Original Article in 2011

The star- and dumbbell-shaped isobutyl-substituted POSS derivatives were synthesized. The star and dumbbell structures of the obtained compounds were confirmed by ¹H-, ¹³C-, and ²⁹Si-NMR and MALDI-TOF-MS analysis. The star-shaped POSS compound formed the optical transparent film, and showed T_g and T_m at 24 and 96 °C, respectively. All the dumbbell-shaped POSS compounds, however, formed opaque whitish films, and showed no T_g and high T_m over 230 °C. The lower T_m and appearenace of T_g in the star-shaped POSS suggested its lower crystallinity, which promoted formation of the transparent film.

We found that isopropyl and tert-butyl propargyl carbonates (1b and 1c) afforded high-molecular-weight polyethers compared with methyl propargyl carbonate (1a) in the polycondensation with bisphenols. The molecular weight (M_n) of the obtained polyethers 3 increased in the order of methyl carbonate 1a<isopropyl carbonate 1b<tert-butyl carbonate 1c.

Poly(ethylene glycol) (PEG) and polyrotaxane are immobilized on a self-assembled monolayer (SAM) of a tri(ethylene glycol)-dodecanethiol conjugate on gold to form a loop or graft structure. From a quartz crystal microbalance with dissipation monitoring measurement, it was found that the loop formation shows less softness than the graft formation, and the polyrotaxane is more rigid than the PEG. Preliminary but interesting feature was observed for the polyrotaxane loop in a fibrinogen adsorption test, and suggests that a polyrotaxane loop is a good platform for the design of biomaterials surfaces.

Condensations of polyhydroxyl monomers with terephthalaldehyde and isophthalaldehyde in the presence of acid catalyst give polyspiroacetals. Model compounds have been synthesized by the condensation of multihydroxyl monomers with benzaldehyde. The effects of different dialdehyde and multihydroxy monomer on polymer properties have been examined. These polymers are found to be chemically and thermally stable.

Second virial coefficients A₂ of polystyrene polymacromonomers (PS PM) with a butyl group at each side-chain end in toluene (15.0 °C) and cyclohexane (34.5 °C) are shown to be in the same order of magnitude, differing from A₂ for PS PM in cyclohexane vanishing at 34.5 °C.

Optically active 4-alkyl-2-(3,5-diiodophenyl)oxazoline was synthesized and polymerized by the Sonogashira–Hagihara coupling reaction to obtain the poly(phenylene-ethylnylene)s bearing oxazoline derivatives with number-average molecular weight ranging from 1060 to 17 300 in 40–72% yields. All the polymers exhibited higher values of specific rotation ([α]_D=+41.6 to +83.7°) than the monomer ([α]_D=−1.2 to −16.9°). On the basis of the results of specific rotation, circular dichroism and ultraviolet analyses, the optical activities of the polymers arise from not only the configurational chirality of the optically active oxazoline pendant groups but also the higher-order structure such as helical conformation.

Redox-active but highly durable nitroxide radicals, that is, 2,2,6,6-tetramethylpiperidinyl-4-oxy (TEMPO), enabled direct electrospinning of radical-containing polymers without additional processing aids (such as polymer blends, post-doping, or protection/deprotection) and produced redox-active fibrous membranes with high surface area. The solution rheological behavior of the TEMPO-substituted polymethacrylate was similar to the neutral conventional polymers, and electrospinning of the radical polymers yielded submicrometer-scaled fibrous membranes without any defects on the radical moiety. The obtained membrane exhibited stable redox response, leading to redox catalysts or electrode-active materials toward organic-based flexible rechargeable battery.

We analyzed the generation mechanism of birefringence in poly(methyl methacrylate (MMA)/styrene (St)) through measurement of infrared (IR) dichroism. Through IR measurement, the conformational changes in the St unit were suggested and found to differ between orientational and photoelastic birefringence generation. We thought that, during photoelastic birefringence generation, the α-CH3 group of the MMA unit hinders the rotation of the benzene ring of St units that are adjacent to MMA units. The influence of compositional distribution on birefringence was also investigated and the results suggested that the compositional distribution of poly(MMA/St) minimally affects the birefringence.

The syntheses of novel copolymers containing indolo[3,2-b]carbazole (INC) moiety were carried out, and the effect of INC content on the physical properties were investigated. All the copolymers were glassy and the decomposition temperatures were nearly 400 °C. It was found that the photoluminescence intensities of the copolymer films decreased with the increase of INC content, which would be caused by the concentration quenching by the intermolecular interaction between INC components. The copolymer with low content of INC moiety exhibited the high emission property and good film-forming ability.

The differential scanning calorimeter of guar gum changes after guar gum being crosslinked by epichlorohydrin. It was obvious that the crosslinked guar gum was more stable compared to guar gum. The crosslinked guar gum had a significantly narrow melting transition.

The impact strength of an amorphous polyamide/organoclay nanocomposite has been increased by means of a rubber modified with maleic anhydride (MAH). The organoclay resided in the polyamide matrix and maintained dispersed rubber particle size upon rubber addition. The changes of the dispersed rubber particle size with modifier and nanoclay addition indicated compatibilization of the nanocomposites and interactions between the dissolved surfactant and the rubber modifier. The obtained nanocomposites had a high stiffness and extremely large toughness values, as determined both by impact strength measurements and by the essential work of fracture method.

Intact glycans were recovered and labeled with common fluorescent dyes by using polymer beads possessing a high density of hydrazide groups. To achieve that, the method for releasing glycans from the beads was examined and optimized. Additionally, fundamental data on our novel method such as recovery ratio, quantitative capability, reproducibility and so forth were obtained. Our hydrazide beads hold the promise for a future standard method due to its high throughput, reproducibility and accuracy of glycan analysis.

This paper deals with the initiation of necking in a high-density polyethylene. The necking initiation was explained by a first-order catastrophic phase transition in analogy of van der Waals gas. Catastrophic arrangement of the lamellar cluster units results in sudden emergence of the locally close-packed layer structure. The layered plate collapses by sliding the units and leads to necking.

By using small-angle X-ray scattering and dynamic light scattering, pH-responsive swelling behavior of the core part of PEGylated nanogels was investigated. The swelling behavior depended on the cross-link density of the core part. When the cross-link density was small, the core swelled with keeping the polydispersity in size and shape constant; to the contrary, the core hardly swelled and only the polydispersity increased when the cross-link density was large. This difference in the swelling behavior is discussed in terms of inhomogeneous structural distribution of cross-links in the core.

In situ observation of the formation process of mesophase of isotactic polypropylene (iPP) is reported in structural point of view. Combining a rapid temperature jump and a high-flux synchrotron radiation X-ray scattering techniques, very rapid transformation from the molten amorphous state to the mesophase has been observed. The transformation proceeded very quickly in a narrow temperature range accompanied by instantaneous fluctuations in micrometer scale, suggesting the mesophase formation proceeds similarly to spinodal decomposition.

We describe the synthesis of a styrene–ethylene copolymer using a trivalent titanium-based polymerization catalyst system, tris(acetylacetonate)titanium/triisobutylaluminum-modified methylaluminoxane (MMAO). The catalyst system yielded a mixture of two different polymers. ¹³C nuclear magnetic resonance analysis of Soxhlet-extracted fractions indicated that the Soxhlet-soluble part contains the syndiotactic styrene–styrene sequence and the ethylene units adjacent to continuous styrene units. Consideration about a relation among sequence distribution, styrene content and thermal property data reasonably indicates that the block-like copolymer was produced, which contains the long syndiotactic polystyrene portions separated by the ethylene units.

The chain dimension of surface-grafted poly[3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate)] brush on silica nanoparticles in aqueous NaCl solution was precisely estimated by dynamic light scattering and synchrotron radiation small-angle X-ray scattering measurements to reveal large dependency on salt concentration. On the other hand, we confirmed that the chain dimension of poly(2-methacryloyloxyethyl phosphorylcholine) brush in aqueous solution was hardly affected by salt concentration.

Conformation changes occurring during the melting of various polyethylene (PE) materials such as HDPE, LLDPE and LDPE are investigated using near-infrared spectroscopy. The trans conformation decreases while the chain ends and/or gauche conformation increases at around melting point.

The melting behavior and the crystallization kinetics of poly(butylene/diethylene naphthalate) and poly(butylene/thiodiethylene naphthalate) random copolymers were investigated by means of DSC. By the Hoffman–Weeks’ method, the T_m° of α and β′-PBN phases were derived: the T_m° value of β′-form was higher, as expected, taking into account that it is thermodynamically favorite and more tightly packed. The presence of oxygen or sulphur atoms in PBN reduced its ability of crystallizing, the crystallization rate regularly decreasing with the co-unit content. α-PBN phase crystallized faster than β′-one, being the more kinetically favorite.

The rapid polymerization and the formation of blue-state polydiacetylene are accomplished by 1D alignment of diacetylene moieties assisted both with β-sheet peptide network and with 2D air–water interface.