Self-seeding method

Scanning Force Microscopic Study of Polyethylene Single Crystals Prepared by a Self Seeding Method... 

Crystallization conditions of HDPE single crystals in self-seeding method. 

Figure 6. Scanning angle dependence of lateral force for the HDPE single crystal with Mw of 520k, 120k and 32k prepared by self-seeding method.

Jiang, X. C., Zeng, Q. H. and Yu, A. B. (2006). A self-seeding coreduction method for shape control of silver nanoplates. Nanotechnology 17 4929-4935. 

Other methods to create nanocrystals include physical vapor synthesis (in which a supersaturated vapor is seeded into a cold gas to nucleate nanocrystals), arc discharge methods (very effective in making buckyballs), and protein-mediated self-assembly methods, among others. Here I focus on wet chemistry methods and vapor deposition onto a surface. 

In order to obtain an ideally nucleated polymer, it is heated to just above its melting point so that large number of residual crystal fragments exist in the melt and act as nuclei. This method is referred to as self-seeding or self-nucleation (Blundell 1966). Zhao et al. have evaluated crystallization behavior of propylene/ethylene copolymer by self-seeding approach (Zhao et al. 2001), which was found in good agreement with the earlier published DSC data (Laihonen et al. 1970,1997). 

Fleisher et al. [12] studied the self-diffusion of oil and water in rape seeds. The selfdiffusion of oil was found to be completely restricted. The experiments could be explained in toms of the model of diffusion within spherical droplets and a Gaussian mass distribution of the droplet radii. At the same time Van den Enden et al. [9] introduced the technique described above. It is a rapid method for the determination of water droplet size distributions in spreads by using low resolution pulsed field gradient NMR. Their method was based on the recognition that a set of echo attenuation values (R) as a function of the field gradient pulsed width, obtained under conditions where R is independent of the time allowed for diffusion, contains all the necessary information on the water droplet size distribution (see above). A log-normal distribution of water droplet sizes was assumed. 

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