Synthèse de polysaccharides amphiphiles à partir de dextrane et application à la stabilisation d'émulsions directes et inverses

Abstract : A new family of amphiphilic dextran derivatives was obtained by reaction of 1,2-epoxydodecane on dextran in basic medium. Two reaction procedures were examined. The first one was carried out in biphasic medium but produced only low degrees of hydrophobic substitution. Epoxide homopolymerization was indeed predominant. On the contrary, the reaction in a homogeneous organic medium allowed the synthesis of dextran derivatives with substitution degrees as high as 164 %. Oil-in-water emulsions were prepared by sonication in the presence of different hydrosoluble derivatives ( 25 %). Oil volume fraction (hexadecane or nujol) ranged from 10 % to 50 %. The size of the emulsion droplets increased with the oil volume fraction but did not depend on the substitution degree of modified dextran between 10 and 25 %. These emulsions behave like a gel which strengthened with the oil volume fraction. Water-in-oil emulsions (water in chloroform) were obtained by sonication in the presence of organosoluble derivatives ( = 164 %). They were stable over at least two months. Furthermore, dynamic emulsification process under shear flow was investigated for oil-in-water emulsions (hexadecane in water). The volume fraction of oil ranged from 10 % to 60 % and various shear rates were applied. Simultaneous in situ measurements of viscosity of emulsions and droplet size were performed. The characteristic time of emulsification depended on shear rate and viscosity ratio but was independent of the oil volume. For the newtonian system, final shear stress and final droplet size depended on the applied shear rate while they were invariant in the non newtonian system
Document type :
Theses
Complete list of metadatas

Cited literature [271 references]  Display  Hide  Download

https://hal.univ-lorraine.fr/tel-01748877
Contributor : Thèses Ul <>
Submitted on : Thursday, March 29, 2018 - 11:51:53 AM
Last modification on : Tuesday, July 24, 2018 - 4:43:00 PM
Long-term archiving on : Friday, September 14, 2018 - 7:59:34 AM

File

2011_COVIS_R.pdf
Files produced by the author(s)

Identifiers

  • HAL Id : tel-01748877, version 1

Citation

Rudy Covis. Synthèse de polysaccharides amphiphiles à partir de dextrane et application à la stabilisation d'émulsions directes et inverses. Autre. Institut National Polytechnique de Lorraine, 2011. Français. ⟨NNT : 2011INPL006N⟩. ⟨tel-01748877⟩

Share

Metrics

Record views

37

Files downloads

650