摘要:

In order to determine the effect of functional structure of ester groups on the stereoregularity of polymers, polymerization of N-ᵬ-methacryloyloxyethyl type monomers containing nucleic acid bases was made by using a free-radical initiator. From the NMR spectrometric determination of the stereoregularity of the polymers obtained, it was found that for polymerization of the monomer with adenine as the side group in dimethyl sulfoxide solution, syndiotactic placement appears to be favored by the additional enthalpy of activation required for isotactic placement.

ISSN:0022-233X    

DOI:10.1080/00222337808066581

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The radiation-induced graft polymerization of ethyl vinyl ether (EVE) onto polyvinyl chloride) (PVC) was studied under a variety of conditions. Graft copolymer and homopoly(EVE) were formed in all cases. The presence of water reduced overall polymerization rates, percentage grafting, and homopoly(EVE) molecular weights. With “superdry” EVE, grafting reached 29% at a total dose of 6.9 Mrad. Grafting to PVC films was less efficient than grafting to PVC powder. Application of a relatively poor swelling agent for PVC resulted in an increase in the efficiency of grafting. From a comparison of studies of radiation-induced EVE homopolymerization and the present work, it was concluded that dry and superdry EVE are grafted to PVC by a cationic mechanism and wet EVE is grafted mainly by a free-radical mechanism.

ISSN:0022-233X    

DOI:10.1080/00222337808066582

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The polymerization of butadiene was studied in deoxycholic acid canal complexes under various reaction conditions. To prepare the starting canal complex containing butadiene, acetone in the deoxycholic acid-acetone canal complex was replaced with butadiene effectively. Post-irradiative polymerization was carried out after irradiation with γ-rays from a Co-60 source. The polymer was found to contain a significant amount of 1,2-units in addition to trans- 1,4-units. Various additives had a marked effect on the polymerization behavior, particularly on the polymer yield and the microstructure of the polymer.

ISSN:0022-233X    

DOI:10.1080/00222337808066583

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

In a previous report, it was found that some of the color components in the starting material of petroleum resin were cyclopentadiene, methylcyclopentadiene, and their dimers. In the present study, other color components than those mentioned above and the cause of coloring petroleum resin by cyclopentadiene and methyl derivative were investigated. Norbornadiene and ethylidene norbornene were found also to be color components, and the structures of some conjugated systems which color the petroleum resin were inferred from the data of ESR spectra.

ISSN:0022-233X    

DOI:10.1080/00222337808066584

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Endcapping of oligo(oxyethylene) glycols was carried out by transesterification of methyl N,N-dimethylaminobenzoate with sodium methoxide as the catalyst or by the reaction of sodium salicylate with the ditosyl ester of the oligo(oxyethyl-ene) glycols. Several other common reactions were tried for the endcapping of the oligo(oxyethylene) glycols but were found to be either more cumbersome or unsuccessful. All products were obtained in high yield and high purity. The reactions of tetraalkylammonium carboxylates with aliphatic halides were found to be very general and mild reactions for the preparation of esters in high yield and high purity. It was found that these reactions could be utilized for the preparation of esters on polymers even if the carboxylate group was directly attached to the polymer chain. It was also demonstrated that the aliphatic halide group could be on the polymer, as in the case of polyepichlorohydrin. Copolymers of epichlorohydrin and glycidyl N,N-dimethylaminobenzoate with up to 90% glycidyl benzoate as the comonomer were prepared, and poly(tetra-butylammonium methacrylate) was effectively transformed with 4-(2-bromoethoxy)-2-hydroxybenzophenone into the corresponding ester. The products were characterized by the usual spectral means.

ISSN:0022-233X    

DOI:10.1080/00222337808066585

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Products of hydrolysis and condensation of organosilicon monomers in the presence of ᵬ-cyclodextrin (cycloheptaamylose ᵬ-CD) were studied by IR, NMR, MS, and x-ray methods. It was established that when an aqueous solution of ᵬ-CD is treated with dimethyldichlorosilane (DMDCS), diphenyldichlorosilane (DFDCS), methylphenyldichlorosilane (MFDCS), or with a mixture of the DMDCS and DFDCS, crystalline compounds of cyclodextrin with appropriate siloxane oligomers, are formed: /3-CD-MSO (69% yield by weight), ᵬ -CD-FSO (6.0% yield by weight), ᵬ-CD-MFSO (16%) yield by weight), ᵬ-CD-(MSO + FSO) (22–63% yield by weight). The content of the obtained products showed: ᵬ-CD:MSO = 1 mole of ᵬ-CD:2 (CH3)2SiO elements; ᵬ-CD:FSO = 1 mole of ᵬ-CD:0.57 mole of (C6H5)2SiO; ᵬ-CD:MFSO = 1 mole of ᵬ-CD:0.87 mole of (CH3) (C6H5)SiO. Contents of ᵬ-CD′ (MSO + FSO) depend on the starting monomer mixture. It is suggested that nonchemical bonds between ᵬ-CD molecules and siloxane elements occur. The topological structure of the obtained substances is analyzed. Analogous compounds are not formed with methyltrichlorosilane, triphenylchlorosilane, diethoxydichlorosilane, dimethyldimethoxysilane, dimethyl -diacetoxysilane, or silica tetrachloride. Compounds with ᵬ-cyclodextrin are not formed from already formed siloxane oligomers. In the processes described above, linear dextrins show a total lack of activity. Methylsiloxanes bound with ᵬ-CD have a cyclic structure, while phenyl ones probably have a linear structure.

