Theoretical Study of Phase Behaviors of Symmetric Linear BABAB Pentablock Copolymer.

The nanostructures that are self-assembled from block copolymer systems have attracted interest. Generally, it is believed that the dominating stable spherical phase is body-centered cubic (BCC) in linear AB-type block copolymer systems. The question of how to obtain spherical phases with other arrangements, such as the face-centered cubic (FCC) phase, has become a very interesting scientific problem.

Formation of Perpendicular Three-Dimensional Network Nanostructures in ABC-Star Copolymers.

Perpendicular arrangements in hierarchical nanostructures show superior mechanical properties and provide great opportunities for the development of advanced membranes because different channels are connected by the perpendicular blocks. To obtain these perpendicular hierarchical nanostructures, we use a simple ABC-star terpolymer because of the existence of a conjunction point by using the A block as a polymer network template, which guides the BC phase separation accordingly. When χ is 10, the formed phase and the corresponding phase diagram of ABC-star are similar to those of the AB triblock because of the mixture between the B and C blocks.

Enlarged Phase Regions of Multi-Continuous 3D Network Nanostructures in ABC Triblock Copolymers.

Aiming to increase the stability region of three-dimensional (3D) multi-continuous morphologies due to great potential application in smart sensors, gas separation membranes, and photonic materials, in this paper, we control the block ratio of different channels of an ABC triblock copolymer according to the curvature of these multi-continuous nanostructures. In the small A volume fraction region, the multi-continuous gyroid nanostructure is stable when / equals 1/3, while two-domain lamellae () and three-layer lamellae () are obtained when B and C blocks have comparable volume fractions, suggesting that changing the / ratio is an effective way of forming multi-continuous polymer network nanostructures. Interestingly, a large phase region of the core-shell gyroid and are found under the condition of / = 4.

Formation of Multicontinuous 3D Network Nanostructures with Increased Complexity in ABC-Type Block Copolymers.

The multicontinuous network nature of polymer nanostructures provides them with many opportunities to fabricate multifunctional materials with specific mechanical, transport, optical, and other novel properties. In this paper, we generate an effective design principle to craft a series of multicontinuous network structures with controllable channels, including multicontinuous gyroid and network morphologies via the self-assembly of ABC-type block copolymers. Importantly, we achieve a much wider (∼25%) compositional range than that of AB diblock copolymers (∼3%), which would increase the widespread application of these multicontinuous polymer networks.

Influence of Branches on the Phase Behavior of (AB) Starlike Block Copolymer under Cylindrical Confinement.

Experimentally, self-assembled morphologies of the (AB) starlike block copolymer are strongly dependent on the number of arms, . For example, the 2- and 4-arm starlike block copolymers exhibited the morphologies of hexagonally arrayed polystyrene cylinder in the polyisoprene matrix while order-bicontinuous nanostructures were observed in 8-, 12-, and 18-arm stars. Theoretically, we found that the transition sequence for (AB) is → → → , which becomes → when > 6.

Rich Variety of Three-Dimensional Nanostructures Enabled by Geometrically Constraining Star-like Block Copolymers.

The influence of star-like architecture on phase behavior of star-like block copolymer under cylindrical confinement differs largely from the bulk (i.e., nonconfinement).

A general route to nanocrystal kebabs periodically assembled on stretched flexible polymer shish.

Assembling nanoparticles into one-dimensional (1D) nanostructures with precisely controlled size and shape renders the exploration of new properties and construction of 1D miniaturized devices possible. The physical properties of such nanostructures depend heavily on the size, chemical composition, and surface chemistry of nanoparticle constituents, as well as the close proximity of adjacent nanoparticles within the 1D nanostructure. Chemical synthesis provides an intriguing alternative means of creating 1D nanostructures composed of self-assembled nanoparticles in terms of material diversity, size controllability, shape regularity, and low-cost production.

Self-assembly of miktoarm star-like ABn block copolymers: from wet to dry brushes.

Self-assembly of miktoarm star-like ABn block copolymer in both selective solvent (A- or B-selective) and miscible homopolymer matrix (A or B homopolymer), that is, formation of micelles, was for the first time investigated by theoretical calculations based on self-consistent mean field theory. Interestingly, the calculation revealed that the size of micelles in solvent was smaller than that in homopolymer under the same conditions. In B-selective solvent, with increasing number of B blocks n in miktoarm star-like ABn block copolymer at a fixed volume fraction of A block, the micellar size decreased gradually.

Self-assembly of 21-arm star-like diblock copolymer in bulk and under cylindrical confinement.

Phase behaviors of a 21-arm star-like diblock copolymer in bulk and under confinement were explored by using the pseudo-spectral method of a self-consistent mean field theory. An asymmetrical phase diagram in bulk was constructed by comparing the free energy of different structures. The gyroid phase was found to possess a large phase region when the inner block in the star-like diblock copolymer has a small volume fraction, suggesting the propensity to form the gyroid phase under this condition.

Phase behaviors and ordering dynamics of diblock copolymer self-assembly directed by lateral hexagonal confinement.

The thermodynamics and kinetics of the self-assembly of cylinder-forming diblock copolymers directed by the lateral confinement of hexagons have been studied by the combination of self-consistent field theory (SCFT) calculation and time-dependent Ginzburg-Landau (TDGL) theory simulation. The SCFT calculations are used to determine the stability of candidate 2D and 3D equilibrium phases formed in small-size hexagons. Our phase diagram predicts the existence of stable phase regions with respect to the hexagonal size, which is centered around the optimal size with an extent of about a period, for the phases of perfect hexagonal cylinders.

The influence of volume fractions on the phase behaviors of linear A(BC)(n)BA' multiblock terpolymers.

The phase behaviors of A(BC)(n)BA' linear multiblock terpolymers are investigated using the pseudo-spectral method of self-consistent field theory by varying the volume fractions of different blocks. The relative stability among the lamellae-in-lamellae structures with different BC internal layers is tuned by the volume fraction of the two long tails. A larger A volume fraction favors the formation of structures with fewer BC thin layers.

Stability of perpendicular and parallel lamellae within lamellae of multiblock terpolymers.

The phase behaviors of multiblock terpolymer A(BC)(n)B (or A(BC)(n)) with equal volume fractions of A and compositional symmetric (BC)(n)B (or (BC)(n)) are investigated by using the pseudospectral method of the self-consistent mean field theory. These terpolymers can self-assemble into hierarchical lamellar phases of perpendicular or parallel lamellae within lamellae, and the number of B/C thin layers in the parallel phase can be varied. The relative stability among these hierarchical lamellar phases can be tuned by the three interaction parameters of χ(AB)N, χ(AC)N, and χ(BC)N.

Real-space self-consistent mean-field theory study of ABC star triblock copolymers.

The phase behavior of ABC star triblock copolymers is examined using real-space self-consistent mean-field theory. The central part of the triangular phase diagram for ABC triblock copolymers with equal A/B, B/C, and C/A interactions is determined by comparing the free energy of a number of candidate ordered phases. In this region of the phase diagram, the dominant microstructures are cylinders with polygonal cross sections or two-dimensional polygon-tiling patterns.

Self-assembly of ABC star triblock copolymers under a cylindrical confinement.

Self-assembly of ABC star triblock copolymers confined in cylindrical nanopores is studied using real-space self-consistent mean-field theory. Specifically, the investigation focuses on the confined self-assembly of a triblock copolymer which forms hierarchical lamellae in the bulk. Generically, the hierarchical lamellae can be parallel or perpendicular to the pore surfaces.