The development of high-strength bonding materials requires a precise balance between key molecular components to allow for efficient adhesion at substrate interfaces and strong cohesive reinforcement in bulk medium. Furthermore, the cooperative tuning of both strength and adhesive ductility is desirable for achieving multiple benefits, including preventing a mismatch between adhesives and a wide-range of substrate moduli (ranging from stiff to flexible), as well as the ability to withstand mechanical load variations that may be sudden or occurring at regular intervals. This work presents a biomimetic design used to access variable strength and ductility in a next-generation adhesive. A host of random linear copolymers comprised of mussel-mimetic anchoring molecular units, and readily available alkyl methacrylates, were thoroughly investigated in order to determine the role of aliphatic interactions in macroscopic bonding. Systematic manipulations of several parameters, including alkyl chain length/structural isomers, composition ratios, and formulation conditions, were carried out to identify the optimal conditions for the best performance. Furthermore, the efficient bonding ability of these adhesives for a wide-range of substrates (e.g. metals, glass, and plastics) in both similar and dissimilar attachments, serves to demonstrate the versatility and tunable functionalities of the present strategy.

Hydrophobized plant polyphenols can be easily prepared by rational and controlled etherification of highly abundant aromatic hydroxyls with linear alkyl chains. The resultant organo-soluble polyphenols spontaneously formed fibrous structures and unravelled to be potential adhesive, anticorrosion, and antibacterial coatings.

The design, synthesis, and functions of cavity structures have been paid much attention in supramolecular chemistry and related nanotechnology. Not limited to simple inclusion phenomena, the manipulation of cavity structures and functions are essential for stimuli-responsive functions. In addition, more advanced functions require regulation of mutual interaction, cooperative actions and harmonized actions between cavity units. With this background, a novel concept of cavity nanoarchitectonics is explained here with recent research examples. In the initial parts of this highlight, molecular cavity manipulations, mainly using modified cyclodextrins for biomedical applications, are exemplified. In these examples, molecular-level architectonics (molecular decoration) and small-scale supramolecular nanoarchitectonics are used to improve properties for pharmaceutical applications and cancer therapy. The later part of this highlight introduces future challenges in cavity nanoarchitectonics. Based on designed constructions of cavity networks and arrays, macroscopic mechanical motions can lead to cavity manipulations for drug delivery and molecular capture. From biomedical applications to mechanical cavity manipulation, the great potential and possibilities of cavity nanoarchitectonics are demonstrated in this highlight.

The anticorrosion ability of ultrathin coatings with bio-inspired organic polymers is demonstrated. We prepared a series of catechol-containing poly(alkyl methacrylate)s by free radical polymerization. These copolymers were spin-coated on various corrosion susceptible metal/alloy substrates of magnesium, aluminum, copper and iron without any harsh pretreatment. Several key factors like molecular structure, composition ratio and processing conditions were wisely tailored to afford a transparent, firm and sub-micron polymer coating on those substrates. Corrosion resistance of the polymer-coated substrates was thoroughly investigated by immersion tests in salt-water and acidic solutions, polarization tests, and visual inspection. Formation of an anomalous dense layer of ca. 5 nm thickness adjacent to the metal surface and a remarkable effect of thermal treatment were clearly observed by neutron reflectivity measurements, leading to a highly protective ability against foreign molecules e.g. water or corrosive ions. A key molecular design for anticorrosive polymer coating was revealed to be a combination of strong and versatile binding ability of catechol units and defect free polymer layers formed on the metal substrates in the presence of hydrophobic alkyl chains.

An efficient hydrosolubilizing reagent for [60]fullerene (C60) was newly developed with a γ-cyclodextrin (γ-CD) derivative having triazole-methoxypyridyl moieties at its 6-hydroxyl positions (PCD). Through solid-state mechanochemical complexation, PCD forms a hydrosoluble inclusion complex of C60 with a concentration of more than 70 mM. This is approximately 90 times greater than that with non-substituted γ-CD prepared by the same method.

