Reviews & Analysis

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.

Rubber-filler systems have been widely used in industry. Fillers are not dispersed homogeneously and often form hierarchical structures in rubber matrices over a wide range of length scale from nanometer to micron meters, such as primary particles, aggregates and agglomerates. The combined scattering methods are powerful tools to characterize the structures quantitatively.

A method is described that can predict the miscibility of the great majority of polyolefins based just on their chemical architecture. The miscibility of polyolefins is shown to be essentially controlled by their solubility parameters, d, which in turn depend on the chain dimensions of the chains through the packing length l_p. A method to estimate l_p from chain architecture is also shown, giving a very powerful mechanism to predict the mixing thermodynamics from chemical structure.

Grazing incidence small-angle neutron scattering (GISANS) allows for the investigation of nanostructures in thin films and at surfaces due to the use of a reflection geometry. Possibilities and challenges of GISANS are reviewed with several different examples of thin nanostructured polymer films. With GISANS buried lateral structures can be probed destruction free using the variable-probed depth as function of the incidence angle. By this, averaged statistical information is detected over the large illuminated sample surface.

This review describes the developments of self-assembled photonic crystals (PCs) of chiral liquid crystals (CLCs) and colloidal crystals (CCs) for laser applications. Both CLCs and CCs have intrinsic capabilities to spontaneously assemble 1D-PCs and 3D-PCs, respectively. By combining fluorescence dyes in the structures, the stimulated laser action can be generated by optical excitation. Moreover, the optically excited lasing is controllable by external stimuli due to their self-organization. This review highlights the research backgrounds of CLCs and CCs, as well as the experimental results of soft and tunable laser applications.

Various properties of ultrathin polymer films differ substantially from their bulk values. However, the critical question is whether the unusual properties are uniform throughout the films. To explore the presence of heterogeneous viscosity distributions, we have established grazing-incidence X-ray photon correlation spectroscopy for single polymer films with embedded metal nanoparticles that act as markers. In addition, the combined use of resonance enhanced X-ray scattering enables us to intensify the probing electrical field in the regions of interest within a single polymer film.

This article reviews recent findings on the optical, electro-optic, and optoelectronic properties of natural and chemically modified DNAs. This review specifically deals with photoluminescence and ET, lasing, NLO, organic light-emitting diode, and photovoltaic characteristics of various compositions based on natural and modified DNAs. Replacement of the Na⁺ counter-ions of natural DNA with functionalized cationic moieties is rapidly broadening the possible utilizations of DNA-based novel materials.

Poly (butylene succinate)(PBS) nanocomposites and PBS ionomer were prepared by in situ polymerization. This review focused on the effect of the modified clay, TS-1 zeolite and ionic group in PBS matrix on physical properties, rheological properties, crystallization behavior and biodegradability control.

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 (T_g) (>350 °C) and good mechanical properties after curing. A void-less polyimide/carbon fiber composite with high T_g 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.

Supramolecular polymer is broadly defined as any type of an assembly formed from one or more molecular components via reversible bonds; therefore, monomeric and polymeric states are in equilibrium over the relevant experimental timescale. Structural and dynamic properties of supramolecular polymers, including the degree of polymerization (DP), chain lifetime and conformational flexibility, are influenced by external stimuli; thus, these result in supramolecular ‘smart’ materials, which offer adaptivity that leads to easy fabrication, stimuli responsiveness and self-healing at the forefront of science and engineering. This review will focus on the recent developments in supramolecular polymers composed of discrete repeating units, as well as novel supramolecular materials produced by the interplay of supramolecular and polymer chemistry.

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 [Co^II(1)₃]Cl₂ and [Fe^II(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.

With the increase in the number of implant-dependent surgeries and biofilm-associated complications, there is a need to counteract and deal with this phenomenon. This has led to various approaches to elucidate the etiology and pathogenesis of the infection. This review critically evaluates the formation, characteristics, pathogenicity and the molecular genetics of both implant- and nonimplant-associated medical biofilm.

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 have proposed the concept and significance of nano-alloyed polymer, which includes nano-dispersed domains, and have developed the biaxially stretched film with higher glass transition temperature and improved dimensional stability as compared with regular poly(ethylene terephthalate) film (Figures 1 and 2). Highly concentrated polyimide master batches are made at much lower temperature compared with regular processing temperature. The nano-alloyed film is obtained by film-making process having biaxial stretching and heat treatment. The nano-sized domains have an important role as pseudo-cross-linkage points, for demonstrating good drawing process ability and high orientation.

Based on the systematic classification and on the isomeric properties of polymer chain topologies, a variety of novel multicyclic macromolecular constructions has now been rationally designed and subsequently realized. In particular, an electrostatic self-assembly and covalent fixation process, optionally in conjunction with effective covalent linking chemistry, has been demonstrated as a new synthetic protocol for unprecedented polymers possessing multicyclic topologies.