The size of particle aggregates produced by flocculation with PNIPAM, as a function of temperature

This work investigates the effect of temperature on the size of alumina aggregates formed by flocculation with temperature responsive Poly(N-Isopropylacrylamide)(PNIPAM). The results are discussed in terms of the effects of temperature on particle collision, particle adhesion and aggregate breakage. It was found that the size of alumina aggregates increases with increasing solution temperature. Particle/particle collision and aggregate breakage are largely unaffected by increasing solution temperature and therefore could not account for the change in aggregate size. The dominant factor in aggregate growth with increasing temperature was found to be the increase in the force of adhesion between alumina particles. The appearance of the adhesive force is triggered by the increase in temperature above the lower critical solution temperature of PNIPAM.

Graphical abstractThe size of alumina aggregates formed in the presence of temperature responsive Poly(N-Isopropylacrylamide) is primarily affected by the force of adhesion between alumina particles, which increases with increasing temperature.Figure optionsDownload full-size imageDownload high-quality image (64 K)Download as PowerPoint slideResearch highlights► Size of aggregates formed with PINPAM increases with increasing temperature. ► Aggregate size increase is attributed to an increase in the adhesive force. ► The adhesive force is caused by increase in temperature above the LCST of PNIPAM. ► The rate of particle collision and aggregate breakage is constant with temperature.