摘要:

AbstractThe non‐parallel chain structure determined for γ‐phase isotactic polypropylene (γ‐iPP) is confirmed by Rietveld analysis for highly isotactic high molecular mass iPP crystallized at 200 MPa. The new refinement shows that: (i) stereoregularity or crystallization pressure do not significantly influence the lattice dimensions; (ii) defect inclusion in γ‐iPP crystals is unlikely. The α and γ forms have nearly identical bulk internal energy and density, but α‐iPP should be normally kinetically favored over γ‐iPP which may in turn predominate due to its greater ability to host defects at the crystalline

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180101

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractTwo kinds of SiO2‐supported Cp*TiCl3(Cp*= η5‐1,2,3,4,5‐pentamethylcyclopentadienyl) catalysts were prepared, using SiO2modified with 3‐aminopropyltrimethoxysilane (NSiO2) and the ordinary SiO2as the carrier. The copolymerization of ethylene and 1‐octene was conducted over them combined with methylaluminoxane (MAO) as cocatalyst. From a detailed analysis of the produced copolymers, it was found that the NSiO2supported Cp*TiCl3catalyst gives poly(ethylene‐co‐1‐octene) with a higher content of 1‐octene and a narrower molar mass distribution as well as a narrowe

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180102

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractSequence‐controlled oligomers of cyclic imino ethers were synthesized by the one‐pot multi‐stage feeding method. Selective formation of the sequence was clearly demonstrated by equimolar reactions between the monomers and 1:1 adducts of an initiator with the monomers. Efficiency of the sequence control is determined by the difference of reactivities of the active ends. A new general prerequisite to synthesize a well‐defined sequence by multi‐stage oligomerization was

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180103

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe crystal structure of poly(aryl ether biphenyl ether ketone ketone) (PEDEKK) was determined to comprise a two‐chain orthorhombic unit cell with dimensionsa= 0.778 nm,b= 0.606 nm andc= 2.375 nm by using wide‐angle X‐ray diffraction (WAXD). According to the orthorhombic system, the 12 reflections of this polymer were indexed. The crystallite size increases with increasing the crystallization temperature. The results of the degree of crystallinity (Wc,x) calculated from WAXD were compatible with those from density (Wc,d) and calorimetry (Wc,h) measure

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180104

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractPoly(siloxyethylene glycol)The term “poly(siloxyethylene glycol)” was used by us in our previous paper10for the following polymer skeleton:with pendant vinyl groups (PVSE) was synthesized by polycondensation of oligo(ethylene glycol) (MW = 300) and diaminodivinylsilane. PVSE300 thus obtained is soluble in cold water. The PVSE300 coupled with a polythiol compound shows properties of a negative working photoresist. A negative tone image was obtained by development with water at 4°C. PVSE300 is a new type of Si‐containing polymer resist which can be developed by

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180105

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractSyndiotactic poly(methyl methacrylate) (st‐PMMA) macromonomer having methacryloyl end group was prepared from st‐PMMA living anion and separated into uniform macromonomers by means of supercritical fluid chromatography. A uniform macromonomer with the degree of polymerization of 32 was polymerized radically in benzene at 60°C. The uniform dimer, trimer and tetramer of the uniform macromonomer were isolated from the polymerization product by means of gel‐permeation chromatography (GPC). The intrinsic viscosity ([η]) in tetrahydrofuran of these uniform comblike polymers was determined by GPC/differential viscometric analysis. The plot of logarithmic [η]against logarithmic molecular weight indicated that the trimer and tetramer assume a little shrinking molecular shape as compared with the unimer a

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180106

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

Abstracttrans‐Polypentenamers with thermotropic liquid‐crystalline side chains cholesteryl and cyanobiphenyl were prepared by ring‐opening polymerization of vinylcyclopropane monomers with proper substituents. Molecular weights of the polymers were in the range of 25000 to 80000 and the ratios of weight‐ to number‐average molecular weightsMw/Mnwere between 3.3 and 3.8. The glass transition temperature values of the polymers were 35°C (4a) and 39°C (4b). Monomers3aand3bpresent cholesteric and smectic mesomorphism, respectively. On the other hand, polymers4aand4bpresent only a smecti

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180107

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe chemoenzymatic synthesis of new side‐chain polyrotaxanes (6) bearing non‐covalently attached cyclodextrins is described. Starting from 11‐methacryloylaminoundecanoic acid, up to 8 units of 12‐hydroxylauric acid were condensed in the presence of a lipase fromCandida antarctica. They were copolymerized with methyl methacrylate to comb‐like polymers (4) bearing free carboxylic groups at the end of the oligoester side chains. These free carboxylic groups were then condensed chemically with a nucleophilic barrier group,N‐(4‐aminobutanoyl)‐4‐triphenylmethylaniline (5), in the presence of dimethylated β‐cyclodextrin, yielding new polyrotaxanes that contain statistically more than 1 ring comp

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180108

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractStatistical copolymers with mesogenic and non‐mesogenic comonomer units were synthesized by partial hydroboration of the 1,2‐units of polybutadiene and subsequent conversion of the alcohol groups to mesogenic units. The nature of the LC phase proves to be dependent on the mesogen content. Below a certain content the smectic C phase vanishes, and the polymer becomes cypotactic nematic.Tg,Ts,n,Tn,iand ΔHs,ndepend on the mesogen content, whereas ΔHn,iis independent. No difference can be detected between the phase behaviour of homopolymers and ABA‐triblock copolymers with a liquid crystalline B‐block and 10 wt.‐% polystyre

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180109

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY