Lamellar and inverse micellar structures of skin lipids: Effect of templating

Unveiling the Interstitial Pressure Between Growing Ice Crystals During Ice-Templating Using a Lipid Lamellar Probe

What is pressure generated by ice crystals during ice-templating? This work addresses this crucial question by estimating the pressure exerted by oriented ice columns on a supramolecular probe composed of a lipid lamellar hydrogel during directional freezing. This process, also known as freeze-casting, has emerged as a unique processing technique for a broad class of organic, inorganic, soft and biological materials. Nonetheless, the pressure exerted during and after crystallization between two ice columns is not known, despite its importance with respect to the fragility of the frozen materia…

Soft lamellar solid foams from ice-templating of self-assembled lipid hydrogels: organization drives the mechanical properties

Ice-templating, also referred to as freeze-casting, is a process exploiting unidirectional crystallization of ice to structure macroporous materials from colloidal solutions. Commonly applied to inorganic and polymeric materials, we employ it here to cast soft self-assembled matter into spongy solid foams. Use of ice-templating to cast soft matter is generally confined to polymers. In the case of polymeric hydrogels, cross-linking ensures a good stability towards the harsh conditions (fast cooling at temperatures as low as-80{\textdegree}C) employed during ice-templating. However, freeze-casti…

Lamellar to micellar phases and beyond: when tactic active systems admit free-energy functionals

We consider microscopic models of active particles whose velocities, rotational diffusivities, and tumbling rates depend on the gradient of a local field, which is either externally imposed or depends on all particle positions. Despite the fundamental differences between active and passive dynamics at the microscopic scale, we show that a large class of such tactic active systems admit fluctuating hydrodynamics equivalent to those of interacting Brownian colloids in equilibrium. We exploit this mapping to show how taxis may lead to the lamellar and micellar phases observed for soft repulsive c…

Kinetic pathways of multi-phase surfactant systems

The relaxation following a temperature quench of two-phase (lamellar and sponge phase) and three-phase (lamellar, sponge and micellar phase) samples, has been studied in an SDS/octanol/brine system. In the three-phase case we have observed samples that are initially mainly sponge phase with lamellar and micellar phase on the top and bottom respectively. Upon decreasing temperature most of the volume of the sponge phase is replaced by lamellar phase. During the equilibriation we have observed three regimes of behaviour within the sponge phase: (i) disruption in the sponge texture, then (ii) aft…

脂质隐式溶剂极简模型中的相变：头尾尺寸比的作用

Phase Transitions In An Implicit Solvent Minimal Model Of Lipids: Role Of Head-Tail Size Ratio

本文通过Monte Carlo模拟研究极简三珠粗粒化隐式溶剂脂质模型，发现头尾尺寸比决定了脂质冷却时自发转变为层状相或胶束相。

Swelling and Dissolution of onion phases: The effect of temperature

Contact experiments have been performed between an onion lamellar phase and brine, in the SDS/octanol/brine system. Using video microscopy we have studied the nonequilibrium behaviour of the swelling and dissolution process of onions. Experiments at T=20degC and 30degC showed that temperature has a strong effect on their bahaviour. At low temperature onions are observed to diffuse away from the onion phase and only swell slightly. However by increasing the temperature we induce the formation of the sponge phase at the onion/brine interface. Onions that initailly swell then dissolve into sponge…