The synthesis of new amphiphilic alpha-phenyl-N-tert-butylnitrone (PBN) derivatives bearing two hydrocarbon tails with 17 carbon atoms (compound A(17)) or 11 carbon atoms (compound B-11) is reported. The amphiphilic and morphological properties of these potential antioxidant compounds were investigated at the air-water interface. The analyses were conducted using Langmuir film balance and Brewster angle microscopy. As it is possible to obtain pressure-area (pi-A) isotherms from pure A(17) and B-11, this means that they can form stable monomolecular films at the air-water interface. Monolayers of pure PBN derivatives exhibited different interface behavior. Indeed, along with compression, the B-11 monolayer showed only a liquid-expanded phase and the A(17) monolayer showed a liquid-condensed phase. Brewster angle microscopy showed the presence of condensed domains within the A(17) monolayer. The lateral interactions of these compounds with the polyunsaturated phospholipids, 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DLoPC) and 1,2-dilinoleoyl-sn-glycero-3-phosphoethanolamine (DLoPE), were evaluated by analysis of 7 A isotherms and excess free energy of mixing. Each PBN derivative was miscible with DLoPC or DLoPE and formed nonideal mixed monolayers at the air-water interface. Only the A(17) molecules exhibited favorable interactions at high surface pressures (over 20 mN/m) with both DLoPC and DLoPE, however. Under these conditions, A(17) should be a better antioxidant than B-11.