Lyotropic Liquid Crystalline Phase Behavior Research Articles

Mix-and-Match Diols: Adjusting Self-Assembly of Micellar Phases in Choline Chloride Eutectics

The common Deep Eutectic Solvent (DES) ‘ethaline’ (1:2 choline chloride:ethylene glycol) was examined here as a basis for the self-assembly of the surfactant dodecyltrimethylammonium bromide (C12TAB). A phase diagram was constructed, showing evidence for a L1 (micellar) phase, confirmed by tensiometry to have a room temperature critical micelle concentration (CMC) of 1.2 wt.%. Small angle neutron scattering (SANS) measurements indicate formation of interacting globular micelles with slightly smaller apparent radii than in water. The apparent mesophase/multiphase region was studied using SWAXS, demonstrating rich mesoscopic lyotropic liquid crystalline phase behaviour, with evidence for lamellar Lα peaks, alongside potential co-crystalline phases. We attempted to tailor the self-assembly by studying binary DES containing longer diols including 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol, and ternary DES where the HBD component was a 1:1 ethylene glycol:diol mixture. However, synchrotron SAXS showed that only ternary ‘propethaline’ mixtures displayed signs of self-assembly and micellization, perhaps due to the reduction in calculated Gordon parameter, which decreases linearly with increasing alkyl chain length. Systematic differences were thus observed in the ability of the solvents to modulate assembly, from globular micelles in ChCl:EG, to weaker assembly in long-tail DES, and complete solubilisation in butaline and pentaline.

Self-assembled Lyotropic Liquid Crystalline Phase Behavior of Monoolein-Capric Acid-Phospholipid Nanoparticulate Systems.

We report here the lyotropic liquid crystalline phase behavior of two lipid nanoparticulate systems containing mixtures of monoolein, capric acid, and saturated diacyl phosphatidylcholines dispersed by the Pluronic F127 block copolymer. Synchrotron small-angle X-ray scattering (SAXS) was used to screen the phase behavior of a library of lipid nanoparticles in a high-throughput manner. It was found that adding capric acid and phosphatidylcholines had opposing effects on the spontaneous membrane curvature of the monoolein lipid layer and hence the internal mesophase of the final nanoparticles. By varying the relative concentration of the three lipid components, we were able to establish a library of nanoparticles with a wide range of mesophases including at least the inverse bicontinuous primitive and double diamond cubic phases, the inverse hexagonal phase, the fluid lamellar phase, and possibly other phases. Furthermore, the in vitro cytotoxicity assay showed that the endogenous phospholipid-containing nanoparticles were less toxic to cultured cell lines compared to monoolein-based counterparts, improving the potential of the nonlamellar lipid nanoparticles for biomedical applications.

Inverse hexagonal and cubic micellar lyotropic liquid crystalline phase behaviour of novel double chain sugar-based amphiphiles

The lyotropic phase behaviour of a library of sugar-based amphiphiles was investigated using high-throughput small-angle X-ray scattering (SAXS). Double unsaturated-chain monosaccharide amphiphiles formed inverse hexagonal and cubic micellar (Fd3m) lyotropic phases under excess water conditions. A galactose-oleyl amphiphile from the library was subsequently formulated into hexosome nanoparticles, which have potential uses as drug delivery vehicles. The nanoparticles were shown to be stable at elevated temperatures and non-cytotoxic up to at least 200μgmL−1.

Liquid crystalline phase behavior of silica nanorods in dimethyl sulfoxide and water.

We report lyotropic smectic liquid crystalline phase behavior of silica nanorods dispersed in binary mixtures of dimethyl sulfoxide (DMSO) and water (H2O). The phase behavior is affected by nanorod size polydispersity and DMSO concentration in the binary solvent. The isotropic to biphasic transition is strongly affected by the relative amount of DMSO in the solvent, but the solvent has little effect on the biphasic to liquid crystal transition above 40/60 DMSO/H2O by volume. At less than 40% DMSO, increasing silica nanorod concentration initially results in the formation of liquid crystalline domains, but further increasing silica concentration results in crystal solvate formation. The morphology of the liquid crystalline phase is strongly affected by the size polydispersity, with lower polydispersity leading to a more uniform structure. As in other lyotropic nanocylinder systems, the microstructure of continuous solid films produced from the dispersions was affected by both the initial microstructure and the applied shear.

Formation of pyrrolidinium fatty acid soap and its lyotropic liquid crystalline phase behavior

The hydrogen bond induced acid–soap like complex has been prepared from a nitrogen-containing heterocyclic compound, pyrrolidine, and the myristic acid (MA). The complex composition and the intermolecular actions between two component molecules have been characterized with techniques of nuclear magnetic resonance (NMR), X-ray diffraction (XRD) and Fourier transformation infra-red (FTIR) spectroscopy. The molar ratio between the soap (pyrrolidium myristate, PM) and the acid (MA) is identified as 1:1. As an important driving force of assembly, the existence of hydrogen bond is further confirmed by a molecular mechanics calculation. It is interesting that such an acid–soap complex (PM–MA) exhibits amphiphilicity and its lyotropic liquid crystal phase in water has been observed over a wide concentration range. A lamellar phase structure is established using the polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS) measurements. The change of lattice spacing indicates a typical one-dimensional swelling scheme for the uptake of water by this lamellar phase. The frequency-independent storage and loss module could be found for these lamellar samples by rheological measurements, reflecting a highly viscoelastic nature. The obtained results should add new insights to better understand the structure and aqueous behavior of long-chain fatty acid–soaps with a large size nitrogen-heterocyclic counterion.

Self‐Assembly of Amphiphilic Block Copolymers in Ternary Solvent Mixtures: Lyotropic Liquid Crystalline Phase Behavior and Structure

AbstractThe effects of the simultaneous addition of two organic solvents (glycerol and ethanol) on the lyotropic liquid crystalline (LLC) phase behavior and structure formed by PEO–PPO–PEO amphiphilic block copolymers in water are examined. Glycerol and ethanol have been selected because of their opposite effect: structure promoting and structure dissolving, respectively. Lattice parameters of Pluronic P105 (EO37PO58EO37) and F127 (EO100PO70EO100) LLC samples in the presence of any type and amount of E+G solvents decrease with increasing volume fraction of the PPO‐rich domains. Lattice parameters for the two block copolymers fall on the same line when normalized with the square root of polymer molecular weight, suggesting weak block segregation.

Nonionic diethanolamide amphiphiles with saturated hydrocarbon chains: Neat crystalline and lyotropic liquid crystalline phase behavior

The solid state and lyotropic phase behavior of a series of nonionic diethanolamide amphiphiles with increasing saturated hydrocarbon chain length (lauroyl, myristoyl, palmitoyl, and stearoyl) has been examined. All four saturated diethanolamide amphiphiles form a crystalline solid with two or three different polymorphic crystalline forms at room temperature. Melting points and associated enthalpies for these four amphiphiles increased with increasing chain length. Approximate partial binary phase diagrams have been constructed for each amphiphile/water system by combining Cross-Polarized Optical Microscopy (POM) and Small-Angle X-ray Scattering (SAXS) results. In the presence of water, all four diethanolamides form an Lα phase, between 10% and 50% water content, and an L2 phase with decreasing hydration and increasing temperature. In addition to the Lα and L2 phases, the shorter chain diethanolamide amphiphiles (lauroyl and myristoyl) also display a normal micellar phase (L1) at higher water contents, occurring to lower temperatures than the Lα phase. By examining the effect of subtle molecular changes on both neat and lyotropic phase behavior, amphiphiles can be designed with properties tailored to a desired application.

Chelating DTPA amphiphiles: ion-tunable self-assembly structures and gadolinium complexes

