摘要:

AbstractThe kinetics of the reaction between alkaline sulfides and halogenated aromatic monomers was studied using lithium sulfide and 4‐chlorobenzophenone(1a)and 4,4′‐dichlorobenzophenone(1b)as models. The release of H2S from reaction medium and the possible formation of a compound between sulfide andN‐methyl‐2‐pyrrolidone (NMP) during the preliminary dehydration step are key steps of the reaction. The reaction proceeds following two successive kinetic regimes: a first one where rapid second‐order reactions of sulfide and thiolate with1aor1btake place, and a second one where the slow release of sulfide from the compound formed during dehydration is rate determining and therefore governs the molecular weight of final polymer. A good agreement was found between theoretical curves calculated from this kinetic scheme and experimental data, indicating a polymerization mechanism based on an SNAr react

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980101

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA system consisting of a novelN‐allyloxypyridinium salt and a radical initiator is highly appropriate for the thermal initiation of cationic polymerizations. Radicals formed upon the thermolysis (at 70°C) of initiators as 2,2′‐azoisobutyronitrile or benzoyl peroxide add to the double bond of the pyridinium saltN‐[2‐(ethoxcarbonyl)allyloxy]‐α‐picolinium hexafluoroantimonate(1). Subsequently, the pyridinium salt is fragmented yielding pyridinium‐type radical cations, species able to initiate cationic polymerizations. In the case of the radical initiator phenylazotriphenylmethane (triphenylmethaneazobenzene), the polymerization is extremely rapid, since additionally the triphenylmethyl cation formed by electron transfer initiates the polymerization. The initiation capability of the system described was demonstrated for a number of monomers, such as cyclohexene oxide, butyl vinyl ether and the bifunctional 3,4‐epoxycyclohexylmethyl 3′,4′‐cyclohexanecarboxylate. With the latter, an insoluble polymer net

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980102

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractRing‐opening polymerization of a new anhydro‐hexose monomer having an azido group, 1,6‐anhydro‐3‐azido‐2,4‐di‐O‐benzyl‐3‐deoxy‐β‐D‐allopyranose (A3ABA), was carried out with Lewis acid catalysts to give a stereoregular (1→6)‐α‐D‐allopyranan derivative having the azido group at the C3 position. The number‐average molecular weights and specific rotations were 5.0 × 103to 24.0 × 103and +71° to +79°, respectively. Reduction of the azido groups into amino groups by lithium aluminium hydride and subsequent debenzylation of the benzyl group into hydroxyl groups by sodium in liquid ammonia gave 3‐amino‐3‐deoxy‐(1→6)‐α‐D‐allopyranan in good yield. In addition, copolymerization of A3ABA with 1,6‐anhydro‐2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranose (LGTBE) in the various feeds was carried out to afford the corresponding copolymers. The monomer reactivity ratios were calculated with the Kelen‐Tüdős method to berA3ABA= 0.66 andrLGTBE= 1.67. After reduction of azido groups and deprotection of benzyl groups of the copolymers, new hetero‐polysaccharides havi

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980103

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractIn adiabatic vacuum and dynamic calorimeters the temperature dependence of the heat capacityCp0of tetrahydro‐1,3‐oxazin‐2‐one (THO) and poly(oxy‐1,3‐propanediyliminocarbonyl) (PTHO) was studied between 5 and 500 K. The melting temperature of the monomer and the polymer, the enthalpies of melting of THO and the glass transition temperature of PTHO were determined. In a calorimeter with a static bomb and an isothermal shield the energies of combustion ΔUcombof the monomer and the polymer were measured. From the experimental data the thermodynamic functionsCp0,H0(T) –H0(O),S0(T),G0(T) –H0(0) were calculated in the range of 0 to 450 K, and enthalpies of combustion ΔHcomb0and thermochemical parameters of formation ΔHf0, ΔSf0, ΔGf0of the compounds studied were estimated atT= 298.15 K and standard pressure. The results obtained were used to estimated the thermodynamic characteristics of the equilibrium of THO polymerization in bulk (ΔHpol0, ΔSpol0, ΔGpol0), with opening of the six‐membered ring and formation of the linear polymer PTHO, in the range 0 to 450 K. It was found that the ΔGpol0values are always negative and change from −18 kJ · mol−1at 0 K to −14 kJ · mol−1at 450 K. Thus, the process equilibrium is everywhere shifted towards the formation of the polymer. The upper (ceiling) limiting temperature of THO polymerization in bulk at standard pressure isTceil= 750 K, that is, considerably higher than the temperature of the onset of the t

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980104

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractSynthesis and free radical polymerization of 1‐(4‐methacryloylaminophenyl)‐3‐phenyl‐2‐propen‐1‐one(2), 1‐[4‐(6‐methacryloylaminohexanoylamino)phenyl]‐3‐phenyl‐2‐propen‐1‐one(7)and 1‐[4‐(11‐methacryloylaminoundecanoylamino)phenyl]‐2‐propen‐1‐one(8)are described. The monomers and a model compound(1)were characterized by NMR and IR spectroscopy. The corresponding homopolymers(9–11)and a copolymer with methyl methacrylate(12)were characterized by DSC, GPC and TG analysis and also spectroscopically. Furthermore, the kinetics ofE/Z‐isomerisations and [2 + 2] cycloadditions of chalcone functions i

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980105

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractFilms of bacterial poly(3‐hydroxybutyrate), obtained by crystallization from the melt at different temperatures up to 120°C, were investigated by powder X‐ray diffraction analysis and optical microscopy. With increasing crystallization temperature (Tc) the diffraction patterns differed more and more from that of the “as received” powder in both relative intensity of the reflections and peak width. The relative peak intensities also varied in response to temperature changes of the melt from which the polymer was quenched to a selectedTc. The differences in the X‐ray diffraction patterns were correlated with changes of average spherulite size (0.1 mm to 2 mm) in films with limited thickness. When the spherulites were large the lamellar crystals were strongly oriented parallel to the film plane. Full profile Rietveld analyses allowed to quantify the preferred orientation effect and to extract additional morphological and structural in

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980106

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractFilms of poly(2‐vinylpyridine)(1), poly(allylamine hydrochloride)(2), poly(5‐methyl‐2‐vinylpyridine)(3)and poly(ethyleneimine)(4)with Ag+, Cu2+, Li+and Ca2+salts as well as complex transition metal ions [Fe(Cn)6]3−are prepared at the interface boundaries of immiscible solvents. The polymer/metal salt complexes exhibit highly ordered structures and high thermal stabilities as revealed by reduced viscosity, X‐ray diffraction, infrared spectrometry, thermogravimetry, differential thermal analysis as well as measurements of swelling coefficients and electroconductivity. Mole ratios of complex formation of the neat polymers as well as the polymer gels with these salts were found at [polymer] : [salt]= 1, 2, 3 and 4 referring to the repeating units of the polymers. It is suggested that the properties of the films are due to ionic bonds, ion‐coordination bonding, coordination bonds and ion‐dipole interactions between the functional groups of the polymeric hydro‐ and organic gels a

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980107

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractPeptide‐containing block copolymers poly(N‐acetyliminoethylene)‐block‐poly(L‐phenylalanine)s(1)form water‐soluble large aggregates in water due to the hydrophobic and hydrogen‐bonding nature of the poly(L‐phenylalanine) block. The solution properties were studied by size exclusion chromatography, dynamic light scattering,1H NMR spectroscopy, and transmission electron microscopy. The results were compared with those of the block copolymers poly(N‐acetyliminoethylene)‐block‐poly(N‐benzoyliminoethylene)s(2)as analogous structures of poly(L‐phenylalanine). The peptide‐containing block copolymers1form aggregates in water even though only short segments of poly(phenylalanine) are provided. The hydrogen‐bonding character of the amide bond in the poly(phenylalanine) segment may induce strong interactions with each polymer chain in water. The interaction of Lipase P with the polymer aggregates in water was studied by means of size exclusion chromatography. The aggregates have a strong capability of incorporating Lipase P and largely increase the hydrolysis activity of Lipase P againstp‐nitrophenyl propionate compared with free Lipase. The guest‐binding ability of 8‐anilino‐1‐naphthalenesulfonic acid for

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980108

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe structure of the aggregates of block copolymers containing poly[(N‐acetylimino)ethylene] as hydrophilic block and poly[(N‐acylimino)ethylene]s as hydrophobic block was studied by size exclusion chromatography, dynamic light scattering, and transmission electron microscopy. The morphology of the aggregates, consisting of spherical and rod‐like micelles, depends on the chemical structure of the block copolymers. The adsorption behavior of human serum albumin (HSA) onto each polymer aggregate was studied by size exclusion chromatography. The maximum amount of HSA bound onto the polymer aggregates depends on the morphology of the polymer aggregates. Adsorption isotherms of HSA for each polymer aggregate are in good agreement with a Langmuir adsorption isotherm. The amount of HSA adsorbed onto the aggregates is not influenced by the fatty acid content in HSA. The electrophoretic mobility of the aggregates without HSA is close to zero, and the negative mobility increases when HSA is incorporated into the aggregates. The experimental results suggest that adsorption of HSA to the aggregates occurs mainly at the surface or at the hydrophilic shell of the polymer aggregates, not at the hydrophobic core of the polymer mic

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980109

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractInfrared temperature studies of a polyurea formed from 2‐methylpentane‐1,5‐diamine and 4,4′‐methylenebis(phenyl isocyanate) are presented, together with those of two model diureas, 2‐methylpentane‐1,5‐diphenylurea and ethylene diphenylurea. The main thrust of the work concerns the interpretation of the infrared changes that are observed in ordered and disordered hydrog

ISSN:1022-1352    

DOI:10.1002/macp.1997.021980110

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY