Surface area and pore structure properties of urethane-based copolymers containing β-cyclodextrin

Area of Science:

• Polymer Chemistry
• Materials Science
• Nanotechnology

Background:

• Polyurethane (PU) copolymers are versatile materials.
• Macromolecular porogens like β-cyclodextrin can create nanoporous structures.
• Controlling pore structure is crucial for material applications.

Purpose of the Study:

• To investigate the surface area and pore structure of PU copolymers.
• To evaluate the impact of different diisocyanates and β-cyclodextrin content.
• To compare surface area measurements using nitrogen adsorption and a dye adsorption method.

Main Methods:

• Synthesis of aliphatic- and aromatic-based PU copolymers using various diisocyanates and β-cyclodextrin.
• Characterization of surface area and pore structure via nitrogen adsorption (BET).
• Determination of surface area using a p-nitrophenol (PNP) dye adsorption method in aqueous solution.

Main Results:

• Nitrogen adsorption showed low BET surface areas (∼10^1 m²/g) and mesopore diameters (16-29 nm).
• Dye adsorption yielded significantly higher surface areas (1.5-6.2×10^2 m²/g).
• Surface area variations correlated with diisocyanate type and mole ratio.

Conclusions:

• The choice of diisocyanate crosslinker and its mole ratio significantly influences copolymer surface area.
• Discrepancies between nitrogen adsorption and dye adsorption methods are attributed to solvent interactions and framework swelling.
• Understanding these differences is key for accurate characterization of nanoporous copolymers.