摘要:

AbstractThe importance of nonexclusion effects in the GPC behavior of several stationary phases was investigated with DMF, 0.01MLiBr, as the mobile phase. Various low MW solutes and narrow MWD polymers, encompassing a wide range of polarities, were studied. The elution of the polymers was examined in terms of “universal calibration” behavior. Styragel and silanized glass both exhibit affinity for apolar polymers in DMF; for the former substrate this effect shows a strong inverse dependence on MW. As a consequence, application of polystyrene calibration curves to GPC analysis of more polar polymers with these substrates leads to overestimations of MW parameters. These errors are not corrected when universal calibration procedures are used. Ideal exclusion chromatography is exhibited by a number of polymers on untreated porous glass substrates. However, polymers with strong hydrogen‐bonding functionality appear to be susceptible to marked adsorption in this s

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150901

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractOxidation of hydroquinone catalyzed by copper(II) complexes of poly‐1‐vinylimidazole, vinylamine‐vinylacetamide copolymer, and polyethyleneimine was studied in aqueous solution at 25°C. The rate of oxidation was determined spectrophotometrically over several pH values. The rate of copper(II) reduction was evaluated from copper(I)–cuproin complex formation, and the reoxidation of copper(I) to copper(II) was observed by visible spectroscopy. Among the copper(II) complexes, poly‐1‐vinylimidazole complex exhibited excellent catalytic activity, which amounted to over 20 times that of aqueous copper(II) ion solution, while the reduction of copper(II) in the former system was slower than that in the latter system. The reoxidation of copper(I) to copper(II) was found to be completed immediately in the presence of polymer ligands such as poly‐1‐vinylimidazole, while copper(I) ion was only slowly reoxidized. The discussion of the reaction mechanism emphasizes the importance of the reo

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150902

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractIn the present work, we use the binary insertion compound LiC12to polymerize styrene, methyl methacrylate, butadiene, isoprene, and to copolymerize isoprene and styrene in various hydrocarbon solvents (aromatics and aliphatic) and etheral solvents. We show that the styrene polymerization in aromatic solvents gives better yields than in the etheral solvents, the polymer being atactic. Methyl methacrylate does not polymerize in toluene but does so completely in DME. More generally, the yields of polymerization are better with KC37than with LiC12because of the different capacities of the monomer to get into the carbon layers. The polymerization of dienes with LiC12shows that the microstructures of the polymer obtained in π‐orn‐donor solvents are similar to the ones obtained by homogenous polymerization with Li cation in such solvents. However, for isoprene in cyclohexane, the results are different. The isoprene styrene copolymers are statistical ones and the mean length of styrene blocks is less than 5. The monomer interaction with the insertion compound and the growing chain geometry between the carbon layers are the facts which control either the stereospecificity of the polymerization or the selectivity of the copolymeriza

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150903

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractCrystallization of polyterephthalates of bis(4‐hydroxy‐3‐chlorophenyl)‐2,2‐propane synthesized by an acceptor–catalytic polyesterification has been investigated quantitatively. It was found that in a homogeneous medium (in solvents for the polymer) amorphous polymers are formed, while polycondensation in a heterogeneous system (in nonsolvents for the polymer) gives rise to crystalline polyarylates, their degree of crystallization being dependent on synthesis conditions. Secondary treatment of resulting polymers can result in their crystallization and amorphization. Along with molecular weight the physicomechanical properties are significantly affected by the prepara

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150904

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractEffect of structure of potassium poly(vinyl sulfate) and its homologs on the metachromatic behavior of methylene blue was investigated spectrophotometrically. The metachromatic behavior with addition of polyanions was followed by the changes in the molar extinction coefficient of the 664 nm band of methylene blue and in the wavelength of metachromatic band. Important factors for metachromasy were the number of anionic sites per polymer molecule, the degree of polymerization, and the flexibility of polymer chain. It was found that the amount of KCl or urea required to destroy the metachromasy was a useful measure for estimating the binding strength of methylene blue to polyanions.

