摘要:

AbstractPrevious attempts to prepare monodisperse styrene/sodium styrene sulfonate copolymer latexes by batch, seeded, and semicontinuous emulsion polymerization were unsuccessful at high concentrations of the functional comonomer. Broad, and sometimes bimodal, size distributions, and large amounts of water soluble homopolymer were obtained. After removal of free monomer, solute and adsorbed homopolymer and copolymer, the overall incorporation of the functional comonomer was found to be low. To overcome these problems, a two stage “shot‐growth” orin situseeding technique was developed. A first stage copolymerization was carried out with a low concentration of sodium styrene sulfonate: the purpose of the functional comonomer was to enhance the stability and regulate the size of the seed particles. When this reaction had reached high conversion (>90%), a second stage monomer mixture was added. The ratio of styrene to sodium styrene sulfonate in this mixture determined the final surface charge density. The mechanism by which the NaSS is incorporated in the polymer particles is considered to be by solution copolymerization with solute styrene monomer to form surface active oligoradicals. These radicals adsorb on the particle surface, initiate polymerization and become inextricably bound, preventing their transfer back to the aqueous phase. By this means, it was possible to vary independently the particle size and surface charge density. High concentrations of functional comonomer could be polymerized without undue wastage (incorporations were only slightly less than 100%) or loss of monodispersity. In extreme cases, the area per functional group fell below the theoretical minimum, indicating considerable hydration of the surface l

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271001

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe polymerization of 9‐anthrylmethyl propiolate using various initiating methods was studied with particular emphasis on the elucidation of the structure of the polymers. A polymer having a pure polyene structure was synthesized by anionic or anionic‐coordination mechanism only. Thermal or transition metal halides polymerization led to a polymer possessing anthrylene methylene groups into the main polymer chain. A plausible mechanism for the obtention of this structure was propo

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271002

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThermal degradation mechanisms of alkyl isocyanate homo‐ and copolymers were studied using TGA and DP–MS. Both analyses showed that these polymers begin decomposing at around 190°C under inert or vacuum conditions. DP–MS analysis showed the formation of trace quantities of monomer from poly(butyl isocyanate) only and none from higher homologs. All polymers studied produced trimers as their principal decomposition product, implying that intramolecular cyclization is the dominant mechanism of decompo

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271003

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractIn the copolymerization of α‐methylstyrene (α‐MeSt) andN‐phenylmaleimide (NPMI), the resulting copolymers were found to have a high alternating structure regardless of the ratio of comonomers in the feed. The monomer reactivity ratios werer1= 0.21 (NPMI) andr2= 0.03 (α‐MeSt) (Kelen–Tüdös method), the equilibrium constant of CT complex K was 0.02 L mol−1, and the energy of activationEAwas 73 kJ mol−1. From the equationRp=Rp(f) +Rp(CT) proposed by Shirota and coworkers,Rp(f) andRp(CT) were calculated, and it was found that in toluene the copolymerization proceeds predominantly by the addition of free monomers. Copolymers prepared at an equimolar ratio of comonomers in the feed have a glass transition temperatureTgof

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271004

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractMicroporous polybenzimidazole of 250–500 μm spherical bead size from Celanese has been reacted with epichlorohydrin and sodium hydroxide and the resulting product with pendant epoxy groups has been reacted with various chelating ligands in order to augment the metal sorption capacity and selectivity of the resin. The chelating ligands used include ethylenediamine, diethylenetriamine, diethanolamine, dimethylglyoxime,L‐cysteine, thiourea, dithiooxamide, glyoxal‐bis‐2‐hydroxyanil, salicylaldehyde‐ethylenediimine, and glyoxal‐bis‐2‐mercaptoanil. The aminolysis of the pendant epoxy groups with the oligoamines has been performed in pyridine under reflux conditions, while the addition reactions with the other ligands which are alkali soluble have been carried out at room temperature in a mixture of dioxane and aqueous KOH using tetra‐n‐butylammonium iodide as the phase transfer catalyst. The products are found to possess high capacity and selectivity in metal sorption depending

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271005

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractA wide range of functional diblock copolymers containing both functional polymer and hydrocarbon polymer, have been prepared by the combination of anionic polymerization and borane chemistry. The distinctive hydroboration reactivity between various polydienes enables us to selectively functionalize one polydiene segment in diblock copolymers which contain two different polydiene segments. In turn, the hydroborated polymers are valuable intermediate compounds which can be converted to a whole family of functional polymers with a variety of other functionalities under mild reaction conditions. The hydroxylated diblock copolymer is used as an example to demonstrate the chemistry. The two‐phase nature of these copolymers is also shown by the observation of two distinctive glass transition temperatures associated with the individual polymer segment

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271006

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractEight new diisocyanate monomers containings‐triazine ring have been prepared from the parent diacids via the Curtius rearrangement of the corresponding diacyl azides. The parent diacids were synthesised by the reaction ofp‐ andm‐hydroxybenzoic acid with 6‐methoxy‐2,4‐dichloro‐s‐triazine, 6‐phenoxy‐2,4‐dichloro‐s‐triazine, 6‐phenyl‐2,4‐dichloro‐s‐triazine, and 2‐diphenylamino‐4,6‐dichloro‐s‐triazine respectively. Polyurethanes have been synthesised by solution polymerization of these diisocyanates with ethylene glycol inN,N‐dimethylacetamide (DMAC). The resulting polymers were characterized by IR spectroscopy, viscosity meas

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271007

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractEnzyme‐catalyzed preparation of polymers offers several potentially valuable advantages over the usual polymerization procedures. (1) Such polymerizations may allow the polymer to retain functionality that would be destroyed under normal polymerization conditions. (2) The selectivity provided by enzyme catalysts may permit polymers, including optically active polymers, to be prepared that are either not accessible or accessible only with difficulty by other methods. (3) The characteristics of the enzyme and the mild polymerization conditions may permit formation of polymers having highly regular sizes and backbone structures. This report describes the first successful use of an enzyme‐catalyzed polycondensation to prepare a chiral (AA–BB)xpolyesters of more than a few repeat units. Polymerization of bis(2,2,2‐trichloroethyl) alkanedioates (BB) with diols (AA) using the enzyme porcine pancreatic lipase (PPL) as a catalyst is detailed. The polycondensations were carried out at ambient temperature in anhydrous, low polarity organic solvents such as ether, THF, and methylene chloride. End group analysis by NMR providedMnvalues of 1300–8200 daltons while GPC providedMwvalues of 2800–14900 daltons for the polymers. Based on proton NMR spectra obtained during the polymerization, relatively rapid formation of an AA–BB “dimer” and an AA–BB–AA “trimer,” slower formation of a BB–AA–BB “trimer,” and subsequent condensation of these to give higher polymers are suggested to be component

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271008

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractChemiluminescence has been used to study the thermooxidation of poly(phenylene sulfide) film at 85–110°C in oxygen. To identify reaction products, the degraded surfaces were immediately analyzed by x‐ray photoelectron spectroscopy, then exposed to light and reanalyzed. In the proposed reaction sequence, thiyl radicals generated by oxidation of thiol end groups undergo chain transfer with polymer and bimolecular termination giving thiones, emitters that account for part of the chemiluminescence spectrum. Reaction is extensive at the surface, and subsequent exposure of the thermooxidized surface to light results in considerable loss of sulfur as well as carbon. The role of the thione products in subsequent degradation and chemiluminescence is discu

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271009

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractEthyl 2‐(vinyloxy)ethoxyacetate (4; CH2CHOCH2CH2OCH2COOC2H5), a vinyl ether having both carboxylic acid ester and oxyethylene unit in its pendant, afforded well‐defined living polymers when polymerized by the hydrogen iodide/iodine (HI/I2) initiating system in toluene at −40°C. The polymers possessed a narrow molecular weight distribution (Mw/Mn≤ 1.15), and their molecular weight (Mn) increased proportionally to monomer conversion or the molar ratio of the monomer to hydrogen iodide. The polymer molecular weight also increased upon addition of a fresh feed of the monomer to a completely polymerized reaction mixture. Polymers of high molecular weights (Mn>5 × 105) and broad molecular weight distributions were obtained by BF3OEt2in toluene at −40°C. Polymerization rate of4with HI/I2is ca. 100 times greater than that of the corresponding alkyl vinyl ether, and thus4was found to be one of the most reactive vinyl ethers thus far studied. Alkaline hydrolysis of the pendant ester groups of the polymers gave a vinyl ether‐based polymeric carboxylic acid6with a narrow molecular

ISSN:0887-624X    

DOI:10.1002/pola.1989.080271010

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY