Department of Environmental Chemistry, Faculty of Chemistry and Biology, Universidad de Santiago de Chile, Av. B. O'Higgins 3363, Santiago, Chile.
Carbohydr Polym. 2013 Jan 30;92(1):157-66. doi: 10.1016/j.carbpol.2012.09.031. Epub 2012 Sep 24.
Graft copolymers were prepared by formation of an amide bond between poly-α-L-guluronic acid (MW 24,000), isolated from sodium alginate and the free amino group of PNIPAAm-NH(2). SEM micrographs revealed the formation of a macroscopic network on the surface of the grafted hydrogels with a porosity diameter of 10-20 μm. Semi-IPN hydrogels were prepared using different proportions of sodium poly-β-D-mannuronate (MW 21,000), isolated from sodium alginate and cross-linked PNIPAAm-NH(2) polymers. SEM micrographs showed porosities of minor size (∼5 μm). Though both types of hydrogels are good water containers, the water retention capacity of graft copolymers is more than 50% higher than that of semi-IPN hydrogels. Both hydrogel types showed significant changes in swelling ratios between 20 and 45 °C: the swelling ratio decreases near the LCST of PNIPAAm. The water absorption and retention capacity of graft hydrogels increases with pH, reaching a maximum value at pH 7.0.
接枝共聚物是通过在从海藻酸钠中分离得到的聚α-L-古洛糖醛酸（MW 24,000）和 PNIPAAm-NH（2）的游离氨基之间形成酰胺键制备的。SEM 显微照片显示，在接枝水凝胶的表面形成了具有 10-20μm 孔隙直径的宏观网络。使用不同比例的从海藻酸钠中分离得到的聚β-D-甘露糖醛酸钠（MW 21,000）和交联的 PNIPAAm-NH（2）聚合物制备了半互穿网络水凝胶。SEM 显微照片显示孔隙较小（∼5μm）。尽管这两种类型的水凝胶都是良好的水容器，但接枝共聚物的保水能力比半互穿网络水凝胶高 50%以上。两种水凝胶类型在 20 至 45°C 之间的溶胀率均发生明显变化：在 PNIPAAm 的 LCST 附近，溶胀率降低。接枝水凝胶的吸水率和保持率随 pH 值增加而增加，在 pH 值为 7.0 时达到最大值。
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