摘要:

AbstractThe copolymerization of 4‐hydroxy‐4′‐vinylbiphenyl (HVB) with α‐chloromaleic anhydride (CMAn) was investigated in THF, 1,4‐dioxane, and acetonitrile. The formation of the 1:1 charge transfer complex between HVB and CMAn was confirmed spectroscopically, and the corresponding equilibrium constant (Keq) was determined as follows:Keq= 0.19, 0.11, and 0.058 mol/L in THF, 1,4‐dioxane, and CH3CN, respectively. The copolymer composition is affected by the solvent, i.e., the content of HVB in the copolymer obtained in THF or 1,4‐dioxane is lower than 50 mol % whereas the copolymer obtained in CH3CN has excess of HVB units. The maximum rate of copolymerization was observed at a 1:1 initial comonomer mole ratio, irrespective of the solvent polarity. Plots ofRp/[HVB] vs. [HVB]gave a straight line with a slope and an intercept for the copolymerization in THF whereas a straight line in CH3CN has no slope. On the basis of these results and13C‐NMR spectra of the copolymers, the mechanism of the predominant formation of alternating copol

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271301

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe kinetic analysis of the transesterification of ethylene glycol (EG) and dimethyl terephthalate (DMT) was studied in a semibatch reactor under nonisothermal conditions. The effect of the temperature profile, EG/DMT ratio, and catalyst concentration on the reaction rate was studied. Models were fitted by using an algorithm of parameter estimation in differential equations based on the Gauss–Newton method improved with the Marquardt extension. It was found that, unlike previous authors, the reaction rate was not a classical third order reaction of first order with respect to EG, DMT, and catalyst concentration, but the EG reaction order was 0.6 and a hyperbolic function was found to fit the relationship between reaction rate and catalyst concentration. Also, it was found that, at high conversions, the effect of the reverse reaction should not be neglecte

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271302

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractTwo‐dimensional NMR spectra of commercially available poly(N‐vinylcarabazole) are presented and analyzed. Complete assignments for the aromatic region of the carbon spectrum are made using the edited spectrum and literature references for model compounds. The proton spectrum is assigned from its correlations with the carbon spectrum and with aJ‐correlated two‐dimensional spectrum. One of the protons (number 1) is shifted to rather unusual high fields by the stacked structure of the carbazole rings, independent on the polymer tacticity. From the aliphatic carbon spectrum a meso probability of 0.45 is estimated for the commercial polymer, and anotherJ‐correlated two‐dimensional spectrum helps assigning the triad and tetrad splittings in the aliphatic prot

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271303

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

Abstract(o‐Methylphenyl)acetylene polymerized with high yields in the presence of W and Mo catalysts. W catalysts were more active than the corresponding Mo catalysts. The weight‐average molecular weight of the polymer formed with W(CO)6–CCl4–hvreached 8 × 105, being higher than the maximum value (ca. 2 × 105) for poly(phenylacetylene). The polymer had the structure\documentclass{article}\pagestyle{empty}\begin{document}$\rlap{--} [{\rm CH} \hbox{=\hskip-1pt=} {\rm C}(o - {\rm CH}_3 {\rm C}_6 {\rm H}_4 )\rlap{--} ]_n $\end{document}. The stereochemical structure of the main chain could be determined by13C‐NMR; the cis content varied in a range of 41–61% depending on the polymerization conditions. The present polymer was thermally more stable than poly(phenylacetylene) according to thermogravimetric analysis. Interestingly, this polymer possessed deeper color than poly(phenylacetylene), and showed a fairly strong absorption in the v

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271304

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractA study of the apparent reaction rate constants of phenylacetylene polymerized in CCl4in the presence of light‐activated W(CO)6and of the molecular weight of the resulting polymer indicates that the propagating centers are conserved to high monomer conversions, though some chain transfer to monomer occurs, limiting molecular weights to about 100,000. Although solutions of the polymer are deep red in color, the molecular conformation is more coil‐like than rod‐like. The NMR spectra suggest that the steric purity of the polymer is limited, so that it can only be referred to as trans‐rich polyphenylacetylene, confirming other results on tungsten‐catalyzed polyphenyl

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271305

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractPolymandelide was prepared in 77% yield by reaction of α‐bromophenylacetic acid and triethylamine. The product was characterized by1H‐ and13C‐NMR and IR spectra and isolation and identification of mandelic acid from hydrolysis of the polymer. The NMR spectra indicate the presence of tacticity at CH in the polymer. Molecular weights were determined by GPC and viscosity measurements;nvalues of 12–20 are comparable to those reported for polymandelides prepared by other methods. The x‐ray powder diffraction pattern showed the product to be completely amorphous. Thermal decomposition was studied

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271306

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractA procedure for synthesizing an open‐chain polyimide has been developed.O‐Substituted hydroxylamines were found to behave as difunctional nucleophiles in acylation under appropriate conditions, and thus the reaction of equimolar amounts of benzyloxyamine and terephthaloyl chloride gave rise to the corresponding novel type of polyimide, an open‐chain polyimide. The results of polymerization under various conditions indicated the reaction to proceed efficiently inN,N‐dimethylacetamide in the presence of an acid acceptor system composed of double the molar quantity of triethylamine and the molar quantity of pyridine to give the polyimide with a high molecular weight. In contrast to the conventional polyimides having cyclic imide structures, the resulting open‐chain polyimide exhibited remarkable solubility in common organic solvents and a low glass transition te

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271307

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractA series of 10 acetylene‐terminated aromatic amide monomers was synthesized by the triethylamine‐promoted reaction of bis[p‐(m‐chlorocarbonylphenoxy)phenyl] sulfone or bis[p‐(m‐chlorocarbonylphenoxyl)phenyl]ketone witho‐ orp‐ethynyl‐ ando‐ orp‐trimethylsilylethynylaniline. Yields were essentially quantitative. Structures were verified by infrared and nuclear magnetic resonance spectroscopy and mass spectral data. Thermal characteristics of the monomers were investigated by means of differential scanning calorimetry and thermogravimetric analysis. The initial glass transition temperatures were generally well below the onset of cure which occurred in the 160–225°C range for the terminal ethynyl monomers and in the 260–295°C range for their trimethylsilylethynyl analogs. Onset of decomposition in air for the resinified terminal ethynyl monomers took place in the 400–485°C range, while resins from the trimethylsilylethynyl monomers underwent breakdown at su

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271308

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe radical copolymerization of unsaturated spiroorthoesters such as 2‐methylene‐1,4,6‐trioxaspiro[4.6]undecane (SOE I) and 2‐methylene‐9‐methyl‐1,4,6‐trioxaspiro[4,5]decane (SOE II) with vinyl monomers was carried out to find that SOE I and SOE II were copolymerized with electron‐poor olefins such as methyl acrylate, acrylonitrile, and methyl methacrylate to obtain the corresponding copolymers containing spiroorthoester moieties, respectively. The obtained copolymers were treated with BF3.OEt2or BzS+SbF −6to afford crosslinked polymers undergoing expansion in volume on crosslinking in those cases o

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271309

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractCationic polyacrylamides (C‐PAM) which contain both primary and quaternary amines were prepared according to the Hofmann reaction by adding choline chloride to a solution of polyacrylamide in water. The reaction was 90% complete after 60 min at 20°C. The degree of amination was over 70% and the proportion of primary and quaternary amines could be altered widely by controlling the relative concentrations of NaOH, NaOCl, and choline chloride.C‐PAM was dansylated (fluorescently labeled) in a homogeneous system using aqueous dimethylformamide as solvent. The optimum excitation wavelength for dansylated C‐PAM in water at room temperature (22 ± 1°C) was 333 nm and the corresponding emission wavelength 538 nm. The fluorescence intensity was almost constant at pH levels above 5, but decreased rapidly below pH 4 and was almost zero

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271310

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY