Showing papers by "Waseda University published in 1974"

Average energy expended per ion pair in liquid argon

Abstract: The measurement of the $W$ value, the average energy expended per ion pair, in liquid argon for internal conversion electrons emitted from $^{207}\mathrm{Bi}$, is carried out by the electron-pulse method. Comparing with the $W$ value (26.09 eV) for $\ensuremath{\alpha}$ particles in a gas mixture of argon (95%) and methane (5%), the $W$ value in liquid argon is determined to be ${23.6}_{\ensuremath{-}0.3}^{+0.5}$ eV. This value is clearly smaller than that in gaseous argon (26.4 eV). Such a reduction of $W$ value in liquid argon can be explained by assuming the existence of the conduction band in liquid argon as in solid argon. Under this assumption, the $W$ value in liquid argon is estimated by applying the energy-balance method, which was used for the rare gases by Platzman. The calculated value thus obtained is in good agreement with the experimental result. Following the same method, the $W$ values for liquid krypton and liquid xenon are also estimated.

Information-Power Machine with Senses and Limbs

Abstract: The WABOT project is aimed at developing an information-power machine to introduce external and internal informations, judge the same by itself and perform a given action autonomously. The WABOT-1 consists of a human-type biped walking machine provided with artificial ears and mouth to receive a vocal command from the operator and make a vocal response, artificial eyes to recognize the position, distance and direction of an object and human-type bilateral hands. Under the control of a mini-computer as the artificial brain and on the basis of external informations received from the visual, auditory and dermal senses, etc., the WABOT-1 performs a given work in linked motions of hands and feet in on-line real time.

Formation of polyion complexes between polycarboxylic acids and polycations carrying charges in the chain backbone

Abstract: The formation of polyion complexes in aqueous medium between polycations carrying charges in the chain backbone and poly(carboxylic acid)s, such as poly(methacrylic acid) (PMAA), poly(carboxylic acid) (PAA), and poly(itaconic acid) (PIA), were studied. It was found that polycations formed more stable complexes than their corresponding low molecular weight cations and that in addition to the chain length, dissociation constants and the hydrophobicity dominated the ability of the formation of a polyion complex. The compositions of the complexes between polycation and polycarboxylic acid were defined mainly by the degree of dissociation (α′) of the poly(carboxylic acid). From these results it is concluded that the complexes are formed by the cooperative interactions between two polymer chains which have charges of opposite sign and the structures of polyion complexes can accept reversible states like loops, ladders, and their intermediate shapes. Die Bildung von Polyionen-Komplexen in wasrigem Medium zwischen Polykationen, die Ladungen in der Kette tragen, und Polycarbonsauren, wie Polymethacrylsaure (PMAA), Polyacrylsaure (PAA) und Polyitaconsaure (PIA), wurde untersucht. Es wurde gefunden, das die Polykationen stabilere Komplexe bilden als die entsprechenden niedermolekularen Kationen und das neben der Kettenlange die Dissoziationskonstanten und die Hydrophobie die Bildungsfahigkeit der Polyionen-Komplexe beeinfluste. Die Zusammensetzung der Komplexe zwischen Polykationen und Polycarbonsauren wurde vor allem durch den Dissoziationsgrad (α′) der Polycarbonsauren bestimmt. Aus diesen Ergebnissen ist zu schliesen, das die Komplexe durch die kooperativen Wechselwirkungen zwischen zwei Polymerketten, die entgegengesetzte Ladungen tragen, gebildet werden und das die Polyionen-Komplexe reversibel Schleifen-, Leiter- und dazwischenliegende Strukturen ausbilden.

Steam Reforming of Hydrocarbons on Noble Metal Catalysts (Part 1)

Abstract: The catalytic activity of Group VIII transition metals except Os for methanesteam reaction under atmospheric pressure at 350∼600°C was investigated. The following activity sequence was obtained: Ru∼Rh>Ni>Ir>Pd∼Pt>>Co∼Fe.Ru and Rh were found to possess high and stable activity over a wide range of steam/methane ratio. The rate of reaction on a Rh-silica catalyst was found to be of the zeroth and 0.5th order with respect to methane and steam, respectively.

Theory of the Optical Property of Visual Pigment

Abstract: Under the assumption that retinal forms a protonated or unprotonated Schiff-base binding with opsin, the effect of the electrostatic interaction between retinal and opsin on the optical property of visual pigment is investigated, using the π-electronic states determined previously with a due account of both σ-π interaction and configuration interaction. It is shown that the wide distribution of the observed wavelengths of absorption maximum of visual pigments can reasonably be explained by both the protonated Schiff-base binding and the electrostatic interaction of retinal with opsin. Furthermore, the origin of the electrostatic interaction is shown to be ascribable to one counter ion such as COO - at the vicinity of the protonated Schiff-base binding.

Mechanism for increase in intracellular concentration of free calcium in fertilized sea urchin egg. A method for estimating intracellular concentration of free calcium.

Abstract: Intracellular free calcium concentration in the sea urchin egg was calculated to increase from 0.1 mM in an unfertilized egg to 1 mM in a fertilized egg 10 min after fertilization, based on measurement of the dissociation constant between free calcium and sea urchin egg homogenate. The dissociation constant between free calcium (dialyzable calcium) and homogenate of sea urchin eggs was measured by means of dialysis equilibrium. The dissociation constant of the unfertilized egg was about 10–4 M and that of the fertilized egg was about 10–3 M in three species of sea urchin, Hemicentrotus pulcherrimus, Anthocidaris crassispina, and Pseudocentrotus depressus. An increase in the dissociation constant of the unfertilized egg homogenate was observed after the addition of calcium ion at a concentration above 0.3 mM, the dissociation constant becoming the same as that observed in the fertilized egg homogenate after the administration of CaCl2 at a concentration above 1 mM. Sodium ion also caused a decrease in the calcium-binding ability of the unfertilized egg homogenate. Therefore, penetration of calcium ion or sodium ion upon fertilization might induce an increase in the dissociation constant and then intracellular concentration of free calcium would increase at fertilization. Almost all calcium-binding ability of the egg homogenate was found in the microsomal fraction, and the substance which bound calcium was thought to be protein in nature, since trypsin could decrease the level of calcium-binding substance in the homogenate of the eggs.

The rôle of the chain length in the stability of polyion complexes

Abstract: To demonstrate the cooperativity in the formation of an interpolymer complex, the stability of polyanion-polycation complexes as a function of their chain length was studied. Poly(methacrylic acid) (PMAA; Pn ≈ 800) was used as source for the polyanion and quaternized alkylamines and polyethyleneimines with various chain lengths (1a–g and 2a–g) as source for the polycation. The reaction was followed by the measurement of [H+] from which the stability constants (K) of the complexes were calculated. It was found that the K-values increased exponentially from 102 to 8.104l mol−1 with increasing chain length of the polycation. Furthermore, it was found that, in addition to COULOMBic forces, the hydrophobic interaction plays an important rǒle in the complexation. Um den kooperativen Charakter der Bildung von Interpolymer-Komplexen zu beweisen, wurde die Stabilitat der Polyanion-Polykation-Komplexe als Funktion der Kettenlange untersucht. Poly(methacrylsaure) (PMAA; Pn ≈ 800) wurde als Ausgangsprodukt fur das Polyanion eingesetzt und quaternare Alkylamine und Polyathylenimine mit verschiedenen Kettenlangen (1a–g und 2a–g) als Ausgangsprodukt fur Polykationen. Die Reaktion wurde durch Messung von [H+] verfolgt, und die Stabilitatskonstante der Komplexe (K) wurden daraus berechnet. Es wurde gefunden, das die Stabilitatskonstante exponentiell von 102 bis 8.104l mol−1 mit steigender Kettenlange des Polykations zunimmt und das die hydrophoben Wechselwirkungen neben der elektrostatischen Wirkung eine wichtige Rolle bei der Komplexbildung spielen.

Charging Effect of Specimen in Scanning Electron Microscopy

Abstract: Flat surfaces of MgO and KCl crystals and teflon sheet were coated with gold evaporated films except for the parallel strip areas approximately 200, 100 and 50 µm wide, and the strip areas without coating were observed by SEM at 15 kV. The images of the uncoated areas were distorted by the surface potential caused by charging. The surface potential was quantitatively measured by distortion as a function of the scanning time and width of the strip areas. The results were analysed numerically. Furthermore, it was found that the charging effect was reduced by the tilting angle θ of the specimen with respect to the incident beam. Critical angle θc at which the secondary electron efficiency β equals 1 was experimentally determined as 75°±2° for teflon and 55°±2° for MgO at 15 kV. The deflection effects of the incident and secondary electrons by the surface potential were also discussed by comparing the distortion and contrast for backscattering and emissive mode images.

