Microdomain dynamics/orientation

While thin polymer films may be very smooth and homogeneous, the chain conformation may be largely distorted due to the influence of the interfaces. Since the size of the polymer molecules is comparable to the film thickness those effects may play a significant role with ultra-thin polymer films. Several recent theoretical treatments are available [136-144,127,128] based on Monte Carlo [137-141,127, 128], molecular dynamics [142], variable density [143], cooperative motion [144], and bond fluctuation [136] model calculations. The distortion of the chain conformation near the interface, the segment orientation distribution, end distribution etc. are calculated as a function of film thickness and distance from the surface. In the limit of two-dimensional systems chains segregate and specific power laws are predicted [136, 137]. In 2D-blends of polymers a particular microdomain morphology may be expected [139]. Experiments on polymers in this area are presently, however, not available on a molecular level. Indications of order on an... 

The crystal orientation of crystalline blocks confined in nanolamellae is also reported [100,103]. Sun et al. [103], for example, investigated the crystal orientation of PCL blocks confined in lamellar microdomains of PCL-h-P4VP as a function of crystalline layer (i.e., PCL layer) thickness d. When d was larger ( 11 nm), the c-axis of PCL crystals was perpendicular to lamella surfaces (Fig. 10.11a), but parallel at smaller d ( 9nm) (Fig. 10.11b), and finally random at extremely small d ( 6nm) (Fig. 10.11c). This difference in crystal orientation is successfully explained by the dynamics of crystal growth within confined nanolamellae. In addition, the crystal orientation also depends significantly on the crystallization temperature T. Zhu et al. [100] reported the crystal orientation of poly(ethylene oxide) (PEO) blocks spatially confined in lamellar microdomains of PEO-( -PS as a function of T. They found that the c-axis of PEO crystals was perpendicular to lamella surfaces at higher (similar to Fig. 10.1 la), whereas it was parallel at lower (Fig. 10.1 lb). 

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