Temperature-triggered capture of dispersed particles using a laponite-poly(NIPAM) temperature-responsive surface

In this study a new method is investigated that enables a conductive surface to be modified so as to capture dispersed particles when the temperature is increased. Poly(NIPAM) (NIPAM is N-isopropylacrylamide) was grafted from electrodeposited Laponite RD particles using surface-initiated atom transfer radical polymerization (ATRP) to give a temperature-responsive surface. This was used to capture dispersed polystyrene particles. In the first part of the study the conditions used to electrodeposit Laponite onto a carbon foam electrode were determined. The ability of the temperature-responsive surface to capture dispersed polystyrene particles was investigated between 20 and 50C. Temperature-triggered particle capture was reversible or irreversible depending on the conditions used during ATRP. A high surface concentration of poly(NIPAM) on the particle electrodes is believed to increase the extent of polystyrene particle capture and also reversibility. A theoretical analysis in terms of interaction energy-distance curves is presented for the capture behavior. It is concluded that the temperature-responsive surface has both electrostatic and steric contributions to the total interaction energy. The steric component (which originates from poly(NIPAM)) is temperature-dependent and provides the basis for temperature-triggered particle capture.