Through polymers polymer structural characteristics

EPITAXY. An oriented crystalline growth between two crystalline solid surfaces of different chemical composition, in which the surface of one crystal provides, through its lattice structure, preferred positions lor the deposition of the second crystal. This behavior is characteristic of some types of high polymers. 

Synthetic strategy has been developed that permits the efficient preparation of organometallic polymers which have structural characteristics necessary for nonlinear optical behavior. Complex t 5-C5H4CH20H - i 5-C5H4CH=C(CN)C02Et Fe (4) was prepared and homopolymerized through a thermally induced transesterification-polycondensation reaction. 

The characteristics of pore structure in polymers is a key parameter in the study of diffusion in polymers. Pore sizes ranging from 0.1 to 1.0 pm (macroporous) are much larger than the pore sizes of diffusing solute molecules, and thus the diffusant molecules do not face a significant hurdle to diffuse through polymers comprising the solvent-filled pores. Thus, a minor modification of the values determined by the hydrodynamic theory or its empirical equations can be made to take into account the fraction of void volume in polymers (i.e., porosity, e), the crookedness of pores (i.e., tortuosity, x), and the affinity of solutes to polymers (i.e., partition coefficient, K). The effective diffusion coefficient, De, in the solvent-filled polymer pores is expressed by ... 

Diffusion through polymers is influenced not only by the polymer s structure, but also by the molecular structure of the solute. The solute structure may also influence the rate of partitioning into the elution medium. However, there is only a low relationship between these factors. The influence of gel structure on the diffusion characteristics of solutes through polyHEMA hydrogels has been reported [146]. 

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