Optical absorption and interband faraday rotation in litao3 and linbo3

Abstract: The optical absorption and the interband Faraday rotation in LiTaO3 and LiNbO3 were measured at room temperature. The optical absorption in both crystals follows Urbach's equation and the effective temperatures defined by this equation are considerably higher than those of the cubic perovskites. The interband Faraday rotations are negative and about one order of magnitude smaller than those of the perovskites. The results are well described by a combination of indirect transition and direct transition which is estimated from the absorption data.

A GENERATION THEOREM FOR SEMIGROUPS OF GROWTH ORDER α

Abstract: Introduction. This paper is concerned with the generation of (operator) semigroups of growth order ƒ¿. Extending the notion of a semigroup of class (C0), Da Prato [1] introduces the notion of a semigroup of growth order n, n is a nonnegative integer. Roughly speaking, a semigroup {T(t); t > 0} of bounded linear operators on a Banach space is of growth order n if •atnT(t)•a is bounded as t tends to zero; in particular, {T(t)} is of growth order 0 if and only if it belongs to class (C0). In [1], Da Prato gave a characterization for the Laplace transform of tnT(t) through the notion of a closable linear operator of type n and its resolvent of order n. Namely, if A0 is the infinitesimal generator of a semigroup {T(t)} of growth order n, then A0 is of type n and its resolvent S(ƒÉ, A0) of order n is equal to the Laplace transform of tnT(t) and satisfies a certain stability condition. Viceversa if B is of type n and its resolvent S(ƒÉ, B) of order n satisfies the stability condition mentioned above, then there exists a unique semigroup of growth order n such that S(ƒÉ, B) = S(ƒÉ, A0), where A0 is the infinitesimal generator of the constructed semigroup. This result was generalized by Zafievskii [10] to the case of fractional ƒ¿ (cf. also Sobolevskii [8]). So, if it can be shown that B = A0, then their result is proved to be a characterization for the infinitesimal generator of a semigroup of growth order ƒ¿. But, this is not expected in general as noted in [2]. The purpose of this paper is to give a characterization for the closure of the infinitesimal generator of a semigroup of growth order ƒ¿. We first clarify some properties of the closure of the infinitesimal generator and then modify the construction of the semigroup stated in [1]. In this way, we obtain a criterion for a closed linear operator in a Banach space to be the closure of the infinitesimal generator of a semigroup of growth order ƒ¿. The main result of this paper is stated in • ̃ 1 and the proof of it is

Model Coordination Method Applied to Power System Control and Estimation Problems

Abstract: This paper presents an application of the Model Coordination Method to the multi-area power system operation and control. The heirarchical structure of the Power Pool composed of member areas is analyzed. The data required for the coordination of each area are defined for the two examples of power system operation, viz., the state estimation and the voltage and reactive power control problems. The memory requirements and computation time are also discussed.

Separation of chicken adenohypophysial gonadotropins.

Abstract: Two different gonadotropic fractions were obtained by the ion exchange chromatography on carboxymethyl cellulose and DEAE cellulose columns, following to the gel filtration through Sephadex G-100 of chicken adenohypophysial glycoprotein. Oneof the fractions possessed a high activity (3.4×NIH-FSH-S8) of follicle stimulating hormone and undetectable activity of luteinizing hormone. The other fraction possessed a low but significant activity (0.085×NIH-LH-S16) of luteinizing hormone and relatively low activity (0.59×NIH-FSH-S8) of follicle stimulating hormone. Gonadotropic activities assessed by chick testes 32P uptake method of the former and latter fractions were 1.6×and 3.0×NIH-LH-S16, respectively.

Quantum-Mechanical Study of Rosette-Motion Channeling

Abstract: Quantum mechanical treatment of the “Rosette-Motion” channeling of energetic electron beams is developed. Energy levels and scattering angles corresponding to channeling are determined. Detailed calculations are performed for W〈111〉 for various energies. The lifetime of such quantum states is discussed making use of the mean free path due to lattice vibrations. Es wird eine quantenniechanische Behandlung der „Rosettenbewegnngs”-Kanalisierung energiereicher Elektronen entwickelt. Energieniveaus und Streuwinkel, die der Kanalisierung entsprechen, werden bestimmt. Detaillierte Berechnungen werden fur W〈111〉 fur verschiedene Energien durchgefuhrt. Die Lebensdauer solcher Quantenzustande wird diskutiert, wobei die mittlere freie Weglange infolge von Gitterschwingungen herangezogen wird.

Reversible oxygenation of heme bound to polyvinylpyridine and polyvinylimidazole.

Abstract: The interaction between heme bound to poly-4-vinylpyridine (PVP) or poly-N-vinyl-2-methylimidazole (PVMI) and molecular oxygen (O2) was studied. In this paper, the reactions of some types of heme with O2 in organic solvents, particularly in N,N-dimethylformamide (DMF) were discussed. The free heme not bound to an axial base was easily oxidized irreversibly to hemin in DMF with bubbled O2. The hemochromogens complexed with pyridine, imidazole, or their polymeric derivatives such as PVP and PVMI bound O2 to one of the axial coordination sites. The characteristic absorption band assignable to the resulting oxygenated heme was observed at 402 nm. This absorption band could be changed back to the characteristic band of the reduced hemochromogen at 418 nm by removing O2 dissolved in the DMF solution by a vacuum or by a stream of nitrogen. Thus, the hemochromogens bound to the synthetic polymers were found to adsorb and desorb O2 reversible in DMF. When the polymeric ligands were used, the equilibrium constants in the complexation of heme with these polymers were about 102 times as large as those of the corresponding monomeric ligands. The oxygenation rates and the capacities of O2 of the polymeric hemochromogens were larger than those of the monomeric hemochromogens. In addition, the oxygenation rate of the polymer complex was changeable owing to the conformational change of the polymeric ligand; this rate increased about ten times under the optimal condition.

The formation of higher structure through hydrophobic interaction of interpolymer complexes

Abstract: Polyion complexes have been thought to be formed at the moment when the solutions of each component polymer are mixed. However, by observing many cases of complexation, it was cleared up that the complexes existed in their non-equilibrium states for a long time under certain conditions and that the external factors, such as time, heat and shear-stress, made the complexes grow up to be particularly structured complexes. The fibrous and network-structured complexes were obtained by combination of the solution of poly(methacrylic acid) and the solution of poly(N,N,N′,N′-tetramethyl-N-p-xylylene-N′-alkylene diammonium dichloride) poly[(dimethylimino)ethylene(dimethylimino)methylene-1,4-phenylenemethylene dichloride]. The formation of higher structures is explained as follows: the hydrophobicity of their relatively extended polymer chains is changed by the neutralization of each ionic site of the polymers, and then these complexes grow regularly along the directions of their main chains by their own hydrophobicity and after a certain stage they expand to network structures by loosing their aggregating directions. Es ist vermutet worden, das Polyionenkomplexe momentan bei der Vermischung der Loungen der einzelnen Polymeren gebildet werden. Jedoch aus der Beobachtung vieler Komplexbildungsvorgange wurde gefunden, das die Komplexe wahrend langerer Zeit im Nicht-Gleichgewichtszustand existierten und das sie, bedingt durch ausere Faktoren, z.B. Zeit, Warme und Scherspannung, anwachsen. Die faserigen und netzwerkstrukturierten Komplexe wurden durch Vermischung der Losungen von Polymethacrylsaure und Poly[N,N,N′,N′-tetramethyl-N-(p-xylylen)-N′-alkylen diammoniumdichlorid] (Poly[(dimethylimino)alkylen(dimethylimino)methylen-1,4-phenylen-methylendichlorid]) erhalten. Die Bildung von hoheren Strukturen wird folgendermasen erklart: die Hydrophobie der relativ gestreckten Polymerketten wird durch die Neutralisation jeder ionischen Stelle verandert, und dann wachsen diese Komplexe geordnet in Richtung ihrer Hauptketten, bedingt durch ihre eigene Hydrophobie, und nach einem bestimmten Stadium wachsen sie zu Netzwerkstrukturen unter Verlust ihrer Aggregationsrichtungen an.

Some observations of abnormal embryos induced by short-period treatment with chloramphenicol during early development of sea urchin

Abstract: Sea urchin embryos, which were treated with 5 × 10−3 M chloramphenicol for 1 to 4 hr at certain stages before hatching, developed to several types of abnormal embryos. No significant effect on the shape of the embryo was observed when the concentrations of chloramphenicol used in the short-period treatment were lower than 2 × 10−3 M. Embryos up to the 2-cell stage, treated with 5 × 10−3 M chloramphenicol for a short period, became small blastulae filled with mesenchyme-like cells (type A). A similar effect of puromycin (2 μg/ml) was also observed at this stage. When the chloramphenicol treatment (for 1 to 4 hr) was applied at 8 ∽ 32-cell stages, vegetalized larvae were produced (type B). Embryos treated with chloramphenicol at 7 hr after insemination at 20°C, developed to another type of abnormal larva different from the previous types (type C). A concentration of puromycin (2 μg/ml) which inhibited protein synthesis to the same degree as 5 × 10−3 M chloramphenicol, induced only type A. Between these chloramphenicol-sensitive stages, there were chloramphenicol-insensitive stages for forming abnormal embryos.

On some properties of stochastic information processes in neurons and neuron populations - Mathematical model approach

Abstract: The information in the nervous spike trains and its processing by neural units are discussed. In these problems, our attention is focused on the stochastic properties of neurons and neuron populations. There are three subjects in this paper, which are the spontaneous type neuron, the forced type neuron and the reciprocal inhibitory pairs. 1. The spontaneous type neuron produces spikes without excitatory inputs. The mathematical model has the following assumptions. The neuron potential (NP) has the fluctuation and obeys the Ornstein-Uhlenbeck process, because the N P is not so perfectly random as that of the Wiener process but has an attraction to the rest value. The threshold varies exponentially and the NP has the constant lower limit. When the NP reaches the threshold, the neuron fires and the NP is reset to a certain position. After a firing, an absolute refractory period exists. In discussing the stochastic properties of neurons, the transition probability density function and the first passage time density function are the important quantities, which are governed by the Kolmogorov's equations. Although they can be set up easily, we can rarely obtain the analytical solutions in time domain. Moreover, they cover only simple properties. Hence the numerical analysis is performed and a good deal of fair results are obtained and discussed. 2. The forced type neuron has input pulse trains which are assumed to be based on the Poisson process. Other assumptions and methods are almost the same as above except the diffusion approximation of the stochastic process. In this case, we encounter the inhomogeneous process due to the pulse-frequency-modulation, whose first passage time density reveals the multimodal distribution. The numerical analysis is also tried, and the output spike interval density is further discussed in the case of the periodic modulation. 3. Two types of reciprocal inhibitory pairs are discussed. The first type has two excitatory driving inputs which are mutually independent. The second type has one common excitatory input but it advances in two ways, one of which has a time lag. The neuron dynamics is the same as that of the forced type neuron and each neuron has an identical structure. The inputs are assumed to be based on the Poisson process and the inhibition occurs when the companion neuron fires. In this case, the equations of the probability density functions are not obtained. Hence the computer simulation is tried and it is observed that the stochastic rhythm emerges in spite of the temporally homogeneous inputs. Furthermore, the case of inhomogeneous inputs is discussed.

Inelastic scattering of slow ions in channeling

Abstract: In slow-ion channeling cases, the stopping power and diffusion coefficient for electronic excitations are calculated making use of the linear-response theory. The velocity dependence and electron-density dependence (or position dependence) are shown. The Firsov theory for the stopping power is reconfirmed, and we show that the diffusion coefficient does not depend on the ion velocity in the velocity range considered.

X-Ray dilatometric study of the phase transition of the improper ferroelectrics KH2PO4 and KD2PO4

Abstract: X-ray dilatometric measurements were made on lattice strains of KH2PO4 and KD2PO4 as a function of temperature and biasing electric field near the Curie point. The electrostriction contained in the lattice strains x1, x2 along the a-and b-axes cannot be explained in terms of the ordinary electrostrictive effect. In order to interpret these new effects, the phenomenological theory of improper ferroelectrics has been successfully applied. The difference of the transition mechanism between KH2PO4 and KD2PO4 is discussed from the same viewpoint of improper ferroelectrics.

Contrast Reversals of Pseudo-Kikuchi Band and Lines Due to Detector Position in Scanning Electron Microscopy

Abstract: The contrast reversals of pseudo-Kikuchi band and lines due to the detector position are observed for Si by using the surface scanning electron microscope. The detector is placed at two positions, i. e. high and low angle positions for the crystal surface. In the high angle detection, the pseudo-Kikuchi band changes its contrast from excess to defect with decreasing the glancing angle and moreover the contrast of Kikuchi lines is also reversed between a pair of lines and along a line in the region of the low glancing angle. These situations are not observed in the low angle detection. These facts are explained qualitatively by applying the reciprocity theorem in electron diffraction and the dynamical theory of two-beam approximation with considering the anomalous absorption and the angular distribution of inelastic scattering electrons in crystal.

