MECHANICAL STABILITY OF TENUOUS OBJECTS.

Abstract

Low-density structures such as colloidal aggregates become increasingly easy to deform mechanically as their size increases. We use recently-proposed scaling properties of such aggregates to investigate the effects of thermal fluctuations and of gravitational forces on such structures. For typical colloidal aggregates, made of 100 A particles, the diameter may not exceed 10**3 to 10**4 particle diameters without significant distortion due to both thermal and gravitational effects. Constituent particles of this order of size are optimal: much larger or much smaller particles make mechanically less stable aggregates.