Preparation and Properties of High Molecular Weight Polyamic Ester Having a Cyclobutane Moiety in the Main Chain

1998 ◽  
Vol 10 (1) ◽  
pp. 11-21 ◽  
Author(s):  
Masaki Hasegawa ◽  
Hirohiko Miura ◽  
Naoki Haga ◽  
Akira Hayakawa ◽  
Kiyoshi Saito

Preparation and properties of the polyimide derived from cyclobutanetetracarboxylic dianhydride (CBDA) with diamines are investigated, focusing on the interfacial polycondensation of cyclobutanetetracarboxylic acid dimethylester dichloride (2a) with diamines. Dimethylester was conveniently prepared from CBDA by refluxing in methanol solution. Dimethylester consists of two regio isomers; one is α-type (1a) with centrosymmetry, the other is β-type (1b) with plane symmetry. Separation of the mixture into each of pure 1a and 1b was successfully performed by fractional crystallization. The structure of the first fraction is 1a, which was determined by x-ray crystal analysis. The second fraction was necessarily assigned to 1b. 1a was converted into 2a by the reaction of thionyl chloride. The interfacial polycondensation of 2a with diamines afforded a high molecular weight polyamic ester. Polyimide was obtained only by heating the polyamic ester to about 230–280 °C. The cyclobutane polyimide thus obtained was thermally stable up to 400 °C, and less stable under hydrolysis than polypyromellitic imide.

1982 ◽  
Vol 47 (03) ◽  
pp. 197-202 ◽  
Author(s):  
Kurt Huber ◽  
Johannes Kirchheimer ◽  
Bernd R Binder

SummaryUrokinase (UK) could be purified to apparent homogeneity starting from crude urine by sequential adsorption and elution of the enzyme to gelatine-Sepharose and agmatine-Sepharose followed by gel filtration on Sephadex G-150. The purified product exhibited characteristics of the high molecular weight urokinase (HMW-UK) but did contain two distinct entities, one of which exhibited a two chain structure as reported for the HMW-UK while the other one exhibited an apparent single chain structure. The purification described is rapid and simple and results in an enzyme with probably no major alterations. Yields are high enough to obtain purified enzymes for characterization of UK from individual donors.


Author(s):  
Shinji Yoshikawa ◽  
Lih-Geeng Chen ◽  
Morio Yoshimura ◽  
Yoshiaki Amakura ◽  
Tsutomu Hatano ◽  
...  

Abstract Our examination of high molecular weight polyphenolic constituents in the leaves of Barringtonia racemosa of the family Lecythidaceae uncovered five previously undescribed ellagitannins. One, barringtin M1 (1), among them was a hydrolysable tannin monomer, while remaining four, barringtins D1 (2), D2 (3), D3 (4) and barricyclin D1 (5), were all dimers. Barricyclin D1 had a first macrocyclic structure formed from casuarictin (6) and tellimagrandin I (7), and the other ellagitannins had structures related to 5. Two additional known phenolics, valoneic acid dilactone (8) and schimawalin A (9), were also isolated from the leaves. These results suggested that the leaves of B. racemosa is a natural resource rich in hydrolysable tannin oligomers.


NANO ◽  
2008 ◽  
Vol 03 (05) ◽  
pp. 317-322 ◽  
Author(s):  
ZHAOHUI LUO ◽  
KEIKO KATAYAMA-HIRAYAMA ◽  
KIMIAKI HIRAYAMA ◽  
TETSUYA AKITSU ◽  
HIDEHIRO KANEKO

Pyrene is a high molecular weight polycyclic aromatic hydrocarbon (PAH) that is found in water systems worldwide. It is harmful to living organisms, even when taken in very small amounts. The photocatalytic degradation of pyrene in porous Pt / TiO 2– SiO 2 photocatalyst (PPtPC) suspension under UV irradiation was investigated in this study. PPtPC was prepared by a simple heat treatment of the compacted powder mixtures of anatase TiO 2 and amorphous SiO 2 with camphor as a pore directing template, followed by coating platinum by the dip-coating method. X-ray diffraction (XRD), scanning electron microscopy (SEM) with an integrated energy-dispersive analysis of the X-ray (EDX) system, and Brunauer–Emmett–Teller (BET) were used to characterize PPtPC. The degradation kinetics of pyrene in different experimental conditions, such as initial concentration of pyrene, oxygen concentrations, pH, and temperature, were investigated. The durability of PPtPC was also tested. The results indicate that the structure of TiO 2 in PPtPC is anatase. The aggregated size of PPtPC is in the range of 10–100 μm, the mean pore diameter is 3 nm, and the BET surface area is 109 m2 g-1. The photocatalytic degradation process of pyrene follows pseudo-first-order kinetics. The rate constants increase as the initial concentration of pyrene and pH decrease. Higher temperature slightly enhances the rate constant. The dissolved oxygen in the photocatalytic degradation process is not as important as in the photolysis process. The recovered PPtPC still shows high photoactivity. This work suggests that PPtPC offers a promising method for high molecular weight PAH removal.


1944 ◽  
Vol 80 (6) ◽  
pp. 549-559 ◽  
Author(s):  
Gail Lorenz Miller ◽  
Max A. Lauffer ◽  
W. M. Stanley

Crude preparations of PR8 influenza virus, obtained by high-speed centrifugation, contain two electrophoretically distinct components. One of these, present to the extent of 10 to 20 per cent, was identified by electrophoresis, centrifuge, and activity tests, as an impurity similar to or identical with a high molecular weight acidic substance shown by Knight to be elaborated by normal uninfected embryos. The other component, present to the extent of 80 to 90 per cent, appeared to represent the active virus. The virus fraction was separated from the impurity by repeated fractional centrifugation. It then appeared homogeneous in the analytical centrifuge and in the Tiselius apparatus, and possessed an isoelectric point at pH 5.3 as measured by the micro-electrophoresis method.


Author(s):  
C. J. Birkett Clews ◽  
F. Schoszberger ◽  
William Lawrence Bragg

Investigations of the micellar structure of fibre substances have given rise to two theories. The older theory (Meyer and Mark 1930; Mark 1932; Siefriz 1934; Meyer 1930; and Nageli 1928) considers the micelles as separate crystallites, between which lie the intermicellar spaces. The micelles consist of “Hauptvalenzketten” bound together along their length by homeopolar bonds and in the transverse direction by van der Waals’ forces, the intermicellar binding being also attributed to van der Waals’ forces. The original model suggested in work published by K. H. Meyer (1930), for cellulose, depicts the micelles arranged like bricks in a wall (fig. 1), and doubtless this is the simplest explanation of the X-ray results. But it is difficult to understand how such an arrangement can give a micellar structure its peculiar mechanical properties, and further how it is possible, when both inter- and intramicellar cohesion are attributed to the same type of force, to cause by swelling experiments an enlargement of the intermicellar spaces, while the “Hauptvalenzketten” remain unaffected. An alternative theory has been put forward by O. Gerngross, K. Herrmann and W. Abitz (1930), W. T. Astbury (1933), A. Frey-Wyssling (1936) and E. Guth and S. Rogowin (1936). These authors suppose that a given “Hauptvalenzkette” is not confined to a single crystalline region but may stretch through more such regions. In general, the arrangement of the neighbouring chains will be truly lattice-like, but a chain may lie at too great a distance from its neighbours or not lie exactly parallel to them, so that the structure as a whole will show statistically distributed spaces. In fig. 2 ordered crystalline regions may be distinguished (drawn in thick line), but their significance is physically different from that of the crystallites of the Meyer model. They are not self-contained units; the whole system is linked together due to the “Hauptvalenzketten” extending beyond a single micelle. Astbury considers that in a substance of high molecular weight of a type capable of swelling that part which produces the X-ray spectrum is the concentration centre of a complicated network of thread-like molecules. He draws an analogy between micellar structure and the secondary structure of Zwicky. He suggests that it is possible that micellar systems, which are characterized by a mixture of perfection and imperfection, are the counterpart in compounds of high molecular weight of the well-known mosaic structure of the more familiar crystals. Frey-Wyssling is of the opinion that the micelles, growing together, enclose lens-shaped spaces running parallel to the fibre axis. Between these intermicellar spaces are small rod-shaped regions of undistorted lattice, which are the so-called micelles of the earlier work (fig. 3). In this figure, which gives a pictorial representation of Frey’s theory, the statistically distributed hollow spaces are shown black; some of these are enclosed in undistorted crystalline regions. A lamellar structure consisting of superimposed monomolecular layers suggested by O. L. Sponsler and W. H. Dore (1930) has been shown to be untenable from the work on double refraction by Baas-Becking and Galliher (1931).


1979 ◽  
Vol 57 (11) ◽  
pp. 1286-1293 ◽  
Author(s):  
T. Chivers ◽  
J. Proctor

Pentasulfur hexanitride, S5N6, has been prepared in good yield by the reaction of [n-Bu4N+][S4N5−] with bromine (or iodine) in methylene chloride at 0 °C. In contrast, the tetrasulfur pentanitride(−1) ion reacts smoothly with chlorine to give S4N5Cl, while the reaction with sulfuryl chloride produces S4N5Cl and S5N6 and the reaction with thionyl chloride produces a mixture of S3N2O, S3N2O2, S4N4, and S5N6. Pentasulfur hexanitride is an air-sensitive, explosive, yellow-orange solid which sublimes at ca. 45 °C/10−2 Torr without significant decomposition. It has been characterised by infrared, Raman, uv–visible, and mass spectra and by a single crystal X-ray structure determination. The crystals are monoclinic and belong to the space group C2/c, a = 8.787(2), b = 11.190(2), c = 7.427(2) Å, β = 106.46(2)°, V = 700.3(5) Å3, Z = 4, Dc = 2.317 g cm−3. The refined structure (Rw = 0.040) has twofold symmetry and resembles a basket in which an —N=S=N— unit (d(S—N) = 1.54 Å) is the handle which bridges an S4N4 cradle via S—N single bonds (d(S—N) = 1.70 Å). The introduction of this bridge widens one of the [Formula: see text] transannular separations in S4N4 to 3.94 Å while the other is shortened to 2.43 Å. Thus, the S4N4 cradle can be viewed as two five-membered rings fused at the S—S bond.


1961 ◽  
Vol 34 (1) ◽  
pp. 101-118 ◽  
Author(s):  
V. E. Gul

Abstract In connection with the wide distribution of high molecular weight compounds and the great successes in the field of synthesis of these materials, the study of the general principles of the processes of irreversible deformation and rupture of high polymer materials may be included among the important tasks of science and technology. In some cases it is desired to increase to the maximum the strength of the high molecular weight material, as for example in preparing articles from synthetic fibers, rubbers, plastics, etc., while on the other hand in others an increase in strength is undesirable. Thus, for example, food products, into whose composition high molecular weight materials are introduced, should naturally not be too strong. The preparation of reclaim from used rubber articles includes grinding. Here it is attempted to find such a combination of grinding conditions that will proceed with the minimum consumption of energy. In order to have the possibility of increasing or decreasing the strength of the high molecular weight substances, it is necessary to clarify the mechanism of ruptures and to know what is the relation between the forces of reaction between the structural elements of the material and tensile strength.


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