Lamellar domain morphology

The effects of composition distribution on the morphology of PS-fc-P2VP diblock copolymers were investigated by Matsushita et al. [160]. They produced PS- -P2VP samples with various composition distributions but with constant average composition by blending. If the polydispersity indices of each block were lower than 1.7, the expected lamellar domains were detected (Fig. 49). 

Fig. 5 Schematic cross-sections of thin film morphologies of the topographic pattern grown by a graphoepitaxy method. A micropattern with different lamellar domain orientation is shown, a Surface-parallel lamellae, typical of film thickness t greater than the natural equilibrium period Lq. b Surface-perpendicular lamellae, typical of film thickness t less than L0. (adapted from [41])...

The effect of surface constraints on the morphology of the star-block copolymers was studied by Thomas and coworkers [337]. Thin film droplets of samples with various functionalities were studied, and the ones that exhibited the OBDD structure in the bulk were found to be cylinders in this case. In an independent study, the lamellar domain spacings of 4-arm and 12-arm star-block copolymers of styrene and isoprene were found, by TEM and SAXS, to be the same as those of the arm material [338]. 

Other typically observed morphologies are co-continuity of phases and dispersion of lamellar domains. Co-continuity might allow to draw on properties of both constituents, yielding for example a stiffness/ductility balance not achievable with pure polymers. Lamellar morphologies will obviously yield improved barrier performance when the proper constituents are selected. 

Figure 15. Concept of microphase stabilized ferroelectric liquid crystal (MSFLC). The black domain represents the coil block. Only lamellar microdomain morphology is shown in the figure. The FLC supramolecular pitch is unwound by the block microdomain [109, 130],...

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