Steric and electrostatic factors on the formation and the structure of polymeric cobalt(III) complexes

Abstract: Polymeric cobalt(III)-complexes (2a, b, c, e, f, g, h, i, j) were prepared by a substitution reaction between a polymeric ligand (1a or 1b) and a Co(III)-chelate. They were characterized by elemental and spectroscopic analyses. The complexation rates of the Co(III)-en- and Co(III)-trien-chelates were found to be smaller than those of the non-charged Co(III)-chelates. This retardation effect was explained by an electrostatic repulsion of the cationic polymeric complexes 2a, b or 2c. The degree of coordination (x) was found to reach a constant level of about 0,65 under the reaction conditions. This experimental x-value of saturation was nearly equal to the value which was calculated statistically. Polymere Kobalt(III)-Komplexe (2a, b, c, e, f, g, h, i, j) wurden durch eine Substitutionsreaktion zwischen einem polymeren Liganden (1a oder 1b) und einem Co(III)-Chelat dargestellt. Sie wurden durch Elementaranalyse und spektroskopische Daten charakterisiert. Fur die Co(III)-en- und Co(III)-trien-Chelate wurde eine kleinere Komplexbildungsgeschwindigkeit gefunden als fur Co(III)-Chelate, die keine Ladung tragen. Dieser Verzogerungseffekt wird mit einer elektrostatischen Abstosung der kationischen polymeren Komplexe 2a, b oder 2c erklart. Der Koordinationsgrad (x) erreichte unter den Reaktionsbedingungen einen konstanten Hochstwert von ungefahr 0,65. Der experimentelle x-Wert der Sattigung und der statistisch berechnete Wert erwiesen sich als beinahe gleich.

Electrostatic effect on electron‐transfer reactions of cobalt(III)‐poly(4‐vinylpyridine) complexes

Abstract: Reductions of cis-[Co(en)2PVPCl]2+ (1) [PVP = poly(4-vinylpyridine)] by ferrous aquoions and ferrous chelate ions were studied. The rate of reduction by Fe2+ is small compared to that of the monomeric analogue, cis-chlorobis(ethylenediamine)pyridine cobalt(2+) (cis-[Co(en)2PyCl]2+) due to the electrostatic repulsion. On the other hand, the reduction by [Fe-(edta)]2− is accelerated by a factor of 20. With increasing degree of coordination the acceleration factor increases, and with increasing ionic strength the factor decreases. The acceleration was found to be due to the electrostatic attraction of the reductant by the polymer as a polycation. The electrostatic effect is discussed in comparison with the catalysis of polyelectrolytes in ionic reactions. Die Reduktion des cis-[Co(en)2PVPCl]2+-Komplexes (1) (PVP = Polyvinylpyridin) mit Ferroionen oder Ferrochelat-Ionen wurde untersucht. Die Reduktion mit Fe2+ verlauft wegen elektrostatischer Abstosung langsamer als die des monomeren Analogons, cis-Chlorobis-(ethylendiamin)-pyridin-kobalt(2+) (cis-[Co(en)2PyCl]2+). Dagegen ist die Reduktion mit [Fe-(edta)]2− um das Zwanzigfache beschleunigt. Mit zunehmendem Koordinationsgrad steigt der Beschleunigungsfaktor, und mit zunehmender Ionenstarke nimmt der Faktor ab. Es wurde gefunden, das die Beschleunigung auf die elektrostatische Anziehung zwischen dem Polymer-Komplex als einem Polykation und dem Reduktionsmittel zuruckzufuhren ist. Die elektrostatische Wirkung wird im Vergleich zu den mit Polyelektrolyten katalysierten ionischen Reaktionen diskutiert.

Radical polymerization of metal‐coordinated monomers with ligands of pyrrole‐containing schiff bases

Abstract: The copper complexes and the cobalt complex with the ligand of 3-(2-pyrrolylmethyl-enimino)propene-1 (PIP) or p-(2-pyrrolylmethylenimino)styrene (PIS) were synthesized and homopolymerizations and the copolymerization with styrene, acrylonitrile, methyl methacrylate and acrylic acid studied. In the polymerization of chelate monomers, inhibition of radical polymerization by the central metal ion was observed, but the chelate polymer could be obtained only if the initiator was present in higher concentrations in the feed. It is considered that the strength of inhibition depends on the electronic configuration of d-orbitals of the central metal ion. The initiation mechanism of the cupric chelate monomer may be reduction of the metal ion by the redox reaction with a primary radical via the intramolecular electron transfer through the π-conjugated system of the ligand prior to the propagation step. This mechanism was verified by studying the redox reaction of various copper complexes with DPPH. In the system of the copper complex containing PIS and acylic acid the alternating copolymer could be obtained at any mole fraction of monomer mixture in feed.