| Summary: | In the wish to replace oil-based chemicals and materials with such based on biodegradable and renewable resources, this work has been performed. In a biorefinary concept, waste birch bark from paper pulp mills and timber production has been evaluated as a potential source for polyesters. In the present thesis investigations are made on synthesis of epoxy-functionalized polyesters from the birch outer bark aliphatic suberin ω-hydroxy fatty acid, cis-9,10-epoxy-18-hydroxyoctadecanoic acid. Studies of accessibility and reactivity of cellulose have been performed as a first step to enable covalent attachment or grafting of the epoxy-functionalized polyesters to cellulose. Candida antarctica lipase B (Novozym 435) is reported to be an efficient catalyst for condensation polymerization of cis-9,10-epoxy-18-hydroxyoctadecanoic acid to form poly(9,10-epoxy-18-hydroxyoctadecanoic acid) with high molecular weight (Mw). Performed in toluene in the presence of molecular sieves a Mw of 20000 (reaction time 68 h, Mw/Mn 2.2) was obtained. Performed in bulk without any drying agent a Mw of 15000 was obtained at a much shorter reaction time (reaction time 3h, Mw/Mn 2.2). Further the same lipase has been used for succesful co-polymerizations of cis-9,10-epoxy-18-hydroxyoctadecanoic acid with lactones. By combining condensation and ring-opening polymerization, epoxy-functionalized linear polyesters and cyclic oligomers have been synthesized. For example, co-polymerization of cis-9,10-epoxy-18-hydroxy-octadecanoic acid and ε-caprolactone performed in toluene in the presence of molecular sieves gave mainly cyclic oligomers, especially at shorter reaction times. Co-polymerization performed in bulk gave linear polyesters with a Mw of 35000 (reaction time 24 h, Mw/Mn 6), irrespective molecular sieves were added or not. The epoxy-functionalized polyesters could be used for surface modification of pulp fibres and cellulose fibrils, which further can be used for production of new valuable composite materials with improved features. ...
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