In the present paper, we ascertain two novel findings on chiral-index-selective binding/separating of single-walled carbon nanotubes (SWNTs) with a nonaromatic polymer, poly(dialkylsilane) (PSi). PSi is a typical σ-conjugated polymer, composed of alkyl side chains attached to the silicon (Si)-catenated main chain. First, PSi’s with linear alkyl side chains showed significant diameter-selective wrapping for SWNTs with ca. 0.9 nm in diameter, resulting in the selective separation of (7,6) and (9,4) SWNTs. Its driving force was demonstrated to be cooperative CH−π interactions among the alkyl side chains of PSi’s and the curved graphene of SWNTs. Second, the dynamic wrapping behavior of PSi’s onto SWNTs was elucidated with time-resolved UV spectroscopy. Highly anisotropic UV absorption of PSi along the Si main chain was utilized as a “chromophoric indicator” to monitor the global/local conformations, which enabled us to track kinetic structural changes of PSi’s on SWNTs. Consequently, we concluded that upon wrapping, flexible/helical PSi with an average dihedral angle (φ) of 145° and Kuhn’s segment length (λ–1) of 2.6 nm interconverted to the more stiffer/planar conformation with 170° and λ–1 of 7.4 nm. Furthermore, through kinetic analyses of the time-course UV spectra, we discovered the fact that PSi’s involve three distinct structural changes during wrapping. That is, (i) the very fast adsorption of several segments within dead time of mixing (<30 ms), following (ii) the gradual adsorption of loosely wrapped segments with the half-maximum values (τ1) of 31.4 ms, and (iii) the slow rearrangement of the entire chains with τ2 of 123.1 ms, coupling with elongation of the segment lengths. The present results may be useful for rational design of polymers toward chiral-index-selective binding/separating of desired (n,m) SWNTs.

Very recently, we have reported preparation of several types of Prussian Blue (PB) particles with varying particle sizes by systematically tuning the synthetic conditions (Angew. Chem., Int. Ed., 2012, 51, 984–988). Here, the obtained PB particles are used for removal of Cs ions from aqueous solutions, which will be useful for remediation of nuclear waste. To evaluate the uptake ability of Cs ions into the PB particles, we utilize quartz crystal microbalance (QCM) for real-time monitoring of uptake behavior of Cs ions into the PB particles. The frequency of the QCM is promptly decreased after injection of Cs ions solution into the QCM cell. Hollow PB nanoparticles of 190 nm in diameter have very high surface area (338 m2 g−1), in comparison with other PB particles, leading to efficient Cs adsorption capability eight times larger than that of the commercial PB particles. The diffusion in terms of dissociation constant (Kd), maximum amount of adsorbed Cs in PB particles (mmax), and the adsorption kinetics (k) of Cs ions into the PB particles are also discussed. Due to the selective uptake for Cs ions based on Kd and k values, the PB particles can be proposed as good candidates in waste management consideration.

A new pH responsive smart carrier of C60 was prepared with 6-amino-γ-cyclodextrin (ACD) for photodynamic therapy. C60 was rapidly released from its inclusion complex with ACD at pH 6.7, due to electrostatic repulsion between ammonium groups, followed by a rapid C60 release at slightly acidic cancer cell surfaces.

Hydrophobized plant polyphenols can be easily prepared by rational and controlled etherification of highly abundant aromatic hydroxyls with linear alkyl chains. The resultant organo-soluble polyphenols spontaneously formed fibrous structures and unravelled to be potential adhesive, anticorrosion, and antibacterial coatings.

An efficient hydrosolubilizing reagent for [60]fullerene (C60) was newly developed with a γ-cyclodextrin (γ-CD) derivative having triazole-methoxypyridyl moieties at its 6-hydroxyl positions (PCD). Through solid-state mechanochemical complexation, PCD forms a hydrosoluble inclusion complex of C60 with a concentration of more than 70 mM. This is approximately 90 times greater than that with non-substituted γ-CD prepared by the same method.

A new pH responsive smart carrier of C60 was prepared with 6-amino-γ-cyclodextrin (ACD) for photodynamic therapy. C60 was rapidly released from its inclusion complex with ACD at pH 6.7, due to electrostatic repulsion between ammonium groups, followed by a rapid C60 release at slightly acidic cancer cell surfaces.