Study of polymer-clay composite particles Preparation, properties and potential applications

A range of polymer-clay composite particles have been prepared and the ability of the dispersed particles to absorb an important contaminant (PO 3- 4 ) from water has been investigated. The clay particles were Wyoming bentonite and the polymer was poly(diallyldimethylammonium chloride), poly(DADMAC). Two types of poly(DADMAC) with differing molecular weights (1·5×10 5 and 4·5×10 5 g mol - 1 ) were used. The adsorption of the polymer (a polycation) onto the clay particles (to form composite particles) was studied using adsorption isotherm measurements and electrophoretic mobility measurements. The data showed that the structure of the polymer layer was affected by the polymer molecular weight. The higher molecular weight polymer appears to have a lower proportion of adsorbed chains with a 'train' conformation as opposed to 'loops'. (Polymer trains are sequences of consecutive monomer units that are adsorbed flat to the surface; whereas loops are sequences of consecutive monomer units that are adsorbed to the surface only at the sequence ends.) Preliminary absorption measurements demonstrated that the composite particles were able to absorb PO 3- 4 from aqueous solution. The data reveal that composite particles prepared with monolayer polymer coverage should have the capacity to absorb up to 14 wt-% PO 3- 4 . This provides scope for application of the composite particles for water purification.