Computational development and validation of a representative MDI-BDO-based polyurethane hard segment model

Area of Science:

• Polymer Science and Engineering
• Computational Chemistry
• Materials Science

Background:

• Segmented polyurethanes possess unique physicochemical properties driven by their hard segment domains.
• MDI-BDO hard segments exhibit unexplained characteristics like isomerism, electronic structure, and reactivity.
• Understanding these hard segments is crucial for advancing polyurethane applications.

Purpose of the Study:

• To develop and validate a computational model system for MDI-BDO hard segments.
• To investigate the structural and chemical properties of these hard segments.
• To provide a foundation for future research into polyurethane hard segments.

Main Methods:

• Development and validation of a computational model system.
• Computational experiments to analyze geometry, isomerism, and electronic structure.
• Calculation of IR spectra and Fukui indices to assess isomer differentiation and reactivity.

Main Results:

• The trans isomer of the urethane bond is more stable than the cis isomer.
• High rotational energy barriers prevent thermal transformation from trans to cis isomers.
• Calculated IR spectra and Fukui indices reveal distinct properties of cis and trans isomers.
• Evidence of intermolecular/intramolecular pi-stacking and hydrogen bonding between hard segments.

Conclusions:

• A validated computational model for MDI-BDO hard segments has been successfully developed.
• The model provides critical insights into isomerism, reactivity, and intermolecular interactions.
• This work opens new avenues for studying the structural and chemical features of polyurethane hard segments.