The Influence of the Hydroxyl Type on Crosslinking Process in Cyclodextrin Based Polyurethane Networks

Area of Science:

• Polymer Chemistry
• Materials Science
• Biomaterials

Background:

• Polyurethane systems are crucial for various applications.
• Controlling network structure and properties is key for material design.
• Cyclodextrins offer unique structures for modifying polymer networks.

Purpose of the Study:

• To investigate the influence of hydroxyl group type (primary vs. secondary) on isocyanate-polyurethane reactions.
• To analyze the impact of hydroxyl group nature on the structure and properties of resulting polyurethane hydrogels.
• To evaluate the role of native cyclodextrin (CD) and its oligolactide derivative (CDLA) in polyurethane network formation.

Main Methods:

• Synthesis of polyurethane hydrogels using β-cyclodextrin (CD) and its oligolactide derivative (CDLA) with isophorone diisocyanate polyethylene glycol-based prepolymers (PEG-(NCO)₂).
• Rheological investigation to analyze system reactivity and the influence of hydroxyl group type.
• Characterization of material properties including swelling behavior, thermal properties, and hydrolytic degradation.

Main Results:

• The nature of hydroxyl groups significantly influences polyurethane hydrogel formation and properties.
• Primary hydroxyl groups in CDLA led to more compact networks with consistent water uptake.
• Predominance of secondary hydroxyl groups, coupled with oligolactide spacers, allowed for fine-tuning of water swelling properties.

Conclusions:

• The type and ratio of hydroxyl groups in cyclodextrins are critical factors in designing polyurethane hydrogels.
• The incorporation of oligolactide chains provides degradability and influences network characteristics.
• This study demonstrates a method for tailoring polyurethane hydrogel properties by controlling the cyclodextrin structure.