The aim of this PhD research was to synthesize poly(cycloacetal/ketals) from renewable resources. With these poly(cycloacetal/ketals), we originally aimed at transparent materials with high glass transition temperatures (Tg > 100 °C) and degradation temperatures (Td > 300 °C). Moreover, the materials were mechanically tested in order to estimate the chance of possible implementation in high-end applications. At the moment, biobased polymers are mostly applied in packaging applications because of limited thermal and mechanical properties. Economically, biobased polymers should seek to compete in higher value and higher performance application areas like thermoplastic elastomers and engineering plastics. Thus, one of the clear challenges in biobased polymers is the search for rigid polymer structures with resulting good thermal and mechanical properties. A possible solution for the above-mentioned challenges in biobased polymers are poly(cycloacetal/ketals) as these polymers are rigid.1 Moreover, by the introduction of multiple aliphatic cycles in the polymer chain, amorphous and therefore transparent polymers should be realized.
Fully and partially renewable poly(cycloacetal/ketals) can be synthesized via three different pathways (Scheme 10.1). When tetraols and dicarbonyls are combined in a direct fashion, poly(cycloacetal/ketals) can be obtained as such. A second pathway consists of the synthesis of cyclic acetal/ketal containing bifunctional monomers from renewable feedstock, followed by a polycondensation or polyaddition reaction. On the one hand, linear poly(cycloacetal/ketals) can be synthesized in this way, while on the other hand polymers, which can be functionalized in a post-polymerization reaction, could be obtained. Lastly, poly(cycloacetal/ketals) were synthesized via a polytransacetalization/ketalization reaction.