The effects of molecular entanglement on rheological properties of quasi 2D polymers

发展了动态光散射光谱研究准二维环境中聚合物分子相互作用的新方法和新设备。我们主要集中于对我们新开发的系统的性能的评估，以及对胶体分散体和2D和3D聚合物溶液的初步测量。我们研制了一台动态光散射光谱仪，它集成了一个光子计数系统和一个多标度器，使我们能够获得时间分辨的光子计数率。将计数率时间序列传输到个人计算机，并用基于软件的频谱分析仪进行分析。最大时间分辨率为5 ns。我们还介绍了一种从散射光中提取微小涨落的外差混合方法，由于不需要对振动的统计性质进行任何人为假设，因此我们可以很容易地分析由我们的系统获得的外差光谱。这对于研究有望呈现反常扩散过程的准2D聚合物体系来说是不可避免的。以胶体分散体和微乳液为模型系统，研究了软物质中界面现象的动力学。通过测量散射光的外差光谱，可以分离胶体溶液中的布朗动力学和流动动力学。对于我们的系统来说，水-气界面上的聚合物薄膜的光散射测量非常弱。不可能获得足够的信号质量。这是由于光纤-光纤耦合效率低造成的。我们将继续提高系统的总吞吐量。综上所述，我们开发了一个通用的动态光散射系统，适用于研究呈现非高斯动力学的复杂流体。

New method and equipment have been developed for dynamic light scattering spectroscopy to investigate molecular interactions of polymer molecules confined to quasi 2D environment. We mainly focused on an estimation of the performance of our newly developed system and the preliminary measurements for colloidal dispersions and 2D and 3D polymer solutions.1. We developed a dynamic light scattering spectrometer which incorporated a photon counting system and a multiscaler which enabled us to get the time-resolved photon-counting rate. Time series of counted rate was transferred to an personal computer and was analyzed with software-based frequency analyzer. Maximum time resolution was 5 ns. We also introduced a heterodyne mixing method for extracting subtle fluctuation from scattered light.We can easily analyze the heterodyne spectra obtained by our system since any artificial assumptions on the statistical properties of fructuation is not required. This is inevitable for investigating quasi-2D polymer systems which is expected to show anomalous diffusion processes.2. Colloidal dispersions and microemulsions were employed as model systems for observing dynamics of interfacial phenomena in soft matter. It was possible to separate the Brownian dynamics and flow dynamics in a colloidal solution by measuring a heterodyne spectrum of scattering light.3. The light scattering measurement for the polymer films spread on a water-air interface was extremely weak for our system. It was not possible to get sufficient quality of signal. This was caused by poor efficiency at fiber-fiber coupling. We will continue to improve the total throughput of the system.4. In summary, we have developed a versatile dynamic light scattering system which is suitable for investigating complex fluid which shows non-gaussian dynamics.