Centre de Recherche Paul Pascal, CNRS UPR 8641 - 115 avenue Dr. Schweitzer, 33600 Pessac, France.
MultiScale Material Science for Energy and Environment, UMI 3466, CNRS-MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
Sci Rep. 2017 Jan 23;7:41185. doi: 10.1038/srep41185.
Agarose gels are viscoelastic soft solids that display a porous microstructure filled with water at 90% w/w or more. Despite an extensive use in food industry and microbiology, little is known about the drying kinetics of such squishy solids, which suffers from a lack of time-resolved local measurements. Moreover, only scattered empirical observations are available on the role of the gel composition on the drying kinetics. Here we study by in-situ interferometry the drying of agarose gels of various compositions cast in Petri dishes. The gel thinning is associated with the displacement of interference fringes that are analyzed using an efficient spatiotemporal filtering method, which allows us to assess local thinning rates as low as 10 nm/s with high accuracy. The gel thinning rate measured at the center of the dish appears as a robust observable to quantify the role of additives on the gel drying kinetics and compare the drying speed of agarose gels loaded with various non-gelling saccharides of increasing molecular weights. Our work shows that saccharides systematically decrease the agarose gel thinning rate up to a factor two, and exemplifies interferometry as a powerful tool to quantify the impact of additives on the drying kinetics of polymer gels.
琼脂糖凝胶是黏弹性软固体，在 90wt%以上的含水量时呈现多孔微观结构。尽管在食品工业和微生物学中得到了广泛应用，但对于这种粘稠固体的干燥动力学却知之甚少，这是因为缺乏时间分辨的局部测量。此外，关于凝胶组成对干燥动力学的影响，只有零散的经验观察结果可用。在这里，我们通过原位干涉测量研究了在培养皿中浇铸的各种组成的琼脂糖凝胶的干燥过程。凝胶变薄与干涉条纹的位移有关，我们使用高效的时空滤波方法对其进行了分析，该方法允许我们以高精度评估低至 10nm/s 的局部变薄率。在盘中心测量的凝胶变薄率是一个稳健的可观测量，可用于量化添加剂对凝胶干燥动力学的作用，并比较负载不同分子量的非凝胶化糖的琼脂糖凝胶的干燥速度。我们的工作表明，糖会系统地降低琼脂糖凝胶的变薄率，最高可达两倍，并举例说明了干涉测量法是一种强大的工具，可用于量化添加剂对聚合物凝胶干燥动力学的影响。
