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m-Terphenyl-based random copolymers of chiral and achiral amidines and its complementary homopolymer of achiral carboxylic acids self-assembled to form complementary double helices with a preferred-handed helical sense via interstrand amidinium–carboxylate salt bridges, thus showing induced cotton effects in the π-conjugated main-chain chromophore regions. A unique amplification of the helical chirality (‘the sergeants and soldiers effect’) was, for the first time, observed during the double-helix formation.
Poly(styrene derivative) particles, average diameter of which is <30nm, were prepared without ionic emulsifier with nonionic emulsifier polyoxyethylene alkyl phenyl ether by polymerizing monomer, emulsifier, water and initiator mixture at around PIT. Effects of initiator concentration, temperature and monomer type on the average diameter of the generated polymer particles are investigated. Smaller particles are obtained with higher rate of radical generation at PIT. The particles of poly(p-methylstyrene) which have an average diameter of 21 nm and a polymer weight fraction of 5% were prepared.
Iodine transfer dispersion polymerization (dispersion ITP) with CHI3 and reversible chain transfer-catalyzed dispersion polymerization (dispersion RTCP) with N-iodosuccimide (NIS) of methyl methacrylate (MMA) were successfully applied to supercritical carbon dioxide (scCO2) medium. Both polymerizations proceeded smoothly and yielded the polymeric product as a powder. In both systems, the number-average molecular weights increased with increasing conversion and polydispersity (Mw/Mn) was maintained at low values throughout the polymerizations. A chain extension test indicated that PMMA prepared by dispersion ITP and dispersion RTCP in scCO2 had high degrees of livingness.
Number of aggregations is very small when THF was used compared with methanol and methanol–water. Aggregation of copolymers was difficult in THF due to back-folding and looping of PDMS block. This was unfavorable as it increases free energy of system. This probably resulted in higher CMC of pHEMA-b-PDMS-b-pHEMA copolymers in THF than in methanol. Micellar size of most of triblock copolymers in THF was smaller than in methanol.
The slopes of G″–G′ decreased to 1.21 for the long-chain branched-polypropylene (LCB-PP) and 1.07 for PP-F07-S5. A decreased slope indicates an increase in elasticity, shear thinning effect and melt strength. The extending Avrami analysis proposed by Ozawa applied to PP, LCP-PP and the composite. The exponents were 3.6 for PP, 2.4 for LCB-PP and 1.5 for the composite.
Poly(ɛ-caprolactone) (PCL) microfiber meshes containing embelin, a poorly water-soluble biactive agent, were prepared by electrospinning. Thermal properties revealed that the crystallinity of embelin was significatively decreased being the drug almost completely dissolved in the PCL fibers. Drug-loading content resulted appropriate for topical applications. Drug-loaded fibrous scaffolds exhibited an increase of 86% in the area-to-volume ratio and provided an effective area per unit mass that was 5.8-fold higher than that presented in drug-loaded films. This polymeric carrier would allow a better in situ bioavailability of embelin.
Various nonspherical polystyrene (PS) particles were prepared by slow evaporation of toluene from homogeneous PS/hexadecane (HD)/toluene droplets dispersed in surfactant aqueous solutions at room temperature, followed by rapid removal of HD from PS/HD particles with various phase-separated morphologies. The morphology of PS/HD particles could be controlled by tuning each interfacial tension employing various types of surfactants. Consequently, hemispherical PS particles with flat surface were obtained from phase-separated PS/HD/toluene droplets having Janus structure, when Emulgen 931 was used as the surfactant.
An enzyme electrode was fabricated by covalent immobilization of acid phosphatase (ACP) on a polyaniline/poly(acrylic acid) composite film for use as the anode of a fuel cell driven with L-ascorbic acid 2-phosphate (ASA2P). The enzyme electrode showed an activity in biochemical dephosphorylation of ASA2P to ascorbic acid (ASA), and succeeded in electrochemical oxidation of ASA. The ASA2P fuel cell equipped with the enzyme electrode gave a maximum power output of 6.0 μW cm−2-anode, reflecting the bioelectrochemical activity of the electrode.
Fluorescence emission spectra of PCL-co-P4HCA50 with UV irradiation at λ=302 nm for various times, and the inset shows the fluorescent intensity changes with UV irradiation time.
Our PI/BaTiO3 hybrid composites were prepared by mixing the organosoluble PI derived from one-step polymerization with BaTiO3 in dimethylacetamide, screen printing the pastes to form composite films and drying at 90 °C for 24h. The low-temperature process is a key for the PI-based flexible devices to be integrated with flexible electronics. The reported PI/BaTiO3 dielectric films were prepared by a two-step process, which needed to be further imidized at 300 °C.
Our study explored layered microstructures and the resistivity of injection stainless steel fiber-filled polymer composite. Figure 2 in this paper shows the microstructures at different layers of the molding, which was used to discuss the distribution and mass fraction of the fibers in the matrix at different layers. Based on the results of Figure 2, we discussed the effects of injection parameters on the resisitivity of each layer of the molding.
Mono- and bis-stannylation at the chain ends of regioregular poly(3-hexylthiophene) (P3HT) were conducted by post-functionalization of P3HT synthesized through Ni-catalyzed Grignard metathesis polymerization. Lithiation of P3HT with s-BuLi and subsequent stannylation with Me3SnCl led to the formation of bis-stannylated P3HT. The highest conversion of 81% was achieved with the additive N,N,N′,N′-tetramethylethylenediamine (TMEDA), which could enhance the stability of the lithiated compound. On the other hand, mono-stannylated P3HT was synthesized without contamination by bis-stannylated P3HT through successive reactions with a Grignard reagent and Me3SnCl.
Microscopic behaviors of explicit water molecules on biocompatible zwitterionic self-assembled monolayer (SAM) surfaces were investigated by molecular dynamics simulations. The orientational distribution of water molecules near the surfaces was evaluated to analyze its structural properties. Consequently, water molecules on the zwitterionic SAMs are randomly oriented. In contrast, those near the surface of poly(vinyl alcohol) are highly oriented, resulting from the structured hydrogen bonding network. Microscopic properties of water molecules on the interfaces would have a key role in the suppression of protein adsorption for zwitterionic biomaterials.
