Polyesters Based on Malic Acid – Pendant Hydroxyl Groups as Distinctive Feature for Versatile Modifications

Beschreibung

As crude oil is a limited resource, the development of bio-based polymers nowadays gains increasing interest. Malic acid, as bio-based raw material for example, shows great potential for the redevelopment of bio-based and additionally biocompatible as well as (bio)degradable polymers. The present thesis deals with the synthesis of hydroxyl functional, aliphatic polyesters based on malic acid, the analyses of their properties and promising possibilities for their functionalisation and application. Therefore different hydroxyl functional polyesters based on aliphatic diols on the one hand and malic acid as well as related dicarboxylic acids on the other hand were synthesised via polycondensation using scandium triflate as catalyst. The resulting linear hydroxyl functional polyesters were intensively characterised with special regard to their thermal properties. The well-defined hydroxyl functional polyesters were afterwards functionalised by different procedures. Firstly, LLA was grafted by ring opening polymerisation onto the OH-groups of the polyesters. Using Zn(oct)2 as catalyst, transesterification reactions were suppressed. Thus, for the first time polyester-graft-polyesters were obtained using a grafting from technique. Secondly, a grafting procedure with MMA demonstrates the weakness of the malate unit if not handled under optimised conditions. As third functionalisation the preparation of thermosensitive shape-memory materials (SMM) is presented in this thesis. Here, the hydroxyl functional polyesters were cross-linked with hexamethylene diisocyanate giving thermosensitve SMMs. The sharp switching temperature is easily adjusted by the use of tailored hydroxyl functional polyesters. A lot of hydroxyl functional polymers were developed during the last decade in our group. An overview on those, where the hydroxyl groups are generated along the polymer chain by avoiding protective group chemistry completes this thesis.

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Christian Joachim Hahn

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hydroxyl groups malic acid polycondensation polyester ring opening polymerisation shape memory effect

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