Nonisocyanate Polyurethane Segmented Copolymers from Bis-Carbonylimidazolides

Area of Science:

• Polymer Chemistry
• Materials Science

Background:

• Traditional polyurethanes (PUs) synthesis relies on hazardous isocyanates.
• Nonisocyanate polyurethanes (NIPUs) offer a safer alternative but require efficient synthetic strategies.
• Developing high molecular weight segmented NIPUs with controlled properties is crucial for advanced applications.

Purpose of the Study:

• To demonstrate the feasibility of using Bis-carbonylimidazolide (BCI) functionalization for synthesizing high molecular weight segmented NIPUs.
• To investigate the effect of hard segment concentration on the phase behavior and morphology of BCI-derived NIPUs.
• To compare the nanophase separation in BCI-derived NIPUs with conventional isocyanate-based PUs.

Main Methods:

• Melt phase polymerization utilizing ED-2003 Jeffamine, 4,4'-methylenebis(cyclohexylamine), and a BCI monomer.
• Dynamic Mechanical Analysis (DMA) and Differential Scanning Calorimetry (DSC) for thermal transition analysis.
• Atomic Force Microscopy (AFM) and Small-Angle X-ray Scattering (SAXS) for morphological and nanophase separation characterization.

Main Results:

• Segmented polyether NIPUs with 40-80 wt.% hard segments were successfully synthesized.
• DMA and DSC revealed distinct thermal transitions (Tg, Tm) corresponding to soft, hard, and mixed phases.
• AFM and SAXS confirmed nanophase separation, with nanoscale rod-like hard segment assemblies observed.
• Phase separation in BCI-derived NIPUs was found to be comparable to isocyanate-derived analogues.

Conclusions:

• BCI functionalization is an effective nonisocyanate pathway for producing high molecular weight segmented NIPUs.
• The synthesized NIPUs exhibit controlled nanophase separation, crucial for tailoring material properties.
• This approach offers a promising route for developing safer, high-performance polyurethane materials.