Rigid biobased polycarbonates with good processability based on a spirocyclic diol derived from citric acid

Research output: Contribution to journalArticle

Abstract

Introducing biobased polymers from renewable sources for use as high-performance thermoplastics with high demands on mechanical rigidity, transparency, thermal stability, as well as good processability, is a significant challenge. In the present work we have designed and prepared a rigid biobased bis-spirocylic diol by di-cycloketalization of a bicyclic diketone (cis-bicyclo[3.3.0]octane-3,7-dione, obtained from citric acid) using trimethylolpropane. This spiro-diol monomer has two reactive primary hydroxyl groups and the synthesis from inexpensive biobased starting materials is straightforward and readily upscalable, involving no chromatographic purification. In order to explore the usefulness of the new monomer, it was employed in melt polycondensations with diphenylcarbonate at up to 280 °C to form rigid fully amorphous polycarbonates (PCs). Molecular weights (MWs) up to Mn = 28 kg mol-1 were achieved, and thermal and dynamic mechanical measurements showed glass transitions up to Tg = 100 °C, with no thermal decomposition until Td ~ 350 °C. Solvent cast films had excellent mechanical flexibility and strength, as well as a high transparency with only slight coloration. Results by dynamic melt rheology implied that the high-MW PCs had a good processability at 170 °C, with a stable shear modulus over time, but started to degrade via chain scission reactions when the temperature approached 200 °C. In conclusion, the present work demonstrates the straightforward preparation of the citric acid-based spiro-diol, and indicates that it is an efficient building block for the preparation of rigid biobased PCs and other condensation polymers.

Details

Authors
Organisations
External organisations
  • University of Jyväskylä
  • University of Tartu
  • National Institute of Chemical Physics and Biophysics
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Polymer Technologies
  • Polymer Chemistry
  • Organic Chemistry
Original languageEnglish
Pages (from-to)3940-3951
Number of pages12
JournalGreen Chemistry
Volume22
Issue number12
Publication statusPublished - 2020
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

Submitted: 09 Mar 2020 Accepted: 27 May 2020 First published: 28 May 2020