摘要:

AbstractThe substitution reaction of PVC with sodium dimethyldithiocarbamate (NaDC) and sodium azide (NaN3) was performed in cyclohexanone and dimethylformamide at various temperatures. The degree of compositional heterogeneity was estimated and found to be important up to conversions of about 0,5%, but to vanish afterwards. The evolution of unreacted iso, hetero and syndiotactic triads was measured by13C NMR spectroscopy. For conversions of at least up to 12%, the content of both the isotactic and heterotactic triads was found to decrease, relative to the syndiotactic ones, but at different relative rates depending on the nucleophile. From these results, together with the kinetic ones, it is concluded that the reaction proceeds by a stereoselective mechanism. The results are discussed on the basis of a hypothesis concerning the role of the local triad conformations in PVC that contain the TT isotactic diad conformation. The results enable the selective substitution of PVC with NaDC and NaN3, which may be used as a useful tool to prepare specific graft copolymers based on PVC.

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900201

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

Abstract1,8‐Bis(dimethylamino)‐4‐(4‐vinylphenyl)naphthalene (33), 1,8‐bis(dimethylamino)‐4‐(4‐vinylbenzyl)napthalene (35), 4,5‐bis(dimethylamino)‐9‐(4‐vinylbenzyl)fluorene (37) and 4,5‐bis(dimethylamino)‐9,9‐bis(4‐vinylbenzyl)‐fluorene (38) were synthe

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900202

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractPoly{1‐[4‐(2‐chloroethyl)phenyl]ethylene} (3) was synthesized by bulk polymerization of 4‐(2‐chloroethyl)styrene (6) in two steps from commercial products. The polymer was characterized by means of GPC (weight‐average molecular weightM̄w= 85 000 and number‐average molecular weightM̄n= 63 500),1H NMR and13C NMR spectroscopy. The first stage of thermal degradation begins at 290°C and ends at about 410°C. The overall activation energy was calculated to be 43 kcal · mol−1(180 kJ · mol−1). The solid residue was crosslinked and insoluble. The volatile products, identified by gas chromatography‐mass spectroscopy (GC‐MS), were chiefly hydrogen chloride, dichloromethane and monomer. In a strongly basic medium, nucleophilic substitution of chlorine was a

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900203

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractPrinciples and new approaches to the synthesis of functional poly(ethylene oxide)s (PEO) are considered. It could be shown that quantitative functionalization during initiation or deactivation of living polymers cannot be reached independently of the demands to achieve a desired molecular weight of the polymer. This is illustrated by the data of the synthesis of dinitrophenyl derivatives of PEO (molecular weights from 3 · 103to about 105) which are synthetic immunogenes. Vinyl ether macromonomers of PEO with molecular weights in the range of 750–3000 were also synthesized by anionic polymerization of ethylene oxide with trimethylamine as initiator. These macromonomers were used for effective grafting of PEO onto a solid surface, grafted PEO being able to selectively binding alkali salts from the solution. Values of binding constants were evaluat

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900204

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractFollowing a preliminary report stating that ethylboron sesquitriflate initiates the polymerization of hexamethylcyclotrisiloxane (D3), a more rigorous investigation was carried out to ascertain that cyclic siloxanes can indeed be polymerized by Lewis acids without the intervention (cocatalysis) of proton‐donor impurities. The evidence gathered with this strong boron Lewis acid suggested that direct initiation does occur, although its efficiency is much lower than that of an equivalent amount of a strong Brønsted acid. The use of a sterically hindered pyridine was a key factor in discriminating between monomer protonation and direct initiati

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900205

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractTelechelic poly(dimethylsiloxane)s (4, 5, 6) with acetoxy, hydroxyl or 2,3‐epoxypropoxy functions as end groups were synthesized. As starting materials chloro‐3‐acetoxy‐[or 3‐(2,3)‐epoxypropoxy]‐propyldimethylsilanes (2and3) were prepared by hydrosilylation of the corresponding allylic derivatives with chlorodimethylsilane, and subsequently condensed with α‐hydro‐ω‐hydroxyoligo‐ (or poly‐) dimethylsiloxanes (1b – d) in the presence of pyridine. The hydroxyl derivatives5a – dwere obtained by hydrolysis of the acetoxy derivatives, and the 3‐(2,3‐epoxypropoxy)propyl derivatives6a, bby reaction of the dio

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900206

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractTelechelic aromatic diamines (11) containing an oligo‐ or polysiloxane chain were prepared in a 4‐step synthesis. In the first step 1‐allyloxy‐4‐nitrobenzene (6) was synthesized and subsequently hydrosilylated with chlorodimethylsilane. In the third step the product (7) was hydrolyzed or condensed with α‐hydro‐β‐hydroxyoligo‐ or polydimethylsiloxane (9aor9b). In the last step the nitro groups were reduced into amino groups. The steps were controlled by means of1H and29

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900207

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractSeveral potentially thermostable polyesters3a–1were prepared by Schotten‐Baumann condensation of 2,2′‐diiodo‐4,4′‐biphenyldicarbonyl dichloride (1) with several aromatic hydroxy compounds2a–1. The reactivity of1towards various phenols was tested and the spectra of the resulting model compounds4a–dwere compared with those of the polymers. With some exceptions (3hand3c) the polyesters were found to be soluble in organic solvents. Their inherent viscosities vary between 0,1 and 0,45 dl · g−1(in CHCl3at 25°C). The values of the inherent viscosity were in the range of 0,06–0,45 dl/g (c= 0,2 g/dl in CHCl3at 25°C). The melting points of the polymers were found

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900208

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractPoly(azine‐ether)s (1aand1b) derived from 2,4‐dihydroxybenzaldehyde and 2,4‐dihydroxyacetophenone, respectively, were synthesized by condensation of the corresponding dicarbonyl monomer (2aor2b) containing 10 methylene units with hydrazine hydrate. For the preparation of1aethanol or acetonitrile were found to be the best solvents, DMF or 1,4‐dioxane for the preparation of1b. The liquid‐crystalline behaviour of the polymers was studied by DSC and on the hot stage of a polarizing microscope. All of them formed nematic mesophases

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900209

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

Abstractω‐Aminoalkyl dihydrogen phosphates5a–c,7and9were obtained in a simple and reproducible fashion byO‐phosphorylation of the corresponding aminoalcohols with ClPO3H2generated in situ by controlled hydrolysis of POCl3. Reaction of these phosphates with acrylic or methacrylic anhydride in water/THF mixture afforded a series of new acrylic monomers (11a–h) bearing a phosphoryl group. Inverted emulsion copolymerization of the latter with the hydrophilic comonomersN‐[1,1‐bis(hydroxymethyl)‐2‐hydroxyethyl]acryl‐ or methacrylamide (12aor12b) and with the cross‐linkerN,N′‐methylenediacrylamide (13) afforded various gels in the form of spherical beads. Preliminary experiments showed that some of these copolymers could be efficiently used as stationary phases for the separation of proteins by ion

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900210

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY