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Gewählte Doctoral Thesis:

Martin Siller (2015): OXIDATIVE MODIFIZIERUNG CELLULOSISCHER FASERN.
Doctoral Thesis - Abteilung für Chemie nachwachsender Rohstoffe, BOKU-Universität für Bodenkultur, pp 149. UB BOKU obvsg

Data Source: ZID Abstracts
Abstract:
Improvements of manmade cellulosic fibres like viscose (rayon) fibres are of large importance in the search for new applications for these biobased materials. Fibres with altered haptic, mechanical, or chemical properties, such as changed hydrophobicity or biocidic activity, are of particular interest. For that purpose, rayon was modified by oxidation to create aldehyde groups that can serve as anchor groups for the attachment of functional molecules in a subsequent step. Modifications should be done under mild reaction conditions that avoid the degradation of cellulose and maintain its mechanical fibre properties. Therefore, size exclusion chromatography (SEC) was used to monitor influence on molar mass distribution (MMD). SEC with rayon is often limited due to solubility problems in the solvent system N,N-dimethylacetamide/lithium chloride (DMAc/LiCl). A new activation protocol with dimethylsulfoxide has been successfully developed to solve this problem. It was shown that periodate oxidation allows for the rapid creation of aldehyde groups without adverse effects on MMD and mechanical fibre properties, while online integration of this modification into the fibre production process is realistic. Influences of oxidation on cellulose polymorphs have been examined in detail. Solid-state nuclear magnetic resonance proved to be a useful tool to obtain structural information about oxidized fibre samples but not for crystallinity determination. Hence, different infrared methods were successfully used for the latter purpose. Distinct subsequent reactions were tested as well. The reducing ability of aldehyde groups was used for the reduction of silver ions and its deposition on the fibres. Other possible applications include covalent attachment of functional molecules mainly through a reaction with N-nucleophiles such as hydrazines or amines. Attachment via hydrazine linkages was demonstrated by a reaction with dansyl hydrazine that served as a fluorescent model compound.

Betreuer: Potthast Antje
1. Berater: Rosenau Thomas
2. Berater:

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