Articles in 2012

Glycopolymers with pendant saccharides are biofunctional polymers that interact with saccharide recognition proteins. The glycopolymers show the strong molecular recognition ability owing to the multivalency. These polymers were prepared by the polymerization with sugar derivatives or by the saccharide addition to the polymer backbone. The glycopolymers can be applied for cell cultivation, drug delivery, and biosensing. The living radical polymerization provided the precise structure of glycopolymer, which was useful for analysis of the protein–saccharide interactions. The living radical polymerization also provided the hybrid biomaterials that can be used for biosensing and biomaterials.

In this study, the useful information for the design of side-chain liquid crystal polymers was described. Side-chain liquid crystal PEIs with different spacer lengths (n) were newly synthesized. In the case of short spacers, only a smectic A phase with a bilayer structure was formed. The long spacers led to the formation of a smectic A, C and F phases with a monolayer structure.

The surface of polyimide (PI) film was successfully patterned by nanoimprinting poly(amic acid) (PAA) film and then hard baking. An appropriate nanoimprinting process was established through the study of the thermal and dynamic mechanical properties of PAA and PI film. Atomic force microscopy revealed that line pattern was transferred from silicon mold to PI film successfully and the nanostructures remain undamaged even though a larger shrinkage took place during the hard baking.

This paper reports multivariate analyses such as principal component analysis and partial least-squares regression of NMR spectra of poly(N-isopropylacrylamide)s [poly(NIPAAm)s]. Principal component analysis successfully interpreted the assignments of ¹H and ¹³C NMR spectra of methylene protons and methine carbons, respectively, of poly(NIPAAm)s in terms of stereostructures. Furthermore, triad tacticity was successfully predicted by partial least-squares regression of ¹H NMR spectra of the methine and methylene groups. Consequently, it is assumed that chemometric analysis of NMR spectra is a promising method for the characterization of synthetic polymers.

The structural development during the CO₂ laser-heated drawing of low-oriented α-crystalline as-spun PBT fibers was analyzed with a time resolution of 0.3 ms. The α-crystal was transformed into an oriented β-form crystal at the necking position, and the crystallite size and orientation were increased <2 ms after necking at the temperature of 100–160 °C. In contrast to the PET and PEN, quasi-smectic structure was not observed before crystallization. The oriented β-crystal of the drawn fiber transformed into the oriented α-crystal when the drawing tension was released.

We report a rapid and reversible morphology control of a polyhedral oligomeric silsesquioxane (POSS) containing block copolymer (PEO-b-PMAPOSS), which composed of poly(ethylene oxide) (PEO) and POSS-containing poly(methacrylate), (PMAPOSS), between ordered arrays of dots and lines for several tens of seconds by combination of thermal annealing and solvent annealing. The reversible morphology change and ordering of phase morphology in a short time are enabled by a distinctive property of PEO-b-PMAPOSS with highly mobility of the chain at the thermal and the solvent annealing states.

Crystallization of calcium carbonate (CaCO₃) in the presence of single-walled carbon nanotube (SWCNT)/fullerodendron supramolecular nanocomposites in aqueous environments was carried out with a CO₂ diffusion method to afford monodisperse spherical SWCNT/CaCO₃ hybrids with a core-shell structure. The crystals nucleate at the carboxyl groups on the surface of SWCNT/fullerodendron supramolecular nanocomposites grow around a spherical scaffold made of the SWCNTs, and finally form spherical calcite crystals embedded and covered by the SWCNTs. After removing the SWCNTs by the calcination in an air flow at 800 °C, the morphology of the core-shell microsphere was maintained.

In order to study the kinetic mechanism of photochlorination of polyethylene, a proposed model was suggested in which the conversion of methylene (—CH₂—) units to chloromethylene (—CHCl—) ones were considered as the main reaction. The simplified versions of the obtained kinetic model indicate that the reaction is first order with respect to the chlorine gas concentration and zero order with respect to the methylene groups concentration up to 40% of chlorination, where the concentration of γ-methylene sequences is high. The mechanism of reaction was exactly reversed at higher conversions.

Chemiluminescence spectra of natural rubber, chloroprene rubber and ethylene propylene diene rubber were measured in N₂ and in air with a multichannel Fourier-transform chemiluminescence spectrometer. Samples were measured before and after γ-ray irradiation in air and in the absence of O₂. A strong emission from ethylene propylene diene rubber was observed in air only when the sample was γ-irradiated in air. The observed spectrum was separated into two bands at 678 and 523 nm because of peroxidic compounds and excited carbonyl groups, respectively.

A fluorinated heme was incorporated into Mb, and the field dependence of the line width of ¹⁹F NMR signals of the protein with S values ranging from 0 to 5/2 was analyzed in order to gain a quantitative insight into the ¹⁹F transverse relaxation mechanism in the protein. In the cases of S=2 and S=5/2 forms, the significant contribution of Curie spin relaxation to the relaxation was demonstrated and analysis of the Curie spin relaxation was useful to estimate the overall correlation time of the protein.

The graphene oxide (GO)-reinforced poly(vinyl alcohol) (PVA) nanocomposites were prepared using a simple and environment friendly process using aqueous medium. GO was revealed to be nanodispersed in the PVA matrix. The Young’s modulus of the nanocomposites largely exceeded the predicted value with only a low content of GO. We also revealed the increase in the thermal resistance and the barrier properties. As a result, not only the excellent properties but also the advantageous effects derived from the sheet-like structure of GO were successfully imparted to the nanocomposites.

Various types of dendrimer-based nanomaterials, such as poly(ethylene glycol)-modified dendrimers, functional shell-bearing dendrimers, thermosensitive dendrimers, dendron-based lipid assemblies and dendrimer-gold nanoparticle (NP) hybrids were developed by surface modification, assembling and hybrid formation strategies. These dendrimers and dendrimer-based nanomaterials exhibited various bio-related functions, such as drug encapsulation, stimuli-responsive transition and photo-induced heat generation. Based on these functions, these dendrimers and dendrimer-based nanomaterials have potential usefulness in the biomedical field, such as target-specific drug delivery and non-invasive therapy.

Analysis of photoproducts derived from 1-(arylmethyloxy) anthracene initiator 1 as well as polymer end groups demonstrated that the arylmethyloxyl radical and arylmethyl carbocation are involved in the initiation steps of St and CHO polymerization reactions, respectively. The ability of the radical and carbocation species to initiate polymerizations increased with the stability of these species.

UV–vis spectra of (a) poly(N-methyl pyrrole) (PNMPy), (b) P(CPDT-co-NMPy) and (c) PCPDT deposited onto indium-tin-oxide-coated at the neutral state. Insets: (A) light yellowish green, (B) reddish brown, (C) purple are de-doped films, and (A′) pale cyan, (B′) light blue, (C′) blue are doped films of PNMPy, P(CPDT-co-NMPy) and PCPDT, respectively. The different electrochromic properties of the three polymers confirmed the occurrence of copolymerization between NMPy with CPDT

A fluorescent-labeled hyper-branched polymer with mesogenic shell was captured by the disclination lines of a liquid crystal. In a Grandjean–Cano wedge cell, the particles of the hyper-branched polymer migrated toward the periodically aligned defect line and thus formed a two-dimensional lattice array.

Euler buckling forms surface microwrinkles ranging in size from sub-micrometers to tens of micrometers as a result of the modulus difference between the surface of the material and the material itself. When the buckling occurs in the limited areas smaller than the wrinkle wavelength, the shape of the buckled surface deforms into concave dimples or convex lenses. The shape of the buckled surface can be controlled by changing the modulus of poly(dimethylsiloxane). Hierarchical patterning by using a photomask was also achieved. This process provides a novel way to pattern soft substrates, including elastomers and gels.

Supramolecular films consisting of guanosine derivatives modified with a tetrathiafulvalene moiety have been prepared. The hydrogen bonding network of the guanosine unit enables the formation of a robust and self-supporting cast film by a solution process. The self-supporting films were mechanically flexible. The physical properties of the films of the derivatives depended on both the length of the alkyl chains and the structure of their terminal group. The composite film of the derivatives with 7,7,8,8,-tetracyanoquinodimethane exhibited electrical conductivity.

Segmented polyurethane prepared using a novel chain extender, calcium lactate along with polytetramethylene glycol and hexamethylene diisocyanate. The properties of the synthesized polyurethane compared with that of polyurethane without any calcium. The prepared polymer has high glass transition temperature and storage modulus, and has improved mechanical properties. In vitro hemocompatibility evaluation reveals that the material is blood compatible and does not induce any hemolysis to blood.

We have successfully developed a system to perform active self-organization of microtubules (MT) using a streptavidin–biotin interaction in a nitrogen atmosphere (inert chamber). Use of inert chamber dramatically improved the lifetime of assembled microtubules and kept them active for a longer period of time compared to the case without using inert chamber. Longer lifetime of assembled microtubules obtained using the inert chamber would be significantly important in further development of biomolecular motor protein-based organized systems.