Study on Volume-Phase Transition in Polyelectrolyte Gels at the Molecular Level

这项研究的目的是实验证明聚电解质凝胶中的体积-相变可以用我们的假设平衡模型(F.Ilmain，T.T.Tanaka，E.Kokufuta，Nature，349,400-401(1991))解释。在这个模型中，转变是通过假设连接到网络上的官能团之间的排斥和吸引之间的平衡来解释的，这些官能团是由四种分子间力的组合产生的：离子、疏水、范德华和氢键。当排斥力(通常是静电)克服了氢键或疏水相互作用等吸引力时，凝胶体积在某些情况下应该不连续地增加，在另一些情况下应该连续增加。触发这种转变的变量会影响这些分子间力，从而影响吸引力和排斥力的平衡状态。因此，我们重点研究了电荷分布对聚电解质凝胶溶胀的影响。我们的凝胶样品…更多的LES从通常的块状凝胶到形状的纳米颗粒。凝胶相中的电荷分布是通过不同的方式产生的：离子表面活性剂的结合，多离子的物理包裹，以及固定化酶反应。很明显，电荷不均匀在离子凝胶的膨胀中起着重要作用，当聚合物结合的负电荷或正电荷之间的排斥力克服了氢键和/或疏水相互作用作为吸引力时，离子凝胶就会发生膨胀。这不能用弗洛里基于移动离子产生的净渗透压的模型来解释。本研究的结论已被应用于构建〓生物化学-机械系统〓，该系统能够通过凝胶的膨胀和收缩将固定化酶反应产生的生化能转化为机械功。在此基础上，设计合成了直径在几十到几百纳米范围内的聚电解质纳米凝胶粒子。较少

The purpose of this study is to experimentally demonstrate that the volume-phase transition in polyelectrolyte gels can be explained by our hypothesizing balance model (F. Ilmain, T. Tanaka, E. Kokufuta, Nature, 349, 400-401 (1991)). In this model, the transition is accounted for by hypothesizing a balance between the repulsion and attraction among functional groups attached to the network which arise from a combination of four interrmolecular forces : ionic, hydrophobic, van der Waals and hydrogen bonding. When a repulsive force, usually electrostatic in nature, overcomes an attractive force such as hydrogen bonding or hydrophobic interaction, the gel volume should increase discontinuously in some cases and continuously in others. The variables that trigger the transition influence these intermolecular forces and thereby the balanced state of the attractive and repulsive forces. We thus focused on the effect of charge distributions on the swelling of polyelectrolyte gels. Our gel samp … More les ranged from the usual bulk gel to nano-sized particles in shape. The charge distribution within the gel phase was created by different ways : binding of ionic surfactants, physical entrapment of polyions ; and immobilized enzyme reaction. It has became apparent that an charge inhomogeneity plays an important role in the swelling of ionic gels which takes place when the repulsion among the polymer-bound negative or positive charges overcomes hydrogen bonding and/or hydrophobic interaction as the attractive force. This is not able to explain in terms of Flory's model based on net osmotic pressure arising from mobile ions. The conclusions obtained from the present study have been applied in the construction of 〓biochemo-mechanical systems〓 capable of converting biochemical energy created as a result of an immobilized enzyme reaction into mechanical work through the swelling and shrinking of the gel. In addition, polyelectrolyte nanogel particles with diameters in the range of tens to hundreds of nanometers have been designed and synthesized on the basis of the present conclusions. Less