摘要:

AbstractNew series of diamines having pyridine rings ando‐,m‐, orp‐phenylenedioxy linkages were prepared by condensation of chloronitropyridine with isomeric dihydroxybenzenes followed by chemical reduction. The polymerization of the diamines with benzo‐phenonetetracarboxylic acid dianhydride gave polyamic acids with the inherent viscosities in the range 0.21 to 1.30 dl/g. The conversion of these polyamic acids to polyimides was carried out thermally and the resulting polyimides exhibited very good solubility in organic s

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120821

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractAromatic benzimidazole polymers have been prepared by reaction of the corresponding tetraamine and diester in refluxing sulfolane or phenyl sulfone. The convenience of using these sulfone solvents together with the good yields, high viscosities and absence of crosslinking make this procedure an attractive new route to this class of polymers. The preparation by this procedure of poly[2,2′‐(m‐phenylene)‐5,5′‐bibenzimidazole], poly‐[2,2′‐(p‐phenylene)‐5,5′‐bibenzimidazole], poly[2,2′‐(m‐phenylene)‐5,5′‐di(benzimidazole) ether], and poly[2,2′‐(m‐phenylene)

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120822

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractA study of the oxidation of poly(vinyl alcohol) (PVAL) by potassium persulfate (KPS) in aqueous solutions showed that the decomposition of KPS was greatly enhanced by the presence of PVAL, its hydroxyl groups being oxidized to ketones in a yield of about one mole of ketone from one mole of KPS. The decomposition rate of KPS was found to be given by the equation, −d[S2O82−]/dt=k[S2O82−] [PVAL]1/2, which was essentially the same as in the oxidation of alcohols of low molecular weight by persulfate ion. The occurrence of gelation of PVAL solutions and graft copolymerization of methyl methacrylate (MMA) onto PVAL in the presence of KPS was evidence for PVAL radical as an intermediate species in the oxidation of PVAL. A characterization study was also carried out for the reaction products of the graft copolymerization of MMA onto PVAL with KPS in dimethyl sulfoxide sol

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120823

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractPoly(γ‐1‐naphthylmethylL‐ andDL‐glutamate) (PNLG and PNDLG) and copolypeptides of γ‐1‐naphthylmethylL‐glutamate and γ‐benzyl‐L‐glutamate were used as sensitizers for isomerization oftrans‐1,2‐diphenylcyclopropane. Quantum yields relative to that of 1‐methylnaphthalene were measured in dichloroethane (DCE) and dichloroacetic acid (DCA). The relative quantum yield in DCE was smaller than unity for PNLG, but greater than unity for PNDLG and copolypeptides. The result is discussed in terms of increased effective collisional radius and energy trapping by excimer formation. The relative quantum yields in DCA were close to unity except for the copolypeptides of higher γ‐benzylL‐glutamate content. This suggests that the naphthalene groups act in the same manner as their monomeric counterparts in the random conformation and that the greater proportion of γ‐benzylL‐glutamate in the copolypeptides lowers the quantum efficiency becausetrans‐1,2‐diphenylcyclopropane must penetrate through the polymeric medium in

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120824

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractThe terpolymerization of sulfur dioxide, butene‐1 and acrylonitrile affords terpolymers containing equimolar amounts of sulfur dioxide and butene‐1 with various acrylonitrile contents. Ultraviolet irradiation was found to accelerate the polymerization and decrease the acrylonitrile content in the polymer. This fact is interpreted by a mechanism through a copolymerization of sulfur dioxide–butene‐1 complex and acrylonitrile, whereby the polymerizability of sulfur dioxide–butene‐1 complexed monomer may be accelerated by ultraviolet light. In fact, a binary system of sulfur dioxide and butene‐1 was found to be accelerated by ultraviolet irradiation, and it affords a maximum rate at a 1:1 composition of feed monomer. Ultraviolet light of 250–300 mμ wavelength is effective for the initiation and the propagation. This may be ascribed to the ultraviolet absorption of the sulfur dioxide–butene‐1 complex. The temperature coefficient was measured in both dark and ultraviolet irradiation reactions. The ultraviolet irradiation enhances the reactivity of sulfur dioxide–butene‐1 complexed monomer at low temperature. In the terpolymerization with sulfur dioxide, isoprene, and butadiene, the ratio of isoprene and butadiene in the terpolymer was not altered by ultraviolet irradiation because both monomers from complexes with sulfur dioxide, perhaps having the same temperature coefficien

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120825

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY

摘要:

AbstractTaking into account the specific base–base interaction existing between nucleic acid molecules, we studied the free‐radical copolymerization ofN‐β‐methacryloyloxyethyl derivative of uracil with that of adenine at 60°C in various solvents.N‐β‐Methacryloyloxyethyltheophylline as well as methyl methacrylate were used also as comonomers. From the data on the rates in different comonomer feed ratios and ther1andr2values obtained, copolymerizability was discussed in some detail. The results suggest that the interaction between uracil and adenine bases plays a role in the copolymeriz

ISSN:0360-6376    

DOI:10.1002/pol.1974.170120826

出版商:John Wiley&Sons, Inc.    

年代:1974

数据来源: WILEY