Synthesis of new Biginelli polycondensates: renewable materials with tunable high glass transition temperatures

The Biginelli reaction was applied as a simple one‐pot multicomponent polycondensation approach to efficiently synthesize a set of 15 new and fully renewable poly(3,4‐dihydropyrimidin‐2(1H)‐one)s. One of six bis‐acetoacetates or three bis‐acetoacetamides, terephthalic aldehyde and (methyl‐)urea were used as renewable starting materials in various combinations, hence significantly expanding the known set of monomers as well as polymer structures. The bis‐acetoacetates and bis‐acetoacetamides with different spacer lengths were synthesized in yields of up to 99% in a one‐step process. Thermal analysis of the obtained set of polymers revealed high glass transition temperatures (T$_{g}$) ranging from 160 to 308 °C. The T$_{g}$ was tunable in small steps of 10 °C by simple variation of bis‐acetoacetate or bis‐acetoacetamide monomers as well as the choice of (methyl‐)urea. The poly(3,4‐dihydropyrimidin‐2(1H)‐one)s showed good thermal stability with T$_{d5%}$ values well above the respective high T$_{g}$ values.