Lamellar Gels Research Articles

Extreme heterogeneity in the microrheology of lamellar surfactant gels analyzed with neural networks.

The heterogeneity of the viscoelasticity of a lamellar gel network based on cetyl-trimethylammonium chloride and cetostearyl alcohol was studied using particle-tracking microrheology. A recurrent neural network (RNN) architecture was used for estimating the Hurst exponent, H, on small sectionsof tracks of probe spheres moving with fractional Brownian motion. Thus, dynamic segmentation of tracks via neural networks was used in microrheology and it is significantly more accurate than using mean square displacements (MSDs). An ensemble of 414 particles produces a MSD that is subdiffusive in time, t, with a power law of the form t^{0.74±0.02}, indicating power law viscoelasticity. RNN analysis of the probability distributions of H, combined with detailed analysis of the time-averaged MSDs of individual tracks, revealed diverse diffusion processes belied by the simple scaling of the ensemble MSD, such as caging phenomena, which give rise to the complex viscoelasticity of lamellar gels.

Design and Properties of Novel Hydrophobic Natural Tea Saponin and Its Organogels.

It was first discovered that the excellent gelation ability of tea saponin can be obtained by introducing long-chain alkyl groups of dodecanoyl chloride into the glycosyl portion with direct esterification. The modified dodecanoyl chloride-tea saponin (DC-TS) was successfully synthesized and characterized with NMR, MS, and FT-IR. The tests showed that the long-chain alkyl group was successfully introduced. Combined with SEM and X-ray diffraction patterns, we found that the stable lamellar shape gels of DC-TS were formed in a variety of solvents. More interestingly, organogel was also obtained by adjusting good solvent and poor solvent as mixed solvent. It is worth noting that the driving force of organogels is the combination of hydrogen bonding and the hydrophobic interaction of the introduced alkyl chains with the rigid backbone of pentacyclic triterpenes. The modified tea saponin, a natural green surfactant, was discovered to have gelation properties, which has broadened tea saponin's scope of application and made it more promising.

Measuring the bending rigidity of microbial glucolipid (biosurfactant) bioamphiphile self-assembled structures by neutron spin-echo (NSE): Interdigitated vesicles, lamellae and fibers

Bending rigidity, k, is classically measured for lipid membranes to characterize their nanoscale mechanical properties as a function of composition. Widely employed as a comparative tool, it helps understanding the relationship between the lipid's molecular structure and the elastic properties of its corresponding bilayer. Widely measured for phospholipid membranes in the shape of giant unilamellar vesicles (GUVs), bending rigidity is determined here for three self-assembled structures formed by a new biobased glucolipid bioamphiphile, rather associated to the family of glycolipid biosurfactants than phospholipids. In its oleyl form, glucolipid G-C18:1 can assemble into vesicles or crystalline fibers, while in its stearyl form, glucolipid G-C18:0 can assemble into lamellar gels. Neutron spin-echo (NSE) is employed in the q-range between 0.3 nm−1 (21 nm) and 1.5 nm−1 (4.1 nm) with a spin-echo time in the range of up to 500 ns to characterize the bending rigidity of three different structures (Vesicle suspension, Lamellar gel, Fiber gel) solely composed of a single glucolipid. The low (k = 0.30 ± 0.04 kbT) values found for the Vesicle suspension and high values found for the Lamellar gel (k = 130 ± 40 kbT) and Fiber gel (k = 900 ± 500 kbT) are unusual when compared to most phospholipid membranes. By attempting to quantify for the first time the bending rigidity of self-assembled bioamphiphiles, this work not only contributes to the fundamental understanding of these new molecular systems, but it also opens new perspectives in their integration in the field of soft materials.

Presence of bicontinuous microemulsion-type domains and dielectrically inert interfacial water layers in lamellar gel-stabilized oil-in-water emulsions

