Nonergodicity transitions in colloidal suspensions with attractive interactions

Colloidal gel and glass transitions are investigated using the idealized mo de coupling theory(MCT) for model systems characterized by short-range attr active interactions. Results are presented for adhesive hard sphere and har d core attractive Yukawa systems. According to MCT, the former system shows a critical glass transition concentration that increases significantly wit h introduction of a weak attraction. For the latter attractive Yukawa syste m, MCT predicts low temperature nonergodic states that extend to the critic al and subcritical region. Several features of the MCT nonergodicity transi tion in this system agree qualitatively with experimental observations on t he colloidal gel transition, suggesting that the gel transition is caused b y a low temperature extension of the glass transition. The range of the att raction is shown to govern the way the glass transition line traverses the phase diagram relative to the critical point, analogous to findings for the fluid-solid freezing transition. [S1063-651X(99)05905-X].