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150905

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe kinetics of free‐radical polymerization of ethyl methacrylate (EMA) have been experimentally studied in bulk and in 50% solution in DMF over the temperature range from 60 to 90°C. At low conversion, the kinetic parameters have been determined, including constants for chain transfer to monomer and solvent. These parameters have then been used to model the kinetic behavior at high conversion using previously derived equations. The results indicate that the equations satisfactorily predict the conversion and molecular weight averages and distributions as a function of time from zero to ca. 95% conversi

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150906

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThree series of block copolymers, namely, polystyrenecaproamide (I), polystyrenehexamethyleneadipamide (II), and poly(styreneethylene terephthalate) (III), were prepared, and the properties of the copolymers in relation to the block sequence lengths and the compositions were studied. Styrene was polymerized in the presence of aluminum chloride and thionyl chloride to give ω,ω′‐dichloropolystyrenes of various degrees of polymerization from 12.0 to 51.0, which were either ammonolyzed to ω,ω′‐diaminopolystyrene or hydrolyzed to ω,ω′‐dihydroxypolystyrene. ω,ω′‐Diaminopolystyre was treated with adipic acid to give the corresponding salts, namely, ω,ω′‐diammoniumpolystyrene adipate, which was melt‐polymerized either with ε‐amino‐n‐caproic acid to give polystyrenecaproamide (I) or with hexamethylenediammonium adipate to give polystyrenehexamethyleneadipamide (II). ω,ω′‐Dihydroxypolystyrene was melt‐polymerized with dimethyl terephthalate and ethylene glycol to give poly(styreneethylene terephthalate) (III). All the block copolymers were of high enough molecular weight to be cast or spun into films or filaments. Upon polymerization, the increase of the block sequence of PSt units increased the amide content but decreased the ester content of the resulting copolymers. Also, an increase inndecreased the inherent viscosities of the copolymers at a constant monomer feedfccounted by the polymer equivalent of PSt but increased the inherent viscosities at a constant monomer feedrccounted by the monomer equivalent of PSt. The melting points of the copolymers decreased with increasingnvalues. Also, an increase inndecreased the densities of I and III but increased the density of II at a constant amide or ester compositionFccounted by polymer units but increased the densities of I, II, and III at a constant amide or

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150907

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe kinetics of anhydride formation of poly(acrylic acid) (PAA) in porous PAA–alumina composites have been investigated by using a thermogravimetric technique (TGA). Three distinct reaction peaks at 200°C (I), 250°C (II), and 390°C (III) were identified in the dynamic TGA thermogram. These peaks were attributed to bound water removal (I), anhydride formation (II), and polymer degradation (III). The kinetics of the anhydride reaction were studied in a temperature range of 220–240°C and found to follow a second‐order mechanism with an activation energy of approximately 38 kcal/mole. In addition, the bound water was found to inhibit the onset of anhydride formation. The degree of conversion to anhydride was correlated with the equilibrium swelling level attained by the composite

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150908

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractA new family of block copolymers have been synthesized and characterized. These copolymers have a central block deriving from the polyaddition ofN,N′‐dimethylethylenediamine to 1,4‐bis‐acryloylpiperazine, and lateral blocks of polystyrene. Preliminary biocompatibility tests have demonstrated that these new products show promise as long‐acting nonthrombogenic

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150909

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractPolyaddition of bisketenimines with various diamines was carried out in dioxane or toluene to afford linear polyamidines. The aliphatic diamines were fairly reactive toward the bisketenimines, and polyamidines having inherent viscosities up to 0.45 dl/g were obtained. The aromatic diamine, on the other hand, showed only poor reactivity, and the derived polyamidines had low inherent viscosities. All the polyamidines were found to be soluble in such polar solvents as dimethylacetamide and m‐cresol. The thermogravimetric analysis (TGA) showed that thermooxidative decomposition started at 230–35

ISSN:0360-6376    

DOI:10.1002/pol.1977.170150910

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY