在本文中,通过将疏水改性壳聚糖(h-CS)与植酸钠(SP)物理交联,制备出粒径均匀的微凝胶。交联密度对界面吸附动力学的影响,粘弹性,应力松弛,和疏水改性壳聚糖微凝胶(h-CSMs)在油-水界面的微流变特性进行了广泛的研究,压缩流变学,和颗粒示踪微流变学。结果与颗粒大小相关,形态学,通过动态光散射和原子力显微镜表征微凝胶的弹性。发现随着交联密度的增加,h-CSM从类似聚合物的状态变为具有较高弹性模量的超软杂乱球。压缩等温线显示出由壳之间和微凝胶核心之间的相互作用引起的多级增加。随着交联密度的增加,h-CSM向油水界面扩散较慢,但在油水界面表现出更快的渗透吸附和重排,由于核心-核心相互作用,最终形成具有较高粘弹性模量的界面层。随着微凝胶弹性的增加,初始张力松弛和界面扩张后的微凝胶重排都变得更快。界面微流变证明了由相邻微凝胶引起的动态笼效应。本文对多糖微凝胶在油-水界面的行为进行了更全面的了解。
In this paper, microgels with uniform particle size were prepared by physically cross-linking the hydrophobically modified chitosan (h-CS) with sodium phytate (SP). The effects of cross-linking density on the interfacial adsorption kinetics, viscoelasticity, stress relaxation, and micorheological properties of the hydrophobically modified chitosan microgels (h-CSMs) at the oil-water interface were extensively investigated by the dilatational rheology, compressional rheology, and particle tracing microrheology. The results were correlated with the particle size, morphology, and elasticity of the microgels characterized by dynamic light scattering and atomic force microscopy. It was found that with the increase of cross-linking density, the h-CSMs changed from a polymer-like state to ultra-soft fussy spheres with higher elastic modulus. The compression isotherms demonstrated multi-stage increase caused by the interaction between the shells and that between the cores of the microgels successively. As the increase of cross-linking density, the h-CSMs diffused slower to the oil-water interface, but demonstrating faster permeation adsorption and rearrangement at the oil-water interface, finally forming interfacial layers of higher viscoelastic modulus due to the core-core interaction. Both the initial tension relaxation and the
microgel rearrangement after interface expansion became faster as the
microgel elasticity increased. The interfacial microrheology demonstrated dynamic caging effect caused by neighboring microgels. This article provides a more comprehensive understanding of the behaviors of polysaccharide microgels at the oil-water interface.