Micellar formation and correlation in the cavity of porous silica glass

Small-angle neutron scattering (SANS) is used to study the scattering length density correlations in a dry porous silica glass (Vycor) and in the glass filled with anionic and cationic surfactant molecules dispersed in water. SANS intensity distributions from empty pores of the glass can be satisfactorily analyzed using a standard late stage spinodal decomposition model in which the porous structure is described by a superposition of random density waves. This model, however, agrees with experiment only if one allows for a suitable distribution of wave numbers for the density waves. Micellar formation is observed in Vycor filled with surfactant solutions. We discuss the interpretation of the intermicellar correlations, measured by SANS, within the pores of the Vycor glass.