ИСТИНА

PNIPAM microgels can simultaneously swell both in water and 1-octanol. These two liquids are immiscible with each other, Figure 1. Addition of a small fraction of 1-octanol into aqueous micro- or macrogel solutions leads to complete exchange of the microgel filling: water is expelled by 1-octanol. Computer simulations reveal a physical reason for the exchange. Localization of the small oil fraction within the microgel is accompanied by formation of a thin polymer layer at the oil-water interface which reduces its surface tension. This effect is not restricted by 1-octanol and water mixture. Other organic solvents, which are immiscible with water, can be used. Their uptake by the microgel becomes possible if the microgel contains at least a small fraction of hydrophobic groups. Computer simulations are performed for hydrophobically modified water-soluble microgels