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The electrostatic self-assembly and covalent fixation (ESA-CF) process, in conjunction with click chemistry and olefin metathesis, was used to construct selectively a variety of unprecedented polymer architectures, such as manacle-shaped and tandem multicycles, as well as doubly fused tricyclic and triply fused tetracyclic topologies. Moreover, the self-assembly of a cyclic amphiphilic block copolymer, which was prepared by intramolecular metathesis, produced a micelle with an approximately 50 °C increase in thermal stability compared with the one from the linear prepolymer. Single-molecule spectroscopic studies also revealed different diffusion modes for cyclic and linear polymers.
Our group has developed a novel method to produce nanocellular and nanoporous structures using block copolymer as template and supercritical carbon dioxide. To characterize nanocells and nanopores, small angle X-ray scattering (SAXS) has an important role. In particular, grazing incident SAXS reveals embedded nanocellular and nanoporous structures in thin films. Additionally, SAXS can be used for in situ measurement to follow the process of nanocellular and nanoporous formation in supercritical carbon dioxide. Our recent progresses of fabrication and SAXS characterization of nanocellular and nanoporous structures will be reviewed.
Biomineralization, the process by which organisms create a variety of sophisticated composites such as bone and shell, is an ideal model toward materials fabrication in an environmentally friendly way. This article reviews recent progress in the biomineralization-inspired synthesis of polymer–inorganic composites including (1) polymer–calcium carbonate thin films synthesized by interaction among insoluble polymer, soluble acidic polymer, and inorganic ions; (2) polymer nanogel–calcium phosphate nanoparticles synthesized on scaffolds of hydrogel nanoparticles; and (3) colloidal silica nanoparticles made to self-assemble into anisotropic structures by interaction with block copolymers.
Novel 4-phenylethynylphthalic anhydride (PEPA) terminated addition-type imide oligomers derived from 1,2,4,5-benzenetetracarboxylic dianhydride or pyromellitic dianhydride (PMDA), and 2-phenyl-4,4′-diaminodiphenyl ether (p-ODA) showed a high solubility and a very low minimum melt viscosity. These imide oligomers were also converted to crosslinked cured resins with a high glass transition temperature (Tg) (>350 °C) and good mechanical properties after curing. A void-less polyimide/carbon fiber composite with high Tg could also be achieved to fabricate via the imide oligomer solution prepregs.
We survey recent studies about amphiphilic polyhedral oligomeric silsesquioxane (POSS)-based functional materials and explain the design concepts for applying the peculiar characteristics of POSS for the material properties. In the former parts, we introduce the examples concerning POSS-based ionic liquids. In the latter parts, we also mention the application of POSS-based materials for bio-relating functional materials. Based on our recent works, the unique properties of the amphiphilic POSS are reviewed.
Polymer micro- and nano-particles have attracted much attention because of their promise for a variety of applications. This focus review introduces an emerging method for producing nanostructured polymer particles, called self-organized precipitation (SORP), and gives an overview of controlling the internal structure of polymer particles by using various polymer blends and block-copolymer systems. The possible applications and future prospects of this technology are also discussed.
Cross-linked liquid-crystalline polymers show photoinduced deformation with change in molecular shape and alignment of the polymers. Polymer materials can transduce light energy to mechanical stress by macroscopic deformation of the polymers (photomechanical effect). Mechanism of the photoinduced deformation of the polymers is investigated. Three-dimensional movements of the liquid-crystalline polymers are achieved by lamination of the polymers into a flexible polymer sheet. This review described a short overview of recent developments in photomechanical effects mainly focusing on design of the polymer materials with photochromic moiety and applications to light-driven polymer actuators.
The lipophilic triazole ligand 1 (C12OC3Trz) has been designed such that an ether linkage exists in the alkyl chain moiety. This flexible ether linkage enhances the solubility of various complexes of this ligand (including [CoII(1)3]Cl2 and [FeII(1)3]Cl2) in organic media and also improves the packing efficiency of the alkyl chains. Such lipophilic modifications of 1D coordination systems can result in dynamic structural transformations leading to unique solution properties, including heat-set gel-like networks, guest-induced structural changes, electrochemical transformations and spin crossover state switching.
This focus review describes a brief overview of our recent achievements on the fabrication of self-assembled nanostructures and following transformation by external stimuli, such as thermal treatment, metal coordination and ultraviolet irradiation. Some stimuli-responsive organic molecules possessing alkyl tails working as adsorption and interaction sites were synthesized to allow the spontaneous formation of various two-dimensional (2D) nanopatterns on a highly oriented pyrolytic graphite (HOPG). The 2D molecular arrangements were investigated by using scanning tunneling microscopy at HOPG/1-phenyloctane interface.
We present a molecular design of a preprogrammed supermolecule that can stabilize frustrated molecular organization of an isotropic liquid-crystalline phase. The tapered amphiphilic compound exhibited an unusual smectic A to cubic phase transition. The chiral T-shaped compound showed amorphous blue phase III with a temperature range of 25 K. We demonstrate high-transmittance, sub-millisecond response and hysteresis-free switching in room temperature amorphous blue phase stabilized by a designed LC supermolecule.
Macroscopic liquid crystal structures have been developed in hydrogels by self-assembly of a semi-rigid polyion complex. During the polymerization of isotropic precursor solution of a cationic monomer in the presence of a semi-rigid polyanion, the polycation will interact with oppositely charged polyanion to form polyion complexes. These semi-rigid complexes self-assemble further to form macroscopically ordered structure that is frozen in a nanoscale network by the following chemical cross-linking reaction.
DNA nanotechnology has enabled precise bottom-up integration of metal nanoparticles (NPs) on a nanometer scale. The DNA origami technique facilitated still more complicated control of the positioning not only in 2 dimensional (D) but also in 3D structures. We constructed an alternating streptavidin/gold NP heteroarray with 26 nm separation using a nanometer-sized cavity (a DNA well) embedded in a 2-nm-thick DNA origami sheet. The basic idea and other recent examples of such metal NP arrays on DNA nanostructures are reviewed.
Hybrid self-assemblers based upon dendritic building blocks such as aliphatic polyether and/or poly(benzyl ether) dendrons can be prepared by a combination of physically different flexible linear and rigid discotic segments. The unconventional self-assemblers organize into various bulk liquid crystalline morphologies, which can be used as a versatile platform for ion-conducting materials.
Application of natural viruses to nanotechnology have attracted much attention due to their fascinating nanostructures. However, chemical strategy to de novo design virus-like nanostructures is still in its infancy. In this review article, we describe novel C3-symmetric molecular design of peptides and their characteristic self-assembly into virus-like nanostructures. We have developed trigonal conjugates of β-sheet-forming peptides, trigonal conjugates of glutathione and a viral β-annulus peptide fragment.
Bicontinuous cubic (Q) lyotropic liquid crystal (LLC) phases formed by the self-organization of amphiphiles in water are intriguing structures for transport applications because they possess ordered, 3D-interconnected water nanochannels. Q-phase polymer materials can be formed by templated polymerization of conventional monomers around Q phases or direct polymerization of Q phases formed by reactive amphiphiles. Herein, we provide an overview of work in these areas, with a focus on our group’s work on polymers prepared by the direct cross-linking of reactive Q phases and their development into functional materials.
