摘要:

AbstractThree vinyl monomers, 2,4,6‐trimethoxystyrene, 4‐(N,N‐dimethylamino)styrene, andN‐methyl‐2‐vinylpyrrole, were synthesized via the Wittig reaction from the corresponding aldehyes. These monomers were homopolymerized by radical polymerization using α,α′‐azoisobutyronitrile (AIBN) as initiator at 60°C. The reaction of these polymers with 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione (phTD) and 4‐methyl‐1,2,4‐triazoline‐3,5‐dione (MeTD) was investigated. Although polytrimethoxystyrene reacts slowly with PhTD at room temperature, the other two polymers react fast and lead to the incorporation of the triazolinedione unit into the side chain of the polymer via electrophilic aromatic substitution. The reaction of bistriazolinediones (BTD) with these polymers was performed in dimethylformamide using 10–20% molar concentration of the BTD. The resulting crosslinked polymers are insoluble in polar as well as nonpolar solvents. Some physical properties of the unmod

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270111

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe interaction of benzil and thioxanthone triplets with triethylamine leads to the production of free radicals that are able to initiate the polymerization of methylmethacrylate and vinyl acetate. The process is mediated by a charge transfer complex. The initiation efficiency is higher in benzene than in acetonitrile, a result explained in terms of competition between back electron transfer, production of free ions and ketyl radical formation. The initiation efficiency decreases when the carbonyl concentration increases, because of the occurrence of a radical molecule reaction such asThe α‐hydroxy radicals produced in this reaction are unable to initiate the polymerization cha

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270112

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractVarious organoaluminum compounds strongly affect reactivity of a sulfonated nickel ylide complex in its reactions with ethylene. The complex, if used alone, is an active single‐component catalyst for ethylene oligomerization to linear 1‐alkenes. Al(C2H5)3and tetraethylaluminoxane completely deactivate the catalyst by reducing it to Ni(O). Alkylaluminum halides, such as Al(C2H5)2Cl and Al(C2H5)Cl2, convert the nickel complex into a very active catalyst for ethylene dimerization to mixtures of butenes. Aluminum alkoxides, e.g., Al(C2H5)2OC2H5, AlC2H5(OC2H5)2, and Al(OC2H5)3, significantly increase oligomerization activity by a factor of 20–100. The distribution of 1‐alkenes (in the C4C40+ range) produced with the sulfonated nickel ylide–aluminum alkoxide catalyst follows the Flory molecular weight distribution law. The ratio of the chain termination to chain propagation rate constants is ca. 0.3 and is not temperature‐sensitive in the 50–120°C range. Kinetic analysis of the ethylene oligomerization reaction with the binary catalytic system showed that the number of active centers is proportional to the nickel complex concentration. The effective activation energy of ethylene oligomerization with the catalyst is ca. 27 kJ/mol. The oligomerization catalysts loose their activity in time. The activity decay follows the first‐order kinetic law. The rate of the decay increases with increasing temperature and is caused mainly by the intrinsic instability

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270113

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe seeded polymerizations of vinyl acetate, using monodisperse poly(vinyl acetate) latex particles prepared in the absence of emulsifiers with potassium persulfate, have been investigated at 70°C with potassium persulfate as an initiator. New small particles were formed in the system containing a small amount of seed particles, but were not observed in the system containing a large amount of seed particles. The size of the secondary particles increased, and their number decreased, with an increase in the seed particle number. The minimum diameter of PVAc particles, which are stabilized by the sulfate ion groups bound at the end of polymer chains during polymerization, was determined to be 0.12 μm diameter from the limiting total surface area of seed particles which prevented further secondary nucleation. The minimum diameter of the particles increased as the speed of the stirrer increased. The new small particle number calculated using this value agreed well with that formed in the seeded polymerizatio

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270114

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractPoly(enamine‐ketones) were prepared by the nucleophilic (Michael‐type) addition of various aromatic diamines to 1,1′‐(1,3‐ or 1,4‐phenylene)bis(2‐propyn‐1‐one)(1,3 or 1,4‐PPO) inm‐cresol at 5–23°C. The low molecular weight polymers (inherent viscosity of 0.25 dL/g) exhibited limited solubility in organic solvents. Glass transition temperatures were generally undetectable by differential scanning calorimetry while polymer decomposition temperatures (10% weight loss), as measured by thermogravimetric analysis, were observed from 355 to 419°C. Polymers prepared from 1,4‐PPO were semi‐crystalline as shown by wide‐angle X‐ray diffraction. The poly(enamine‐ketone) structure was confirmed by matching infrared spectral characteristics of the polymers with those of well

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270115

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe donor–acceptor interaction of acrylonitrile (AN) with indene (In) has been investigated by means of ultraviolet spectroscopy and dielectric polarization measurements. The latter method yielded a value of 0.5 for the association constant of the charge‐transfer‐complex (CTC) and a 4.02 D for its dipole moment. The copolymerization of the two monomers was characterized by a tendency towards alternation when conducted in the bulk. This might be due to the participation of a weak CTC in the process of copolymerization. However, this tendency disappeared in polar solvents such a

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270116

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe role of the cosurfactant (hexadecane) in the miniemulsion copolymerization of 50 : 50 molar ratio vinyl acetate–butyl acrylate monomer mixture is analyzed from an experimental point of view. The main factor responsible for the different kinetic behavior between the miniemulsion and conventional emulsion copolymerization processes was found to be the different particle nucleation mechanism operating in each process. Experimental evidence is presented indicating that in the miniemulsion copolymerization particle nucleation takes place in the preformed stable submicron monomer droplet

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270117

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractCopolymers of methyl methacrylate with an anthracene derivative are photodegraded in the solid state to give crosslinked material. The mechanism of insolubilization is dependent on the nature of the substituents at both the 9 and 10 positions of the anthracene chromophore. Photodimerization is the primary and most efficient cause of insolubilization if one of these positions is unsubstituted. Photodimerization does not occur if both of these positions are substituted; instead crosslinking is caused by photolysis of the endoperoxide of the parent anthracene. Bromination can sensitize the initial photooxidation and subsequent crosslinking in a copolymer where photodimerization does not occur. As a consequence of the crosslinking the rate of photobleaching of the anthracene chromophore by1ΔgO2is severly curtailed. Poly(methyl methacrylate), a positive‐tone polymer when exposed to UV light, is made negative acting by the incorporation of bound anthracene chromophor

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270118

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe reaction of 4‐substituted‐1,2,4‐triazoline‐3,5‐diones(4R‐TD's), i.e., MeTD(4‐methyl substituted) and PhTD(4‐Phenyl substituted) with electron rich aromatic compounds were investigated.N,N‐Dimethylaniline undergoes reaction instantaneously with MeTD and PhTD. Electrophilic aromatic substitution occurred at room temperature at the para position without use of any catalyst.N,N,N′,N′‐tetramethyl‐m‐phenylenediamine (TMPDA) undergoes reaction with 2 mol of PhTD and MeTD which lead to the formation of 2:1 adducts in high yields. These compounds were fully characterized by IR,13C‐NMR,1H‐NMR and elemental analysis and were used as model compounds. The reaction of bistriazolinediones with TMPDA was performed in dimethylformamid at room temperature. The reactions are exothermic, fast, and gave novel polymer structures via electrophilic aromatic substitution. Some physical properties and structural characterization of these new polymers have bee

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270119

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractIsotactic poly(2‐hydroxyethyl methacrylate) (PHEMA) is soluble and has the compact random coil structure in water solution. The effect of six ureas (thiourea, urea, methylurea, ethylurea, 1,3‐dimethylurea, and tetramethylurea) on the viscometric behavior of aqueous solutions of isotactic PHEMA as a function of urea concentrations at 25°C has been investigated. The compact random coil structure is found to disappear as ureas are added. The result is discussed in terms of water structure breaking and making effect of solutes, and hydrophobic interactions. In addition, experiments were performed with aqueous isotactic PHEMA solutions at four different temperatures. Isotactic PHEMA in pure water has the most compact conformation at

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270120

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY