Photoluminescent honeycomb films templated by microwater droplets

Honeycomb-patterned hybrid films of surfactant-encapsulated polyoxometalates by a breath figure method and its electrocatalysis for BrO3−

Surfactant-encapsulated POMs can self-assemble into ordered porous honeycomb films under a moist atmosphere. We successfully fabricated (DODA)₁₀{Cu₄(PW₉)₂} honeycomb films by using a one-step method.

Breath Figure Method for Construction of Honeycomb Films

Honeycomb films with various building units, showing potential applications in biological, medical, physicochemical, photoelectric, and many other areas, could be prepared by the breath figure method. The ordered hexagonal structures formed by the breath figure process are related to the building units, solvents, substrates, temperature, humidity, air flow, and other factors. Therefore, by adjusting these factors, the honeycomb structures could be tuned properly. In this review, we summarized the development of the breath figure method of fabricating honeycomb films and the factors of adjusting honeycomb structures. The organic-inorganic hybrid was taken as the example building unit to discuss the preparation, mechanism, properties, and applications of the honeycomb films.

Porphyrin-based honeycomb films and their antibacterial activity

Micrometer-sized porous honeycomb-patterned thin films based on hybrid complexes formed via electrostatic interaction between Mn(III) meso-tetra(4-sulfonatophenyl) porphine chloride (an acid form, {MnTPPS}) and dimethyldioctadecylammonium bromide (DODMABr). The morphology of the microporous thin films can be well regulated by controlling the concentration of MnTPPS-DODMA complexes, DODMABr, and polystyrene (PS), respectively. The formation of the microporous thin films was largely influenced by different solvents. The well-ordered microporous films of MnTPPS-DODMA complexes exhibit a more efficient antibacterial activity under visible light than those of hybrid complexes of nanoparticles modified with DODMABr, implying that well-ordered microporous films containing porphyrin composition can improve photochemical activity and more dominance in applications in biological medicine fields.

Multiple interfaces in self-assembled breath figures

Progress in the breath figure method is reviewed by emphasizing the role of the multiple interfaces and the applications of honeycomb films in separation, biocatalysis, biosensing, templating, stimuli-responsive surfaces and adhesive surfaces.

Advances in Fabrication Materials of Honeycomb Structure Films by the Breath-Figure Method

Creatures in nature possess almost perfect structures and properties, and exhibit harmonization and unification between structure and function. Biomimetics, mimicking nature for engineering solutions, provides a model for the development of functional surfaces with special properties. Recently, honeycomb structure materials have attracted wide attention for both fundamental research and practical applications and have become an increasingly hot research topic. Though progress in the field of breath-figure formation has been reviewed, the advance in the fabrication materials of bio-inspired honeycomb structure films has not been discussed. Here we review the recent progress of honeycomb structure fabrication materials which were prepared by the breath-figure method. The application of breath figures for the generation of all kinds of honeycomb is discussed.

Honeycomb-patterned film segregated with phenylboronic acid for glucose sensing

Phenylboronic acid (PBA)-functionalized materials have attracted considerable attention because of their potential applications in many fields. In this paper, we report a PBA-segregated honeycomb-patterned porous film (HPPF) for glucose sensing. Polystyrene-block-poly(acrylic acid-co-acrylamidophenylboronic acid) with different contents of PBA pendants was synthesized via atom transfer radical polymerization (ATRP) followed by a coupling reaction. PBA-functionalized HPPFs were then fabricated by the breath figure method. Results indicate that the composition of the copolymers and the relative humidity play key roles in pore size and regularity of the films. Using Alizarin Red S (ARS) that does not emit fluorescence itself as a fluorescent probe, it is confirmed that PBA pendants are mainly distributed at the pore wall, instead of at the outer surface of HPPFs. This distribution is caused by the segregation of hydrophilic PBA-blocks toward the condensed water droplets, which act as templates for the pore formation. Quartz crystal microbalance results demonstrate that the PBA-functionalized HPPFs show high sensitivity in glucose sensing, which is owing to the segregation of PBA pendants at the pore wall as well as the large specific surface area of the porous films.

Macroporous honeycomb films of surfactant-encapsulated polyoxometalates at air/water interface and their electrochemical properties

A series of surfactant-encapsulated polyoxometalates which have different compositions, shapes, and sizes, are able to self-assemble to the highly ordered honeycomb-structured macroporous films at the air/water interface without any extra moist airflow across the solution surface. The honeycomb film pores in the average diameter of 2-3 μm are obtained, which are independent of the polyoxometalates. It is speculated that the cooled micrometer water droplets act as the necessary templates for the formation of macropores, and the stability of these water droplets is crucial during the self-assembly. With increasing the concentration of surfactants, various morphologies from lowly ordered honeycomb films to highly ordered honeycomb films and then to disordered fragments can be modulated. The interfacial tension between chloroform solution and water droplets induces the changes of films. High-resolution TEM observations indicate a close-packed lamellar structure in the ordered honeycomb film walls. The self-assembly successfully performs the transfer of functional polyoxometalates from bulk solutions to interfacial films. Consequently, the produced honeycomb films present electronic activities, such as ferromagnetism and electrochemical properties. These detailed researches will enrich the studies based on materials obtained by encapsulations in cationic surfactants to construct newly nanostructures of polyoxometalates at interfaces, and promote the potential applications of the honeycomb films of surfactant-encapsulated polyoxometalates in advanced materials.