SCREENING NONIONIC SURFACTANTS FOR PORE-ARCHITECTURE DESIGN IN PHYSICALLY FOAMED β-TRICALCIUM PHOSPHATE CERAMICS USING RAPID FREEZING AND FREEZE-DRYING

Porous -tricalcium phosphate (-TCP) ceramics were fabricated by physical foaming, followed by rapid freezing in liquid nitrogen and freeze-drying to preserve the transient bubble architecture prior to sintering.Eight nonionic surfactants with different molecular architectures (DECAGLYN 1-L, BT-7, BT-9, BT-12, TMGCO-7, TRIGLYN 1-KF, TL-10, and GO-440V) were screened under a fixed processing protocol with a constant volumetric surfactant dose (4.0 mL).All specimens retained spherical macro-sized pores after sintering, demonstrating high fidelity of foam-to-pore transfer.The mean pore diameter was tunable from 60 22 m to 117 45 m depending on the surfactant, while open porosity remained high (72.6-84.8%)and closed porosity was negligible (0.1-0.85%).Compressive strength followed the expected porosity-strength trade-off; specimens prepared with TMGCO-7, TRIGLYN 1-KF, and GO-440V exceeded 2 MPa.No monotonic correlation was found between pore diameter and HLB, suggesting that HLB alone was not sufficient to predict the resulting pore size in this multicomponent slurry.It was found that, particularly when using linear nonionic surfactants, surface tension influences foamability and foam stability, thereby enabling control of the pore diameter in the resulting porous material.