Frenzel Lara, Dartsch Michael, Balaguer Gerard Martí, Westermeier Fabian, Grübel Gerhard, Lehmkühler Felix
Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany.
Phys Rev E. 2021 Jul;104(1):L012602. doi: 10.1103/PhysRevE.104.L012602.
We study the structure and dynamics of colloidal particles with a spherical hard core and a thermo-responsive soft shell over the whole phase diagram by means of small-angle x-ray scattering and x-ray photon correlation spectroscopy. By changing the effective volume fraction by temperature and particle concentration, liquid, repulsive glass. and attractive gel phases are observed. The dynamics slow down with increasing volume fraction in the liquid phase and reflect a Vogel-Fulcher-Tamann behavior known for fragile glass formers. We find a liquid-glass transition above 50 vol.% that is independent of the particles' concentration and temperature. In an overpacked state at effective volume fractions above 1, the dispersion does not show a liquid phase but undergoes a gel-glass transition at an effective volume fraction of 34 vol.%. At the same concentration, extrema of subdiffusive dynamics are found in the liquid phase at lower weight fractions. We interpret this as dynamic precursors of the glass-gel transition.
我们通过小角X射线散射和X射线光子相关光谱法，研究了在整个相图范围内具有球形硬核和热响应软壳的胶体颗粒的结构和动力学。通过改变温度和颗粒浓度来改变有效体积分数，观察到了液相、排斥性玻璃相和吸引性凝胶相。在液相中，动力学随着体积分数的增加而减慢，反映出脆性玻璃形成体所具有的Vogel-Fulcher-Tamann行为。我们发现，在体积分数高于50%时存在一个与颗粒浓度和温度无关的液-玻璃转变。在有效体积分数高于1的过填充状态下，分散体不显示液相，而是在有效体积分数为34%时经历凝胶-玻璃转变。在相同浓度下，在较低重量分数的液相中发现了亚扩散动力学的极值。我们将此解释为玻璃-凝胶转变的动态前驱体。
