Structurally Ordered NIPUs via Catalyst-Free Synthesis with Hard Segments Based on Erythritol and a Long-Chain...

Area of Science:

• Polymer Chemistry
• Materials Science
• Organic Synthesis

Background:

• Polyurethanes (PUs) are versatile polymers with widespread applications.
• Traditional PU synthesis involves hazardous isocyanates, driving research into safer alternatives.
• Isocyanate-free polyurethanes (NIPUs) offer a sustainable and environmentally friendly approach.

Purpose of the Study:

• To synthesize and characterize novel linear isocyanate-free polyurethanes (NIPUs).
• To investigate the influence of different polyether soft segments (PEG, PPO, PEG/PPO) and chain extender concentration on NIPU properties.
• To elucidate the structure-property relationships in these NIPUs.

Main Methods:

• Synthesis of NIPUs via aminolysis of erythritol dicarbonate (EDC) with diamino-polyethers and 1,12-diaminododecane (DADD).
• Chemical structure analysis using Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (¹H NMR).
• Structural and thermal characterization using Wide-Angle X-ray Diffraction (WAXD), Small-Angle X-ray Scattering (SAXS), Differential Scanning Calorimetry (DSC), and Dynamic Mechanical Analysis (DMA).

Main Results:

• FTIR and ¹H NMR confirmed the successful synthesis of NIPUs.
• WAXD revealed ordered crystalline domains from DADD segments and preserved crystallinity in PEG/PEG-PPO soft segments.
• SAXS indicated long-range order in hard segments and weak phase separation.
• DSC and DMA showed distinct thermal behaviors (melting, glass transition) influenced by the polyether type and NIPU composition.

Conclusions:

• The type of polyether soft segment critically impacts the thermal and microphase morphology of the synthesized NIPUs.
• The concentration of the DADD chain extender affects the ordering and interplanar spacing within the hard segments.
• These findings contribute to the development of tunable, high-performance NIPUs for diverse applications.