摘要:

AbstractNew thermotropic, liquid‐crystalline polyesters (5a, b, 6a, b) with mesogenic bipyridinediyl units were synthesized. They form complexes with Fe(II) and Cu(II) salts. Homopolyesters5a, b, containing no metal or less than a certain amount of metal, are smectic. A nematic mesophase was observed in the case of copolyester6a, b. The structural properties of a polyester complex5awith Cu, as crystal, liquid‐crystal and isotropic liquid, were examined by

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900101

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractHeterogeneous, polymeranalogous reactions between polybutadieneepoxides (PBDE) and inorganic surfaces (SiO2, Al2O3, hydroxyapatite) were investigated. The composition of the resulting composites was determined by gravimetric methods and expressed as “degree of reaction” (RG). Interface reactions could be followed by spectroscopic methods and by differential scanning calorimetry. The results of the reaction mechanisms are discussed. Infrared and13C solid state NMR studies suggest that the PBDE macromolecules are linked by bonds to the SiO2surface and by and bonds to the Al2O3surf

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900102

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractDuring the photo‐initiated free‐radical bulk polymerization of 4‐biphenylyl 4‐(6‐acryloyloxy‐hexyloxy)benzoate (1) in the liquid‐crystalline state, the ordering is maintained, leading to an oriented liquid‐crystalline side‐chain polymer. The course of the photopolymerization depends on the phase of monomer1. In the monotropic smetic‐A and in the monotropic nematic phase the polymerization rate and conversion are affected by crystallization during polymerization. In the stable nematic phase the bulk polymerization is fast and complete. In this temperature region the transition from nematic1to smectic poly(1) is passed during which temporary segregation may occur, affecting the molecular ordering. Starting with isotropic1, the polymerization proceeds consi

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900103

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractSeveral kinds of MgCl2‐supported catalysts were prepared by grinding the mixtures of MgCl2and MtCln(MtCln= TiCl4, ZrCl4, HfCl4, VCl3). Polymerization of propene was conducted at 40°C and 1 atm with these solid catalysts by using Cp2MtMe2(Mt = Ti, Zr, Hf, V) as cocatalyst. Polymerization took place only with the use of the TiCl4/MgCl2catalyst. Both the activity and isospecificity were found to strongly depend upon the cocatalyst used. The polymers produced were fractionated with boiling heptane and analyzed by means of13C NMR, the results of which suggested the existence of two types of catalytic centers, isospecific and aspecific. Plausible models of these catalytic centers are propos

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900104

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe recently found catalyst system, composed of Solvay‐type TiCl3and (RCp)2TiMe2, producing extremely high isospecific polyolefins, was used for copolymerizations of ethylene with various α‐olefins (propene, 1‐butene,1‐hexene and 4‐methyl‐1‐pentene) to obtain monomer reactivity ratios for isospecific centers. It was found that no homopolymer was formed actually. Using the copolymer composition obtained by13C NMR, the monomer reactivity ratios were calculated according to the Fineman‐Ross and Kelen‐Tüdős method. For the ethylene/propene pair the same values of reactivity ratio were also obtained from the diad distribution of comonomers. The relative reactivity of these olefins was found to decrease in the following order; ethylene>propene>1‐butene>1‐h

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900105

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractMethacrylate‐terminated poly(tetrahydrofuran) (MA‐PTHF) and acrylate‐terminated poly‐(tetrahydrofuran) (A‐PTHF) macromonomers (M2) were radically copolymerized with 2‐vinylnaphthalene (2‐VN, M1). The composition of copolymers was determined by UV spectroscopy taking advantage of the very high absorption coefficient (UV) of the monomeric units of 2‐VN in copolymer. The monomer reactivity ratiosr1andr2evaluated are as follows. MA‐PTHF:r1=1,3 ± 0,21, ± 0,05; A‐PTHF:r1= 2,5 ± 0,35,r2= 0,10 ± 0,05. These reactivity ratios were compared with those in the copolymerizations of 2‐VN with the corresponding small monomers and were discussed in terms of polymer (hindering) effect and the concept of equal re

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900106

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractLithium monoalkylamide, in the presence of monoalkylamine, was found to initiate the polymerization of isoprene to form oligoisoprenes. The molecular weight distribution of products formed in the lithium isobutylamide initiated isoprene oligomerization strongly depends on the initial mole ratio [Isoprene]0/[Amine]0/[Amide]0; with an initial mole ratio of 60/1/8, oligomers with a number‐average molecular weight of about 800 were obtained. The presence ofN,N,N′,N′‐tetramethylethylenediamine in the reaction system was found to be effective for the selective formation of secondary amino‐ended oligo

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900107

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe block polymerization of styrene with 2‐oxetanone (β‐propiolactone) proceeds fast with a yield of more than 90%, in the presence of potassium solutions in THF containing 18‐crown‐6. Poly(2‐oxetanone)‐block‐polystyrene‐block‐poly(2‐oxetanone) ABA triblock polymers having the expected molecular mass and composition are formed. Their glass transition and melting temperatures as well as their melting enthalpies determined by DSC show a strict correlation with block polymer composition. The mechanism of this block polymerization involving acyloxygen and alkyl‐oxygen bond scission in 2‐oxetanone is in good agreement with previous results of the homopolymerization of β‐lactones by alkali metal solutions ab

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900108

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractTo verify the possibility of developing a ligand delivery system which is controlled by light pulses, we synthesized copolymers ofN‐(2‐hydroxypropyl)methacrylamide (1) containing sidechains terminated in ligands (Boc‐Gly, fluorescein, tetramethylrhodamine) bound via photocleavable 2‐nitrobenzyl groups. Copolymers in solution were exposed to light of wavelength ≈︁ 360 nm which resulted in release of the bound ligands. Depending on the experimental conditions (type of solvent, presence of oxygen) changes in the structure of released fluorochromes were observed (photofading effect). These effects were quantified by determining the binding constants of released modified fluorochromes with monoclonal antifluorescyl

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900109

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractIntramolecularly crosslinked macromolecules (ICM) from unsaturated polyesters (UP) and styrene, respectively from technical divinylbenzene (t‐DVB), were prepared by emulsion copolymerization (ECP). Saturated polyesters of different compositions and molar masses between 1200 and 2400 were used as emulsifiers (ESP). The influence of molar mass and structure at various concentrations of the ESP on yield, number and diameter of the ICM and their composition was studied. For comparison, also sodium dodecyl sulfate (SDS) was used as emulsifie

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900110

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY