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The radiation-induced ionic polymerization of bulk styrene has been studied under extremely dry conditions. It was found that the rate of propagation increases with more rigorous drying of the monomer, and this effect is accompanied by a change in the exponent n for the doserate dependence of rate of polymerization from n values near unity to 0.6. A mechanism involving bimolecular termination of free ions is thereby indicated. The kp value is estimated to be >3.5×106 1. mole−1 sec.−1 by the electrical conductivity method. The large kp value is explained as a characteristic ion dipole reaction for the free-ion propagation process and by the considerable freedom of the growing end of a free ion in comparison with that of an ion pair end. Similar results were observed with isobutene, nitroethylene, and cyclic monomers such as trioxane and BCMO. The initiation mechanism induced by the ion radical formed by radiation was confirmed by direct observation with ESR, optical absorption, and mass spectrometry.

The structure of polymer obtained by gamma -radiationinduced solid- state polymerization was examined by x-ray diffraction analysis. The polymers of 3,3-bischloromethylcycloxabutane, trioxane, and tetraoxane were shown to have an oriented mosaic structure of twin crystallites, of which two polymers of oxymethylene were in helical configuration. The polymer of BETA -propiolactone was not in the twin crystal form. Two kinds of polymers obtained from BETA - propiolactone and 3,3-bischloromethylcycloxabutane were found to be in planar zigzag configuration. (auth)

The lowering of degree of polymerization in cationic copolymerization was investigated for the isobutene–styrene copolymerizations in particular. In this system the simultaneous presence of a reactive isobutene cation and reactive styrene monomer acting as a chain transfer agent, a situation which cannot be visualized in homopolymerization, was proved to be responsible for giving low molecular weight copolymers. The ratios of rate constant for the monomer transfer reaction from isobutene cation to styrene monomer, a cross–transfer reaction, were determined kinetically. Carrying out the copolymerizations in solvents of different dielectric constant, in solvents of similar dielectric constant but of different solvating power, and with the Wichterle catalyst, and comparing the results with those by homogeneous catalyst, the polar and the nonpolar, possibly solvation effects of the solvent, and the effect of a heterogenity of catalyst on the crosstransfer reaction were investigated. A mechanism for the reaction was proposed. The choice of a comonomer or reaction conditions to minimize the cross-transfer reaction in isobutene copolymerization was discussed in the light of the information about the styrene-type monomer transfer reaction which has been reported previously by the present authors.

Historically, there are three classes of macromolecules that occupied and now occupy the focus of our interest: first, natural polymers (non-living); second, synthetic polymers; and third, biological polymers (living). From the author’s viewpoint of axes of existence (see Chap. 4), polymers may occupy, firstly, the spatial axis (for non-living or passive materials), secondly, the space + time axes (for living or active materials), and thirdly, the space + time + memory axes (for human being).

A consideration is described on the “Properties” of materials as the basis of science and technology, in connection with my early research on textile- The “Functionality” is then discussed in some details and the stream from property to “Sensibility” is viewed through “Functionality” in my own style. Biocompatibility has been regarded as one of the functionalities of polymers and studied in our laboratory a decade ago, as one of the prestages of the sensibility or humanity concepts. Finally, the arts in science are briefly imagined in two ways; one, comprehensive approach downward (anti-clockwise, in the top part of Figure 2) from the arts to science, and the other, individual one upward (in the bottom part of Figure 2) from science to the arts.

Bulk butadiene was polymerized by a cationic mechanism in a wide dose rate range. The anti M/sub n/ of the product was about 2300, independent of dose rate. The polymer had 83% residual unsaturation and the remaining double bond was 77% trans and 23% vinyl and had no cis unit. When the polymer yield exceeded 10% gel was formed, but the value of the residual unsaturation in the polymer remained unchanged. This indicated a mechanism that correlated propagation, cyclization, and crosslinking reactions with a cationic intermediate.

Further investigations of the photopolymerization of N-vinylcarbazole(VCZ) sensitized by sodium chloroaurate(III) in nitrobenzene were undertaken under irradiation of near-ultraviolet light at 30°C. Copolymerization with isobutyl vinyl ether and the kinetic behavior of polymerization were studied. These propagation and chain-breaking features were discussed in comparison with those obtained in the thermal polymerization. Electron spin resonance spectroscopy was conducted at 77°K in various systems.

Polymerization of butadiene by electron-beam irradiation was studied in n-hexane solution. Kinetic features of the polymerization and microstructure of the product were similar to those in bulk polymerization, which indicated a cationic mechanism. Both the rate of polymerization and average molecular weight of the product decreased by about 20% in the solution system. Soluble polymer was obtained up to ca. 40% conversion at the monomer concentration of 50 mol%, whereas in the bulk system the gel formed in polymer conversion exceeded 10%. A kinetic equation was proposed to explain the change in rate of polymerization with the monomer concentration.

The radiation-induced crosslinking of poly(2-phenylbutadiene) (PPB) in ethylene dichloride solution was studied in vacuum at 303 K. The G value of the crosslinking was estimated to be about 7.2. In order to detect the reaction intermediates under irradiation, optical absorption spectra in rigid matrices and ESR spectra in bulk were measured. The absorption spectra due to radical cation of PPB and due to α,α-disubstituted benzyl cation were observed in butyl chloride glass. ESR spectra owing to polyenyl type radical was found in the irradiated specimens of PPB and Diels-Alder type dimer of 2-phenylbutadiene. The primary processes in radiation-induced cross-linking of PPB were discussed on the basis of the results obtained.

The primary species of irradiated 1,3-butadiene in butyl chloride and carbon tetrachloride (CCl4) matrices have been studied by means of optical absorption and electron spin resonance (ESR) techniques. The absorption bands at 390 and 580 nm observed at 77K in the butyl chloride matrix are assigned to the butadiene cation radical. The optical densities of these bands as a function of the mole fraction of butadiene in the butyl chloride matrix have a maximum at about 0,02, and they decrease with the elapsed time of storage at 77K. The optical density of the band at 430 nm assigned to the allyl-type radical increases with the increase of the butadiene concentration, and further enhancement of the allyl-type radical is observed during storage at 77K. These results suggest that the cationic initiation by the butadiene cation radical occurs at 77K in the butyl chloride matrix, forming the allyl-type radical at the polymer chain end. This mechanism is consistent with the results obtained by ESR study. In the CCl4-matrix, the butadiene cation radical is also observed by both optical absorption and ESR measurements. The yield of the butadiene cation radical remains almost constant even by increasing the butadiene concentration or heating to 150K. This fact indicates that no polymerization occurs in the CCl4-matrix. Die primaren Spezies von bestrahltem 1,3-Butadien in einer Matrix aus Butylchlorid und Tetrachlorkohlenstoff wurden mit Hilfe der optischen Absorption und der ESR-Technik untersucht. Die bei 77K beobachteten Absorptionsbanden bei 390 und 580 nm in einer Butylchlorid-Matrix werden dem Butadienkation-Radikal zugeordnet. Die optischen Dichren dieser Banden zeigen bei einem Molenbruch von ca. 0,02 fur Butadien in der Butylchlorid-Matrix ein Maximum, und nehmen im Verlauf der Aufbewahrungszeit bei 77K ab. Die optische Dichte der dem Allyl-Typ zugeordneten Bande bei 430 nm nimmt mit der Butadien-Konzentration zu, und eine weitere Zunahme an Radikalen vom Allyl-Typ wird wahrend der Aufbewahrung bei 77K beobachtet. Diese Ergebnisse fuhren zur Annahme, das die kationische Initiierung durch das Butadienkation-Radikal bei 77K in der Butylchlorid-Matrix stattfindet, wobei das Radikal vom Allyl-Typ am Ende der Polymerkette gebildet wird. Dieser Mechanismus ist im Einklang mit den Ergebnissen der ESR-Untersuchungen. Auch in der CCl4-Matrix wird das Butadienkation-Radikal sowohl mit Hilfe der optischen Absorption als auch der ESR-Messungen beobachtet. Seine Ausbeute bleibt nahezu konstant, selbst bei Erhohung der Butadien-Konzentration oder beim Erwarmen auf 150°K. Diese Tatsache weist darauf hin, das in der CCl4-Matrix keine Polymerisation atattfindet.

The radiation-induced polymerization of acrylonitrlle in frozen aqueous zinc chloride solution was carried out at low temperatures. A marked enhancement both in the rate and the degree of polymerization was observed at zinc chloride/acrylonitrile molar ratios above unity, which indicated the importance of formation and stabilization of complexes in the frozen medium. The rate of polymerization R was found to follow the relation, R α [M-ZnCl2]2 I, where I is the dose rate and [M-ZnCl2] is the concentration of zinc chloride complexed with equimolecu-lar monomer. It is considered that the role of zinc chloride is here dual, both as a reagent for complex formation and also as a source of initiating species on irradiation. The effect of coexisting saturated nitriles were also discussed.

