牛頓流體和濃縮高分子溶液在剪力下的反應在單分子的層次被究，57%的蔗糖溶液做為牛頓流體而將λ-DNA 溶入TE 緩衝溶液中得到濃度5 ug/ul做為濃縮高分子溶液，Mn2+離子被加入濃縮高分子溶液中做為cross-linker. 螢光粒子被用來追蹤速度剖面圖，並以染色DNA 分子則用來觀察高分子微觀行為，剪力流場是由驅動一片在樣本之上的平板來產生。藉由螢光顯微技術，研究在牛頓流體和濃縮高分子溶液中單一高分子在剪力下的動態行為，在濃縮高分子溶液中速度剖面圖並非直線且DNA 分子的橢圓率也不是常數，當剪力停止之後濃縮高分子溶液表現出緩慢的舒張過程，由含有cross-linker 的濃縮高分子溶液中的單分子觀察並配合速度剖面圖和舒張過程，我們認為含有cross-linker 的高分子溶液為一具有堅固的三維連結網狀系統。 The responses of Newtonian fluid and concentrated polymer solutions under shear are studied at single molecule level. In this experiment, Newtonian fluids are 57% sucrose solutions and high concentration polymer solutions are prepared by dissolving λ‐DNA in TE buffer at 5 μg/μl concentration. The Mn2+ ions are added in the concentrated polymer solution to investigate the polymer solution at cross‐linked state. Fluorescence tracer particles are introduced in various flows; to measure the velocity profiles. Dye labeled DNA molecules mixing with unlabeled ones are tracer molecules to observe the single molecule behaviors. The shear flow is generated by driving a plate on top of the fluid sample. Through the fluorescent microscopy, the dynamical behavior of individual molecule in the Newtonian fluid and concentrated DNA solution under shear is investigated. The velocity profiles are nonlinear and the ellipse ratio of individual DNA molecules is not homogeneous in sheared concentrated polymer solution. The concentrated polymer solutions also show a slow relaxation process after shear. Base on the measured velocity profiles and the post‐shear relaxation process, we propose that, the cross‐linked concentrated polymer solution seems to be a strongly coupled 3D polymer network.
