高强度多孔聚乙烯醇水凝胶的制备

Preparation of High Strength Porous Poly(vinyl alcohol) Hydrogels

为制备兼顾多孔性和高强度的水凝胶,本研究利用循环冷冻和冷冻干燥联用设计和制备了一系列聚乙烯醇水凝胶。从聚乙烯醇溶液的浓度、循环冷冻次数、单次冷冻时长三个方面对水凝胶的力学性能、内部微观形貌、含水量进行了研究。结果表明：以质量分数14%浓度的聚乙烯醇水溶液经过3次循环冷冻过程（16h冷冻,8h解冻）和液氮冷冻冰干后的支架,再经溶胀平衡后得到的PVA水凝胶具有最佳的力学性能,此时PVA水凝胶的拉伸强度为5.74MPa,断裂伸长率为347%;改变循环冷冻次数可有效地调节PVA水凝胶的含水量;水凝胶力学性能提高来源于体系结晶度的增大。

In order to obtain hydrogel with porous structure and excellent mechanical properties,the combination of freeze-thaw method and liquid nitrogen freezing method was utilized to design and prepare a series of PVA hydrogels. The mechanical properties,inner microstructure and water uptake content were regulated through three aspects,including original concentration of PVA,freeze-thaw cycle number and freezing time length. The results revealed that PVA hydrogel prepared form solution with 14 wt% original concentration after freeze-thaw（ freeze for16 h and thaw for 8h） for 3 cycles and liquid nitrogen freezing possesses the optimal mechanical properties,while the scaffold can also has good porous structure. The tensile strength and elongation at break of optimized porous hydrogel can reach 5. 74 MPa and 347%,respectively. The water uptake content of PVA hydrogel can be modulated by changing freeze-thaw cycle. And the improvement of hydrogel mechanical properties is due to the increase of PVA crystallinity.