HypothesisLamellar gels are widely formulated in household and cosmetic products because of their eminent ability to improve long-term stability of thermodynamically unstable oil-in-water emulsions. However, despite long study, how and why membrane internal structure and membrane-membrane interactions are modified by the presence of polar and nonpolar oils remains elusive. ExperimentsUsing small- and wide-angle X-ray scattering, dielectric spectroscopy, and field-emission transmission electron microscope, we investigate intermembrane interactions and water-mediated microscopic interfacial properties in lamellar gels and lamellar gel-stabilized oil-in-water emulsions based on cetyltrimethylammonium chloride and 1-hexadecanol. FindingsReducing membrane surface charge density enhances undulation fluctuation disorder, resulting in a crossover of dominant interactions from electrostatic double-layer repulsion to Helfrich interaction. Oil-emulsification induces similar structural impacts to the reduced 1-hexadecanol ratio, confirming preferential dissolution of higher-alcohol in oil phases. An emerging Teubner-Stray scattering component upon emulsification of nonpolar oil evidences that oil droplets and lamellar gels are indirectly connected via bicontinuous microemulsion-type domains. Dielectric spectra reveal strikingly small water permittivity in the lamellar gel and emulsion samples, which is quantitatively explained by a cumulative effect of a dielectrically inert interfacial thin water layer (<1nm) and a highly polarizable bulk-like water layer. This phenomenon appears to be intrinsic to diverse lamellar stack architectures.

Relaxation mechanisms in hydrogels with uniaxially oriented lamellar bilayers

Hydrogels are excellent candidates for biomedical applications but often show poor resistance to fracture. Recent development in the field, such as lamellar gels, aimed at improving their mechanical properties. Here, we study lamellar gels composed of rigid and hydrophobic bilayers of self-assembled polymeric DGI (Dodecyl Glyceryl Itaconate) molecules periodically intertwined in soft and elastic polyacrylamide (PAAm) hydrogel (called PDGI/PAAm hydrogels), which, thanks to their anisotropic structure, constitute good model systems to mimic the properties of biotissues such as skin and muscle. In this paper, we present an analysis of the dynamic mechanical properties of PDGI/PAAm gels depending on their structure, along with an examination of the different energy dissipation mechanisms at play. Using tensile testing, we show for the first time that the relaxation process is due to the rupture of physical bonds within the PDGI bilayers, with a characteristic time in the order of 10 s.

Structure and Unique Functions of Anisotropic Hydrogels Comprising Uniaxially Aligned Lamellar Bilayers

Abstract In this account, we provide an overview of unique anisotropic hydrogels comprising uniaxially aligned lamellar bilayers embedded in amorphous gel matrix. Owing to their unique structures, the lamellar gels exhibit many unique functions that cannot be obtained from conventional hydrogels featuring amorphous and isotropic structures. For example, the periodical multilayer structure having interlayer spacing of several hundreds of nanometers imparts beautiful structural colors to the gel that respond sensitively to mechanical and chemical stimuli, the water-impermeable nature of the bilayers imparts one-dimensional swelling and diffusion, and the hydrophobic association of the bilayers serves as sacrificial bonds to impart high mechanical strength and toughness during deformation. This work demonstrates the significant potential of hydrogel materials fabricated by introducing anisotropic ordered structures.

Rheology of α-Gel Formed by Amino Acid-Based Surfactant with Long-Chain Alcohol: Effects of Inorganic Salt Concentration.

Mixtures of surfactants, long-chain alcohols, and water sometimes yield lamellar gels with hexagonally packed alkyl chains. This assembly is called “α-gel” or “α-form hydrated crystal.” In this study, we characterized the rheological properties of α-gel prepared using disodium N-dodecanoylglutamate (C12Glu-2Na), 1-hexadecanol (C16OH), and water at different NaCl concentrations. The α-gel structure was assessed using small- and wide-angle X-ray scattering (SWAXS). The SWAXS measurements revealed that an increased NaCl concentration (0–200 mmol dm–3) resulted in a decreased d-spacing caused by the screening of electrostatic repulsion between lamellar bilayers. This led to an increased amount of excess water (i.e., the water present between the α-gel domains), and hence, the viscosity of the α-gel decreased in the range of the NaCl concentration. A further increase in the NaCl concentration (200–1000 mmol dm–3) resulted in decreased electrostatic repulsion between the α-gel domains and/or an increased number of α-gel domains (multilamellar vesicles). These effects increased the domain-to-domain interactions, leading to increased viscosity. Therefore, we concluded that the viscosity of the α-gel was controlled by the amount of excess water and the domain-to-domain interactions. Once the network structure collapsed under the strain, it was difficult to recover the original network structure. The low recoverability resulted from increased cohesion between the domains at high NaCl concentrations.

