Sliding-diffusion thickening

There are three kinds of diffusion (i) within the isotropic phase (ii) the interface (between the isotropic and the crystalline phases) and (iii) the crystalline phase. In the case of a polymer system, the topological nature of polymer chains assumes an important role in all three kinds of diffusion, which has been shown in the chain sliding diffusion theory proposed by Hikosaka [14,15]. It is obvious that any nucleus (a primary nucleus and a two-dimensional nucleus) and a crystal can not grow or thicken without chain sliding diffusion. 

This continuous thickening is obviously controlled by the chain-sliding diffusion in the crystals. The similar thickness profiles at the edges of lamellar polymer crystals have been observed in experiments (Reiter 2014). 

The logarithmic-time dependence of crystal thickness can be deduced easily. By assuming a frictional barrier (AfJ for chain-sliding diffusion proportional to the lamella thickness (/), thus the thickening rate of monolayer lamellar crystal under a certain temperature is... 

Wang M, Gao H, Zha L, Chen E-Q, Hu W. Systematic kinetic analysis on monolayer lamellar crystal thickening via chain-sliding diffusion of polymers. Macromolecules 2012 46 164-171. 

To one such slide, a tissue dampened with 0.1 N HCl, 2% starch and 10% potassium iodide solution (made fresh daily) is applied. A weak color reaction, which is much stronger at the locations of charcoal flecks and any white droplets are potassium oxides and carbonate. A tissue overlay of hexamethylene rosaniline hydrochloride (crystal violet) is applied to another fresh slide. Bleaching and pH effects are observed. Other pH indicators and other peroxide sensitive solutions should be applied. The author finds that thickening the reagents with carbohydrate and polyvinyl alcohol to slow diffusion rates is advisable in some cases. 

---