具有短程吸引和长程排斥的体系中胶体凝胶的结构、稳定性及形成途径。

Structure, stability, and formation pathways of colloidal gels in systems with short-range attraction and long-range repulsion.

作者信息

van Schooneveld Matti M, de Villeneuve Volkert W A, Dullens Roel P A, Aarts Dirk G A L, Leunissen Mirjam E, Kegel Willem K

机构信息

Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.

出版信息

J Phys Chem B. 2009 Apr 9;113(14):4560-4. doi: 10.1021/jp809659g.

DOI:10.1021/jp809659g

PMID:19267487

Abstract

We study colloidal gels formed upon centrifugation of dilute suspensions of spherical colloids (radius 446 nm) that interact through a long-range electrostatic repulsion (Debye length approximately 850 nm) and a short-range depletion attraction (approximately 12.5 nm), by means of confocal scanning laser microscopy (CSLM). In these systems, at low colloid densities, colloidal clusters are stable. Upon increasing the density by centrifugation, at different stages of cluster formation, we show that colloidal gels are formed that significantly differ in structure. While significant single-particle displacements do not occur on the hour time scale, the different gels slowly evolve within several weeks to a similar structure that is at least stable for over a year. Furthermore, while reference systems without long-range repulsion collapse into dense glassy states, the repulsive colloidal gels are able to support external stress in the form of a centrifugal field of at least 9g.

摘要

我们通过共聚焦扫描激光显微镜（CSLM）研究了由球形胶体（半径446纳米）的稀悬浮液离心形成的胶体凝胶，这些胶体通过长程静电排斥（德拜长度约850纳米）和短程耗尽吸引（约12.5纳米）相互作用。在这些系统中，在低胶体密度下，胶体簇是稳定的。通过离心增加密度时，在簇形成的不同阶段，我们表明形成的胶体凝胶在结构上有显著差异。虽然在小时时间尺度上不会发生明显的单粒子位移，但不同的凝胶会在几周内缓慢演变成一种至少在一年以上稳定的相似结构。此外，虽然没有长程排斥的参考系统会坍缩成致密的玻璃态，但具有排斥作用的胶体凝胶能够以至少9g的离心场形式承受外部应力。