在研究凝膠的結構與性質中，流變學扮演了重要的角色，本論文中，我們試圖由線性流變的方法探討瓊脂醣凝膠網目黏彈性質，並利用網目彈性與瓊脂醣濃度的幂律關係，決定凝膠結構所響應之彈性特徵。然而在本研究中，我們發現由於複雜的老化效應，無法直接由標度理論特徵網目的彈性性質。為了釐清結構與彈性響應的關係，我們進一步利用非線性流變學的方法進行研究。

首先在大振幅剪切振盪(LAOS)的實驗中，我們由微纖狀的凝膠網目表現出應變硬化的行為，證明瓊脂醣凝膠的熵彈性本質。其次在prestress protocol的實驗中，我們由微分彈性模數與施加預應力的標度關係，K^'~σ_0，再進一步證明，瓊脂醣凝的熵彈性本質與肌動蛋白網目不同，是響應出軟交聯的特徵，與我們研究室之前提出的纖網目模型一致。

此外，結合時間分辨流變實驗和小角光散射的結果，也證實瓊脂醣分子鏈在溶液中，以蠕蟲狀鏈的形式存在，並表現出結構流體的特徵，即在小應變下，流體的G^'>G^''。

Rheology plays an important role in the studies of gel structure and properties. In this thesis, we attempt to use the linear rheological method to probe the viscoelastic properties of the agarose hydrogels and use the power law relationship between network elasticity and the concentration of the agarose hydrogels to determine the characteristic elastic response of the gel structure. However, we discover the complex aging effect so that we cannot directly characterize the elastic properties of networks by scaling theory in this study. In order to clarify the relationship between the structure and the elastic responses, we further investigate this system by nonlinear rheological methods.

First, we verify the intrinsic entropic elasticity of the agarose hydrogels due to the fibrillar networks reveal the behavior of strain stiffening in the large amplitude oscillatory shear (LAOS) experiments. Secondly, the scaling relationship between the differential modulus and the applied prestress from the prestress protocol, K^'~σ_0, further confirms that the intrinsic entropic elasticity of the agarose hydrogels responds the characteristic of soft cross-links, which is different from the F-actin networks, and is similar to the fibrillar network model we previously propose.

In addition, we combine the results of time-resolved rheological measurements and small-angle light scattering, and verify that the agarose chains behave as worm-like chains in the solutions. The agarose chains appear the feature of structured fluid. Namely, the storage modulus of the fluid is higher than loss modulus under the small amplitude.

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