A series of chelating amphiphiles and their gadolinium (Gd(III)) metal complexes have been synthesized and studied with respect to their neat and lyotropic liquid crystalline phase behavior. These amphiphiles have the ability to form ion-tunable self-assembly nanostructures and their associated Gd(III) complexes have potential as magnetic resonance imaging (MRI) contrast enhancement agents. The amphiphiles are composed of diethylenetriaminepentaacetic acid (DTPA) chelates conjugated to one or two oleyl chain(s) (DTPA-MO and DTPA-BO), or isoprenoid-type chain(s) of phytanyl (DTPA-MP and DTPA-BP). The thermal phase behavior of the neat amphiphiles was examined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and cross polarizing optical microscopy (POM). Self-assembly of neat amphiphiles and their associated Gd complexes, as well as their lyotropic phase behavior in water and sodium acetate solutions of different ionic strengths, were examined by POM and small and wide angle X-ray scattering (SWAXS). All neat amphiphiles exhibited lamellar structures. The non-complexed amphiphiles showed a variety of lyotropic phases depending on the number and nature of the hydrophobic chain in addition to the ionic state of the hydration. Upon hydration with increased Na-acetate concentration and the subtle changes in the effective headgroup size, the interfacial curvature of the amphiphile increased, altering the lyotropic liquid crystalline structures towards higher order mesophases such as the gyroid (Ia3d) bicontinuous cubic phase. The chelation of Gd with the DTPA amphiphiles resulted in lamellar crystalline structures for all the neat amphiphiles. Upon hydration with water, the Gd-complexed mono-conjugates formed micellar or vesicular self-assemblies, whilst the bis-conjugates transformed only partially into lyotropic liquid crystalline mesophases.

Lyotropic liquid crystalline phase behaviour in amphiphile–protic ionic liquid systems

Approximate partial phase diagrams for nine amphiphile-protic ionic liquid (PIL) systems have been determined by synchrotron source small angle X-ray scattering, differential scanning calorimetry and cross polarised optical microscopy. The binary phase diagrams of some common cationic (hexadecyltrimethyl ammonium chloride, CTAC, and hexadecylpyridinium bromide, HDPB) and nonionic (polyoxyethylene (10) oleyl ether, Brij 97, and Pluronic block copolymer, P123) amphiphiles with the PILs, ethylammonium nitrate (EAN), ethanolammonium nitrate (EOAN) and diethanolammonium formate (DEOAF), have been studied. The phase diagrams were constructed for concentrations from 10 wt% to 80 wt% amphiphile, in the temperature range 25 °C to >100 °C. Lyotropic liquid crystalline phases (hexagonal, cubic and lamellar) were formed at high surfactant concentrations (typically >50 wt%), whereas at <40 wt%, only micelles or polydisperse crystals were present. With the exception of Brij 97, the thermal stability of the phases formed by these surfactants persisted to temperatures above 100 °C. The phase behaviour of amphiphile-PIL systems was interpreted by considering the PIL cohesive energy, liquid nanoscale order, polarity and ionicity. For comparison the phase behaviour of the four amphiphiles was also studied in water.

Monodisperse Nonionic Isoprenoid-Type Hexahydrofarnesyl Ethylene Oxide Surfactants: High Throughput Lyotropic Liquid Crystalline Phase Determination

The neat and lyotropic phase behavior of eight new ethylene oxide amphiphiles (EO = 1-8) with a hexahydrofarnesyl chain (3,7,11-trimethyldodecyl) and narrow polydispersity (>98.5% purity) is reported. Below five EO units the behavior of the neat surfactants show only a glass transition, Tg ∼ -90 °C. Above four EO units, crystallization (Tcrys) and crystal-isotropic liquid (Tm) transitions are also observed that increase with degree of ethoxylation of the surfactant headgroup. The lyotropic liquid crystalline phase behavior spans a complex spectrum of surfactant-water interfacial curvatures. Specifically, inverse phases are present below ambient temperatures for EO < 4, with HFarn(EO)2 exhibiting an inverse hexagonal (H(II)) phase stable to dilution. The phase diagram of HFarn(EO)3 displays both the gyroid (Ia3d) and double diamond (Pn3m) inverse bicontinuous cubic phases, with the latter being thermodynamically stable in excess water within the physiological regime. There is a strong preference for planar bilayer structures at intermediate headgroup ethoxylation, with the crossover to normal phases occurring at HFarn(EO)(7-8) which exhibits normal hexagonal (H(I)) and cubic (Q(I)) phases at ambient temperatures. The toxicity of colloidal dispersions of these EO amphiphiles was assayed against normal breast epithelial (HMEpiC) and breast cancer (MCF7) cell lines. The IC50 of the EO amphiphiles was similar in both cell lines with moderate toxicity ranging from ca. <5 to 140 μM in an in vitro cell viability assay. Observations are qualitatively rationalized in terms of the molecular geometry of the surfactant. The physicochemical behavior of the HFarnesyl ethylene oxide amphiphiles is compared to other ethylene oxide surfactants.

Nonionic diethanolamide amphiphiles with unsaturated C18 hydrocarbon chains: thermotropic and lyotropic liquid crystalline phase behavior

The neat and lyotropic liquid crystalline phase behavior of three nonionic diethanolamide amphiphiles with C18 hydrocarbon chains containing one, two or three unsaturated bonds has been examined. This has allowed the effect of degree of unsaturation on the phase behavior of diethanolamide amphiphiles to be investigated. Neat linoleoyl and linolenoyl diethanolamide undergo a transition from a glassy liquid crystal to a liquid crystal at ∼-85 °C, while neat oleoyl diethanolamide undergoes a transition at ∼-60 °C to a liquid crystalline material before re-crystallizing at -34 °C. Oleoyl diethanolamide then undergoes a third transition from a crystalline phase to a smectic liquid crystalline phase at ∼5 °C. In the absence of water, the transition temperature from a smectic liquid crystal to an isotropic liquid decreases with increasing unsaturation. The addition of water results in the formation of a lamellar phase (L(α)) for all three amphiphiles. The lamellar phase is stable under excess water conditions up to temperatures of at least 70 °C. Approximate partial binary amphiphile-water phase diagrams generated for the three unsaturated C18 amphiphiles indicate that the excess water point for each amphiphile occurs at ∼60% (w/w) amphiphile.

Nonionic diethanolamide amphiphiles with isoprenoid-type hydrocarbon chains: thermotropic and lyotropic liquid crystalline phase behaviour

The thermotropic and lyotropic liquid crystalline phase behaviour of a series of diethanolamide amphiphiles with isoprenoid-type hydrocarbon chains (geranoyl, H-farnesoyl, and phytanoyl) has been investigated. When neat, both H-farnesoyl and phytanoyl diethanolamide form a smectic liquid crystalline structure at sub-zero temperatures. In addition, all three diethanolamides exhibit a glass transition temperature at around -73 °C. Geranoyl diethanolamide forms a lamellar crystalline phase with a lattice parameter of 17.4 Å following long term storage accompanied by the loss of the glass transition. In the presence of water, H-farnesoyl and phytanoyl diethanolamide form lyotropic liquid crystalline phases, whilst geranoyl diethanolamide forms an L(2) phase. H-farnesoyl diethanolamide forms a fluid lamellar phase (L(α)) at room temperature and up to ∼ 40 °C. Phytanoyl diethanolamide displays a rich mesomorphism forming the inverse diamond (Q(II)(D)) and gyroid (Q(II)(G)) bicontinuous cubic phases in addition to an L(α) phase.

Nanostructured Nonionic Thymidine Nucleolipid Self-Assembly Materials

Three nucleoside lipids have been synthesized: 3'-oleoylthymidine, 3',5'-dioleoylthymidine, and 3'-phytanoylthymidine. Differential scanning calorimetry and X-ray diffraction have been employed to characterize the physical properties of these neat lipids. Polarizing optical microscopy, small-angle X-ray scattering, and cryo-transmission electron microscopy techniques have been used to investigate the phase behavior in aqueous systems. Both oleoyl-based nucleoside lipids adopted a lamellar crystalline phase in the neat form at room temperature, and the phytanoyl derivative exhibited a fluid isotropic phase. Under excess water conditions, the presence of one branched (phytanoyl) or one unsaturated (oleoyl) chain promoted the formation of a liquid-crystalline lamellar phase at physiological temperatures. In contrast, the 3',5'-dioleoylthymidine derivative is nonswelling and does not exhibit lyotropic liquid-crystalline phase behavior. The nucleolipids' propensity for DNA-type binding and recognition has been evaluated by using a monolayer system to measure surface pressure-area isotherms in a Langmuir trough and indicates that the nucleoside base is available for nonspecific hydrogen bonding in the monolayer liquid expanded state for the single-chain nucleolipids but not for the dual-chain amphiphile.

