摘要:

AbstractThe polymerization of isobutylene with BF3, BCl3, and BBr3coinitiators has been investigated. The polymerization with BCl3requires the presence of a cationogen, e.g., H2O. The presence of a polar solvent is also necessary. Surprisingly, large quantities of polar solvent are required for effective polymerization. To obtain high conversions, the mixing sequence of the reagents is critical: BCI3must be added last to charges containing the monomer and H2O in a polar solvent. Ultimate conversions increase by decreasing the temperature. Kinetic termination exists. Experiments with BF3and BBr3revealed that polymerizations induced with BF3proceed in nonpolar and/or polar media. Polymerization stops with BF3at less than complete conversion (termination exists). In contrast to findings with BCl3, polymer yields with BF3increase with increasing temperatures. BBr3is a very inefficient coinitiator, even in the presence of polar solvent, over the −10 to −90°C temperature range. A hypothesis which explains these observations has been devel

ISSN:0360-6376    

DOI:10.1002/pol.1977.170151201

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe ultraviolet‐initiated polymerization of octadecyl methacrylate (ODMA, octadecyl 2‐methyl‐2‐propenoate) as a monomolecular layer at the gas‐water interface was studied. The polymerization was carried out at 27°C at the nitrogen‐water interface; air inhibits the polymerization. At 27°C the ODMA monolayer exhibits three different states which were characterized by surface pressure‐area diagrams and by surface potential measurements. The ODMA monolayer was polymerized under constant surface pressure in the range between 0 and 10 dyne/cm. The polymerization was followed by recording the contraction of the film. The conversion was determined by comparison of the area per monomer unit during polymerization with the area of mixed monolayers formed from ODMA and poly‐ODMA as well as by infrared spectroscopy. The polymerization in the condensed state of the monolayer (at high surface pressure) is considerably faster than in the expanded state (at low surface pressure). As the polymer has a condensing effect on the monomer in the mixed monolayer, autocatalysis is suggested at low surface pressures. The resulting polymer was studied by x‐ray diffraction. The structure of the freshly collapsed film is determined by the conformation of the polymer at the interface; the data after crystallizing the same sample from the melt point to higher tacticity of the poly‐ODMA prepared in monolayers than that of poly‐ODMA prepared by normal radical pol

ISSN:0360-6376    

DOI:10.1002/pol.1977.170151202

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractBy the methods of infrared and mass spectroscopy, the structure of grafted copolymer of polycaproamide (PCA) with polyacrylonitrile (PAN) was examined. It is shown on the grounds of analysis of infrared absorption bands and mass spectrum of the volatile products of grafted copolymer thermodestruction that the graft copolymerization in the redox system Fe+3/H2O2is carried out at the expense of the radicals, formed on COOH groups of PCA. The structure of grafted chains PAN changes owing to formation of cycles containing S and CN groups at the grafted copolymer treatment with Na2S. By the means of complex thermal analysis, the steadiness of the obtained products to thermooxidizing destruction was investigated. It was found that the presence of sulfur in the grafted copolymer PCA–PAN considerably intensifies the processes of grafted‐chain PAN cyclization as compared with the PAN homopolymer. It was shown that Na2S treatment brings to the product with the minimized absorption of oxygen at the isothermal heating that indicates its stability with regard to thermooxidizing d

ISSN:0360-6376    

DOI:10.1002/pol.1977.170151203

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractElectron mean free paths as a function of kinetic energy have been measured by the substrate overlayer technique forin situ‐polymerized films of poly(p‐xylylene) and the monochloro‐ and monobromo‐substituted derivatives. The results are compared with previous estimates of mean free paths available in the literature for organic materials. Comparison is also drawn with corresponding experimental data for typical metals and semiconductors, and it is shown that organic polymers fit into a consistent picture which may be rationalized on the basis of existing theory. For electrons of kinetic energy ∼969 eV, ∼1170 eV, 1202 eV, and 1403 eV, mean free paths of ∼14 Å, ∼22 Å, ∼23 Å, and ∼29 Å, respectively, are obtained for the poly(p‐xylylene) polymer f

ISSN:0360-6376    

DOI:10.1002/pol.1977.170151204

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe proposition that BCl3‐coinitiated olefin (isobutylene, styrene) polymerizations terminate by chlorination has been corroborated by model experiments. Key experiments showed that under simulated polymerization conditions neithertert‐butyl chloride nor 2‐chloro‐2,4,4‐trimethylpentane reacts with BCl3; that H2O/BCl3+ 2,4,4‐trimethyl‐1‐pentene (TMP) produce 2‐chloro‐2,4,4‐trimethylpentane; and that H2O/BCl3+ isobutylene gives rise totert‐butyl chloride. Extended model studies demonstrated that certain alkyl and benzyl chlorides produce carbenium ions in the presence of BCl3and that TMP can readily be alkenylated by using 1‐substituted allyl chlorides in conjunction with BCl3. These experiments led to the discovery that olefin polymerizations may be initiated by suitable allyl or benzyl chlorides and BCl3. Accordingly, polymerizations of isobutylene have been carried out with RCl/BCl3, where R is allyl or benzyl. These experiments suggest that both controlled initiation and termination, i.e., initiation by alkenylation and termination by chlorination, can be achieved with the allyl chloride/BCl3initiator system opening new avenues toward the synthesis of asymm

ISSN:0360-6376    

DOI:10.1002/pol.1977.170151205

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractPoly‐N‐ethynylcarbazole (PEC) was prepared thermally, by using Ziegler‐Natta catalysts, and also by using TiCl4and phosphine complexes for initiation. The spectral data (infrared, NMR, x‐ray diffraction, and ultraviolet) were best interpreted based on acis‐transoidal/cis‐cisoidalstereoblock structure for (both soluble and insoluble) polymers prepared by Ziegler‐Natta catalysts and on atrans‐cisoidalstructure for the polymers prepared with the other catalysts. Thecis‐transoidal/cis‐cisoidalstereoblock structure isomerized thermally into atrans‐cisoidalstructure, at temperatures which were dependent on t

ISSN:0360-6376    

DOI:10.1002/pol.1977.170151206

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

Abstract4‐Methyl, 4‐octene model molecules of the 1–4 polyisoprenic chain have been chemically modified in corresponding alcohol and chloroformate. These model molecules have been allowed to react with pharmaceuticals such as testosterone, cholesterol, and quinine to link the drug with a carbonate bound. Spectral data of these compounds are compared to those of previously synthetized polymers with potential pharamaceutical prope

ISSN:0360-6376    

DOI:10.1002/pol.1977.170151207

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractA sample of polystyrene with narrow molecular weight distribution (M̄w/M̄n= 1.03) has been formed into a 3‐mm sheet and subjected to γ‐irradiation at 25°C in air. Simultaneous crosslinking and scission of polymer chains resulted. Analyses by velocity and equilibrium sedimentation, gelpermeation chromatography, and osmometry of the polystyrene subjected to doses in the range 0‐90 Mrad, all within the pre‐gel region, have yielded average values ofG(S) =G(X) = 0.022 ± 0.002 for the complete sample. Combination of these various experimental techniques has been successful in yielding consistent values ofG(S) andG(X) and should be applicable with advantage to other polymers, particularly when neitherG(S) norG(X) is zero. The wide variation in literature values of G(S) and G(X) for irradiation of polystyrene under vacuum precludes any unequivocal conclusion on the effect of air on the radi

ISSN:0360-6376    

DOI:10.1002/pol.1977.170151208

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractA series of copolypeptides of poly(methyl glutamate‐glutamic acid) (PBC) and poly(methyl benzyl glutamate) (PMB) were prepared from homopolymeric poly(methyl D‐glutamate) (PMDG) via a variety of synthetic routes. Following their characterization, these copolymers were then investigated via dynamic mechanical spectroscopy, stress‐strain analysis (wet and dry), and wide‐angle x‐ray scattering (WAXS). It was found that the copolymers could be prepared from homopolymeric PMDG with minimal chain degradation or side reactions. The mechanical properties of either series did not follow a simple trend, in that specific properties such as Young's modulus went through either a maximum or minimum with composition ratio of the two comonomers. based on the WAXS studies, some rationalization for this behavior was established. Specifically, the nature of the side‐chain interaction, and therefore chain packing, was strongly affected by como

ISSN:0360-6376    

DOI:10.1002/pol.1977.170151209

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractTwo sets of methylmethacrylate‐vinylidene chloride copolymers were prepared via radical copolymerization in dimethylformamide. The first set is carried out in batches. Gas‐chromatographic analysis of samples allows a kinetic study from which the reactivity ratiosrM‐ 2.73 andrC‐ 0.24 are derived. For the second set a new apparatus, briefly described, has been used. It permits to keep constant the composition of the monomer mixture, through addition of methyl methacrylate, monitored by a chromatographic analysis. The two sets of copolymers are analyzed using nuclear magnetic resonance (60 MHz) leading to the triad distribution, from which the reactivity ratios are derived. Owing to the composition drift, the method cannot be applied to the first set of copolymers; but in that case, it is possible to calculate the triad distribution, the knowledge of the reactivity ratios, and the calculation fits quite well the experimental

ISSN:0360-6376    

DOI:10.1002/pol.1977.170151210

出版商:John Wiley&Sons, Inc.    

年代:1977

数据来源: WILEY