Solvent-annealing-induced microphase separation in polyether polyurethane: a small-angle X-ray scattering study

Area of Science:

• Polymer Science
• Materials Science
• Surface Chemistry

Background:

• Polyurethane (PU) microphase separation is crucial for material properties.
• Thermal annealing can refine PU microstructure but requires high temperatures.
• Solvent vapor annealing presents a lower-temperature alternative for PU modification.

Purpose of the Study:

• To investigate the effects of solvent vapor annealing on polyurethane microphase separation.
• To compare the influence of different solvent vapors (MEK, acetone, toluene) on PU microstructure.
• To evaluate the thermal stability of solvent-annealed PU compared to conventionally annealed samples.

Main Methods:

• Small-angle X-ray scattering (SAXS) to analyze microphase separation structure.
• In situ variable-temperature SAXS to assess thermal stability.
• Analysis using a polydisperse hard-sphere model.

Main Results:

• Solvent annealing increased the degree of phase separation in PU.
• The effectiveness of solvents followed the order: MEK > acetone > toluene.
• Solvent-annealed PU exhibited enhanced thermal stability compared to quenched samples.
• Solvent annealing induced higher phase separation without significant domain growth.

Conclusions:

• Solvent vapor annealing is an effective method for refining PU microstructure at lower temperatures.
• MEK is a particularly effective solvent for enhancing PU phase separation and thermal stability.
• These findings offer a pathway for optimizing PU processing for advanced applications sensitive to heat.