氧化石墨烯对聚乙烯醇/硼酸水凝胶流变性能的影响

Influence of Graphene Oxide on the Rheological Properties of Poly( vinyl alcohol)/Borate Hydrogel

研究了氧化石墨烯(GO)对聚乙烯醇(PVA)/硼酸(borate)水凝胶线性及非线性流变性能的影响。通过扫描电子显微镜、硼谱核磁共振波谱以及流变研究了水凝胶的流变性能。结果表明,GO质量浓度在稀溶液区时,GO片层与PVA链间通过硼酸根离子形成了具有弹性活性的缔合点,有效地提高了水凝胶的平台模量、松弛时间和零切粘度;当GO进一步增加到亚浓溶液区,部分的交联剂被GO的团聚体捕获并处于非弹性活性的缔合状态,处于有效缔合状态的交联剂变少,导致平台模量、松弛时间和零切粘度降低。稳态剪切测试下,样品在剪切增稠区的粘度增加随着GO添加量的增加明显加强,这与剪切场下取向的氧化石墨烯片层参与网络结构的重排有关。

The influence of graphene oxide（ GO） on the linear and nonlinear rheological properties of poly（ vinyl alcohol）（ PVA）/borate hydrogel was explored in this work. Results of scanning electron microscopy,11 B nuclear magnetic resonance and rheology reveal that elastically active points formed between dispersed GO sheets and PVA chains have enhanced plateau modulus（ G0）,relaxation time（ τ） and zero shear viscosity（ η0） of samples when the mass concentration of GO（ ρ（ GO）） is in the dilute concentration regime.As ρ（ GO） is further increased to the semi-dilute concentration regime,part of cross-linkers is occupied by GO aggregation and exists as non-elastically active GO-borate-GO bond,then G0,τ and η0 of samples are decreased with ρ（ GO）. Under steady shear,the enhancement of viscosity in shear thickening regime always increases with ρ（ GO） in different concentration regimes,which is related with the participation of oriented GO sheets to reorganization of the network.