We determine the osmotic pressure of microgel suspensions using membrane osmometry and dialysis, for microgels with different softnesses. Our measurements reveal that the osmotic pressure of solutions of both ionic and neutral microgels is determined by the free ions that leave the microgel periphery to maximize their entropy and not by the translational degrees of freedom of the microgels themselves. Furthermore, up to a given concentration it is energetically favorable for the microgels to maintain a constant volume without appreciable deswelling. The concentration where deswelling starts weakly depends on the crosslinker concentration, which affects the microgel dimension; we explain this by considering the dependence of the osmotic pressure and the microgel bulk modulus on the particle size.

中文翻译：

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由带电微凝胶组成的悬浮液的渗透压

我们使用膜渗透压法和渗析法测定具有不同柔软度的微凝胶的微凝胶悬浮液的渗透压。我们的测量表明，离子型和中性微凝胶溶液的渗透压取决于离开微凝胶外围以使其熵最大化的游离离子，而不是由微凝胶自身的平移自由度决定。此外，在给定浓度下，微凝胶在能量上有利于保持恒定的体积而没有明显的溶胀。消胀开始的浓度取决于交联剂的浓度，这会影响微凝胶的尺寸。我们通过考虑渗透压和微凝胶体积模量对粒度的依赖性来解释这一点。