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Dynamic Light Scattering Studies on Strong Interaction between Polymer Liquid Crystals and the Gelation Process.

聚合物液晶与凝胶化过程之间强相互作用的动态光散射研究。

基本信息

批准号：
08651063
负责人：
OIKAWA Hidetoshi
金额：
$ 1.34万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08651063/
关键词：
poly (gamma-benzyl-alpha, L-glutamate)Polymer Liquid Crystal Dynamic Light Scattering Polymer Liquid Crystal Gel Sol-Gel Transition Autocorrelation Function Cooperative Diffusion Scattering Spectrum

项目摘要

Static and dynamic light scattering measurements have been performed on the association and gelation processes for poly (gamma-benzyl-alpha, L-glutamate) (PBLG) -toluene systems. In the quasi-equilibrium state of gelation (I), the slow mode has been observed in the obtained autocorrelation function (ACF), which was assigned to be a cooperative self-diffusion mode for aggregated PBLG chains in an isotropic phase. In addition, the ACF measured was modulated vibrationally near the gelation threshold. The apparent frequency of this modulation was influenced by thermal hysteresis and the time of elapse. In fact, the modulation was diminished after about one day. This phenomenon could be explained by the superposition of the fluctuation of concentration and the viscoelastic interaction between pre-gel domains. Thus, these facts seem that the gelation may occur by the nucleation and growth process in this case (I). On the other hand, it has become apparent experimentally that the gelation in the quenched non-equilibrium of gelation (II) has proceeded by the spinodal decomposition process, according to the Cahn's theory. As a result, the spinodal temperature could be first determined experimentally in the PBLG-toluene phase diagram. The fractal dimension increased and the correlation length decreased with increasing concentration of toluene solution, and, especially, the correlation length in PBLG gel was shorter than the characteristic maximum wavelength for concentration fluctuation occurred just after quenching, which describes that gel formed by the quenching made a more dense structure.

用静态和动态光散射法研究了聚谷氨酸苄酯（PBLG）-甲苯体系的缔合和凝胶化过程。在凝胶化的准平衡状态（I），慢模式已被观察到在所获得的自相关函数（ACF），这被指定为一个合作的自扩散模式的聚集PBLG链在各向同性相。此外，所测量的ACF在凝胶化阈值附近被振动调制。这种调制的表观频率受热滞后和经过时间的影响。事实上，调制在大约一天后减弱。这一现象可以用浓度波动和预凝胶微区间粘弹性相互作用的叠加来解释。因此，这些事实似乎表明，在这种情况下（I），凝胶化可以通过成核和生长过程发生。另一方面，根据Cahn理论，在猝灭的非平衡凝胶化（II）中的凝胶化通过亚稳分解过程进行，这在实验上已经变得明显。因此，可以首先在PBLG-甲苯相图中通过实验确定旋节温度。随着甲苯溶液浓度的增加，分形维数增加，相关长度减小，特别是PBLG凝胶的相关长度小于淬灭后浓度波动的特征最大波长，说明淬灭后形成的凝胶结构更加致密。