摘要:

AbstractA series of new poly(amide‐imide)s were synthesized by direct polycondensation of the 1,6‐bis(trimellitimido)diamantane (1) with various aromatic diamines inN‐methyl‐2‐pyrrolidone (NMP) containing lithium chloride. The poly(amide‐imide)s had inherent viscosities of 0.33–1.55 dL/g. The new polycyclic monomer1was synthesized from 1,6‐diaminodiamantane with trimellitic anhydride. Dynamic mechanical analysis revealed polymers3a–cto have main transitions at 385°C, 385°C, and 330°C, respectively. Moreover, these polymers were stable at high temperatures and maintained good mechanical properties (G′ ≈ 108Pa) up to temperatures close to the main transition well above 350°C. Their 5% weight loss temperatures ranged from 421 to 448°C in nitrogen, and from 417 to 426°C in air. A glass transition of poly(amide‐imide)s3was not observed. Poly(amide‐imide)s3(except3e) were soluble in NMP, pyridine, ando‐chlorophenol. Some of the polymers (3a–c) could be cast into flexible films. Their cast films had tensile strengths ranging from 35.5 to 46.9 MPa, elongations at break from 5.8 to 7.5%, and

ISSN:1022-1352    

DOI:10.1002/macp.1996.021970401

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe variation of copolymerization rate with composition obtained for the system methyl acrylate (1)/methyl methacrylate (2)/benzene/2,2′‐azoisobutyronitrile using standard techniques of polymerization rate measurements has been interpreted on the basis of a penultimate effect upon the propagation reaction, giving values ofs1= 0.547 ands2= 1.668 for the chain‐end reactivity r

ISSN:1022-1352    

DOI:10.1002/macp.1996.021970402

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractFilms of synthetic poly(β‐hydroxybutyrate)s (PHB)s ranging from highly isotactic to moderately syndiotactic were cast from each of several polymer fractions isolated from ring‐opening polymerizations of racemic β‐butyrolactone and were subjected to degradation by the extracellular PHB depolymerases of the bacteriumPseudomonas lemoigneiand the fungusAspergillus fumigatusM2A. Films of bacterially produced PHB were also degraded for comparison. Gravimetric determinations of enzymatic degradation were measured relative to control experiments in which no depolymerase was added. Each sample was exposed to the same concentration of enzyme, as determined by the activity of the enzyme solutions towards bacterial PHB powder, and the degradation behavior varied strongly with the tacticity of the samples. Weight loss was greatest for the bacterial polymer, with films being completely degraded by either enzyme in 48 h. The degradation of the synthetic samples by both enzymes followed similar trends, although the fungal depolymerase effected less rapid degradation for all synthetic samples than did the bacterial enzyme. Of the synthetic PHB samples, those of intermediate tacticity (55–60% isotactic diads) exhibited the greatest rate of weight loss, while those most syndiotactic in nature (34–45% isotactic) degraded the most slowly. The observed rates are interpreted in terms of isotactic contents, tacticity sequence distributions, and sample crys

ISSN:1022-1352    

DOI:10.1002/macp.1996.021970403

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe in depth examination (by1H and13C NMR, DSC, SEC and TGA) of the low‐molecular‐weight poly(imide‐amide)s synthesized with the mixture [4,4′‐methylenedi(phenyl isocyanate) (M) + trimellitic acid anhydride (T) + benzoic acid (B)] inN‐methyl‐2‐pyrrolidone (NMP) at temperatures lower than 180°C allowed the identification and quantitative determinations of all the unexpected and relatively stable structures. While amide functions are readily synthesized, the formation of imide from anhydride and isocyanate functions passes through 4‐amido‐1,2‐benzenedicarboxylic acid (Ti), 1,4‐di‐amido‐2‐benzenecarboxylic acid (T″) and disubstituted urea (u). At 180°C Ticompletely disappears but traces of T″ and u remain; thus, the formation of imide can never reach its theoretical quantity. Traces of moisture in NMP may play the role of catalyst in the formation of imide, a

ISSN:1022-1352    

DOI:10.1002/macp.1996.021970404

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe cationic polymerization of cyclic ethers such as cyclohexane oxide (CHO) and vinyl monomers such as butyl vinyl ether (BVE) andN‐vinylcarbazole (NVC) is initiated upon irradiation at λ 380 nm in CH2Cl2solution containing an allylic sulfonium salt, namely, 2‐ethoxycarbonyl‐2‐propenylthiophenium hexafluoroantimonate (1) (EMT+SbF6−), and one of the following compounds: benzophenone, anthracene, thioxanthone, perylene or phenothiazine. Electron transfer and hydrogen abstraction mechanisms were proposed for the initiation step. Stable cation radicals of phenothiazine were also prepared, and the cationic polymerization of butyl vinyl ether was initiated by these catio

ISSN:1022-1352    

DOI:10.1002/macp.1996.021970405

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA novel soluble polydiacetylene with 3,6‐dialkyl‐substituted carbazolyl side groups (polyDCHD‐S) has been prepared. Its electronic and vibrational properties have been studied in the crystalline state. The results are compared with those of polyDCHD taken as reference. PolyDCHD‐S shows a very high conjugation length like polyDCHD but an increased interchain separation. High non‐linear optical response is then expected; that — together with the processability of the polymer — suggests attractive applications in photonic devices based on thin fi

ISSN:1022-1352    

DOI:10.1002/macp.1996.021970406

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThree isomeric bis(ether carboxylic acid)s, 4,4′‐[1,2(1,3 or 1,4)‐phenylenedioxy]dibenzoic acid (o‐,m‐, orp‐3) were prepared by nucleophilic substitution reaction of the potassium phenolate of catechol, resorcinol, and hydroquinone, respectively, withp‐fluorobenzonitrile, giving the corresponding bis(ether nitrile)s, followed by alkaline hydrolysis. There series of isomeric polyamides were synthesized by direct polycondensation of the bis(ether carboxylic acid)s with various aromatic diamines inN‐methyl‐2‐pyrrolidone (NMP) solution containing dissolved metal salts such as CaCl2or LiCl using triphenyl phosphite and pyridine as condensing agents. The resultant polyamides had inherent viscosities of 0,52–1,63 dL/g. Most of the polymers were soluble in polar aprotic solvents such asN,N‐dimethylacetamide (DMAc),N,N‐dimethylformamide (DMF), NMP, and dimethyl sulfoxide. The catechol‐based polyamides revealed markedly higher solubility than those based on hydroquinone or resorcinol. Transparent, flexible and tough films could be cast from the DMAc or NMP solutions of most of the polyamides. All the casting films were characterized by tensile tests. The glass transition temperatures (Tg's) of most polyamides could be determined with the help of differential scanning calorimetry (DSC) traces, which were recorded in the range of 183–232°C. In general, the polyamides based on catechol hadTg's comparable with the ones of the hydroquinone‐based polyamides and higherTg's than the corresponding resorcinol‐based ones. Thermogravimetric analysis data of these polymers indicated that all the polyamides were stable up to 400°C i

ISSN:1022-1352    

DOI:10.1002/macp.1996.021970407

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractCopolymerization of γ‐butyrolactone (γBL) with ε‐caprolactone (εCL) initiated with aluminium isopropoxide trimer ([Al(OiPr)3]3, (A3)) is described. Copolymers with molecular weights (Mn) up to 3 · 104and containing up to 43 mol‐% repeating units derived from γBL are prepared. Their molecular weight is controlled by the concentrations of the consumed comonomers and the starting concentration of initiator {Mn= (86.09 · [γBL]c+ 114.14 · [εCL]c)/3[Al(OiPr)3] + 60.10}.13C NMR and DSC data are indicative of a pseudoperiodic or random copo

ISSN:1022-1352    

DOI:10.1002/macp.1996.021970408

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe syntheses of new types of vinyl sugars are described whose vinyl groups are connected with the monosaccharide by a CC bond. Such monomers can be polymerized by radical as well as by anionic initiation. Starting fromD‐mannitol,D‐gluconolactone,D‐galactose, andD‐fructose, the isopropylidene‐protected aldehydes (R)‐2,3‐isopropylidene‐D‐glyceraldehyde (3), 2,3;4,5‐di‐O‐isopropylidene‐aldehydo‐D‐arabinose (4), 1,2;3,4‐di‐O‐isopropylidene‐α‐D‐galacto‐hexodialdo‐1,5‐pyranose (5), and 2,3;4,5‐di‐O‐isopropylidene‐β‐D‐arabino‐hexosulo‐2,6‐pyranose (6) were prepared. Grignard reaction of the aldehyde compounds with 4‐vinylphenylmagnesium chloride in tetrahydrofuran (THF) yielded the new styryl monomers of type1, in each case as a mixture of two diastereoisomers. The corresponding reaction with vinylmagnesium bromide furnished a mixture of two diastereoisomeric allyl alcohol derivatives. Subsequent Swern oxidation (DMSO/(COCl)2) gave the vinyl ketones of type2. A scale‐up procedure (20 L flask) allowed eight different monomers to be prepared on a 50–200 g scale. Furthermore, the synthesis of the 2,

ISSN:1022-1352    

DOI:10.1002/macp.1996.021970409

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe space charge distribution of three samples of poly(vinyl chloride) of different isotactic content has been studied by the thermal step technique, with a view to investigating the influence of some defined microstructural features on that important behaviour. It has been observed that the space charge increases substantially as the content of the local tetrad configuration,mmr, at the end of isotactic sequences increases. A first tentative interpretation is given.

ISSN:1022-1352    

DOI:10.1002/macp.1996.021970410

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY