摘要:

Abstractα,ω‐Dihydroxy‐terminated‐PMMA was synthesized by the bulk polymerization of methyl methacrylate in the presence of a functional “iniferter,” viz.,N,N′‐diethyl‐N,N′‐bis(2‐hydroxyethyl)thiuram disulfide (DHTD). The kinetics of the polymerization were studied by determining the polymerization rate as a function of the “iniferter” concentration at 60, 70, 85, and 95°C. Evaluation of the data by a computerized multiple regression analysis led to calculation of the various kinetic parameters and the activation energies of the related phenomena. The maximum observed in theRp–initiator concentration curve was found to shift to lower initiator concentration as the temperature increased. The formal reaction order with respect to the concentration of the initiator decreased with increasing temperature and concentration of DHTD. The chain transfer constants of DHTD with MMA were calculated from the molecular weights of the resulting polymers. The functionalities of the oligomers were calculated from the elemental analysis of the chain end groups. Thermogravimetric analysis revealed that the polymer chain ends were devoid of unsaturated groups and that the polymer underwent degra

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270601

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe radical polymerization of tetraallyl ammonium chloride (TAAC) was carried out in water using azo‐initiator as compared to that of diallyl dimethyl ammonium chloride (DADMAC); the rate of polymerization was quite low for TAAC, around one‐third of DADMAC. Kinetic discussion revealed the importance of degradative chain transfer in the polymerization of TAAC. The cyclopolymerizability of TAAC was estimated kinetically as the ability of 5‐membered monocyclic radical to form a bicyclic ring, giving the cyclization constant of 21 mol/L at [M] = 2 mol/L. Gelation occurred at around 20% conve

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270602

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractAlternating copolymers of vinyl acetate (VAC) and acrylic acid (AA) were obtained by free radical polymerization in the presence of GeCl4and BCl3. For the GeCl4system, the reaction rate was proportional to [initiator]1/2. Optimum rate was obtained when the molar ratio of the monomers was 1:1. The chain transfer agent CCl4had no effect on the reaction. By means of ultra‐violet spectra analysis, it was concluded that both VAC and AA formed complexes with GeCl4. ESR analysis gave us the information that salt complexed acrylic acid radical had greater cationic characteristics than uncomplexed radical. Thus the nature of alternation may be due to both complexed AA radical and activated monomer complexe

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270603

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

Abstract1,1‐Dichloro‐2‐vinylcyclopropane (Ia), 1,1‐dichloro‐2‐methyl‐2‐vinylcyclopropane (Ib), 1,1,2‐trichloro‐2‐vinylcyclopropane (Ic) were prepared from the corresponding dienes and chloroform in the presence of a phase transfer catalyst (PTC), R4N+Cl−. MonomersIa–Icunderwent a clean 1,5‐type radical ring‐opening process to afford the corresponding polymers in good yield. Further, the relative rate of polymerization and reaction of (I)

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270604

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe reaction of cyclohexyl isocyanate with phenylglycidyl ether was selected as model reaction for the synthesis of cycloaliphatic isocyanate‐based poly(2‐oxazolidone)s. The selectivity of AlCl3and AlCl3‐triphenylphosphine oxide (AlCl3–TPPO) and AlCl3‐hexamethylphosphoric triamide (AlCl3–HMPA) complexes was studied for 2‐oxazolidone formation. The reaction products were identified by means of the melting point,1H‐NMR, and IR spectroscopy. The kinetics of the model reaction was studied using AlCl3‐TPPO ino‐dichlorobenze

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270605

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractDiacetylenes substituted with various amide groups were prepared and their solid‐state polymerization behavior was studied. A calorimetric study of the isothermal polymerization of 1,6‐diacetylamino‐2,4‐hexadiyne was performed in detail. This compound has an extremely high reactivity. The reaction proceeded very quickly and the ultimate conversion reached over 40% slightly above room temperature. The feature of the reaction resembles those observed in the solid‐state polymerization of other diacetylene compounds, i.e., the reaction proceeds slowly in the initial stage, but the rate of reaction increases drastically at about 5% conversion to polymer. Quantitative conversion, however, was not attained at any temperature, and the reaction leveled off within 1.5 h. It is assumed that the reaction cannot continue owing to the distortions generated in the crystals during the polymerization process. The crystalline state of the polymer obtained was highly d

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270606

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effect of adding an electrolyte on the rate of the heterogeneous dilute acid hydrolysis of cellulose was studied using 1.3Mhydrochloric acid containing varying amounts of sodium chloride up to 0.17M. A general increase in the rate of hydrolysis was observed. In particular, a linear relationship was observed between the rate of hydrolysis of the later portion of the hydrolysis curve and the concentration of added electrolyte, thus confirming that Donnan's theory of membrane equilibria can be applied to the heterogeneous hydrolysis of cellulose in dilute acid. A kinetic model, based on this theory and whose predictions are consistent with the above experimental results is presented.

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270607

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractCrosslinked polystyrene latexes with high surface charge densities have been prepared with 1, 3, and 5 mol% divinylbenzene and 0.5–5.0 mol% of 12‐(o‐styryloxy)dodecyltrimethylammonium bromide (1). Within experimental error all of surfactant1was incorporated into the particles. Analysis of the latex particles by transmission electron microscopy showed nonspherical shapes, aggregates, and number average diameters ranging from 22 to 95 nm. The particle size decreases and the polydispersity increases with increasing amounts of surfactant1and of divinylbenzene in the monomer mixture. A mechanism is proposed for particle formation by precipitation of crosslinked polymer from monomer droplets to form primary particles, coagulation of the primary particles to colloidally stable aggregates, and growth by further polymeriz

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270608

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractAmphiphilic block copolymers, i.e., poly(methyl methacrylate)‐b‐poly(2‐dimethylethylammoniumethyl methacrylate), were synthesized by the reaction between two prepolymers. Carboxyl‐terminated poly(methyl methacrylate) and hydroxyl‐terminated poly(2‐dimethylaminoethyl methacrylate) were prepared by radical polymerization of the corresponding monomers in the presence of thioglycolic acid and 2‐mercaptoethanol as a chain transfer agent, respectively. Two condensation methods, i.e., DCC and the acid chloride method, were used for the reactions of these prepolymers. The subsequent quarternization produced the amphiphilic block copolymers. Surface property of poly(methyl methacrylate) films containing this amphiphilic block copolymer was examined by measuring contact angles for water. The addition of only 0.5 wt% of the block copolymer was sufficient to make poly(methyl methacrylate) surfaces hydrophilic. The block copolymer formed a polymeric micelle in acetone–wate

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270609

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractOligomers containing 2,5‐thienylene and 2,5‐furanylene units were synthesized by NiCl2(dppp) (dppp = Ph2PCH2CH2CH2PPh2) coupling of Grignard compounds with the appropriate bromothiophene or bromofuran; UV and electrochemical data are given and discussed in terms of number and kind of heterolene units in the oligomeric spec

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270610

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY