Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
This focus review describes that modular and hybrid molecular design approach used to introduce artificial chemical reactive groups into biomolecules or bio-related molecules enable the semi-rational construction of stimuli-responsive supramolecular systems.
DNA undergoes large volume transition to organize several higher-order structures, including globular, rod-shaped, and ring-shaped (toroid) structures by polyion complexation with block copolymer comprising hydrophilic segment and polycations. This review discusses the origin of this versatile higher-order structure formation. The knowledge of underlying physical mechanisms might ultimately improve our understanding of the formation of hierarchically ordered structures in the nucleosomes and the operating principles governing how DNA functionality emerges, and also provide a solid strategy to prepare structured nonviral gene vectors.
The formation of multiple intramolecular hydrogen bonds (IHBs) is a reliable method for obtaining conjugated oligomers with helical secondary structures, and imidazole with both proton-accepting and proton-donating abilities plays an important role. On the basis of its optical properties in conjunction with DFT calculations, a conjugated oligomer composed of alternating imidazole and 1,4-dihydroxybenzene units was found to (1) form robust IHBs, (2) be susceptible to both acid and base treatment, and (3) potentially adopt a helical conformation.
Benzoxazine bridged by a flexible polysulfide rubber chain (BLP) was conveniently prepared through the ring-opening addition of thiol-capped liquid polysulfide rubber (LP-3) and bisphenol-A/aniline-based benzoxazine (B-a). BLP was a highly viscous fluid at room temperature with a low curing temperature. After curing, the polymerized BLP (PBLP) presented excellent flexibility, outstanding thermal stability, and an extremely high char yield.
Fully aromatic polyimide particles were obtained in a single step via the polycondensation of diethyl (hexafluoroisopropylidene)diphthalate and 4,4’-oxydianiline using polyvinylpyrrolidone (PVP) as a steric stabilizer in ethylene glycol. Since the monomers are soluble in ethylene glycol, but the polyimide is insoluble, the polyimide particles grew gradually during the polycondensation process. The particle size and size distribution were controlled by varying the molecular weight and amounts of PVP.
We developed 2,5-furanylene sulfide-containing polymers bearing different spacers as repeating units and evaluated the interactions between the furanylene sulfide units in the polymer. Treatment of a 2,5-dichlorofuran derivative with dithiolates at 200 °C promotes polycondensation via nucleophilic aromatic substitution to give the corresponding furanylene sulfide-containing polymers. Through tensile measurements and spectral analyses, it was found that the furanylene sulfide moieties form remarkably stable π–π stacking structures based on the enhanced dipole moment induced by sulfur linkages. When the polymer has a long spacer between repeating furanylene sulfide units, the polymer behaves as a chemically stable network polymer comprised of π–π stacking structures as cross-linking units.
When bulk polymerization of MMA is conducted at room temperature, polymerization-induced phase separation occurs. Separation into MMA-rich and PMMA-rich phases coincides with the onset of the Trommsdorff effect. The highlighted region of the phase diagram represents a part of the phase state that depends upon the processing path: in one case (path 1), there are two phases present, in the other (path 2), the material is single-phase.
Large dielectric constants were measured for nylon 93. A displacement–electric hysteresis loop was obtained for a slowly cooled sample of nylon 93. The structure of nylon 93 was investigated in detail to clarify the origin of these unusual electric properties. The results obtained by X-ray diffraction, polarizing optical micrography, and differential scanning calorimetry indicated that α- and γ-crystals were formed in the slowly cooled and quenched samples, respectively, and the γ-crystals in the quenched samples were gradually changed into α-crystals by annealing.
A soluble polysilsesquioxane containing macrocyclic structure (PSQ-MC) is successfully prepared by the hydrolytic condensation of a dual site-type silane coupling agent, i.e., bis{3-[3-(trimethoxysilyl)propylthio]propyl}phthalate (BTPP). PSQ-MC is assumed to be a polymer in which an 8-membered cyclic siloxane having two 23-membered rings is linked by a single siloxane bond. In addition, PSQ-MC could capture palladium ions.
