4(%3)3 - Ecole nationale supérieure de chimie de Montpellier

In order to be dispersed into a material, the hydrogel must be prepared as microparticles. Toachieve this, inverse suspension technique was utilized which allowed to obtain hydrogel particles havinga broad size distribution but average diameter lesser than 1 µm. When the swelling curves are comparedwith that of bulk hydrogel, the micro hydrogel demonstrated a very high rate of swelling, reaching 70 %water uptake within few minutes as compared to bulk hydrogel which took more almost 200 minutes togain the same amount of water (Figure – 5.2).The above findings points that the as the size of hydrogel particles is reduced, theiroverall swelling characteristics is amplified several folds. In order to further reduce the size of thehydrgels, inverse miniemulsion technique was used, which further reduced average particle size to 300nm (Figure – 5.3). However, further decrease in the size could not be reached in spite of varying differentparameters like surfactant amount, ultrasonication time, temperature, etc. Additionally, the size of theparticles gradually increased over time leading to eventual coagualation. However as expected, thereduced sized particles showed even faster swelling than suspension prepared particles (Figure – 5.4).Figure – 5.3: Size distribution of nano hydrogel prepared using miniemulsion technique.127