Star‐shaped polystyrenes with glycoconjugated periphery and interior: Synthesis and entrapment of hydrophilic molecule

Star‐shaped polystyrenes with acetyl glucose in the periphery and interior were synthesized via two‐steps, 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO)‐mediated living radical polymerizations. In the first step, styrene (St) was polymerized with 4‐[1′‐(2″,2″,6″,6″‐tetramethyl‐1″‐piperidinyloxy)ethyl]phenyl 2,3,4,6‐tetra‐O‐acetyl‐β‐D ‐glucopyranoside, 1 , at 120 °C to afford a TEMPO‐terminated polystyrene with acetyl glucose in the chain‐end, arm‐polymer 2 . Similarly, St was polymerized with 1‐phenyl‐1‐(2′,2′,6′,6′‐tetramethyl‐1′‐piperidinyloxy)ethane, 3 , to obtain a TEMPO‐terminated polystyrene, arm‐polymer 4 . In the second step, the coupling reaction of arm‐polymer 2 was performed using divinylbenzene (DVB) as a linking agent in m‐xylene at 138 °C, giving a star‐shaped polystyrene with acetyl glucose in the periphery, 5 . The coupling reaction of arm‐polymer 4 with DVB was carried out in the presence of 1 , which produced a star‐shaped polystyrene with acetyl glucose in the interior, 6 . Dynamic laser light scattering (DLS) measurements indicated that 5 and 6 existed as the particles in toluene with the average diameters ranging from 12–40 nm. The numbers of the arm (N_arm) were 12–23 and 6–64 for 5 and 6 , respectively, which were determined by their isolated yields and static laser light scattering (SLS) measurements. The numbers of the acetyl glucose units (N₁) were 12–23 and 9–104 for 5 and 6 , respectively, which were determined from specific rotation ([α]₃₆₅). Finally, 5 and 6 were modified by deacetylation using sodium methoxide, producing star‐shaped polystyrenes with glucose in the periphery and interior, 7 and 8 , respectively. The final architectures were found to entrap a hydrophilic molecule at their glycoconjugated periphery or interior in good solvents for polystyrene such as chloroform. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4373–4381, 2005     

Role of molten fraction on the structural evolution in stretching and cooling of crosslinked low‐density polyethylene: Real‐time mechano‐optical measurements

We investigated the uniaxial deformation behavior of crosslinked low‐density polyethylene in partially and substantially molten states using a real‐time true stress–strain birefringence system. The stress–birefringence behavior exhibits a multiregime behavior during stretching and holding process. The details of this regime behavior are primarily governed by the degree of unmelted crystallinity as it has a dominant role in the long‐range structural connectivity. When the long‐range physical connectivity is present, a three‐regime nonlinear stress–optical behavior was observed. When the long‐range connectivity is substantially eliminated at higher temperatures, the regime I behavior disappears. Structural studies including cooling process reveal that the lower the proportion of molten material during stretching, the higher the concentration of fibrillar structure and the shorter are the lengths of the kebabs that exhibit twisted lamellae after solidification. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1825–1841, 2005     

Syntheses and properties of a thiacrown ether and its acyclic model compound modified with germanium moieties

A thiacrown ether (1) and its acyclic model compound (2), modified with germanium moieties, were synthesized and their structures confirmed by NMR spectrometry and elemental analysis. The germanium atom, located in one of the side chains of 2, is pentacoordinated by virtue of a weak hypervalent O → Ge interaction. The cation capture/transport ability is almost null for both compounds, probably owing to the proximity of the cation and anion binding sites. Copyright © 2005 John Wiley & Sons, Ltd.     

Multi-functionalization of gallic acid towards improved synthesis of α- and β-DDB

The synthesis of mono-, di- and trisubstituted gallic acids and their ester with similar or different groups including different acetal and ketals is described. Regioselective bromination on two ortho-positions of methyl gallate, which is very crucial for many organic syntheses, was achieved in high yield and purity. The α- and β-DDB were synthesized in high overall yield and purity from the regioselective bromoderivatives.     

Synthesis of well‐defined AB20‐type star polymers with cyclodextrin‐core by combination of NMP and ATRP

The synthesis of an AB₂₀‐type heteroarm star polymer consisting of a polystyrene arm and 20‐arms of poly(methyl methacrylate) or poly(tert‐butyl acrylate) was carried out using the combination of nitroxide‐mediated polymerization (NMP) and atom transfer radical polymerization (ATRP). The NMP of styrene was carried out using mono‐6‐[4‐(1′‐(2″,2″,6″,6″‐tetramethyl‐1″‐piperidinyloxy)‐ethyl)benzamido]‐β‐cyclodextrin peracetate ( 1 ) to afford end‐functionalized polystyrene with an acetylated β‐cyclodextrin (β‐CyD) unit (prepolymer 2 ) with a number‐average molecular weight (M_n) of 11700 and a polydispersity (M_w/M_n) of 1.17. After deacetylation of prepolymer 2 , the resulting polymer was reacted with 2‐bromoisobutyric anhydride to give end‐functionalized polystyrene with 20(2‐bromoisobutyrol)s β‐CyD, macroinitiator 4 . The copper (I)‐mediated ATRP of methyl methacrylate (MMA) and tert‐butyl acrylate (tBA) was carried out using macroinitiator 4 . The resulting polymers were isolated by SEC fractionation to produce AB₂₀‐type star polymers with a β‐CyD‐core, 5 . The well‐defined structure of 5 with weight‐average molecular weight (M_w)s of 13,500–65,300 and M_w/M_n's of 1.26–1.28 was demonstrated by SEC and light scattering measurements. The arm polymers were separated from 5 by destruction with 28 wt % sodium methoxide in order to analyze the details of their characteristic structure. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4271–4279, 2005     

Progresses of coal liquefaction catalysts in Japan

Research and development of catalysts and their performances for coal liquefaction are reviewed, enphasizing the contribution of recent 20 years from Japan. A variety of iron based catalysts were extensively examined to define the pyrrhotite as the active species produced in the liquefaction process. Synthetic pyrite, synthesized hydroxy ferric oxide, finely ground pyrite and limonite have been applied in the process development of coal liquefaction. Iron impregnation onto coal particles using waste water was examined also in a continuous-flow reactor. Finer particles were found to reduce significantly the amount of the catalyst to obtain the same oil yield. Usefulness of such catalysts is proved in the continuous operation of a large scale pilot plant. Iron, iron–nickel, and iron–molybdenum sulfides were found to be active catalysts when they are supported on nano-particles of carbon. Catalysts for recovery and repeated use and for selective aromatic ring opening are under current research.     

On tactical decompositions of class number 2

In this article we consider tactical decompositions of class number 2 of symmetric designs. Our main result says that if the orders are prime, then the only decompositions are of affine type. Moreover, we study symmetric decompositions of finite projective planes and show that, except in some cases, they are related to Baer subplanes, unitals, or 2 - ((m ² - m + 1)m, m, 1)designs.