Perfection and homogeneity of single crystals

In many cases it is possible to convert a single crystal of monomer completely to a single crystal of polymer in a homogeneous process, the perfection of the product crystal being comparable to that of the parent. The synthesis in this way of polymer crystals over IS cm long and 10 g in weight has been described (193). 

A simplistic view, but one that has some merit, rationalizes the dual nature of LE as follows the resemblance to solid expls is due to the similar densities of most LE and solid explosives the similarities with gaseous expls are due to the homogeneity of LE and gaseous expls (solid expls except for perfect single crystals are heterogeneous)... 

Not all anisotropic materials are perfect single crystals, and not all of them give such tidy results as electronic and optoelectronic wafers. But measurements on these more difficult inhomogeneous anisotropic specimens may be significant nonetheless, especially if they can be related to similar measurements on homogeneous specimens of the constituents as they were with the dental enamel in 9.4.2. Angle-resolved Rayleigh wave measurements can also be used to characterize the anisotropy of heavily drawn metal-metal composites. 

Macroscopic polymer single crystals with a high degree of perfection can be produced by the homogeneous topochemical polymerization of conjugated diacetylene monomers (1). The polydiacetylenes thus formed have a fully conjugated planar backbone and possess unusual optical and electronic properties... 

The conversion from monomer to polymer in the crystal proceeds via a diffusionless phase transition to form perfect polymer single crystals with the lattice parameters close to those of the original monomer crystals. During the course of the polymerization, the polymer chains and the monomer matrix form a homogeneous solid solution without any nucleation of the product phases, thus neither destruction nor fibrillation can be observed in the resultant polymer single crystals. Solid state polymerization of conjugated diynes is... 

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