本研究主要探討在聚葡萄糖(dextran)水膠中固定合成前驅高分子(dex-MA)的取代度(定義在100個葡萄糖單體中接上methacrylate group的個數)，分別加入不同體積比例以及不同分子量的聚乙二醇(PEG)，交聯後形成在網路結構交聯點間的鏈段上具有PEG側鏈結構的水膠，藉由改變PEG在高分子中的比例及分子量來探討不同接枝參數形成之網路結構對熱力學與黏彈性的影響。
在側鏈的影響下水對PEG的親合力大於dextran，使水膠含水率隨PEG在水膠中含量遞增，卻不受PEG長度影響而變；當PEG與dextran的重量比大於11％之後形成的水膠，含水率則隨PEG在高分子中含量減少而減少。由應力-應變實驗的結果顯示，彈性模數(G)值隨PEG含量或長度增加而上升，可知水膠內的有效交聯密度(νe)隨著側鏈的含量或長度增加而變大。
G值受化學交聯與物理交聯影響，藉由應力-應變數據與slip link模型計算Ns（物理交聯密度）和Nc（化學交聯密度）值。在計算結果中發現，Ns為負值，代表水膠網路中發生物理解纏現象；Ns、Nc的絕對值皆隨著PEG在水膠中含量或長度增加而遞增，PEG的增加造成物理解纏程度上升，並使水膠的化學交聯的程度增加。由Ns與Nc的比值約為定值得知，物理解纏和化學交聯的相對程度不隨水膠中的PEG含量或長度增加而改變。
側鏈密度增加，造成水膠網路的交聯密度增加，使交聯點間的分子量（Mc）隨著密度增加而變小；僅改變側鏈長度，水膠的交聯密度同樣有增加，但對於交聯點間的分子量卻沒有明顯影響。水膠網目大小（ξ）則隨著含水率增加而變大。
對梳狀高分子膨潤自由能進行因次分析，瞭解含水率與側鏈密度、側鏈長度、拒斥體積(excluded volume)、交聯密度的關係，計算結果發現水膠交聯密度增加，高分子含水率會減少；含水率隨著側鏈在高分子中的長度增加而增加再減少；側鏈密度越大，側鏈拒斥效應越大，含水率隨之減少。
由實驗結果評估此模型，發現此模型不適用於側鏈為親水性高分子的範圍，必須再加入specific interaction造成的自由能修飾，側鏈對總自由能的影響，本模型描述不真。

In this study, comb-type grafted dextran hydrogels with various volume content or various molecular weight of PEG were prepared by polymerization of aqueous solution of glycidyl methacrylate derivatized dextran(dex-MA). The objective is to demonstrate the influence of grafting parameters on the thermodynamics and viscoelasticity in PEG-grafted dextran hydrogels.
With increasing contents of PEG, PEG grafted chains make water contents of hydrogels increased, but as the volume ratio of PEG to dex-MA is over 10%, water contents decrease with it. In the compressive stress experiment, the modulus and the effective crosslinking density (ve) increased with the increasing contents or length of grafted chains. As the crosslinking densities increase, the molecular weights between the crosslinks (Mc) of gels decrease.
Flory-Huggins parameter (χ) between polymer and water decreases with the increasing contents of water. The hydrogel mesh size (ξ) in the swollen state was calculated, and the data illustrate the correlation between the mesh size and water contents.
The stress-strain data of hydrogels fitted with the slip-link model indicate that there are significant disentanglements and chemical crosslinkings in the network, increasing with not only contents but also molecular weights of the grafted chains.
With the dimensionless analysis on the swelling free energy of brush polymers, the relations between water content and the grafting parameters are illustrated. With the model simulation, water contents of hydrogels decrease with increasing the crosslink density. Water contents decrease with the grafting density because of the effect of excluded volume caused by PEG chains. Particularly, there exists maximum water content at a certain length of the grafting chain.
To compare the model simulation with the experimental results of this study, it is calculated that the model is suitable for the range of grater grafting density. The model overestimates the effect of grafting chain on the total free energy at the lower
grafting densities.

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