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Development of Polymer Molecule Manipulation by Means of Flow Field and Its Application to Polymer Dynamics

流场操控聚合物分子的研究进展及其在聚合物动力学中的应用

基本信息

批准号：
08455447
负责人：
SASAKI Naoki
金额：
$ 2.37万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

It has been well established that flexible polymers manifest a conformational transition in a well-defined elongational flow field : a coil stretch transition (CST). We investigated the CST of polymers under various conditions and tried to manipulate a polymer molecule by stretching in the elongational flow field. The elongational flow field was generated by a four-roller mill system where the response of the polymer molecule to the elongational field was monitored by a flow birefringence.(1) Coil-globule transition of a T4 phage DNA molecule was investigated by means of the elongational flow field birefringence method in conjunction with a fluorescent micrograph method. A random coil is expected to be elongated by the flow field and generate birefringence signal while a globular molecule is considered not deformed and there should be no birefringence. The expectation was empirically revealed to be the case. A birefringent globular molecule was discovered by a comparison of the birefringence data with that of fluorescent micrograph. Such a birefringent globular molecule was found to be in the shape of an ellipsoid with an optical anisotropy by the stopped flow experiment using the four-roller mill system.(2) A polyelectrolyte changes its flexibility with the salt concentration in the solution. The flexibility change of the polyelectrolyte was quantified by the CST observation in the elongational flow. By changing NaC1 concentration of the aqueous DNA solution, the CST at each NaC1 concentration was observed. A critical strain rate where CST occurs increased linearly with NaC1 concentration. These facts indicate that the DNA molecule was electrically neutralized by Na^+ ions gradually and simultaneously whole through the molecule.The regulation of the conformational transition by the elongational flow field was not realized because of the limit of the strain rate generated by the present flow generator. By improving the apparatus, we will retry the experiment.

已经确定的是，柔性聚合物在明确定义的拉伸流场中表现出构象转变：线圈拉伸转变（CST）。我们研究了聚合物在各种条件下的CST，并试图通过拉伸流场中的拉伸来操纵聚合物分子。拉伸流场由四辊磨机系统产生，其中聚合物分子对拉伸场的响应由流动双折射监测。(1)用拉伸流场双折射法结合荧光显微照相法研究了T4噬菌体DNA分子的卷曲-球状转变。预期无规线圈被流场拉长并产生双折射信号，而球形分子被认为没有变形并且不应该有双折射。经验表明，这种预期是正确的。通过与荧光显微镜下的双折射数据比较，发现了一个双折射球形分子。这种双折射球状分子被发现是在一个椭圆体的形状与光学各向异性的停止流动实验使用四辊磨系统。(2)随着溶液中盐浓度的变化，弹性会发生变化。在拉伸流动中，通过CST观察来量化纤维的柔性变化。通过改变DNA水溶液的NaCl浓度，观察每个NaCl浓度下的CST。CST发生的临界应变速率随NaCl浓度线性增加。这些事实表明，Na^+离子对DNA分子的电中和作用是逐步的，并且是同时贯穿整个分子的，由于现有流场发生器产生的应变速率的限制，拉伸流场对构象转变的调控作用不能实现。我们将改进仪器，再试一次这个实验.