Abstract
In this study novel, fully and partially bio-based polyamides containing spiroacetal moieties in the backbone derived from bio-glycerol and bio-ethanol were prepared and characterized. The renewable diamine employed to obtain a series of polyamides was synthesized by means of thiol-ene click chemistry and therefore contains flexible thioether as well as rigid spiroacetal moieties. Two different chemical pathways for the polymerization were investigated and evaluated. The polymerization of polyamide salts proved to be the most promising method and therefore salt polymerization was applied in the synthesis of polyamides with aliphatic and aromatic dicarboxylic acids. Subsequently, the structure of the polymers was confirmed by Maldi-ToF analysis and additionally thermal and mechanical properties were investigated revealing Tg’s between 24 and 80°C and ductile materials with moduli between 1.0 and 1.5GPa. Both semicrystalline and amorphous polyamides were thermally stable and therefore suitable for thermal processing. In the end, degradation studies were performed on the acetal containing polyamides which showed that the polymers were stable at pH 3 and higher.
Highlights
Spiropolymers are a subclass of ladder polymers in which adjacent rings share a common atom [1,2]
A new spiroacetal containing diamine monomer was synthesized via thiol-ene chemistry. 3,9-Divinyl-2,4,8,10-tetraoxaspiro[5.5] undecane (1) was reacted photochemically with cysteamine hydrochloride and Dimethoxy-2-phenylacetophenone 99% (DMPA) as initiator
Two approaches towards the synthesis were investigated and the most promising results were obtained via melt polymerization of the polyamide salts
Summary
Spiropolymers are a subclass of ladder polymers in which adjacent rings share a common atom [1,2]. This class of polymers is known for its high rigidity and high thermal stability. In the early work on spiropolymers, it was shown that the regular structure of these polymers resulted in highly crystalline materials with limited solubility in organic solvents [3,4,5,6,7,8,9]. There have been two strategies to enhance the solubility of rigid polymers; enriching the polymer backbone with solubilising groups (e.g. alkyl groups) [10,11] or introducing irregularities which diminish linearity of the polymer [12]. In order to completely understand what these strategies mean, it is necessary to learn how spiropolymers are made
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