Controlling the Porous Structure of Cellulose Acetate Derived by Fatty Acid Molecules in Breath-Figure Templating

Porous cellulose acetate films were fabricated via the breath figure array method using fatty acid-modified derivatives and PEG, and the effects of fatty acid chain length and substitution level on their morphology, rheology, and surface properties were systematically investigated. Spectroscopic analyses (FT-IR and ¹H NMR) confirmed the successful esterification of CA and the incorporation of decanoyl and lauroyl chains, while thermogravimetric analysis (TGA) indicated reduced thermal stability due to fatty acid modification. Rheological results showed that fatty acid chain length and concentration modulate viscoelastic relaxation, energy dissipation, and chain dynamics in the polymer solutions. Also, contact angle analysis demonstrated that longer alkyl chains enhanced the hydrophobicity of CA films. SEM observations showed that both the chain length and substitution level strongly influenced pore size and uniformity; the average pore diameter increased from approximately 0.6 μm for CAL1 to 1.2 μm for CAL3 films with higher fatty acid substitution. Notably, higher substitution of long-chain fatty acids led to heterogeneous and coalesced pore structures. These results offer valuable insights for controlling the pore architecture of CA-based porous films through molecular design and breath figure templating toward sustainable and functional material applications.