Weak segregation limit

The expressions 2.7-2.12 which define the Leibler structure factor have been widely used to interpret scattering data from block copolymers (Bates and Fredrickson 1990 Mori et al. 1996 Rosedale et al. 1995 Schwahn et al. 1996 Stiihn et al. 1992 Wolff et al. 1993). The structure factor calculated for a diblock with / = 0.25 is shown in Fig. 2.39 for different degrees of segregation JV. Due to the Gaussian conformation assumed for the chains (Leibler 1980), the domain spacing in the weak segregation limit is expected to scale as d Nm. 

Fig. 2.40 Phase diagram for diblock copolymers in the weak segregation limit (Leibler 1980).

Matsen (1995ft) also calculated sections through the phase diagram in the weak segregation limit for a fixed value for blends with given values of/ . Because asymmetric copolymers were considered, ordered phases other than lamellae... 

Figure 13.11 Phase diagram for a diblock copolymer in the weak-segregation limit predicted by (a) the Leibler mean-field theory and (b) the Fredrickson-Helfand fluctuation theory. (From Bates et al., reprinted with permission from J. Chem, Phys. 92 6255, Copyright 1990, American Institute of Physics.)...

In the weak-segregation limit, Amundson and Helfand (1993) estimated... 

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