellar smectic-A phase, and in the presence of a magnetic field, the coupled active nematic reorganizes its flow and orientational patterns from the turbulent into a quasilaminar regime aligned perpendicularly to the field. Remarkably, while the phase transition of the passive fluid is known to be continuous, or second order, our observations reveal intermittent dynamics of the order parameter and the coexistence of aligned and turbulent regions in the active nematic, a signature of discontinuous, or first order, phase transitions, similar to what is known to occur in relation to flocking in dry active matter. Our results suggest that alignment transitions in active systems are intrinsically discontinuous, regardless of the symmetry and momentum-damping mechanisms.

Photoinduced bidirectional mesophase transition in vesicles containing azobenzene amphiphiles.

The functionality and efficiency of proteins within a biological membrane are highly dependent on both the membrane lipid composition and the physiochemical properties of the solution. Lipid mesophases are directly influenced by changes in temperature, pH, water content or due to individual properties of single lipids such as photoswitchability. In this work, we were able to induce light- and temperature-driven mesophase transitions in a model membrane system containing a mixture of 1,2-dipalmitoyl-phosphatidylcholine phospholipids and azobenzene amphiphiles. We observed reversible and reproducible transitions between the lamellar and Pn3m cubic phase after illuminating the sample for 5 min with light of 365 and 455 nm wavelengths, respectively, to switch between the cis and trans states of the azobenzene N=N double bond. These light-controlled mesophase transitions were found for mixed complexes with up to 20% content of the photosensitive molecule and at temperatures below the gel-to-liquid crystalline phase transition temperature of 33°C. Our results demonstrate the potential to design bespoke model systems to study the response of membrane lipids and proteins upon changes in mesophase without altering the environment and thus provide a possible basis for drug delivery systems.

Synchronized Codelivery of Combination Chemotherapies Intratumorally Using a Lipidic Lyotropic Liquid Crystal System.

In this work, an injectable in situ depot-forming lipidic lyotropic liquid crystal (L3C) system is developed to codeliver a precisely synchronized combination of chemotherapeutics intratumorally. The developed L3C system is composed of amphiphilic lipids and surfactants, including monoolein, phosphatidylcholine, tocopherol acetate, and d-α-tocopherol polyethylene glycol 1000 succinate. Owing to its amphiphilic nature, the developed formulation can coaccommodate both hydrophobic and hydrophilic chemotherapeutic moieties simultaneously. The study presents a proof of concept by designing a combination chemotherapy regimen in vitro and demonstrating its in vivo translation using doxorubicin and paclitaxel as model hydrophilic and hydrophobic drug moieties, respectively. The synchronized combination of the two chemotherapeutics with maximum synergistic activity was identified, coloaded in the developed L3C system at predefined stoichiometric ratios, and evaluated for antitumor efficacy in the 4T1 breast tumor model in BALB/c mice. The drug-loaded L3C formulation is a low-viscosity injectable fluid with a lamellar phase that transforms into a hexagonal mesophase depot system upon intratumoral injection. The drug-loaded depot system locally provides sustained intratumoral delivery of the chemotherapeutics combination at their precisely synchronized ratio for over a period of one month. Results demonstrate that the exposure of the tumor to the precisely synchronized intratumoral chemotherapeutics combination via the developed L3C system resulted in significantly higher antitumor activity and reduced cardiotoxicity compared to the unsynchronized combination chemotherapy or the synchronized but uncoordinated drug delivery administered by a conventional intravenous route. These findings demonstrate the potential of the developed L3C system for achieving synchronized codelivery of the chemotherapeutics combination intratumorally and improving the efficacy of combination chemotherapy.

