摘要:

AbstractFollowing the earlier development of highly active supported propene polymerization catalysts prepared by activating supports derived from Mg dialkyl complexes with the rare and very expensive ethyl esters of 2,6‐dimethyl‐ (1) or 2,4,6‐trimethylbenzoic acid (2), research was undertaken to uncover low‐cost and commercially available substitutes for1and2. Several phosphonate, phosphate, and phosphite alkyl esters, as well as ethers and amines, were investigated. Dibutyl butylphosphonate (5b) adducts with Mg dialkyl were found to produce catalysts with comparable activity, improved, narrower particle size distribution, and only slightly lower stereospecificity and polymer powder bulk density relative to catalysts made using MgR2adducts with1or2as starting materials (R =n‐C4H9). Optimized catalysts based on MgR2·5badducts, prepared by precipitating the support by reaction of a solution of the adduct with SiCl4and subsequent activation by treatment of the support with TiCl4and diisobutyl phthalate in chlorobenzene, realize yields of 16–17 kg polypropylene/g catalyst in 2‐h hexane slurry polymerizations at 70°C, 10,2 atm, with 1,2–1,5 wt.‐% boiling hexane extractables and 0,40–0,41 g/ml polymer powder bulk density. The cocatalyst‐external modifier package used consists of Al(C2H5)3‐dimethoxydiphenylsilane. The narrow particle size distribution of the polymer powder produced renders the new catalysts suitable for use in both slurry and solventless propene polymerization processes, while the low cost and ready availability of5bmake the catalyst preparat

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900901

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

Abstract2‐Bromoethyloxirane (2b), 3‐bromopropyloxirane (2c), and 4‐bromobutyloxirane (2d), were prepared by epoxidation of the corresponding bromoalkenes. Treatment of the oxiranes with a triethylaluminium/acetylacetone/water mixture afforded the polyethers3b–din good yield as tacky, white elastomers. Substitution of bromide by benzoate ion established essentially equal reactivities for the three polymers; each was substantially more reactive than any of the halogenated polyether elastomers available her

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900902

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractL‐Mandelic acid‐1,2‐O‐(4‐vinylphenyl)boronate (2) was copolymerized with divinylbenzene to yield a highly crosslinked macroporous polymer. 59% of incorporatedL‐mandelic acid (used as template) could be split‐off on hydrolysis. The resulting polymer, with phenylboronic acid groups in the chiral cavities of typeP1, was equilibrated in a batch process withD,L‐mandelic acid in acetonitrile. The change of covering percentage, and that of the efficiency for racemic resolution, with time were followed by acidimetric titration and measurement of the optical rotation. A reasonable mechanism for the polymer‐substrate interaction could de deduced. The selectivity terms for each of the forward and reverse reaction could be separately evaluated. Diffusional limitations significantly affect the observed efficiency of racemic resolution. Thermodynamically controlled separation, attainable by a suggested exchange reaction, required much more time than the considerably less effective kinetically cont

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900903

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractSynthesis of a novel conjugate of anticancer drug adriamycin, poly(ethylene glycol)‐block‐poly(aspartic acid), and immunoglobulin G is reported. Poly(ethylene glycol)‐block‐poly(aspartic acid), binding adriamycin on the poly(aspartic acid) chain, showed an excellent water‐solubility despite the introduction of a large amount of strongly hydrophobic adriamycin, and was found to form a micellar structure in aqueous solution. Efficient coupling between poly(ethylene glycol)‐block‐poly(aspartic acid) binding adriamycin and immunoglobulin G was achieved via disul

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900904

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractPolyimides were prepared by Diels‐Alder (DA) reaction of furfuryl alcohol (FA) resin [poly(2,5‐furandiylmethylene)] with the bis(maleimides)N,N′‐hexamethylenebis(maleimide) andN,N′‐1,4‐phenylenebis(maleimide), respectively. The DA reaction was carried out in tetrahydrofuran as solvent, as well as in bulk, followed by aromatization of tetrahydrophthalimide intermediates in the presence of acetic anhydride. All the polyimides were characterized by elemental analyses, IR spectral studies and thermogravimetry. The results show that polyimides based on FA resin exhibit moderate thermal stability. The results of preliminary tests for glass reinforcement of produced polyimides suggest that laminates with good mechanical strength ca

