Polymer Journal

Okada, Masahiko; Ikai, Shigeru; Chiba, Kazumasa; Hirota, Masahiro; Yamashita, Yuya

doi: 10.1295/polymj.1.1pmid: N/A

Copolymerization of 1,3-dioxolane(DOL) and isoprene(Ip) by BF3·Et2O has been studied, particularly laying stress on the microstructure of the products. The diad fractions determined by NMR analysis have indicated that both monomer units are distributed randomly in the copolymer chain. The loss of unsaturation (the fraction of saturated Ip units to total Ip units), which was generally observed in cationically prepared Ip homopolymers, diminished with increasing DOL fraction and became practically negligible in the copolymers rich in DOL units. The structure of Ip units in the copolymer was also found to depend on the composition, namely, the fraction of the 1,4-structure, which was prevailing in Ip homopolymers prepared by the cationic initiator, decreased markedly with increasing DOL fraction in the copolymer.

Saegusa, Takeo; Yatsu, Tadao; Miyaji, Satoru; Fujii, Hiroyasu

doi: 10.1295/polymj.1.7pmid: N/A

Copolymerization of ethylene with vinyl acetate was carried out at room temperature by the ternary catalyst system consisting of equimolar amounts of AlEt3, ZnCl2 and CCl4. By solvent fractionation and thin layer chromatography analysis, the copolymerization product was found to consist of two different copolymer fractions. One was the 1:1 alternating copolymer and the other was identified with the copolymer produced by the usual free radical initiator under the same reaction conditions. Two different catalyst sites were assumed, i.e., the site of the usual free radical polymerization and the one responsible for the 1:1 alternating copolymerization. The addition of pyridine to the ternary catalyst system decreased mainly the yield of the 1:1 alternating copolymer fraction. Therefore, it was suggested that the coordination of monomer was essential for the catalyst site of the alternating copolymerization.

Yuki, Heimei; Okamoto, Yoshio

doi: 10.1295/polymj.1.13pmid: N/A

Anionic copolymerizations of 1,1-diphenylethylene (DPE) with o- and p-methoxystyrene (o- and p-MeOSt) were investigated with n-butyllithium (n-BuLi) and other anionic initiators. In THF, alternating copolymers of DPE with o- and p-MeOSt were obtained. In aromatic hydrocarbons, the copolymerization of DPE and o-MeOSt with n-BuLi gave a polymer having higher o-MeOSt content, while an almost alternating copolymer was obtained in the copolymerization of DPE and p-MeOSt. The NMR spectra of the alternating copolymers of DPE with o- and p-MeOSt showed the splittings due to the tactic difference with respect to the methoxy group. The latter alternating copolymer was shown by polarized light and X-ray examinations to be crystalline.

Masuda, Tadashi; Higashimura, Toshinobu; Okamura, Seizo

doi: 10.1295/polymj.1.19pmid: N/A

The possibility of copolymer formation and the effect of polymerization conditions on monomer reactivity ratios (MRR) were investigated for cationic copolymerizations of a vinyl ether with styrene derivatives. 2-Chloroethyl vinyl ether (CEVE) was used as the vinyl ether, and p-methoxystyrene (pMOS), p-methylstyrene (pMS) and α-methylstyrene (αMS) as styrene derivatives. Copolymerization was carried out in toluene or methylene chloride, being catalyzed by BF3·O(C2H5)2 or SnCl4·CCl3CO2H at −78°C. The copolymer composition was determined from each monomer consumption through gas chromatography. The copolymer formation was confirmed by fractionation and NMR spectrum of the product. In CEVE–αMS system, the relative reactivity of each monomer was independent of the kind of the propagating chain ends (r 1×r 2≅1). In contrast, composition curves showed an S-shape in CEVE-pMOS and CEVE–pMS systems (r 1×r 2>1). This difference may be attributed to the difference in stability between the growing carbonium ions of αMS and the ring-substituted styrenes. It was found that polymerization conditions significantly affect MRR; the CEVE content in the copolymer was greater for BF3·O(C2H5)2 than for SnCl4·CCl3CO2H, and greater in toluene than in methylene chloride.

Izu, Masatsugu; O’Driscoll, Kenneth F

doi: 10.1295/polymj.1.27pmid: N/A

Equations are derived based on the previously developed diad model to describe the composition and sequence distribution in a copolymer formed in an equilibrium state in the presence of the two monomers. Applications of these equations to typical models reveal the analogies between monomer-copolymer equilibria and binary liquid-vapor equilibria.

Saegusa, Takeo; Matsumoto, Shu-ichi; Hashimoto, Yoshihiko

doi: 10.1295/polymj.1.31pmid: N/A

A kinetic study on the polymerization of tetrahydrofuran catalyzed by the system AlEt3–H2O(2:1)-promoter was carried out. Epichlorohydrin, propylene oxide and β-propiolactone were employed as the promoter. The concentration of propagating species [P*] was determined at several times during polymerization by means of a new method in which the propagating species at polymer chain end was converted into the corresponding phenyl ether by end-capping with sodium phenoxide, and the phenyl ether group was analyzed by UV spectroscopy. On the basis of the plot of [P*] vs. time, the rate constant of propagation kp was calculated according to

Yuki, Heimei; Hatada, Koichi; Niinomi, Toshikazu; Kikuchi, Yukio

doi: 10.1295/polymj.1.36pmid: N/A

Polymerizations of trityl (TMA), diphenylmethyl (DMA) and benzyl (BMA) methacrylates were carried out mainly by n-butyllithium (n-BuLi) and the tacticities of the polymers were studied by NMR spectroscopy. Polymerization of TMA by n-BuLi gave a highly isotactic polymer in toluene as well as in tetrahydrofuran (THF). The polymer obtained in radical polymerization by AIBN catalyst had about 60% isotacticity in triads. From these results the growing-chain-controlled mechanism was proposed to this polymerization. In the polymerization of DMA by n-BuLi a highly isotactic polymer was obtained in toluene at lower temperatures and a highly syndiotactic one in THF. The radical polymerization gave a predominantly syndiotactic polymer. Temperature dependence of the NMR signal-width of the isotactic polymer indicates that the conformational arrangement of the polymer chain in solution is much rigid up to a fairly higher temperature. These results suggest that the growing-chain-controlled mechanism may contribute to some extent to the stereoregulation of DMA in toluene. BMA behaved very similarly to methyl methacrylate in the polymerization by n-BuLi. Probably the same polymerization mechanisms can be applied for both monomers. Polymerization of TMA, DMA and BMA by phenylmagnesium bromide or diethylaluminum diphenylamide was also investigated.

Miyamoto, Takeaki; Inagaki, Hiroshi

doi: 10.1295/polymj.1.46pmid: N/A

The stereocomplex formation between isotactic and syndiotactic poly(methyl methacrylate) (PMMA) molecules is studied in detail, using the techniques of thin layer chromatography (TLC), ultracentrifugation, X-ray diffraction, viscometry, and high-resolution NMR. It is shown that the 1:1 (iso/synd) complex is formed as the primary structure; further associations between the 1:1 complex and free syndiotactic molecules, when they exist in solution, occur to form the 1:2 (iso/synd) complex.The so-called “stereoblock” PMMA samples prepared with n-butylmagnesium chloride and diphenylmagnesium are analyzed by using tic technique. Evidence is thus shown for the stereochemical identity between the stereoblock PMMA and the stereocomplex which is formed by isotactic and syndiotactic PMMA in the ratio 1:2 (iso/synd). On the basis of this result, we conclude that the 1:2 stereocomplex may be formed during stereospecific polymerization of methyl methacrylate (MMA) with different Grignard’s types of catalysts.In relation to the above conclusion stereospecific polymerizations of MMA at −50°C with n-butylmagnesium chloride in toluene were carried out in the presence of either isotactic or syndiotactic PMMA. The results suggest that the stereospecific polymerization of MMA is closely linked to the stereocomplex formation. The presence of the isotactic polymer chains promotes preferentially the polymerization of MMA to the syndiotactic polymer chains, while the presence of the syndiotactic polymer chains appears to be a prerequisite for initiating the polymerization to the isotactic polymer chains so far as this catalytic system is employed at −50°C.

Teramoto, Akio; Norisuye, Takashi; Fujita, Hiroshi

doi: 10.1295/polymj.1.55pmid: N/A

Approximate expressions, which are amenable to straightforward numerical calculation, are derived from Nagai’s theory for such important molecular quantities of polypeptides in solution as helical content fN, number of helical sections gN, mean-square radius of gyration ‹S 3›, and particle scattering function P(θ), subject to the condition that sqrt{σ}<<1,N −1<<1, and Nsqrt{σ}>3. Here N denotes the degree of polymerization of the polypeptide molecule and σ the helix initiation parameter. The derived expressions are compared numerically with the exact ones for some typical cases of the parameters involved, and it is shown that they are accurate enough for practical purposes. A brief discussion is given on how each of them can be of use for characterizing polypeptides in dilute solution.

Matsui, Fumio; Ise, Norio; Okubo, Tsuneo

doi: 10.1295/polymj.1.64pmid: N/A

Isopiestic vapor pressure measurements were carried out for the ternary system water-sodium polyvinyl sulfate-sodium chloride. The variation of the isopiestic ratio with the concentration fraction of an electrolyte component is as large as that for water-sodium polyacrylate-sodium chloride. The mean activity coefficients of sodium polyvinyl sulfate and sodium chloride were obtained. The activity coefficient of the polyelectrolyte increases with polymer concentration. It decreases with increasing simple electrolyte concentration and through a minimum increases. The activity coefficient of sodium chloride decreases with its own concentration, obeying the cube-root rule. The presence of the polyelectrolyte enlarges the range of fit of the rule. The activity coefficient of sodium chloride decreases at first with increasing polymer concentration and then increases when the simple electrolyte concentration is low, whereas it increases monotonously with polymer concentration for high simple electrolyte concentrations. These results are compared with those previously obtained for the sodium polyacrylate system.