Molecular Design of Aromatic Polythionoesters

Area of Science:

• Polymer Science and Engineering
• Computational Chemistry
• Materials Science

Background:

• Developing novel polymers with tailored properties is crucial for advanced material applications.
• Understanding structure-property relationships is key to designing new polymeric materials.
• Computational methods offer a powerful approach for predicting polymer characteristics before synthesis.

Purpose of the Study:

• To explore the molecular design of new polymers, specifically focusing on poly(ethylene thionoterephthalate) (PET[S2]) and related compounds.
• To predict the structures and properties of not-yet-synthesized polymers using theoretical calculations.
• To investigate the potential of polythionoesters for practical applications through molecular design.

Main Methods:

• Ab initio molecular orbital (MO) theory and rotational isomeric state (RIS) scheme were employed to calculate configurational properties.
• Periodic density functional theory (DFT) was used for crystal structure optimization and mechanical property evaluation.
• Nuclear Magnetic Resonance (NMR) experiments confirmed MO calculations.

Main Results:

• Configurational properties of PET[S2] were predicted and compared with analogous polyesters and polythioesters.
• Young's moduli for PET[S2] crystal were calculated along different axes, showing significant differences from PET.
• Properties of randomly thiono-substituted PET (PET[S O1-z]) can be tuned by adjusting sulfidity (z).

Conclusions:

• Theoretical computations successfully predicted the structures and properties of novel polymers.
• Polythionoesters offer tunable properties, opening possibilities for new material development.
• This study demonstrates the successful achievement of theoretical molecular design for new polymers.