Biomedical subjects

Elise Lorenceau

Publications and source records attributed to Elise Lorenceau.

5 recordsLinked to original sources

PubMed2005

Generation of polymerosomes from double-emulsions.

Diblock copolymers are known to spontaneously organize into polymer vesicles. Typically, this is achieved through the techniques of film rehydration or electroformation. We present a new method for generating polymer vesicles from double emulsions. We generate precision water-in-oil-in-water double emulsions from the breakup of concentric fluid streams; the hydrophobic fluid is a volatile mixture of organic solvent that contains dissolved diblock copolymers. We collect the double emulsions and slowly evaporate the organic solvent, which ultimately directs the self-assembly of the dissolved diblock copolymers into vesicular structures. Independent control over all three fluid streams enables precision assembly of polymer vesicles and provides for highly efficient encapsulation of active ingredients within the polymerosomes. We also use double emulsions with several internal drops to form new polymerosome structures.

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PubMed2004

Air entrainment by a viscous jet plunging into a bath.

A liquid jet plunging into a container of liquid often entrains a thin film of air with it, producing bubbles. This bubble production is detrimental to many industrial processes, such as filling a container with a molten glass or polymer, or in coating processes. Conversely, in making a foam, one uses this effect; hence it is important to control the rate of bubble production. Here, we measure the amount of air entrained by a viscous jet over a wide range of parameters and explain the phenomenon theoretically. Simple scaling arguments are shown to predict entrainment rates over 4 orders of magnitude in the dimensionless jet speed.

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PubMed2004

Capturing drops with a thin fiber.

We study experimentally the dynamics of drops impacting horizontal fibers and characterize the ability of these objects to capture the drops. We first show that a drop larger than a critical radius cannot be trapped by a fiber whatever its velocity. We determine this critical size as a function of the fiber radius. Then we show that for smaller drops, different situations can occur: at a low impact velocity, the drop is entirely captured by the fiber, whereas some liquid is ejected when arriving faster. We quantify the threshold velocity of capture.

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PubMed2003

Drops impacting a sieve.

We study experimentally the impact of liquid drops against thin plates pierced with small holes. When the drop is larger than the hole, different situations can occur: (i) at a small velocity, the drop is entirely captured by the plate; (ii) above a threshold speed, some liquid is ejected below the surface. We characterize this critical speed and these two different situations, focusing on the forces able to slow down the drop. We also quantify the amount of liquid ejected out of the hole.

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PubMed2003

Fracture of a viscous liquid.

When a viscous liquid hits a pool of liquid of the same nature, the impact region is hollowed by the shock. Its bottom becomes extremely sharp if increasing the impact velocity, and we report that the curvature at that place increases exponentially with the flow velocity, in agreement with a theory by Jeong and Moffatt. Such a law defines a characteristic velocity for the collapse of the tip, which explains both the cusplike shape of this region, and the instability of the cusp if increasing (slightly) the impact velocity. Then, a film of the upper phase is entrained inside the pool. We characterize the critical velocity of entrainment of this phase and compare our results with recent predictions by Eggers.

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