本研究主要探討在聚葡萄糖水膠中，利用第一階段合成前驅高分子(dex-MA)時加入不同含量的GMA，來改變前驅高分子的取代度(定義為在100個葡萄糖單體中接上methacrylate group的個數)，並在第二階段改變前驅高分子在溶液中反應的濃度，經過自由基反應後形成不同含水率及交聯度的水膠。隨著聚葡萄糖水膠的取代度增加及網路中的化學交聯增加，其有效交聯密度(νe)呈現遞增，並由有效交聯密度計算出χ值，隨著含水率遞增，水膠與水之間的親和作用力愈來愈強，χ值遞減。經由熱力學方程式計算所得網目大小，隨著化學交聯增加，水膠中交聯點間分子量減少，其網目大小(ξ)呈現遞減。藉由微差掃瞄熱卡計(DSC)觀察，水膠在0℃附近會有吸熱峰，由吸熱峰的面積可估算出鍵結水與非鍵結水(界面水與自由水)含量。
藉由拉伸力及剪切力，量測不同含水率(78%至88%)的水膠與玻璃間的摩擦係數。摩擦係數隨著水膠含水率愈高而降低。摩擦係數對含水率冪次關係中的指數，低含水率試樣的指數為-3.2，高含水率試樣的指數為-4.3，半稀薄高分子溶液模型指數為-3.1與-4.2，在低速時，實驗值與模型的指數較為接近，這是因為模型僅為考慮靜摩擦。水膠內鍵結水的成分愈低，其摩擦係數愈高；摩擦係數對鍵結水含水率冪次關係中的指數分別為0.44與1.98，顯示鍵結水對玻璃與水膠間的摩擦為反潤滑作用，非鍵結水則產生潤滑作用。
藉由水膠與二液滴(水與十六烷)接觸角，估算水膠的表面能量，結果顯示水膠的總表面能量或表面能量的極性成分愈高，水膠與玻璃摩擦係數愈低，這是因為水膠與玻璃間的黏著能(估計所得)較大。水膠表面能量中的極性成分隨著含水率愈高而遞增，而非極性成分則隨著含水率愈高而遞減，極性成分的比例較非極性成分大，且隨含水率變化較為敏感。

Dextran hydrogels were prepared by polymeriza¬tion of aqueous solution of glycidyl methacrylate derivatized dextran (dex-MA), and then they were crosslinked with each other in PBS. The effective crosslink density (νe) is increased with increasing the degrees of substitutions and chemical crosslinking. The χ values were calculated from the effective crosslink densities, which were decreased with increasing the interaction between hydrogels and water. The mesh sizes (ξ) of hydrogels were calculated from the thermodynamic equilibrium equation, which were decreased with decreasing the molecular weight between crosslinking points. The melting peaks around 0℃ from DSC thermograms of hydrogels can be used to estimate the contents of bound and non-bound (i.e.,interface and free) water.
We measured the friction coefficients between hydrogels (water content 78 to 88%) and glass from a tensile/shear force apparatus . The friction coefficients are decreased with increasing saturated water content of hydrogels. The exponents of power relations of friction coefficients versus water contents from experiment (-3.2 for lower water content sample and -4.3 for higher water content sample) were compared with prediction from semi-dilute polymer solution model (-3.1 and -4.2, respectively). The exponent values of experiment was closer to those at the slower sliding velocity, because the model didn't incorporate the influence of velocity on the friction coefficients. The friction coefficients were decreased with increasing the bound water content of hydrogels. The power relations of friction coefficients versus content of bound water with exponents equal to 0.44 and 1.98, respectively. This implies the anti-lubrication caused by the immobile bound water in hydrogels acted upon by the shear friction.
We used contact angles of gels to determine surface energy of gels in air. The friction coefficients were decreased with increasing the total surface energy and polar component of surface energy for hydrogels, because that the calculated adhesion energy between dextran and glass surface were increased. The polar components of surface energy of hydrogels are increased with increasing the water content of hydrogels. Besides, the non-polar components of hydrogels surface energy were decreased. Regarding the surface energy of hydrogels, the proportion of polar component of surface energy was larger than the non-polar, and the polar components are more sensitive to the variation of the water contents.

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