Thermoresponsive liquid crystalline formulation of Exemestane: Design and structural characterization

Exemestane (EXE), a drug used for the treatment of breast cancer, has limited aqueous solubility of 0.08 mg/mL and log P∼ 4.22. The only available marketed formulation in form of tablets possess limitations of poor oral absorption (∼ 42 %), low solubility, extensive hepatic metabolism and numerous adverse effects due to its peripheral absorption. In order to address these issues, an alternative route of topical application is attempted through a lamellar liquid crystal based formulation. Pluronic® was used as stabilizer due to its higher surface activity and gelling properties. The solubility enhancement of EXE was achieved using liquid crystal formulation. We have investigated the effect of concentration of oil, Smix (surfactant – cosurfactant mixture) and EXE on lattice parameter, rheology and drug release for various combinations of the formulation. The small angle x-ray scattering (SAXS) measurement demonstrated an evidence of a lamellar structure with lattice parameter ∼15 nm, which increases with corresponding increase in oil and EXE due to increase in hydrophobic interactions leading to an expansion of lamella. The inter lamellar distance decreases at higher surfactant concentration, due to the distribution of the same amount of oil and drug within larger concentration of surfactant molecules. The rheology measurement exhibited gel like properties at low shear rate indicating soft gel formation, which converts to Newtonian type flowing liquid at higher shear rate. At constant Smix with increasing oil content, the viscosity decreases, which is attributed to the dilution of the lamellar structures with oil. The temperature sweep rheology reveals a change in the viscosity near physiological temperature, which may be attributed to the structural transition of lamellae. The formulation remains gel like at room temperature, which aids in proper application to skin and converts it to free flowing liquid above 37 °C. The invitro drug release of optimized formulation for 24 h was ∼ 38 % at 37 °C, which increased to 50 % at 42 °C. Accordingly, this formulation containing thermoresponsive lamellar liquid crystal gels of EXE represents a viable option for hyperthermia induced enhanced drug release. The characteristic and advantageous features offered by this formulation includes improved bioavailability of EXE due to enhanced solubility, permeability and absorption.

Ocular lamellar crystalline gels for sustained release and enhanced permeation of resveratrol against corneal neovascularization

Corneal neovascularization (CNV) is the major cause of blindness after eye injury; however, only several drugs can be applied and the invasive administration ways (i.e., intravitreal injection and subconjunctival injection) are used. Resveratrol is a highly effective anti-VEGF agent against CNV. However, its applications are limited due to its strong hydrophobicity and instability. Here, we developed a resveratrol-loaded ocular lamellar crystalline gel (ROLG) for high inhibition of CNV. ROLGs were composed of resveratrol, glyceryl monooleate (GMO), ethanol, and water, and their lamellar crystalline structures were identified by polarizing light microscopy and small-angle X-ray scattering. High drug loading (4.4 mg/g) of ROLGs was achieved due to the hydrogen bonding between GMO and resveratrol. Resveratrol showed sustained release with 67% accumulative release in 7 h, which was attributed to the slow erosion of gels. Resveratrol in ROLGs had a high corneal permeation 3 times higher than resveratrol in hyaluronic acid suspensions (RHSs). ROLGs were administered to rats only once a day because of their strong retention on the cornea surface. ROLGs were safe due to the very little contact of ethanol in ROLGs to the cornea. CNV post-rat corneal alkaline injury was highly inhibited by ROLGs, resulting from the attenuation of corneal VEGF expression and then corneal healing was improved. The ROLG was a promising ocular medicine for the prevention of CNV.

Microstructure design of CTAC:FA and BTAC:FA lamellar gels for optimized rheological performance utilizing automated formulation platform.