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900905

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractRadical copolymerizations of styrene with acrylates of magnesium, calcium, strontium and barium were carried out in dimethyl sulfoxide. The monomer reactivity ratios were determined by the Yezrielev‐Brokhina‐Roskin and the Kelen‐Tüdős methods. In all cases the monomer reactivity ratio for styrene exceeded one and those for the salts were less than one. TheQ‐values of the Alfrey‐Price scheme for the metal acrylates were within the range 0,1 − 0,2. For the values of the polarity parameterethe following sequence was found:eMgA2

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900906

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractPoly(9,10‐dihydroanthrylenetrimethylene) (2) comprises a novel chain‐type structure in which 9,10‐dihydroanthracene units are linked by flexible spacer groups. Upon dehydrogenation with sulfur at elevated temperature, polymer2is converted into the corresponding polyanthrylene system3. NMR‐ and UV‐spectroscopic data provide firm evidence for the dehydrogenation process. The polymer3was subjected to reduction with active lithium, and the resulting polyanions were characterized by NMR spectroscopy and by quenching experiments. It appears that each anthracene unit of the chain can be charged with two

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900907

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractCrosslinked polymers containing sulfinyl groups were prepared by free‐radical terpolymerization ofp‐methylsulfinylstyrene, styrene, and divinylbenzene. These polymers serve as phasetransfer catalysts for the reaction of 1‐bromooctane with sodium iodide in toluene‐water system. The catalytic reaction is affected by some experimental parameters, such as stirring speed, particle size, degree of crosslinking, and solvent. The catalytic activity also depends strongly on copolymer composition, which causes differences in the adsorption of alkali metal ions and in the microenvironment around the active site. On the basis of the results of reactions of benzyl bromide with phenoxide, and of an alkyl methanesulfonate with sodium halides, it is evident that phase‐transfer reactions catalyzed by insoluble polymeric sulfoxides take place in the organic phase where a small amount of water exists. Furthermore, these polymers work as catalysts even in the absence

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900908

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractChiral poly(crown ether)s were synthesized by cationic cyclopolymerization of (S)‐2,2′‐bis(2‐vinyloxyethoxy)‐3,3′‐dimethyl‐1,1′‐binaphthyl [(S)‐1b] and (R)‐2,2′‐bis[2‐(2‐vinyloxyethoxy)‐ethoxy]‐3,3′‐dimethyl (or 3,3′‐diphenyl)‐1,1′‐binaphthyl [(R)‐3bor (R)‐3c]. The substituents in the 3,3′‐positions of binaphthyl moiety disturb the intramolecular cyclization in the polymerization of monomer (S)‐1b, but have no influence on the cyclopolymerization tendency of monomers (R)‐3band (R)‐3c. The polymers from (R)‐3band (R)‐3c[(R)‐4band (R)‐4c] have a higher ability of chiral recognition towardsa‐amino acids, such as phenylglycine, phenylalanine, valine, and methionine, than the polymer from (R)‐3a[(R)‐4a], which has no substituent in 3,3′‐positions. The methyl and the phenyl substituents in the 3,3′‐positions undoubtedly act as additional barrier causing an increase in the ability of chiral recog

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900909

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractPhotosensitive polymers were synthesized by the copolymerization of 4‐(9‐fluorenylideneiminooxysulfonyl)styrene (1) with 2‐dimethylaminoethyl methacrylate (2), 2‐diethylaminoethyl methacrylate (3), or methacrylic acid (4). On irradiation with UV light the decomposition of monomeric units of1 (A)in the polymers led to the formation of sulfo groups in their side chain. Although the quantum yield of photodecomposition of unitsAwas found to be independent of the fraction of unitsAin the copolymers, it is dependent on the polymer structure in the film. Effects of the fraction of unitsAin the copolymers and of the polymer structure on the photoinduced dissolution of the polymers in water were

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900910

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY