Articles in 2012

SWNTs have been successfully grafted with polyisoprene (PIp) via anionic polymerization initiated by carbanion-bearing SWNTs. Carbanions were fixed on SWNTs by treating SWNTs with sec-butyllithium, and then the PIp chains grew from these carbanion. The polymer chains were covalently attached to the SWNTs, which leads to the coating of carbon nanotubes and finally to the destruction of the nanotube bundles.

Individual holes and fractal-like structures have been prepared using solid films of conjugated polymers via solvent vapor annealing. A high environmental humidity is crucial for the formation of the holes and the fractal-like structures. But, the formation of the holes and the fractal-like structures is not dependent on the polarity of the surfaces of the substrates. The fractal-like structures can be preserved upon conversion of the thermal cleavable polythiophene films to the insoluble polythiophene films.

Pentaerythritol-zinc (Penzinc) has been synthesized and its thermal stability, especially its synergism with β-diketone and calcium stearate, was characterized. Experimental results show that PVC stabilized with complex of Penzinc and β-diketone has an excellent initial color and long-term thermal stability. Moreover, the thermal stability mechanism of Penzinc and β-diketone are also discussed with the help of quantum chemical calculations. Results indicate that both α-H atom of β-diketone and zinc atom of Penzinc, having low electron density, can easily react with labile chloride atom of PVC, which has high electron density.

Two and three times repeats of the self-assembling peptide RADA16 (RADARADARADARADA), namely RADA16x2 and RADA16x3, were genetically produced. The peptides were expressed as fusion proteins while retaining the activity of the fusion partner protein. The expressed peptides exhibited both fibril formation and cell adhesive activity. Moreover, the hydrogels formed by the peptides via addition of a medium provided a three-dimensional environment for cell proliferation.

The elastin-like peptide (ELP)–gold nanoparticle (AuNP) hybrid can be aligned selectively on the micro-patterned polystyrene ridges by directed assembly based on a thermo-triggered hydrophilic and hydrophobic phase transition of the ELP shell.

The nanoscale structures of graft-type PEMs, prepared by radiation-induced graft polymerization of styrene onto poly(ethylene-co-tetrafluoroethylene) (ETFE) films followed by sulfonation, were investigated using a small-angle neutron scattering (SANS) technique. The SANS profiles of the grafted films showed shoulder peaks at a d-spacing of ∼30 nm, which were attributed to the polystyrene grafts introduced into the amorphous phases between the ETFE lamellar crystals. In the ETFE PEMs, this d-spacing increased to 34 nm because the graft regions were enlarged by the volume of the attached sulfonic acid groups.

A versatile post-modification method for polyimides using CT complex formation between electron-deficient naphthalenediimide units in the polyimide and electron-rich dihydroxynaphthalene was developed. The film preparation by CT complex formation reported in this paper is an attractive method for functionalization of polyimides because many donor molecules and polyimides can be used. The supramolecular methodology shown here is quite simple, but is an innovative method for polyimide modification.

Addition and ring-opening metathesis polymerizations of new monomers (Me₃Si- and Me₃Ge-substituted tricyclononene and tricyclononadienes) were carried out on Pd- or Ni-catalyst systems and Grubbs first-generation catalyst, respectively. New addition polymers were obtained with good yields up to 70% and molecular weight (M_w) up to 5.6 × 10⁵. The yields of the first obtained metathesis polymers were higher than 80% and M_w were up to 8.8 × 10⁵. It was shown that the novel addition polymer poly[(3-trimethylgermyl)tricyclononene-7] possesses high gas-transport parameters and solubility-controlled permeation of gaseous hydrocarbons.

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.

Carrageenan-based magnetic composites were prepared via in situ synthesis of iron oxides in a gelatinous network of the polysaccharide. Magnetic properties and morphology were characterized by SQUID magnetometry, X-ray diffractometry and electron miscroscopy. By operation of 3–4 cycles of the standard synthesis route, a carrageenan composite imparting a high value of saturation magnetization (∼25 emu (g sample)⁻¹) was easily realized while the superparamagnetic property at room temperature was maintained. Insight was provided into the evolution mechanism in oxidation state and dimensional distribution of the cyclically loaded iron oxide nanoparticles.

In this manuscript, we report the doped thin films consisting of a nanofiber network of a conducting polymer, poly(3-hexylthiophene), were fabricated, and optical transmittance and electrical conductivity measurements were carried out. The superior properties of the nanofiber films in the transparency and conductivity were ascribed to the effective conducting pathways, a large void fraction, and a high dopant concentration due to the large surface area.

