Side lamellar morphology

Figure 21.12 Structural models for PEP-fr-PEO-fr-PHMA block copolymer-aluminosilicate lamellar morphologies with a small PEP block. Top (a) and side (b) views of the pillared-lamellae structure.37 (Reprinted with permission from G. E. S. Toombes et al., Chem. Mater. 2008, 20, 3278-3287. Copyright 2008 American Chemical Society.)...

Figure 5.16 shows the WAXS profiles of PTeOX prepared at 80 °C, which shows no lamellar morphology as mentioned above. The profile of the 009 reflection (Fig. 5.16 a) of this polymer exhibits an asymmetrical tail at the lower angle side like the polymer prepared at 105 °C (Fig. 5.15), but not clearly distinguished in the 0018 reflection (Fig. 5.16b). Irradiation as well as aimealing change the asymmetry of the profile into a symmetrical form reducing the tail at the lower angle side this behavior is quite similar to that of the polymer prepared at 105 °C.

Cubic lipid phases have a very much more complex architecture than lamellar and hexagonal phases. Their structural characteristics have been elucidated only very recently, and it has become clear that their subtleties are the key to a variety of biological problems. We will consider those subtleties in some detail. The three fundamental cubic minimal surfaces - the P-surface, the D-surface and the gyroid (or G-surface), introduced in Chapter 1, can all be foimd in cubic lipid-water phases. The lipid bilayer is centred on the surface with the polar heads pointing outwards. Water fills the labyrinth systems on each side of the surface. These cubic phases will be termed Cp, CD and CG/ respectively. It is likely that there are other more complex IPMS morphologies in cubic phases of lipid-water mixtures, as yet uncharacterised. 

In liquid-crystalline polymers, order may include packing of mesogenic, rigid side chains. Correspondingly, terrace-like (layered) morphologies can form in size-domains, which are in the range of typical lamellar dimensions. These can easily be visualized by AFM. 

Fig. 42. Theoretical phase diagram for diblock copolymers in the weak segregation limit The left side shows the mean field result of LeiUer [43], the right side the theory of Fredrickson and Jfelfand [58] which includes fluctuation corrections, for an effective degree of polymerization N = 104. LAM, Hex, BCC denote the various mesophases lamellar, hexagonal (Le., cylindrical morphology) and body-centered cubic (i.e., spherical micellar morphology). From Bates and Fredrickson (39)...

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