Volume 44 Issue 3, March 2012

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.

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.

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.

The diisocyanate structure has an important role in the phase separation behavior of hybrid materials. SAXS curves for both PUs show the typical broad band at q=0.1 Å⁻¹. Incorporation of the acrylic component reduced the intensity of this maximum. Hybrid based on H12MDI has a high degree of phase mixing for 50 wt% acrylic content but a separated phase at 70 wt% is observed. TMXDI-based hybrids that form homogeneous systems with higher acrylic content and phase separation are observed only at 90 wt%.

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.

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.

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.

A new soluble conjugated polymer, poly[{9-(4-methoxyphenyl)-9H-carbazole}(9,9-dioctylfluorene)(2,5-diphenyl-1,3,4-oxadiazole)](PCFO), was synthesized and was sucessfully used to fabricate a PCFO-based nonvolatile memory device. This device showed typical bistable electrical switching and nonvolatile write-once read-many-times memory performance, with a turn-on voltage of about −2.3 V and an ON/OFF state current ratio of ∼10⁵.

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.

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.

Perylene diimide (PDI) derivatives with cyclodextrins (PDI-CD₂s) exhibit specific emission properties, which depend on the type of CDs in an aqueous solution. Herein we create an emission from film kneaded PDI-CD₂s derivatives via effective tumbling of the altropyranose unit. We have observed the selective emission of PDIC₇-3βCD₂ in aqueous solutions and prepared emission films kneaded into polyvinyl alcohol (PVA) films. The emission depends on the cavity size of the altro-CDs formed through altro-CD tumbling.

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.

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.