Intermaterial Dividing Surfaces

Winey KI, Thomas EL, Fetters LJ (1991) Ordered morphologies in binary blends of diblock copolymer and homopolymer and characterization of their intermaterial dividing surfaces. J Chem Phys 95(12) 9367-9375... 

Figure 36 Schematic of proposed arrangement of A/B junctions on a flat intermaterial dividing surface (IMDS) for (a) the TB-4 lamellar (all interior blocks form loops) and (b) the SB-2 lamellar structures (interior blocks form bridges and loops), (c) Portion of a triply periodic IMDS of constant mean curvature for the SB-4 structure (interior blocks form bridges and loops). Reprinted from Tselikas, Y. Hadjichristidis, N. Lescanec, R. L. et at. Macromolecules 9S6, 29, 3390. °...

Figure 10 Scheme for the change of curvature of the intermaterial dividing surfaces by changing the relative interactions between the middle and the outer blocks in an ABC triblock terpolymer via chemical modification of B to B (xab = Xbc. Xab < Xb c)-... 

Besides a macrophase separation between the two block copolymers, also blends with the sequence ABC CB BC CBA can occur (a centrosymmetric structure of double layers of both diblock and triblock terpolymers). Another possibility is a kind of random sequence between BC and ABC block copolymers, which will occur when the C blocks of both diblock and triblock terpolymer do not show any preferential mixing with either C block. In this case, an aperiodic superstructure will be obtained. Another possible superstructure is the incorporation of the BC diblock with the same molecular orientation into the ABC structure, which will lead to a real effective increase of the volume fractions of both C and B with respect to A. Thus, a lamellar superstructure may only be expected for small volume fractions of diblock copolymer. For larger amounts of diblock chains a lamellar superstructure will be disfavored with respect to a superstructure with curved intermaterial dividing surfaces, such as cocontinuous, cylindrical, or spherical morphologies. Experiments on blends of lamellar S-B-M with lamellar B-M [242], and also of lamellar S-B-T with lamellar B-T, when all blocks were of about the same length proved the existence of the last case in Figure 22. 

Figure 17 Schemes for blends of lamellar ABC and BC block copolymers (a) macrophase separation (b) centrosymmetric double layers of diblock and triblock copolymer (c) centrosymmetric mixed layers of diblock and triblock copolymer (d) induction of curvature into the intermaterial dividing surfaces due to the increased effective volume...

When the copolymer is star shaped such as the ABC miktoarm star copolymer in which there are three different blocks (A-C blocks) with a common joint junction, the richer phase stmc-ture can be found [34,35]. When the interaction and length are the same, a symmetrical honeycomb structure can be found (Fig. 15.5a, only phases of blocks A and B are shown) and each block self-assembles into cylinder phase. The junction points are inhomogeneously distributed over the intermaterial dividing surface around cylinders formed by the respective blocks A-C. The region I shown in Figure 15.5a is the interface of different domains, which contains the mixtures of blocks A-C and star junctions. 

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