COMPATIBILITY BETWEEN SOLID PARTICLES AND A LAMELLAR PHASE - A CRUCIAL ROLE OF THE MEMBRANE INTERACTIONS

From previous studies, we know that Helfrich-stabilized smectic phases can incorporate solid particles of typical size 10 nm between their m embranes; the incorporation of magnetic particles yields a ''ferrosmec tic'' phase. We present here a study of the compatibility between such solid particles and a lamellar phase versus the interactions between membranes. The type of stabilizing forces, from purely electrostatic t o purely entropic, is varied via the concentration of salt (NaCl) in a swollen lamellar phase. The experimental results reported in this pap er show that the Helfrich phases can incorporate particles within thei r lamellar matrix, whereas particles are excluded from the electrostat ic phases. A semiquantitative interpretation based on considerations a bout the interactions between particles and membranes is given.