The Role of the Ionic Specificity on the Nanogel Aggregation

GONZALEZ, VERÓNICA D.G.; BASTOS GONZÁLEZ, D.; CALLEJAS FERNÁNDEZ, J.; TIRADO MIRANDA, M.

San Sebastián

Encuentro; 5th Iberian Meeting on Colloids and Interfaces (RICI5); 2013

Nanogels are cross-linked polymeric chains dispersed in water that are able to swell or deflate in response to changes in external triggers such as pH, temperature and biomolecules. This behaviour makes them useful for applications in fields such as drug delivery, regenerative medicine, nanopatterning and chemical biosensing. In this work, we focused on thermosensitive nanogels composed of poly(N-isopropyl acrilamide). This system has a lower critical solution temperature, around 32 ºC in aqueous solutions. Thus, the nanogel swells at low temperatures and collapses at high ones. We studied the aggregation kinetics and morphological properties of nanogels as function of temperature, ionic specificity and electrolyte concentration. Depending on the nature of the ion employed, we found a variety of behaviour ranging from no aggregation to DLCA regime. However, the ionic specificity revealed an equilibrium distribution of clusters-nanogels for determined experimental conditions. This equilibrium distribution was able to keep up to 100 minutes and then, the aggregation process continued spontaneously.