ISSN:1042-7147    

DOI:10.1002/pat.1995.220060701

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060702

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractPoly(ethylene oxide)‐b‐poly(styrene) block copolymers were prepared in the form of latex particles by emulsion polymerization of styrene with poly(ethylene glycol)–azo‐initiators as well as with the redox initiation system poly(ethylene glycol)/Ce4+. The emulsion polymerization can be carried out in the absence of additional stabilizers if the chain length of the poly(ethylene glycol) is greater than 40. The latex particles as well as the copolymers were characterized by capillary hydrodynamic fractionation,13C‐nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared spectroscopy. By13C‐NMR spectroscopy a side reaction of the primary radicals arising from the azo‐initiator was found which can contribute to the low efficiency of azo‐initiators in emulsion

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060703

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractAssociating polymers have been prepared by radical copolymerization in water of acrylamide with a micelleforming cationic polymerizable surfactant. To estimate the locus of initiation, the polymerizations were carried out in the presence of initiators and radical inhibitors of various solubilities (water‐soluble or oil‐soluble), and the decay of inhibitor concentration has been monitored by electron spin resonance spectroscopy. Conversion–time curves simultaneously determined. The experimental data have been interpreted by taking into account the concentration and lifetime of the different radical species (primary radicals, oligoradicals, inhibitors), their partitioning between the micelles and the aqueous continuous phase, and the dynamics of the micellar system. Analysis of the data provided some insight into the copolymerization mechanism of these micellar sy

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060704

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractMonomeric emulsifiers with different copolymerization reactivities were used as stabilizers in emulsion polymerization of styrene initiated by 2,2′ azobisisobutyronitrile (AIBN). A significant change in emulsifier function was observed between equal micellar concentrations of surface‐active sodium sulfopropyl alkyl maleates and the corresponding sodium sulfopropyl dodecyl fumarate. In the presence of less reactive maleates, copolymerization mainly occurs in the interface of the monomer swollen particles, while copolymerization with the fumarate in the first period of emulsion polymerization leads to polyelectrolyte formation in the water ph

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060705

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractEmulsifier‐free latexes with immobilized carbohydrate residues have been prepared by batch or seed (co)polymerization of styrene in the presence of 11‐(N‐p‐vinylbenzyl)amido undecanoyl maltobionamide (LIMA). The critical micelle concentration and the molecular surface area of LIMA were determined by surface tension and fluorescence measurements. Batch polymerization of LIMA with styrene was first performed using potassium persulfate, proving the efficiency of LIMA as emulsifier. Seed copolymerization was then investigated using polystyrene seed particles with varying experimental conditions (especially the LIMA surface coverage). Material balance of LIMA between aqueous phase and particles was obtained by separating both phases by ultracentrifugation and it was found that the surfaceactive monomer is preferentially on or in the particle (nearly 100% in batch and at most 70% in seed copolymerization). The presence of the carbohydrate residues at the particle surface was directly evidenced by1H‐nuclear magnetic resonance, electron spectroscopy for chemical analysis and electrophoretic

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060706

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractAmong the variety of possible structures for polymerizable surfactants, it seems clear that the most interesting should be those with the reactive group located in the hydrophobic part of the molecule. We report here a study based on such a surfactant. Its general formula is\documentclass{article}\pagestyle{empty}\begin{document}$$ CH_2d\hbox{---}CH\hbox{---}C_6 H_4\hbox{---}CH_2\hbox{---}O(CH_2)_n\hbox{---}O(CH_2CH_2\hbox{---}O)_m\hbox{---}H $$\end{document}A set of surfactants has been produced with m varying from 23 to 48 and n = 6 or 12. The compounds have been characterised by1H‐NMR (nuclear magnetic resonance), size exclusion chromatography, surface tension measurements and turbidimetry.These surfactants have been copolymerized with styrene in emulsion polymerization. The coagulum is rather important, except if m is large enough. Although the incorporation of the surfactant in the latex is rather high. Most of the anchored surfactant remains at the surface and is not too buried inside. The particle size decreases with both the amount of surfactant and the length of its hydrophilic part. The use of these polymerizable surfactants leads to an excellent stability of the latex against the addition of electrolytes, and also against freeze‐thawing constrai

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060707

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThiol‐ended polyethylene oxide (I) has been prepared from the esterification of thioglycolic acid with monomethylether of polyoxyethylene glycol. Emulsion polymerization of styrene (and, in a few cases, methylmethacrylate as comonomer) was carried out in the presence of I using either water‐soluble azo initiator or t‐butylhydroperoxide. In the former case, bimodal particle size distribution was obtained while monodisperse latexes could be prepared in the latter case. Then a redox system was formed from I and t‐BuOOH so that I was both an initiator and a transfer agent. Good steric stabilization of the latexes was observed. The polyethylene oxide sequence of I was partly incorporated at the surface of the latex particles, but the incorporation yield remained limited (between 7 and 18%). Most of the resdue of I remained in th

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060708

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractFunctionalized polystyrene latex particles were obtained either by seed particle functionalization or by the shot‐growth procedure using 2,2′‐azobis (2‐amidino‐propane) dihydrochloride as an initiator and vinylbenzylamine hydrochloride as a cationic monomer. The capabilities of both processes to produce functionalized particles in terms of functionalization yields coming from surface amino group titrations were compared. Different titration methods were performed and a new technique was introduced using fluo

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060709

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractCationic poly(N‐isopropylacrylamide) (NIPAM) copolymer latexes have been prepared at 70°C using methylene‐bisacrylamide (MBA) as the crosslinking agent,2‐2′‐azobis‐(2‐amidinopropane hydrochloride) (V50) as the initiator and in the presence of 2‐aminoethyl‐methacrylate hydrochloride (AEM). It was found that the concentration of AEM plays a major role in the polymerization kinetics and particle nucleation. However, too high a concentration (2–5 mol%/NIPAM) caused the latex to be polydispersed together with the production of large amounts of polyelectrolytes. The presence of surface amino groups on the final particles under the protected form was revealed both by an ultraviolet spectrometry and nuclear magnetic resonance methods. It was indirectly evidenced through the electrophoretic mobility behavior of the latex particles (below and above the lower critical solubility temperature of the poly(NIPAM)) as well as by their stability against a mo

ISSN:1042-7147    

DOI:10.1002/pat.1995.220060710

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY