The colloid chemistry of organoclays

The delamination and dispersion of organoclays in hydrophobic polymeric systems involves a complex balancing of surface chemical interactions between the basal and edge surfaces of the organoclay and the polymer matrix, The proper design of surfactant coatings used to make organoclays remains a critical technical/economic obstacle to the commercial production of engineered plastics for high volume applications. At a minimum, modification of the clay surface is needed to satisfy wetting requirements, but the literature is replete with examples showing that surface wetting alone is insufficient to ensure exfoliation. This difficulty has led to the use of oligomeric compatibilizers but this approach is both expensive and inefficient. The thermodynamic factors which effect organoclay swelling and dispersion will be discussed and a basis for the design of self-dispersing organoclays will be presented.