Ultralong cylindrical micelles impregnated with gold nanoparticles were fabricated via the convergence of a surface-templated self-assembly method and the fragmentation of gold nanowires driven by Rayleigh instability. This approach could be proposed as an unconventional method for the fabrication of hybrid nanomaterials.

Janus particles with two different compartments have enormous potential as building blocks of hierarchically multifunctional nanomaterials. One of the most versatile and powerful methods to fabricate Janus micelles is through the solution-state self-assembly of block copolymers. In this study, we applied the Monte Carlo simulation to study the self-assembly of a AB/BC diblock copolymer mixture in A- and C-selective solvents. Our simulations predicted a variety of novel Janus micelles, which include Janus-like cylinders, lamellas, vesicles, and rings, all of which were self-assembled from amphiphilic A4B6/B6C4 copolymers. The effects of control parameters, which include the solvent quality for solvophobic B blocks (εBS) and the incompatibility between the solvophilic A and C blocks (εAC), on the formation of Janus micelles were examined, and a generic phase diagram in εBS × εAC was constructed. The phase diagram demonstrates that the micellar shape mainly depends on εBS, whereas the formation of the Janus architecture is controlled by εAC. Moreover, the formation pathways of the Janus lamella, vesicle, and ring were investigated and their formation mechanisms were investigated.

Liquid chromatography at the critical condition (LCCC) method has been proposed as an attractive method to characterize individual blocks in block copolymers because it can make one block chromatographically “invisible” at the critical condition of its corresponding homopolymer. However, observable dependence of retention time on the “invisible” block length was reported in LCCC experimental studies of diblock copolymer [Macromolecules 2001;34:2353–2358; Anal Chem 2001;73:3884–3889.]. In this study, we re-examined the validity of the LCCC method for AB, BAB and ABA block copolymers by the lattice Monte Carlo simulation method with using random walk (RW) and self-avoiding walk chain (SAW) models. In the current study, the A block is set in the size exclusion mode and is chromatographically “visible”. The interaction between the B type monomer and the column surface are varied to identify the critical condition of B block in the block copolymer. Our simulation results establish that individual block, i.e. B block in the current work, from the block copolymer has its own critical condition for the first time. However, it was also found that the critical condition of B block might be different from the critical condition of B homopolymer. The critical condition of B block in the AB diblock is exactly equal to the critical condition of B homopolymer only when the chain is modeled by RW model. However, deviations of the critical condition of B block away from that of the B homopolymer are observed for AB copolymer using SAW model, and also for BAB and ABA copolymers whether the chain is modeled by RW or SAW models. Moreover, under the critical condition of B homopolymer, no dependence of the partition coefficient on the “invisible” B block length was observed for the AB and BAB copolymers when the copolymer chains were modeled by RW model. Distinct dependence of the partition coefficient of these two types' copolymers on the B block length was found when the chain was modeled by SAW model. For the ABA triblock copolymer, slight dependence of the partition coefficient on B block length was observed even for the RW model while this dependence became much stronger when the chain was modeled by SAW model. Moreover, it was also found that the partition coefficient of ABA copolymer is much smaller than those of AB and BAB copolymers under the critical condition of B homopolymer because of the chain architecture effect. The current study confirms that the block in the block copolymer is hard to be made completely chromatographically “invisible” because the intrinsic nature of the excluded volume interaction existed in real polymer system.

We present a simple but efficient route to prepare a highly anisotropic conductive plastic thin film from the polypropylene/(styrene-ethylene/butadiene-styrene) triblock copolymer/graphene blend via shear-induced self-assembly. Under the shear-flow induction, GE nanosheets dispersed in the polymer matrix can spontaneously assemble into ordered parallel stripes, which endow the materials significantly conductive anisotropy. The electrical resistivity in the direction parallel to the graphene stripes is almost four orders of magnitude lower than that which is perpendicular to the stripes. This study provides a new method for the precise control of the organization of functional nano-objects in polymer matrix, which can be widely extended to the fabrication of other multifunctional anisotropic materials of interest in various fields.Keywords: conductive anisotropy; graphene; self-assembly; shear flow; thin films;

Polystyrene (PS) and poly(methyl methacrylate) (PMMA) blends filled with octadecylamine-functionalized graphene (GE-ODA) have been fabricated to obtain conductive composites with a lower electrical percolation threshold according to the concept of double percolation. The dependence of the electrical properties of the composites on the morphology is examined by changing the proportion of PS and PMMA. Our results reveal that the electrical conductivity of the composites can be optimal when PS and PMMA phases form a cocontinuous structure and GE-ODA nanosheets are selectively located and percolated in the PS phase. For the PS/PMMA blend (50w/50w), the composites exhibit an extremely low electrical percolation threshold (0.5 wt %) because of the formation of a perfect double percolated structure. Moreover, the rheological properties of the composites are also measured to gain a fundamental understanding of the relationship between microstructure and electrical properties.Keywords: double percolation; electrical properties; functionalized graphene; immiscible polymer blends; rheological properties;

In the current study, we applied the Monte Carlo method to study the self-assembly of linear ABC amphiphiles composed of two solvophobic A and B blocks and a solvophilic C block. A great number of multicompartment micelles are discovered from the simulations and the detailed phase diagrams for the ABC amphiphiles with different block lengths are obtained. The simulation results reveal that the micellar structure is largely controlled by block length, solvent quality, and incompatibility between the different block types. When the B block is longer than or as same as the terminal A block, a rich variety of micellar structures can be formed from ABC amphiphiles. By adjusting the solvent quality or incompatibility between the different block types, multiple morphological transitions are observed. These morphological sequences are well explained and consistent with all the previous experimental and theoretical studies. Despite the complexity of the micellar structures and morphological transitions observed for the self-assembly of ABC amphiphiles, two important common features of the phase behavior are obtained. In general, the micellar structures obtained in the current study can be divided into zero-dimensional (sphere-like structures, including bumpy-surfaced spheres and sphere-on-sphere structures), one-dimensional (cylinder-like structures, including rod and ring structures), two-dimensional (layer-like structures, including disk, lamella and worm-like and hamburger structures) and three-dimensional (vesicle) structures. It is found that the micellar structures transform from low- to high- dimensional structures when the solvent quality for the solvophobic blocks is decreased. In contrast, the micellar structures transform from high- to low-dimensional structures as the incompatibility between different block types increases. Furthermore, several novel micellar structures, such as the CBABC five-layer vesicle, hamburger, CBA three-layer ring, wormlike shape with bumps on the sides, and disk shape with bumps on the edge, are predicted in this study. The formation pathways of ring, hamburger, and worm-like micelles are also examined and their formation mechanisms are well elucidated.

Multicompartment micelles, especially those with highly symmetric surfaces such as patchy-like, patchy, and Janus micelles, have tremendous potential as building blocks of hierarchical multifunctional nanomaterials. One of the most versatile and powerful methods to obtain patchy multicompartment micelles is by the solution-state self-assembly of linear triblock copolymers. In this article, we applied the simulated annealing method to study the self-assembly of ABC linear terpolymers in C-selective solvents. Simulations predict a variety of patchy and patchy-like multicompartment micelles with high symmetry and also yield a detailed phase diagram to reveal how to control the patchy multicompartment micelle morphologies precisely. The phase diagram demonstrates that the internal segregated micellar structure depends on the ratio between the volume fractions of the two solvophobic blocks and their incompatibility, whereas the overall micellar shape depends on the copolymer concentration. The relationship between the interfacial energy, stretching energy of chains and the micellar morphology, micellar morphological transition are elucidated by computing the average contact number among the species, the mean square end-to-end distances of the whole terpolymers, the AB blocks in the terpolymers, the AB diblock copolymers, and angle distribution of terpolymers. The anchoring effect of the solvophilic C block on micellar structures is also examined by comparing the morphologies formed from ABC terpolymers and AB diblock copolymers.