Ott, Marcus (2017)
Tailor-made cellulose graft copolymers by controlled radical polymerization techniques.
Technische Universität Darmstadt
Dissertation, Erstveröffentlichung
Kurzbeschreibung (Abstract)
Cellulose is a versatile, abundant and biocompatible polymer. New biobased polymers with tailor-made properties can be obtained by chemical modification with small organic molecules. Furthermore, well defined cellulose based graft copolymers can be generated with controlled radical polymerisation techniques of organo soluble cellulose derivatives. In this area atom transfer radical polymerisation (ATRP) and reversible addition fragmentation chain transfer (RAFT) are predominant. In case of a grafting-from approach the cellulose is transformed into a macroinitiator prior to the polymerization. These cellulose-based macroinitiators are often only soluble in certain polar solvents and show some degree of insolubility. Aside from that, often only a fraction of the initiator groups are chemically available due to steric hinderance or limited solvatisation which may lead to low grafting yields. In this work a strategy is persued, where well organo soluble cellulose RAFT-macroinitiators can be synthezised by transformation of remaining hydroxy groups of the cellulose backbone into solubilizing groups. The performance of these macroinitiators during polymerization is investigated by RAFT polymerisation with styrene as monomer. The graft copolymers are analyzed by NMR as well as by SEC. The living nature of the polymerisation can be shown by the increase of the molar mass with proceeding monomer conversion. Linear polystyrene with Ð<1.5 is generated during the polymerisation due to the use of sacrifitial, free RAFT agent. With fractional precipitation the cellulose graft copolymers can be isolated from the crude product. Polymergrafts can be cleaved-off the cellulose backbone under strong alkaline conditions. SEC analysis proves excellent control over the polymer grafting from cellulose, since the polymer grafts and the free homopolymer show the same molecular weight distribution over the whole polymerization process. Furthermore, in this work cellulose based graft copolymers bearing two different types of polymer grafts are successfully synthesized by combination of ATRP with RAFT technique, or by combination of a grafting-to approach using poly(ethylene gylcol) and and a grafting-from approach using ATRP technique, alternatively .
Typ des Eintrags: | Dissertation | ||||
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Erschienen: | 2017 | ||||
Autor(en): | Ott, Marcus | ||||
Art des Eintrags: | Erstveröffentlichung | ||||
Titel: | Tailor-made cellulose graft copolymers by controlled radical polymerization techniques | ||||
Sprache: | Englisch | ||||
Referenten: | Biesalski, Prof. Dr. Markus ; Andrieu-Brunsen, Prof. Dr. Annette | ||||
Publikationsjahr: | 2017 | ||||
Ort: | Darmstadt | ||||
Datum der mündlichen Prüfung: | 19 Dezember 2016 | ||||
URL / URN: | http://tuprints.ulb.tu-darmstadt.de/5933 | ||||
Kurzbeschreibung (Abstract): | Cellulose is a versatile, abundant and biocompatible polymer. New biobased polymers with tailor-made properties can be obtained by chemical modification with small organic molecules. Furthermore, well defined cellulose based graft copolymers can be generated with controlled radical polymerisation techniques of organo soluble cellulose derivatives. In this area atom transfer radical polymerisation (ATRP) and reversible addition fragmentation chain transfer (RAFT) are predominant. In case of a grafting-from approach the cellulose is transformed into a macroinitiator prior to the polymerization. These cellulose-based macroinitiators are often only soluble in certain polar solvents and show some degree of insolubility. Aside from that, often only a fraction of the initiator groups are chemically available due to steric hinderance or limited solvatisation which may lead to low grafting yields. In this work a strategy is persued, where well organo soluble cellulose RAFT-macroinitiators can be synthezised by transformation of remaining hydroxy groups of the cellulose backbone into solubilizing groups. The performance of these macroinitiators during polymerization is investigated by RAFT polymerisation with styrene as monomer. The graft copolymers are analyzed by NMR as well as by SEC. The living nature of the polymerisation can be shown by the increase of the molar mass with proceeding monomer conversion. Linear polystyrene with Ð<1.5 is generated during the polymerisation due to the use of sacrifitial, free RAFT agent. With fractional precipitation the cellulose graft copolymers can be isolated from the crude product. Polymergrafts can be cleaved-off the cellulose backbone under strong alkaline conditions. SEC analysis proves excellent control over the polymer grafting from cellulose, since the polymer grafts and the free homopolymer show the same molecular weight distribution over the whole polymerization process. Furthermore, in this work cellulose based graft copolymers bearing two different types of polymer grafts are successfully synthesized by combination of ATRP with RAFT technique, or by combination of a grafting-to approach using poly(ethylene gylcol) and and a grafting-from approach using ATRP technique, alternatively . |
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Alternatives oder übersetztes Abstract: |
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URN: | urn:nbn:de:tuda-tuprints-59338 | ||||
Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 500 Naturwissenschaften und Mathematik > 540 Chemie | ||||
Fachbereich(e)/-gebiet(e): | 07 Fachbereich Chemie > Ernst-Berl-Institut > Fachgebiet Makromolekulare Chemie 07 Fachbereich Chemie |
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Hinterlegungsdatum: | 22 Jan 2017 20:55 | ||||
Letzte Änderung: | 22 Jan 2017 20:55 | ||||
PPN: | |||||
Referenten: | Biesalski, Prof. Dr. Markus ; Andrieu-Brunsen, Prof. Dr. Annette | ||||
Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: | 19 Dezember 2016 | ||||
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