Bis-pyrrolidone-type monomers (obtained from itaconic acid, which is a renewable chemical identified in the top 12 value-added chemicals from biomass) with alkylidene spacers of variable size were synthesized and polycondensed with various diamines. The resulting polycondensates were used as compatibilizers to improve interfacial adhesion in poly (butylene succinate) (PBS)/plasticized starch blends. The interfacial adhesion between PBS and plasticized starch was improved using these polycondensates.

A series of maleimide–thiophene copolymers presenting pendent 2-hydroxyethyl and 6-hydroxyhexyl units were synthesized. The maleimide–thiophene copolymers containing different contents of OH groups were then reacted with 3,3′-dimethoxy-4,4′-biphenylene diisocyanate in solution to form the interchain-linked polymers. The photovoltaic performances of the PSCs incorporating the interchain-linked copolymers were superior to those of the corresponding PSCs based on the OH-containing copolymers.

Stereocomplex poly (lactic acid) films were prepared by casting chloroform, acetonitrile or tetrahydrofuran solution of a mixture, mix-poly(lactic acid) (PLA), of poly (L-lactic acid) and poly (D-lactic acid). Time dependence of cloud point (Figure 1), as well as the morphology of the cast films (Figure 2) was markedly different in these three cast-solvents. The cast-solvent dependence of the morphology was studied by assuming that structure of stereocomplex is constructed through two processes.

4,4′-Bismaleimidediphenylmethane (BMI) was cured finally at 250 °C with cardanol (CD) or CD novolac (CDN) prepared by the reaction of CD and paraformaldehyde with CD/maleimide unit ratios 1/2, 1/4 and 1/6. The obtained cured resins with CD/maleimide ratio lower than 1/2 did not show glass transition until 300°C and had 5% weight loss temperature higher than 450°C. The curing mechanism was elucidated by means of the proton nuclear magnetic resonance (¹H-NMR) and Fourier transform infrared spectroscopy (FTIR) analyses of the model reaction products of CD and N-phenylmaleimide (PMI) and the cured resins.

We performed small-angle and wide-angle X-ray scattering (SAXS/WAXS) measurements on poly(ethylene terephthalate) (PET) uniaxially drawn from amorphous state above the glass transition temperature. The measurements were done at a new beamline (BL) BL03XU (Frontier Softmaterial Bamline) in the synchrotron radiation X-ray facility, SPring-8, which is dedicated to development of advanced soft materials and belongs to the Advanced Softmaterial BL Consortium. We performed a calculation to reproduce the observed 2D SAXS patterns. Based on the results of the calculation we discussed the distribution of lamellar stacking direction and the relation between the lamellar length and the stacking direction.

We studied the structure of polybutadiene rubber (BR) crosslinked with zinc diacrylate (ZDA) by complementary use of small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) to confirm the high crosslink density region in the matrix rubber. This is the first finding of the high crosslink density segments in BR (HC-BR) crosslinked by ZDA. Tensile measurements revealed that the size and the number density of the HC-BR and ZDA aggregates are related to the mechanical property of the rubber materials.

In the present work, we demonstrated that the amount of both donor and acceptor materials in the fabrication of BHJ OPVs could be strongly reduced using a high viscosity P3HT solution with the M_w of 680 900. In addition, only slight fluctuations were observed in PCEs of around 3.8% for all OPVs based on P3HT for M_w ranging from 46 600 to 680 900.

We present a mechanistic study of the structural formation on the curing process of the liquid–crystalline epoxy with the simultaneous measurement of SAXS/WAXS using synchrotron radiation. The following behaviors were revealed: after the temperature-jump to the curing temperature, first the system forms the nematic domains; the nematic-to-smectic conversion proceeds after an incubation period; the transformation continues beyond the conversion of 80% of epoxide-amine bond formation and corresponding entire polymer network formation.

The effect of the Molecular weight dispersity (MWD) on the interfacial width between a hPS brush and unbound dPS matrix has been investigated by NR measurement. The intermixing between hPS brush with narrow MWD and dPS matrix hardly occurred even after thermal annealing at 398 K because of dry-brush regime. In contrast, the intermixing of hPS brush with broad MWD and free dPS proceeded to increase the interfacial width like a wet-brush condition, in spite of high grafting density.