Mechanical Properties of a Series of Macro- and Nanodimensional Organic Cocrystals Correlate with Atomic Polarizability

A correlation between Young’s
modulus, as determined by
using nanoindentation atomic force microscopy (AFM), and atomic polarizability
is observed for members of a series of cocrystals based on systematic
changes to one cocrystal component. Time domain spectroscopy over
terahertz frequencies (THz-TDS) is used for the first time to directly
measure the polarizability of macro- and nanosized organic solids.
Cocrystals of both macro- and nanodimensions with highly polarizable
atoms result in softer solids and correspondingly higher polarizabilities.