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

聚电解质凝胶分子水平的体积相变研究

基本信息

批准号：
11305066
负责人：
KOKUFUTA Etsuo
金额：
$ 21.31万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2002
项目状态：
已结题

项目摘要

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

本研究的目的是通过实验证明聚电解质凝胶中的体积相变可以通过我们假设的平衡模型来解释（F. Ilmain, T. Tanaka, E. Kokufuta, Nature, 349, 400-401 (1991)）。在该模型中，通过假设连接到网络的官能团之间的排斥力和吸引力之间的平衡来解释这种转变，这些官能团是由四种分子间力的组合产生的：离子力、疏水力、范德华力和氢键。当排斥力（通常是静电性质）克服吸引力（例如氢键或疏水相互作用）时，凝胶体积在某些情况下应不连续增加，而在其他情况下则连续增加。触发转变的变量影响这些分子间力，从而影响吸引力和排斥力的平衡状态。因此，我们关注电荷分布对聚电解质凝胶膨胀的影响。我们的凝胶样品范围从常见的块状凝胶到纳米尺寸的颗粒。凝胶相内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、聚离子的物理捕获；和固定化酶反应。很明显，电荷不均匀性在离子凝胶的溶胀中起着重要作用，当聚合物结合的负电荷或正电荷之间的排斥力克服作为吸引力的氢键和/或疏水相互作用时，就会发生离子凝胶的溶胀。这无法用基于移动离子产生的净渗透压的弗洛里模型来解释。从本研究中获得的结论已应用于构建“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。此外，根据目前的结论，还设计并合成了直径在数十至数百纳米范围内的聚电解质纳米凝胶颗粒。较少的