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

Abstract

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 (Tg) ranging from 160 to 308 °C. The Tg 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 Td5% values well above the respective high Tg values. © 2020 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.