The permeability of diamond and other microphase-separated morphologies in copolymer films.

A method is proposed for the theoretical assessment of potential membrane properties in materials based on microphase-separated block copolymer films subjected to the etching of one of the components. The concepts of topological permeability and connectivity contrast introduced by the authors are used to compare the percolation characteristics of simple cubic, diamond, and diamond-like morphologies compatible with the slit geometry and specified by a given distribution of the order parameter. The diamond-like morphology, which has the most promising transport characteristics, can be formed in a thin film of diblock copolymer AB placed on a chemically structured substrate.

3D bicontinuous diamond-like morphologies in thin films of soluted block copolymers.

As shown theoretically earlier via both weak segregation and self-consistent field theories, ordering of confined molten di- and tri-block copolymer morphologies in the presence of a proper 1D patterned substrate could induce the formation of 3D bicontinuous (in particular, diamond-like) morphologies (DLMs). The purpose of the present paper is to study, unlike the previous studies, how the stable DLMs are formed not in a melt but in a solution of symmetric diblock copolymers with a nonselective solvent that wets the thin film on the patterned substrate. It is shown, via a straightforward self-consistent field calculation of the total solution free energy for various competing phases, that the DLM could be formed in the solutions (with the solvent volume fraction of 0.

Thermodynamics of 3D diamond-like epitaxial (film) morphologies on 1D modulated substrate: Weak crystallization theory.

Being inspired by recent theoretical findings in block copolymer ordering, we present, within the simplest version of the Landau weak crystallization theory, a consistent treatment of the thin film thermodynamics. It is first shown that a proper design of the period of a 1D modulated substrate results in the formation of a 3D morphology whose symmetry is close to a cubic diamond one and differs from the latter due to a symmetry violation caused by the block copolymer-substrate interaction. The corresponding phase portraits are built.

Nonmonotonic incommensurability effects in lamellar-in-lamellar self-assembled multiblock copolymers.

Using the self-consistent-field theory numerical procedure we find that the period D of the lamellar-in-lamellar morphology formed in symmetric multiblock copolymer melts A(mN/2)(B(N/2)A(N/2))(n)B(mN/2) at intermediate segregations changes nonmonotonically with an increase in the relative tail length m. Therewith D reveals, as a function of the Flory chi-parameter, a drastic change in the vicinity of the internal structure formation, which can be both a drop and a rise, depending on the value of m. It is argued that the unusual behavior found is a particular case of a rather general effect of the incommensurability between the two length scales that characterize the system under consideration.

Nonconventional morphologies in two-length scale block copolymer systems beyond the weak segregation theory.

The order-disorder and order-order transitions (ODT and OOT) in the linear multiblock copolymers with two-length scale architecture A(fmN)(B(N2)A(N2))(n)B((1-f)mN) are studied under intermediate cooling below the ODT critical point where a nonconventional sequence of the OOTs was predicted previously [Smirnova et al., J. Chem.

Adsorption of multiblock copolymers onto a chemically heterogeneous surface: a model of pattern recognition.

We present a statistical mechanical model, which is used to investigate the adsorption behavior of two-letter (AB) copolymers on chemically heterogeneous surfaces. The surfaces with regularly distributed stripes of two types (A and B) and periodic multiblock copolymers (Al)B(l))(x) are studied. It is assumed that A(B)-type segments selectively adsorb onto A(B)-type stripes.