End-Terminated Poly(urethane-urea) Hybrid Approach toward Nanoporous/Microfilament Morphology

Area of Science:

• Polymer Science
• Materials Chemistry
• Supramolecular Chemistry

Background:

• Soft-segment-free polymers like polyurethane (P-UT) and polyurea (P-UR) are crucial in materials science.
• Understanding the role of hydrogen bonding in polymer properties is essential for designing advanced materials.
• Heteroatomic hydrogen bonding influences the morphology and properties of polymers.

Purpose of the Study:

• To investigate the impact of heteroatomic hydrogen bonding on the properties of soft-segment-free polymers.
• To synthesize and characterize polyurethane (P-UT), polyurea (P-UR), and their hybrid (P-UT-UR).
• To explore the relationship between chemical structure, hydrogen bonding, and material morphology.

Main Methods:

• Synthesis of P-UT, P-UR, and P-UT-UR polymers.
• Characterization using Atomic Force Microscopy (AFM) to analyze surface morphology.
• Analysis of hydrogen bonding interactions (homoatomic vs. heteroatomic) and their effect on polymer structure and transparency.

Main Results:

• P-UT exhibited a spherulitic structure, while P-UR showed a fibrillar structure.
• The P-UT-UR hybrid displayed a nanospherulitic structure with high interconnectivity and negative surface skewness.
• Increased heteroatomic H-bonding (-N-H···O-H) in P-UT-UR led to decreased transparency.
• A pentafluorophenyl end-functional hybrid (PFI-P-UT-UR) formed filaments due to self-aggregation and end folding.

Conclusions:

• Altering the chemical structure of urethane-urea hybrids influences the type of hydrogen bonding (homoatomic vs. heteroatomic).
• Nano-ordered structures can be achieved in polyurethanes and their hybrids by subtle chemical modifications.
• The study demonstrates control over polymer morphology through tailored hydrogen bonding.