具有各向异性结构的聚乙烯醇水凝胶的制备及性能表征

首先对聚乙烯醇（PVA）水溶液进行定向冷冻-解冻制备出具有各向异性结构的PVA水凝胶，然后采用⁶⁰Co-γ射线对其进行辐射交联以提高其热稳定性和力学性能。扫描电子显微镜（SEM）结果显示PVA水凝胶保持了各向异性的微观结构，在平行冷冻方向上具有相对规整的取向结构，在垂直冷冻方向上呈现均匀孔洞结构。热稳定性测试结果表明：辐射剂量在30~70 kGy范围内、定向冷冻次数为1次的PVA水凝胶在60℃热水浴中保持凝胶状态长达10 h以上。对辐射交联PVA水凝胶进行拉伸力学性能测试，凝胶具有各向异性的拉伸性能，且拉伸强度和弹性模量均有提高，辐射剂量为10 kGy、定向冷冻次数为3次的PVA水凝胶（DFT-RC-3-10）在垂直定向冷冻方向上的拉伸强度和弹性模量分别为0.86和0.10 MPa。

Preparation and Property Characterization of Polyvinyl Alcohol Hydrogel with Anisotropic Structure

Polyvinyl alcohol(PVA) hydrogels with anisotropic microstructures were firstly prepared by directional freezing-thawing(DFT) of PVA aqueous solution, and then they were crosslinked with ⁶⁰Co γ-rays irradiation to improve their thermal stability and mechanical properties. Scanning electron microscopy(SEM) showed that original anisotropic microstructures of PVA hydrogels could be maintained after radiation-induced crosslinking. Long aligned channels were found along the parallel direction, pores with similar sizes were found along the perpendicular direction. The thermal stability tests showed that the PVA hydrogels prepared with one directional freezing-thawing cycle and irradiated with 30-70 kGy ⁶⁰Co γ-rays could maintain their original gel states in 60℃ water for more than 10 h. Tensile mechanical testing showed that the radiation crosslinked PVA hydrogels(DFT-RC-3-10) maintained their anisotropic tensile properties, moreover, the tensile strengths and elastic moduli of the radiation crosslinked PVA hydrogels(DFT-RC-3-10) were enhanced, for the PVA gel samples prepared with three directional freezing-thawing cycles and irradiated with 10 kGy ⁶⁰Co γ-ray, the tensile strength and elastic modulus in the direction perpendicular to the freezing direction were enhanced to 0.86 and 0.10 MPa, respectively.