The main objective of this paper was to optimize hair conditioner performance through variation of composition utilizing automated cosmetic formulation platform and advanced characterization techniques as well as develop understanding of how performance (wet combing and wet lubrication) of hair conditioner is affected by its rheology (i.e. yield stress) and controlled breakdown of the formulations (dilution). The experimental results show that yield stress greatly impacts rheology, stability and performance of the lamellar gels for hair conditioning. All samples were prepared on the Chemspeed Flex Formax. A mechanical rheometer was used to measure bulk viscosity and yield stress in each sample. Dia-stron tensile tester was used to measure the lamellar gels ability to reduce combing force. Potential stronger lamellar gel network formation in the formed lamellar gels potentially leads to higher yield stress exhibited. Viscosity values were also measured after a controlled breakdown (i.e. dilution) of each sample. This was also carried out using a mechanical rheometer. Yield stress of the formulations was engineered through composition variation and was recorded in each system. The highest yield stress value is 251.179Pa at a BTAC/CA ratio of 6:10, and the lowest yield stress is 50.14Pa at a BTAC/CA ratio of 6:5. The highest yield stress value is 50.14Pa at a CTAC/CA ratio of 6:10, and the lowest yield stress is 19.98Pa at a CTAC/CA ratio of 2:10. The highest overall yield stress values can also be observed in the BTAC/CA system, whereas the CTAC/CA system has relatively lower yield stress values. Dilution of each formulation caused a breakdown in viscosity of each formulation with the formulations with highest yield stress maintaining higher viscosity than the other formulations. The formulations with highest yield stress in each system which also maintains the highest dilution viscosity (6% BTAC/10% CA and 6% CTAC/10% CA) have the best effect on reducing overall combing force, that is from dry hair tress to wet hair tress and after product is rinsed off. At a BTAC/CA system of ratio 6:5, there is an 89% reduction in combing force and a 95% reduction in combing force in the BTAC/CA system of ratio 6:10. At a CTAC/CA system of ratio 2:10, there is a 65% reduction in combing force and a 88% reduction in combing force in the CTAC/CA system of ratio 6:10. A 'conditioned' soft feel was observed on each hair tress as the sample was applied and after it was rinsed off. The overall performance of the lamellar gels for hair conditioning can be engineered through optimization of the formulation microstructure and formulation microstructure breakdown on dilution.

Single-molecule lamellar hydrogels from bolaform microbial glucolipids.

Lipid lamellar hydrogels are rare soft fluids composed of a phospholipid lamellar phase instead of fibrillar networks. The mechanical properties of these materials are controlled by defects, induced by local accumulation of a polymer or surfactant in a classical lipid bilayer. Herein we report a new class of lipid lamellar hydrogels composed of one single bolaform glycosylated lipid obtained by fermentation. The lipid is self-organized into flat interdigitated membranes, stabilized by electrostatic repulsive forces and stacked in micrometer-sized lamellar domains. The defects in the membranes and the interconnection of the lamellar domains are responsible, from the nano- to the micrometer scales, for the elastic properties of the hydrogels. The lamellar structure is probed by combining small angle X-ray and neutron scattering (SAXS, SANS), the defect-rich lamellar domains are visualized by polarized light microscopy while the elastic properties are studied by oscillatory rheology. The latter show that both storage G' and loss G'' moduli scale as a weak power-law of the frequency, that can be fitted with fractional rheology models. The hydrogels possess rheo-thinning properties with second-scale recovery. We also show that ionic strength is not only necessary, as one could expect, to control the interactions in the lamellar phase but, most importantly, it directly controls the elastic properties of the lamellar gels.

Synergistic structures in lyotropic lamellar gels.

In this work we present a systematic study on the microstructure of soft materials which combine the anisotropy of lyotropic liquid crystals with the mechanical stability of a physical gel. Systematic small-angle neutron (SANS) and X-ray (SAXS) scattering experiments were successfully used to characterize the lyotropic lamellar phase (Lα) of the system D2O -n-decanol - SDS which was gelled by two low molecular weight organogelators, 1,3:2,4-dibenzylidene-d-sorbitol (DBS) and 12-hydroxyoctadecanoic acid (12-HOA). Surprisingly, a pronounced shoulder appeared in the scattering curves of the lamellar phase gelled with 12-HOA, whereas the curves of the DBS-gelled Lα phase remained almost unchanged compared to the ones of the gelator-free Lα phase. The appearance of this additional shoulder strongly indicates the formation of a synergistic structure, which neither exists in the gelator-free Lα phase nor in the isotropic binary gel. By comparing the thicknesses of the 12-HOA (25-30 nm) and DBS (4-8 nm) gel fibers with the lamellar repeat distance (7.5 nm), we suggest that the synergistic structure originates from the minimization of the elastic free energy of the lamellar phase. In the case of 12-HOA, where the fiber diameter is significantly larger than the lamellar repeat distance, energetically unfavored layer ends can be prevented, when the layers cylindrically enclose the gel fibers. Interestingly, such structures mimic similar schemes found in neural cells, where axons are surrounded by lamellar myelin sheets.

A Thermally Stable Polyamine/Unsaturated Fatty Acid System: Gelation Behaviors and Application

AbstractThe gelation behavior of diethylenetriamine (DETA) and oleic acid (OLA) with different molar ratios in water was investigated. The gels, which were composed of lamellar phase and vesicles, were characterized using small‐angle X‐ray scattering (SAXS) and freeze‐fracture transmission electron microscopy (FF‐TEM). The responsive rheological properties were also investigated. Our results show that lamellar gels and rodlike micelles were formed successively with the increase of the DETA/OLA molar ratio. The lamellar gels exhibiting high thermal stability can be obtained in a wide range of polyamine/unsaturated fatty acid molar ratios. The mechanism of lamellar gel formation was explained by the packing parameter and the noncovalent interactions between the building blocks. Moreover, gel–sol transition can be triggered by tuning pH and ionic strength. This system has a good emulsification property, and no obvious nanoemulsion droplet coarsening is observed upon dilution after 30 days.

Effect of Hydrophobic Modification on the Properties of Polymer‐Blended Microemulsion Gels

AbstractPhase behavior of sodium oleate (NaOl)/isoamyl alcohol‐based lamellar gel phase in cedar oil/water medium in the presence of the nonionic polymer hydroxyethyl cellulose (HEC) and its hydrophobic modified product (HMHEC) is investigated for the development of polymer‐embedded surfactant gels. HMHEC is more soluble in oil‐in‐water (o/w) microemulsions, but nonionic HEC shows limited solubility in the lamellar microemulsion (o/w type). Quantitative estimation of rate of adsorption of the polymer on lamellae bilayers can be easily done by Sudan solubilization and methylene blue complexation methods. Addition of HMHEC to the lamellar gel phase increases the polymer solubilization limit of lamellar gels as well as the viscoelasticity and thermal stability. The polymer‐embedded microemulsion gel acts as a “clean gel” since it exhibits good solubilization in different hydrocarbon media at ambient conditions. Elastic modulus of the polymer‐embedded gel influences directly the suspension performance of gels at high temperature and yields a reasonable sand‐settling velocity acceptable according to fracturing standards. The thermal characteristics and viscoelastic properties of polymer‐embedded gel were found to be suitable for moderate‐temperature reservoir stimulation where the bottom hole temperature is in the range 70–75 °C. Already a large amount of experimental data on pure microemulsions (without polymer) exists. Our studies indicate that the developed polymer‐embedded microemulsion gel has great potential as a model system for the study of polymer–microemulsion interactions.

Experimental and DFT studies on aggregation behavior of dodecylsulfonate-based surface active ionic liquids in water and ethylammonium nitrate

The present work aims to systematically study the aggregation behavior of one halogen-free surface active ionic liquid (SAIL), i.e., 1-butyl-3-methylimidazolum dodecylsulfonate ([C4mim][C12H25SO3]), in water and ethylammonium nitrate (EAN), respectively. Multiple-state ordered aggregates, viz. lyotropic liquid crystals (LLCs) (normal hexagonal and laminar lyotropic liquid phases, i.e. H1 and Lα phases) and lamellar gels, were facilely tuned only by the concentration of SAIL or solvent type. Furthermore, it is particularly interesting that LLC phases were constructed in H2O while lamellar gels were obtained in the EAN media environment, which were characterized by polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS). According to the investigative SAXS patterns, some structural parameters were calculated, suggesting that a higher concentration of SAIL results in a denser arrangement whereas an opposite trend generates because of a higher temperature. FT-IR spectra and density functional theory (DFT) calculations reveal that both strong H-bonding and electrostatic interactions between EAN and the headgroups of [C4mim][C12H25SO3] facilitate gelation. For the self-assembled lamellar gels formed by [C4mim][C12H25SO3] in EAN, a thermally reversible sol–gel transition was observed by differential scanning calorimetry (DSC). The rheological results show that the H1 phase formed by [C4mim][C12H25SO3] in water exhibits a viscoelastic gel-like behavior among the whole frequency region while Lα phase displays a viscous behavior at lower frequencies and an elastic behavior at higher frequencies. This work is expected to set a basis for application of the eco-friendly halogen-free SAIL in some fields, e.g. electrochemistry, supramolecular chemistry and drug delivery.