Numerical analysis of machinability and surface alterations in cryogenic machining of additively manufactured Ti6Al4V alloy

Metal additive manufacturing (AM) technology has been utilized in many industries including automotive, aerospace, and medical. AM Ti6Al4V (Ti64) alloy is highly noticed for production of medical instruments such as dental implants and the machining process is mostly needed during the production or post-processing of these components. Numerical model, as a powerful tool, can be efficiently used for analyzing the machining process. A customized model was employed using a user-written subroutine in this work to evaluate machinability and microstructural changes in cryogenic machining of AM Ti64 alloy. For this purpose, the microstructural changes were simulated as the new numerical outputs. The numerical results of cutting forces, temperature, nano-hardness, and alpha lamellae thickness (grain size) were successfully verified by corresponding experiments from literature. Then, the impact of tool geometry (including rake and clearance angles, cutting edge radius, and nose radius) on the machinability performance was examined. It was found that, the variation of clearance and rake angles were more effective on depth of the hardened layer compared to the other parameters. Thickness of alpha lamellae phase near the machined surface and depth of the affected layer by nano-hardness changes were changed from 0.9 to 1.58 µm, and from 18 to 40 µm, respectively. Overall, it was concluded that the variation of insert positioning made by tool holder (change in rake and clearance angles) was an effective parameter on the process outputs when machining AM Ti64 alloy.

Self-Assembly of Lamellae-in-Lamellae by Double-Tail Cationic Surfactants.

The molecular structures of surfactants play a pivotal role in influencing their self-assembly behaviors. In this work, using simulations and experiments, an unconventional hierarchically layered structure in the didodecyldimethylammonium bromide (DDAB)/water binary system: lamellae-in-lamellae is revealed, a new self-assembly structure in surfactant system. This self-assembly structure refers to a lamellar structure with a shorter periodic length (inner lamellae) embedded in a lamellar phase with a longer periodic length (outer lamellae). The normal vectors of these two lamellar regions orient perpendicularly. In addition, it is observed that this lamellar-in-lamellar phase disappears when the two tails of the cationic surfactants become longer. The formation of the lamellar-in-lamellar architecture arises from multiple interacting factors. The key element is that the short tails of the DDAB surfactants enhance hydrophilicity and rigidity, which facilitates the formation of the inner lamellae. Moreover, the lateral monolayer of the inner lamellae provides shielding from the water and prompts the formation of the outer lamellae. These findings indicate that molecular structures and flexibility can profoundly redirect the hierarchical self-assembly behaviors in amphiphilic systems. More broadly, this work presents a new strategy to deliberately program hierarchical nanomaterials by designing specific surfactant molecules to act as tunable scaffolds, reactors, andcarriers.

Optical and molecular features of negatively curved surfaces created by POPE lipids: A crucial role of the initial conditions

Membrane fusion is closely related to plasma membrane domains rich in cone-shaped phosphatidylethanolamine (PE) lipids that can reverse membrane curvature under certain conditions. The phase transition of PE-based lipid membranes from the lamellar fluid phase (Lα) to the inverse hexagonal phase (HII) is commonly taken as a general model in reconstructing the membrane fusion pathway, and whose structural features have been mostly described so far using structural and microscopic techniques. The aim of this paper is to decipher the optical and molecular features of Lβ → Lα and especially of Lα → HII transition of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) lipids at pH = 7.0 when they are initially prepared in the form of both multi- and unilamellar liposomes (MLVs and LUVs). The distinction between optical properties of MLS- and LUVs-derived HII phase, provided from turbidity-sensitive temperature-dependent UV–Vis spectra, was attributed to different formation mechanisms of HII phase. Most importantly, from FTIR spectroscopic data of POPE lipids in Lβ (15 °C), Lα (50 °C) and HII (85 °C) phases we identified the changes in molecular features of POPE lipids during phase transitions. Among the latter, by far the most significant is different hydration pattern of POPE lipids in MLVs- and LUVs-derived HII phase which extends from the polar-apolar interface all the way to the terminal amino group of the POPE lipid, along with the changes in the conformation of glycerol backbone as evidenced by the signature of α-methylene groups. Molecular dynamics simulations confirmed higher water penetration in HII phase and provided insight into hydrogen bonding patterns.