聚乙烯醇/碳点形状记忆发光水凝胶的制备与性能

Photoluminescence and Shape Memory of Poly(Vinyl Alcohol)/Carbon Dots Hybrid Hydrogel

借助水热技术,以壳聚糖为碳源,通过简单的"一锅法"直接合成荧光碳点,研究了其紫外吸收与荧光光谱,并通过扫描电子显微镜表征了其形貌与大小。结果表明,所制备的纳米碳点有着近球形的形貌,并具有良好的光致发光性能。在此基础上,以生物医用材料聚乙烯醇水凝胶为基材,通过与碳点的物理复合以及适当的化学交联,制备了同时兼具光致发光与形状记忆二重功能的聚乙烯醇/碳点杂化水凝胶。通过优化"冷冻-解冻"时间调整水凝胶的结晶微区,可以得到形状固定率与回复率均超过85%的聚乙烯醇/碳点形状记忆杂化水凝胶,而且水凝胶的三维交联网络,对碳点的荧光衰减行为起到了良好的抑制作用,使其发光稳定性得到明显改善,这些发现将有利于拓展聚乙烯醇以及荧光碳点在生物医学领域的应用。

By means of hydrothermal technology,the carbon nanodots were synthesized directly through a simple‘one-pot＇method using chitosan as carbon source.The UV-vis,fluorescence spectroscopic technique and the scanning electron microscope were employed to characterize the resultant products,indicating that the carbon nanodots were well prepared with the nearly spherical morphology and good photoluminescence properties.Furthermore,by dispersing the carbon nanodots into PVA hydrogel matrix,the hybrid hydrogel with the dual functions of photoluminescence and shape memory can be fabricated under the appropriate chemical crosslinking and＂freezing-thawing＂manipulation.The shape fixing and recovery ratio of the PVA/carbon nanodots hybrid hydrogel are able to achieve above 85% by just adjusting the＂freezing-thawing＂time scale.Moreover,the 3 Dcrosslinking network of hydrogels can suppress the fluorescence attenuation of the carbon nanodots and improve the stability of the luminescence.These findings will be helpful for the development of polyvinyl alcohol and fluorescent carbon spots in the biomedical field.