Self-assembling block copolymers provide access to the fabrication of various ordered phases. In particular, the ordered spherical phases can be used to engineer soft mesocrystals with domain size at the 5-100 nm scales. Simple block copolymers, such as diblock copolymers, form a limited number of mesocrystals. However multiblock copolymers are capable to form more complex mesocrystals. We demonstrate that designed B1AB2CB3 multiblock terpolymers, in which the A- and C-blocks form spherical domains and the packing of these spheres can be controlled by changing the lengths of the middle and terminal B-blocks, self-assemble into various binary mesocrystals with space group symmetries of a large number of binary ionic crystals, including NaCl, CsCl, ZnS, α-BN, AlB2, CaF2, TiO2, ReO3, Li3Bi, Nb3Sn(A15), and α-Al2O3. This approach can be generalized to other terpolymers as well as to tetrapolymers to obtain ternary mesocrystals. Our study provides a new concept of macromolecular metallurgy for producing crystal phases in a mesoscale and thus makes multiblock copolymers a robust platform for the engineering of functional materials.

The ordering dynamics of cylinder-forming diblock copolymer/homopolymer blends confined in hexagonal potential wells is systematically investigated using timedependent Ginzburg−Landau (TDGL) theory. It is demonstrated that a high-efficient method to obtain large-scale ordered hexagonal patterns is to utilize corner-induced heterogeneous nucleation processes, in which nucleation events with controlled positions and orientations are triggered exclusively at the six corners of the confining hexagonal wells. Subsequent growth of the six domains originated from the corners leads to the formation of perfectly ordered patterns occupying the entire hexagonal well. The heterogeneous nucleation rate is regulated by the homopolymer concentration as well as the surface potential of the confining walls. Defect-free hexagonal patterns are obtained in hexagons with a diagonal size containing up to 61 cylinders (about 2 μm). The robustness of the method is examined by studying the tolerance window of the size-commensurability of the confining wells. The results indicate that controlled heterogeneous nucleation provides an efficient method for the fabrication of large-scale ordered patterns using graphoepitaxy of block copolymer self-assembly.

The formation of ordered phases from block copolymers is driven by a delicate balance between the monomer-monomer interaction and chain configurational entropy. The configurational entropy can be regulated by designed chain architecture, resulting in a new entropy-driven mechanism to control the self-assembly of ordered phases from block copolymers. An effective routine to regulate the configurational entropy is to utilize multiarm architecture, in which the entropic contribution to the free energy could be qualitatively controlled by the fraction of bridging configurations. As an illustration of this mechanism, the phase behavior of two AB-type multiarm block copolymers, B0-(Bi-Ai)m and (B1-Ai-B2)m where the minority A blocks form cylindrical or spherical domains, are examined using the self-consistent field theory (SCFT). The SCFT results demonstrate that the packing symmetry of the cylinders or spheres can be controlled by the length of the bridging B blocks. Several nonclassical ordered phases, including a novel square array cylinder with p4mm symmetry, are predicted to form from the AB-type multiarm block copolymers.

Developing functional porous materials as a platform for the heterogeneous catalytic oxidation reaction provides a good way to solve the high environmental issues resulted by traditional oxidation processes in the industry. This article reported a design and facile synthesis of N-rich functional porous organic polymers with mesopores such as Azo-POP-4, Azo-POP-5, and Azo-POP-6 based on the triaminotriphenylazobenzene subunit for the first time. The nitrogen-rich POPs with the triaminotriphenylazobenzene subunit was found to remove 85% of copper ions from water within 30 min. The as-synthesized Cu@Azo-POP-4 demonstrated high catalytic reactivity and selectivity in aerobic C–H bond oxidation to afford the desired ketones in high yield. In addition, the catalyst could be reused easily five times without decreasing the reactivity, which will help to design catalysts reducing environmental pollution and advance the chemical technology.

No abstract