ISSN:0022-233X    

DOI:10.1080/00222337808066586

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The polymerization of vinyl monomers initiated with the system of polyvinylferrocene (PVFc) and carbon tetrachloride (CCl4) was carried out in dark. Methyl methacrylate (MMA) and acrylonitrile (AN) could be polymerized, while styrene (St) was hardly polymerized under the conditions used. The polymerization proceeded through a free-radical mechanism and was concluded to be initiated by attack of vinyl monomer, having a polarized vinyl group, on the charge-transfer complex of PVFc/CCl4. In the polymerization of MMA, the initiating ability of PVFc was much larger than that of ferrocene (Fc-H) or poly(ferrocenylmethyl methacrylate) (PFMMA) and was comparable to that of polyferrocenylenemethylene (PFM). The overall activation energy was estimated to be 34.2 kJ/mole.

ISSN:0022-233X    

DOI:10.1080/00222337808066587

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The radiation-induced polymerization of acrylonitrile in the frozen aqueous solutions of various metal chlorides and zinc halides was studied to compare the accelerating effect of metal cations and halogen anions. Among metal chlorides examined, zinc, stannous, manganese, and nickel cations gave greater rates and degrees of polymerization. Of the halogen anions, the rate of polymerization decreased in the order, Br−, CI−, SCN−≪ I−, CH3CO2−, and the degree of polymerization decreased in the order, Br−, SCN−≪ CI−≪ I−≪ CH3CO2−. The increase of the rate and the degree of polymerization was confirmed below the eutectic temperatures of the hydrated metal chlorides and ice. This suggests that the increment of the rate and the degree of polymerization is attributed to formation of hydrated metal chloride-acrylonitrile complexes accompanied by their solidification in eutectic mixtures with ice. The radioactivation analysis of polymers obtained in frozen dilute aqueous zinc bromide solution reveals appreciable contribution of water to generation of initiating species.

ISSN:0022-233X    

DOI:10.1080/00222337808066588

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Crosslinked polymer beads containing regions of acid and basic groups are the preferred structures for the efficient operation of a thermally regenerable ion-exchange process. The studies reported in this paper were designed to examine the question of grafting between the acidic and basic regions in the resins. Two approaches were used. First, trapped macroradicals from acrylamide were prepared and then either acrylic acid or triailylamine added. The conditions were first optimized for the generation of trapped polyacrylamide macroradicals. Their presence was shown by the grafting of acrylic acid prior to attempted grafting of triailylamine hydrochloride to these macroradicals. The best solvent for the generation of trapped polyacrylamide macroradicals was dioxane. The temperature at which the macroradicals were generated was not very important but grafting to the macroradicals occurred only at elevated temperatures. With acrylic acid up to 25% graft was achieved but the best graft of triailylamine hydrochloride was less than 1%. Secondly, the grafting of triailylamine hydrochloride to an autoxidized polyisopropylstyrene sample containing hydroperoxide groups was attempted. However, no grafting of triallylamine hydrochloride occurred even though the hydroperoxide groups, in the presence of cobalt naphthenate, initiated rapid and quantitative grafting of acrylic acid.

ISSN:0022-233X    

DOI:10.1080/00222337808066589

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Anionic polymerization of methyl methacrylate (MMA) initiated by lithium tert-butoxide (t-BuOLi) was investigated in different mixtures of benzene and piperidine. The latter compound activates the associated alkoxide, as evidenced by the observed increase in the rate of polymerization, proportional to piperidine concentration and also by the lowering of the overall kinetic order of the polymerization reaction with respect to initial monomer concentration. However, at higher piperidine concentration the rate of the polymer growth significantly decreases after a short period of time; a probable reason for this retardation or termination effect is the decay of active growth centers by a termination reaction with the methacrylate carbonyl group. The molecular weight of the polymer is significantly lowered by even a small addition of piperidine as a result of increased initiator efficiency that leads to a higher absolute concentration of active centers and approaches the theoretical limit given by the stoichiometric ratio of monomer and initiator concentrations. The microstructure of the product is affected by the presence of the polar solvent to a considerably lesser degree than in the case of classical alkylmetal initiators. The isotacticity slowly decreases with piperidine concentration over the whole investigated range. The high stability of the complex active center of growth formed by the alkoxide initiator and also the gradual change in the character of the ionic pair at the end of the growing polymer chain are responsible for the relatively small changes of the microstructure.

ISSN:0022-233X    

DOI:10.1080/00222337808066590

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor