Su Enyi, Li Qing, Xu Mengyue, Yuan Yang, Wan Zhili, Yang Xiaoquan, Binks Bernard P
Laboratory of Food Proteins and Colloids, School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, South China University of Technology, Guangzhou 510640, China.
School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, China.
J Colloid Interface Sci. 2021 Apr;587:797-809. doi: 10.1016/j.jcis.2020.11.039. Epub 2020 Nov 13.
Natural saponin glycyrrhizic acid (GA) and GA nanofibrils (GNFs) are effective foaming agents for formulation of aqueous food-grade foams. Through the synergistic combination of soft semiflexible GNFs with rigid nanofiller cellulose nanocrystals (CNCs), it should be possible to create advanced composite foams with a more complex structure and diverse properties including high stability and stimuli responsiveness.
Foams containing mixtures of GNFs and CNCs were prepared, and their formation and stability were investigated. A range of microscopy techniques and small deformation oscillatory shear were adopted to examine the microstructure and viscoelasticity of foams, and a stabilization mechanism for highly stable foams was then established. Further, the temperature-responsive destabilization of foams was evaluated.
CNCs are homogeneously distributed in the architecture and mechanically reinforce the GNF fibrillar network, leading to a highly viscoelastic composite network in the continuous phase of foams, which is the key factor responsible for their high stability. Such ultra-stable gel foams display tunable thermo-responsive behavior and a rapid on-demand destabilization upon heating by inducing a phase transition of the bulk composite network. Our work opens up new scenarios on the use of a novel combination of all-natural, sustainable nanoscale building blocks to develop aqueous "superfoams" which are highly stable, stimulable and processable.
天然皂苷甘草酸（GA）和GA纳米纤维（GNFs）是用于配制水性食品级泡沫的有效发泡剂。通过柔软的半柔性GNFs与刚性纳米填料纤维素纳米晶体（CNCs）的协同组合，应该能够制造出具有更复杂结构和多样性能（包括高稳定性和刺激响应性）的先进复合泡沫。
制备了含有GNFs和CNCs混合物的泡沫，并研究了它们的形成和稳定性。采用一系列显微镜技术和小变形振荡剪切来检查泡沫的微观结构和粘弹性，然后建立了高稳定性泡沫的稳定机制。此外，还评估了泡沫的温度响应失稳情况。
CNCs均匀分布在结构中，并在机械上增强了GNF纤维网络，导致在泡沫连续相中形成高度粘弹性的复合网络，这是其高稳定性的关键因素。这种超稳定的凝胶泡沫表现出可调节的热响应行为，并且在加热时通过诱导整体复合网络的相变而迅速按需失稳。我们的工作为使用新型的全天然、可持续纳米级构建块组合开发高稳定性、可刺激和可加工的水性“超级泡沫”开辟了新的前景。
