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Valorisation des polysaccharides marins : élaboration de nanocomposites et synthèse de graphène dopé

Abstract : The chemistry have to develop new research axis both respectful of the nature and joining an eco-compatible global approach. In this context, use natural polysaccharides allow to synthesize innovative materials for applications in many industries fields. The aim of this work is add value to the marine polysaccharide such as chitosan and κ-carrageenan through two research axis.The first axis is consecrated to increase the mechanical, electrical and color sorption properties by introduce graphene filler in biopolymer matrice. An easy and original protocol allowed scattering very effectively graphene in chitosan to design films and aerogels nanocomposites. The analyse of nanocomposite films show an improvement of stiffness, tensile strength and elongation break at the same time with low content of graphene. However, the percolation threshold was not reach to bring electrics properties in films. The study of chitosan/graphene aerogel reveals that graphene allows an increase of color agent adsorbing power such as eosin Y compared with aerogels chitosan.The second axis concerns the introduction of heteroatom in graphene carbon structure. To obtain nitrogen-doped graphene and sulphur-doped graphene, it requires the synthesis of marine polysaccharide aerogel, and their pyrolysis under controlled conditions. The carbon aerogels are exfoliated in water with sonification. Amine groups in chitosan allowed through this process a nitrogen-doped graphene with high yield and nitrogen rate of 5 %. Moreover, it was possible to modulate nitrogen rate with ionic liquid such as [EMIm][dca]. So the nitrogen atom rate increases from 5% to 11%. In similar way, sulfate group in κ-carrageenan gives sulphur-doped graphene with sulphur rate of 1,5%.
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Submitted on : Tuesday, December 12, 2017 - 12:21:35 AM
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  • HAL Id : tel-01661461, version 1

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Honore Tsotetzo. Valorisation des polysaccharides marins : élaboration de nanocomposites et synthèse de graphène dopé. Chimie organique. Normandie Université, 2017. Français. ⟨NNT : 2017NORMC216⟩. ⟨tel-01661461⟩

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