Transdermal baicalin delivery using diethylene glycol monoethyl ether-mediated cubic phase gel

This study investigated the transdermal permeability of baicalin, a hydrophobic and readily hydrolyzed drug, delivered by glyceryl monooleate (GMO)-based cubic phase gel (CPG) mediated with Transcotol® P (TP, diethylene glycol monoethyl ether). A range of CPGs was produced by varying GMO, water, and TP levels. Examination of their physicochemical properties revealed that the optically isotropic CPG showed higher viscosity than lamellar phase gels (LPG), and the baicalin cargo increased CPG viscosity. The GMO:TP ratio and water content also altered viscosity. CPG-mediated delivery increased baicalin’s skin permeation, with 76.65- to 200.24-fold higher (p<0.05) transdermal flux than that of a Carbopol®-based hydrogel (HDG), and 6.72- to 17.55-fold (p<0.05) higher than that of LPG, with the same water content. Rat in vivo microdialysis showed that CPG produced sustained baicalin release, with superior pharmacokinetic parameters to those of HDG. Furthermore, cutaneous drug absorption was more efficient on rat abdominal skin, compared to that in the chest or scapular region. Effective fusion between the CPG lipid matrix and the stratum corneum may explain this enhancement of transdermal permeation. CPG containing TP therefore, achieved excellent transdermal drug delivery and good baicalin stability, indicating that this system represents a promising transdermal delivery vehicle.

Defects, Solvent Quality, and Photonic Response in Lamellar Block Copolymer Gels

Stimuli-responsive photonic gels are made from the lamellar block copolymer (BCP) poly(styrene-b-2-vinylpyridine) (PS–P2VP), where the photonic responses are triggered by swelling/deswelling of the P2VP block with a selective solvent. When compared to isotropic swelling in chemically cross-linked homopolymer gels, the P2VP block in the lamellar BCP shows significantly lower degrees of swelling in alcohol–water cosolvents. The glassy PS layers completely constrain the lateral expansion of the P2VP gel layers and the dislocation defect network that develops during BCP self-assembly provides a counter force to vertical swelling. A model based on Flory–Huggins mixing and dislocation network strain energy is proposed to capture the swelling behavior of the BCP and is then used to estimate the dislocation network density in the lamellar BCP. This work establishes the quantitative relationship between the reflective color of the photonic gel, the effective χ parameter of the swellable block and the solvent, and ...

Dynamic Swelling of Tunable Full-Color Block Copolymer Photonic Gels via Counterion Exchange

One-dimensionally periodic block copolymer photonic lamellar gels with full-color tunability as a result of a direct exchange of counteranions were fabricated via a two-step procedure comprising the self-assembly of a hydrophobic block-hydrophilic polyelectrolyte block copolymer, polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP), followed by sequential quaternization of the P2VP layers in 1-bromoethane solution. Depending on the hydration characteristics of each counteranion, the selective swelling of the block copolymer lamellar structures leads to large tunability of the photonic stop band from blue to red wavelengths. More extensive quaternization of the P2VP block allows the photonic lamellar gels to swell more and red shift to longer wavelength. Here, we investigate the dynamic swelling behavior in the photonic gel films through time-resolved in situ measurement of UV-vis transmission. We model the swelling behavior using the transfer matrix method based on the experimentally observed reflectivity data with substitution of appropriate counterions. These tunable structural color materials may be attractive for numerous applications such as high-contrast displays without using a backlight, color filters, and optical mirrors for flexible lasing.

Modeling mechanochromatic lamellar gels

Consisting of alternating swelling and nonswelling polymeric layers (SLs and NLs), lamellar gels are one-dimensional photonic crystals with mechanically tunable optical properties. The lamellar structure induces a constraint between the SLs and the NLs, resulting in a highly anisotropic swelling behavior that is coupled with deformation. The coupling gives rise to the mechanochromatic effect, i.e., the color change in the material in response to mechanical deformations. A quantitative understanding of the coupling behavior is the key to many applications. This paper formulates a nonlinear continuum model for lamellar gels by considering the constrained swelling and anisotropic deformation in both layers. A finite-element method is further developed to simulate the mechanochromatic response of a lamellar gel undergoing a nonuniform field.

Foam Superstabilization by Lamellar Liquid Crystal Gels

Abstract Highly stable microbubble dispersions with mean bubble radii of less than 100 µm stabilized solely with nonionic surfactant of glyceryl monostearate are reported, and the stability was sustained for more than 10 months which is attributed to the presence of lamellar liquid-crystal gels. The elastic response of the interface provides a physical barrier to collapse of dispersed microbubbles. Our study identifies a route to fabricate extremely stable dispersions of microbubbles.