Lamellar thickness quantized

The lamellar thickening proceeds through many metastable states, each metastable state corresponding to a particular number of folds per chain, as illustrated in Fig. 8. In the original simulations of [22], Kg was monitored. Rg is actually very close to the lamellar thickness due to the asymmetric shape of the lamella. The number of folds indicated in Fig. 8 were identified by inspection of the coordinates of the united atoms. This quantization of the number of folds has been observed in experiments [50], as already mentioned. The process by which a state with p folds changes into a state with p - 1 folds is highly cooperative. The precursor lives in a quiescent state for a substantial time and suddenly it converts into the next state. By a succession of such processes, crystals thicken. If the simulation is run for a reasonably long time, the lamella settles down to the equilibrium number of folds per chain. 

Fig. 8 Quantized lamellar thickening. Rg is the radius of gyration of the lamella [22] Lamellar Thickness and Quench Depth... 

When the lamellae are annealed at a given temperature, they thicken with time. The thickening is usually continuous and L increases logarithmically with time. However, there are several examples, where the lamellar thickness increases in a stepwise manner. For example, the initial lamella may contain chains each with four folds (five stems). As thickening process continues, the lamellar thickness jumps discontinuously to three folds, and so on. This phenomenon is referred to as quantized thickening [25]. 

In some cases to conserve the volume, when the film initial thickness does not permit the construction of uniform layers of BC islands and holes are produced. This effect, known as quantization of the film thickness, has been observed, among others, in symmetric diblock copolymers able to form lamellar phases. 

---