The influence of dipalmitoyl phosphatidylserine on phase behaviour of and cellular response to lyotropic liquid crystalline dispersions

Lyotropic liquid crystalline nanoparticles (cubosomes) have the potential to act as amphiphilic scaffolds for the presentation of lipids and subsequent application in, for example, bioseparations and therapeutic delivery. In this work we have formulated lyotropic liquid crystalline systems based on the synthetic amphiphile 1,2,3-trihydroxy-3,7,11,15-tetramethylhexadecane (phytantriol) and containing the lipid dipalmitoyl phosphatidylserine (DPPS). We have prepared a range of DPPS-containing phytantriol cubosome formulations and characterized them using Small Angle X-ray Scattering and Cryo-transmission electron microscopy. These techniques show that increased DPPS content induces marked changes in lyotropic liquid crystalline phase behaviour, characterized by changes in crystallographic dimensions and increases in vesicle content. Furthermore, in vitro cell culture studies indicate that these changes correlate with lipid/surfactant cellular uptake and cytotoxicity. A model cell membrane based on a surface supported phospholipid bilayer was used to gain insights into cubosome–bilayer interactions using Quartz Crystal Microgravimetry. The data show that mass uptake at the supported bilayer increased with DPPS content. We propose that the cytotoxicity of the DPPS-containing dispersions results from changes in lipid/surfactant phase behaviour and the preferential attachment and fusion of vesicles at the cell membrane.

Charge Reversal of the Rodlike Colloidal fd Virus through Surface Chemical Modification

There is increasing interest in the use of viruses as model systems for fundamental research and as templates for nanomaterials. In this work, the rodlike fd virus was subjected to chemical modifications targeting different solvent-exposed functional groups in order to tune its surface properties, especially reversing the surface charge from negative to positive. The carboxyl groups of fd were coupled with different kinds of organic amines by carbodiimide chemistry, resulting in modified viruses that are positively charged over a wide range of pH. Care was taken to minimize intervirus cross linking, which often occurs because of such modifications. The surface amino groups were also grafted with poly(ethylene glycol) (PEG) end-functionalized with an active succinimidyl ester in order to introduce a steric stabilization effect. By combining charge reversal with PEG grafting, a reversible attraction between positively and negatively charged PEG-grafted fd viruses could be realized, which was tuned by the ionic strength of the solution. In addition, a charge-reversed fd virus forms only a pure nematic phase in contrast to the cholesteric phase of the wild type. These modified viruses might be used as model systems in soft condensed matter physics, for example, in the study of polyelectrolyte complexes or lyotropic liquid-crystalline phase behavior.

Ordered Nanostructured Amphiphile Self-Assembly Materials from Endogenous Nonionic Unsaturated Monoethanolamide Lipids in Water

The self-assembly, solid state and lyotropic liquid crystalline phase behavior of a series of endogenous n-acylethanolamides (NAEs) with differing degrees of unsaturation, viz., oleoyl monoethanolamide, linoleoyl monoethanolamide, and linolenoyl monoethanolamide, have been examined. The studied molecules are known to possess inherent biological function. Both the monoethanolamide headgroup and the unsaturated hydrophobe are found to be important in dictating the self-assembly behavior of these molecules. In addition, all three molecules form lyotropic liquid crystalline phases in water, including the inverse bicontinuous cubic diamond (Q(II)(D)) and gyroid (Q(II)(G)) phases. The ability of the NAE's to form inverse cubic phases and to be dispersed into ordered nanostructured colloidal particles, cubosomes, in excess water, combined with their endogenous nature and natural medicinal properties, makes this new class of soft mesoporous amphiphile self-assembly materials suitable candidates for investigation in a variety of advanced multifunctional applications, including encapsulation and controlled release of therapeutic agents and incorporation of medical imaging agents.

Predictive synthesis of ordered mesoporous silica with maltoside and cationic surfactants based on aqueous lyotropic phase behavior

Self-assembled nonionic alkyl glycoside surfactants are of interest for creating functional adsorption and catalytic sites at the surface of mesoporous sol-gel-derived materials, but they typically impart poor long-range order when they are used as pore templates. Improved order and control over the functional site density can be achieved by mixing the alkyl polyglycoside surfactant with a cationic surfactant. Here, we investigate the rarely reported lyotropic liquid crystalline (LLC) phase behavior of aqueous solutions of a nonionic disaccharide surfactant, n-dodecyl-beta-d-maltoside (C(12)G(2)/DM), and cetyltrimethylammonium bromide (C(16)TAB) by low-angle powder X-ray diffraction (XRD) and polarized optical microscopy (POM). An approximate ternary phase diagram of the C(16)TAB-C(12)G(2)-water system is developed at 50 degrees C, which includes 2-D hexagonal (P6mm symmetry), bicontinuous cubic (Ia3 d symmetry), lamellar, and rectangular (cmm symmetry) LLC phases. By replacing the volume of water in the phase diagram with an equivalent volume of silica, ordered mesoporous materials are prepared by a nanocasting technique with variable C(12)G(2)/C(16)TAB ratios. For large regions of the phase diagram, this approach is predictive. However, silica materials synthesized with comparatively high C(12)G(2)/C(16)TAB ratios are only poorly ordered in a way that does not correspond to their lyotropic liquid crystalline phase behavior. Also, in contrast with our previous study of mixed C(16)TAB/n-octyl-b-d-glucopyranoside templating [37] the boundary between hexagonal and bicontinuous cubic materials is shifted towards higher surfactant content than in the aqueous LLC system.

