Structure and properties of triolein-based polyurethane networks

Area of Science:

• Polymer Chemistry
• Materials Science
• Biomaterials

Background:

• Polyurethanes from vegetable oils are complex, hindering structure-property correlation.
• Vegetable oil-based polyurethanes often have heterogeneous compositions.
• Establishing clear structure-property relationships is crucial for optimizing these materials.

Purpose of the Study:

• To create model polyurethane networks for benchmark structure-property analysis.
• To investigate the impact of dangling chains on polyurethane network properties.
• To correlate polyol structure with final polyurethane network characteristics.

Main Methods:

• Synthesis of model polyurethane networks using triolein and 4,4'-diphenylmethane diisocyanate (MDI).
• Preparation of a second network from metathesis-modified triolein to remove dangling chains.
• Analysis of network structure via swelling, mechanical testing, and elasticity theories.
• Detailed characterization of polyol precursors.

Main Results:

• Achieved cross-linking densities close to theoretical values for both networks.
• The triolein-based model network demonstrated properties of hard rubbers: modulus (~6 MPa), tensile strength (8.7 MPa), and elongation at break (136%).
• Glass transition temperatures were 25°C for the triolein network and 31.5°C for the metathesis analogue.

Conclusions:

• Model polyurethane networks from triolein provide a reliable basis for studying structure-property relationships.
• The presence and nature of dangling chains significantly influence network properties.
• These bio-based polyurethanes show promise as alternatives to conventional synthetic rubbers.