The cationic polymerization of 1,2-butylene oxide initiated by radical catalysts has been investigated in detail in the presence of maleic anhydride. The active species of this ionic polymerization was thought to be a conjugated radical of poly(maleic anhydride).

Radiation-induced polymerization of acrylonitrile (AN) in the ZnCl2-AN-H2O ternary system was carried out at temperatures ranging from 30 to −78°C, and correlation between the polymerization rate and the concentration of complexed AN with zinc atom was clarified. The selected systems were in the supercooled liquid state at −78CC with the molar composition ratio of ZnC12:AN:H2O of 1:1:3. The polymerization is free-radical in character. The 0.5-power dependence of the polymerization rate on the dose rate at 30°C indicates bimolecular termination, while the 0.9-power dependence at −78°C shows predominant unimolecular termination because of the high viscosity of the systems at Just above the glass transition temperature. The negative temperature dependence of the polymerization rate is indicative of the tendency of the complex concentration to increase with lower temperatures. The polymerization rate, therefore, is proportional to the 2 and 1.5 powers of the complex concentration at −78 and 30°C, res...

The radiation-induced polymerization of zinc chloride-acrylonitrile (AN) complexes, both the amorphous ZnCl2-AN (1:l) type and the crystalline (1:2) type, was carried out at 30 and -35°C. The rate of polymerization of the 1:1 type exceeds that of the 1:2 type not only in bulk but also in their benzene (BZ) solution, which seems to be attributable to the difference in the relative concentration of ZnCl2 to AN rather than to difference in their phases. The addition of a small amount of water to both type complexes results in an increase in the rate of polymerization. In the BZ solution of the 1:2 type complex (Zncl2:AN:BZ = 1:2:2), the addition of water, methanol, and acetic acid increases the rate of polymerization, and the apparent G value of initiation increases with the added amount of water. The findings indicate considerable contribution of the added ligands coordinated to zinc cation to formation of initiating species on irradiation. The bromine atom number NBr per polymer chain was measured...

ESR Studies on Primary Processes in Radiation-Induced Reactions. VI. Isoprene and 1,3-Pentadiene in Alkyl Halide Matrices

The oxidative degradation of poly(α-methylstyrene) initiated by the photodecomposition of azobisisobutyronitrile was studied at 30°C in benzene solution. The progress of the reaction was followed by measuring the rate of chain scission of the polymer. It has been confirmed by GPC measurements that random scission of the polymer chain occurs in the present system. Chain scission did not occur in the absence of AIBN and oxygen. The rate was proportional to the initiation rate and independent of polymer concentration and oxygen pressure under these experimental conditions. Phenol was an effective inhibitor to this reaction. The mechanism of chain scission during oxidation is discussed, and a six-membered transition is proposed.

Bulk polymerization of chloroprene was studied at 25/sup 0/C in a wide dose rate range. Variations of the rate of polymerization (R/sub p/) and molecular weight as a function of dose rate were essentially the same as those in several monomers that are capable of radical and cationic polymerizations. The polymerization proceeds with radical mechanism at low dose rate and with radical and cationic mechanism concurrently at high dose rate. The number-average molecular weight of the high-dose-rate products was ca. 2400. Microstructure of the polymers was mainly of trans-1,4 unit with small fractions of cis-1,4 and 3,4-vinyl unit. Fractions of the vinyl unit and the inverted unit in trans-1,4 sequence which increased at high dose rate reflected the change of dominant mechanism of polymerization. 6 figures, 2 tables.

The copolymerization of butadiene with vinyl chloride was demonstrated in homogeneous phase by radiation. The reactivity parameters were r/sub 1/ = 10 and r/sub 2/ = 0.02 (M/sub 1/ = butadiene) in bulk at -10/sup 0/C. The average molecular weight of the product was about 1000 to 2500, depending reaction conditions.

Three kinds of trapped radicals are observed in poly(maleic anhydride) (Poly-MAH) which were prepared by the use of radical initiators such as AIBN or BPO. It was found that these radicals were transformed to the active species so as to initiate the cationic polymerization. The structure of these radicals was studied by the ESR and the kinetic analysis of MAH polymerization in the presence of various additives.

Photoreactions of N -Vinylcarbazole Induced by Metal Salts. IV. Kinetic Studies of the Thermal and Photosensitized Cationic Polymerization Induced by Silver(I) Perchlorate in Benzene

Kinetic Behavior of the bulk polymerization by electron beam irradiation was studied on several vinyl and diene monomers. In most cases of monomers polymerizable both by radical and cationic mechanisms, the two polymerizations take place concurrently and with increasing dose rate the cationic mechanism predominated. The essential characteristics of the steady state kinetics developed at low initiation rate were also maintained at high dose rate for both of radical and cationic polymerizations. In some monomers, low molecular weight product whose DP n was 2–6 and/or high molecular weight product of M n exceeding 105 was observed in GPC spectrum other than the main radical and cationic products.

Applied radiation chemistry seems to take position between pure radiation chemistry and radiation processing. APPLIED means, by the dictionary such as Larouse, “related or turned to practical knowledge or use” and is differentiated from the pure one and its application. Pure science, however, stretches on a continuous line and becomes “turned to practical use” in the way of research, frequently far to the application over through the applied one. These continuities between the pure, the applied and the application of sciences may easily be connected over each other, sometimes by a scientific enthusiasm. Here the importance is correct distinction, but not simple discrimination. To-day in my presentation I would like to put main emphasis on APPLIED radiation chemistry but not exclude out simply PURE radiation chemistry and radiation PROCESSING. In addition, the word of ADVANCES means the progresses in the past, including some expectations in the future. The expectation is looked forward by the selection, connected with future applicability and with strongly individual character. The topics related to advances here in my talk shall be focused mainly for the works investigated in Japan Atomic Energy Research Institute (JAERI) Laboratories from standpoint of my short experience.

Effects of electron beam irradiation on liquid polybutadiene in n-hexane solution were studied at −10°C. With irradiation, crosslinking of the polymer and loss of double bond by cyclization took place at the same time. These reactions were retarded by the addition of DPPH or triethylamine which indicated that both radical and cationic mechanisms contributed to this system.

ESR Studies on Primary Processes in Radiation-Induced Reactions. V. Polymerization of 1,3-Butadiene on Silica Gel at 77°K Studied by Computer Analysis

The radiation-induced polymerization of acrylonitrile in the frozen aqueous solutions of various metal chlorides and zinc halides was studied to compare the accelerating effect of metal cations and halogen anions. Among metal chlorides examined, zinc, stannous, manganese, and nickel cations gave greater rates and degrees of polymerization. Of the halogen anions, the rate of polymerization decreased in the order, Br−, CI−, SCN− ≪ I−, CH3CO2 −, and the degree of polymerization decreased in the order, Br−, SCN− ≪ CI− ≪ I− ≪ CH3CO2 −. The increase of the rate and the degree of polymerization was confirmed below the eutectic temperatures of the hydrated metal chlorides and ice. This suggests that the increment of the rate and the degree of polymerization is attributed to formation of hydrated metal chloride-acrylonitrile complexes accompanied by their solidification in eutectic mixtures with ice. The radioactivation analysis of polymers obtained in frozen dilute aqueous zinc bromide solution reveals a...

The radiation-induced polymerization of acrylonitrile in a frozen urea-ethylene glycol solution at −78° C was investigated. The thermal behavior of the system was also analyzed by using differential thermal analysis. The presence of urea enhanced the polymerization in a supercooled liquid state. In the IR spectra of polymers obtained in the supercooled liquid state, the absorption band at 2030 cm−1 due to the keteneimine structure was observed.

Radiation-induced polymerization of acrylonitrile-urea canal complexes formed in frozen ethylene glycol or tert-butyl alcohol media was investigated. Formation of canal complexes in the frozen state was prolonged. The initial rate of polymerization was enhanced in the frozen state. The degree of polymerization of polymers obtained is found to show no depression at high conversions and is higher in the frozen state, suggesting stabilization of canal complexes by the frozen medium.

In a previous paper1 it was mentioned that trapped radicals in poly(maleic anhydride) (Poly-MAH) have the ability to initiate cationic polymerization. In this paper, the cationic polymerization of isobutyl vinyl ether (IBVE) is described using Poly-MAH as the initiator. These radicals show different behavior during polymerization depending upon their structure. In particular, large conjugated radicals initiate ionic polymerizations.