Soft ordered mesoporous materials from nonionic isoprenoid-type monoethanolamide amphiphiles self-assembled in water

The thermal and lyotropic liquid crystalline phase behaviour of a series of amide and monoethanolamide amphiphiles with isoprenoid-type hydrocarbon chains has been investigated. The amphiphilic nature of these molecules combined with their ability to form nanostructured self-assemblies makes them ideal candidates as delivery vehicles of bioactive molecules. For both families of molecules, increased branching in the hydrophobic chain, associated with increasing chain length, results in a decreased melting point. The melting points of the amides are significantly higher than their monoethanolamide homologues. Interestingly, both hexahydrofarnesoyl (H-farnesoyl) and phytanoyl monoethanolamide exhibit a glass transition temperature at around −72 °C to −74 °C. H-Farnesoyl and phytanoyl monoethanolamide form lyotropic liquid crystalline phases in water, whilst H-farnesoyl and phytanoyl amide form a spontaneous emulsion at the amphiphile–water interface. In particular, at room temperature H-farnesoyl and phytanoyl monoethanolamide form the Schwarz diamond (QIID) and the Schoen gyroid (QIIG) bicontinuous cubic phases which are retained down to temperatures as low as 1 °C. Furthermore, phytanoyl monoethanolamide displays a QIID, QIIG and inverse hexagonal phase (HII) at physiological temperature. Both phytanoyl and H-farnesoyl monoethanolamide form mesoporous cubic phases at room temperature that are easily dispersed into cubosomes. The robust nature of the nanostructured phase formation of these two monoethanolamides over a wide range of temperatures makes them ideal candidates for a variety of applications.

Impurities in Commercial Phytantriol Significantly Alter Its Lyotropic Liquid-Crystalline Phase Behavior

The lyotropic liquid-crystalline phase behavior of phytantriol is receiving increasing interest in the literature as a result of similarities with glyceryl monooleate, despite its very different molecular structure. Some differences in the phase-transition temperature for the bicontinuous cubic to reverse hexagonal phase have been reported in the literature. In this study, we have investigated the influence that the commercial source and hence the purity has on the lyotropic phase behavior of phytantriol. Suppression of the phase-transition temperatures (by up to 15 degrees C for the bicontinuous cubic to reverse hexagonal phase transition) is apparent with lower-purity phytantriol. In addition, the composition boundaries were also found to depend significantly on the source and purity of phytantriol, with the bicontinuous cubic phase + excess water boundary occurring at a water content above that reported previously (i.e., >5% higher). Both the temperature and compositional changes in phase boundaries have significant implications on the use of these materials and highlight the impact that subtle levels of impurities can play in the phase behavior of these types of materials.

Nanostructured self-assembly materials formed by non-ionic urea amphiphiles

Urea is an extremely versatile molecule that has been widely used for many years in a diverse range of applications. The physicochemical properties of urea have been well studied with respect to the role of hydrogen bonding in biological and chemical systems. Urea-based amphiphiles, in contrast, have received little attention with respect to physicochemical properties. Studies reported in the last few years have demonstrated that specific urea amphiphiles display interesting lyotropic liquid crystalline phase behaviour. These nanostructured self-assembly phases are potential candidates for a number of novel applications. In this work, we review the physicochemical properties of non-ionic urea-based amphiphiles, including those of the solid state, insoluble monolayers residing at the air-water interface, Langmuir-Blodgett films deposited on solid substrates and lyotropic liquid crystalline phases. In addition, we present new data that extends the characterisation of the solid state and lyotropic properties of isoprenoid branched urea surfactants.