Crystalline Morphology of Block Copolymers with Glassy Amorphous Blocks

2 Crystalline Morphology of Block Copolymers with Glassy Amorphous Blocks 

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). 

It is clear from many experimental results that crystalline blocks confined in isolated nanodomains surrounded by glassy (or hard) matrices show unique crystal orientations as compared with those by soft matrices (Section 10.3.3.). However, the physical properties of such block copolymers with crystalline microdomain structures have scarcely been investigated up to now. 

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