摘要:

AbstractPreparatory to triblock synthesis experiments, the cationic polymerization of α‐methylstyrene (αMeSt) was investigated using the 2‐chloro‐2,4,4‐trimethylpentane (TMPCI)/TiCl4initiating system in the presence of triethylamine (Et3N) as electron donor (ED) and CH3Cl/n‐hexane mixed solvent in the −80 to −40°C range. Conversions are influenced by temperature, [TiCl4], [Et3N], and [αMeSt]. The polymerization of αMeSt is living at −80°C: Both termination and chain transfer to monomer are frozen out, however, initiation is slow relative to propagation. Highly syndiotactic (>94%) Pα Mest was obtained. At−60deg;C initiator efficiency is ca. 100%, but termination becomes evident. Et3N may act both as Ed and as proton scavenger. Novel poly(α‐methystyrene‐b‐isobutylene‐b‐α‐methylstyrene) (PαMeSt‐PIB‐PαMeSt) triblocks have been synthesized by adding αMeSt to biliving polyisobutylene carbocations (⊕PIB⊕) in the −80 to −40°C range. The effects of temperature, solvent polarity, and [Et3N] on the block copolymerization have been investigated. At −80°C, the rate of crossover from ⊕PIB⊕ to αMeSt is lower than that of propagation of PαMeSt⊕, so that the triblock is contaminated by PIB and PIB‐b‐PαMeSt. At −60°C, crossover occurs preferentially. The rate of propagation relative to that of crossover is also reduced by lowering the solvent polarity and increasing the [Et3N]. High crossover efficiency and blocking efficiency can be obtained under optimum blocking conditions. The tribloc

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320301

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractN,N‐di (2‐hydroxyethyl)‐3‐aminopropionic acid (M3) was synthesized and used for the preparation of a series of polyesters having amino acid moieties in the main chain and carboxyl groups as the side group. Polycondensation ofM3, diols, bisphenol A, and isophthaloyl dichloride were performed in the presence of tertiary amine by solution and interfacial methods. Molecular weights of the polymers obtained by the solution method were not high, because oligomers produced at the early stage of reaction are ionized by H+ions from the by‐product, and become nonreactive triethylamine hydrochloride. Polymers with highM̄w(1–10 × 104) were obtained in a high yield by organic/organic two‐phase interfacial polycondensation using DMAc andn‐heptane as solvents. The combined nucleophilic and basic complex catalytic action ofN,N,N′,N′‐tetramethyl ethyiene diamine (TEMED) is suggested for the present organic phase/organic phase interfacial polycondensation. This method can be applied for the preparation of novel functional polyesters. © 1

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320302

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

Abstract3,3‐Bis[4‐(4‐aminophenoxy)phenyl]phthalide (II) was used as a monomer with various aromatic dicarboxylic acids and dianhydrides to synthesize polyamides and polyimides, respectively. The diamineIIwas derived by a nucleophilic substitution of phenolphthalein withp‐chloronitrobenzene in the presence of K2CO3. PolyamidesIVa‐ghaving inherent viscosities of 0.77–2.46 dL/g were prepared by the direct polycondensation of diamineIIwith diacidsIIIa‐gusing triphenyl phosphite and pyridine as condensing agents. The polyamides were readily soluble in a variety of solvents such asN, N‐dimethylformamide (DMF),N,N‐dimethylacetamide (DMAc), andN‐methyl‐2‐pyrrolidinone (NMP) and afforded transparent and flexible films from the polymer solutions. These polymers had glass transition temperatures (Tgs) in the 227–307°C range and 10% weight loss temperatures occurred up to 450°C. PolyimidesVIa‐ebased on diamineIIand various aromatic dianhydridesVa‐ewere synthesized by the two‐stage procedure that included ring‐opening, followed by thermal or chemical conversion to polyimides. Most of the polyimides obtained by chemical cyclodehydration procedure were found to soluble in DMF, NMP,o‐chlorophenol, andm‐cresol. TheTgs of these polyimides were in the 260–328°C range and showed almost no weight loss up to 500°C under air and nitro

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320303

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe new polymer‐forming diimide‐diacid, 2,3‐bis(4‐trimellitimidophenoxy) naphthalene (I), was readily obtained by the condensation reaction of 2,3‐bis (4‐aminophenoxy) naphthalene with trimellitic anhydride. A series of novel aromatic poly (amide‐imide)s were prepared by the direct polycondensation of diimide‐diacid I with various aromatic diamines using triphenyl phosphite inN‐methyl‐2‐pyrrolidone (NMP)/pyridine solution containing dissolved calcium chloride. The resultant polymers have inherent viscosities in the range of 0.65–1.02 dL/g at 30°C inN, N‐dimethylacetamide. These polymers were readily soluble in various organic solvents and could be cast into transparent, tough, and flexible films. Their casting films showed tensile strength at break up to 86 MPa, elongation to break of 5–9%, and initial moduli up to 2.35 GPa. The wide‐angle X‐ray diffraction revealed that those polymers containingp‐phenylene orp‐oxyphenylene group are partially crystalline, and the other polymers are evidenced as amorphous patterns. These polymers show a glass transition in the range of 213–290°C in their differential scanning calorimetry (DSC) traces. The thermal stability of the polymers was evaluated by thermogravimetry analysis, which showed the 10% weight‐loss temperatures in the range of 508–565°C in nitrogen and 480–529°C

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320304

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe effect of monomer micellization on the polymerization was studied from the standpoint of stereochemistry in the polymerization. Quaternary salts (CnBr) of dimethylaminoethyl methacrylate withn‐alkyl bromide havingN(=4, 8 and 12) carbon atoms were polymerized with radical initiators in isotropic and anisotropic media and the resulting polymers were converted to poly (methyl methacrylate) (PMMA) to determine their tacticity. Tacticities of poly (C12Br)s were little affected by initiators and solvents used for their preparations. There was little dependence of the tacticities on alkyl chain length (N) for poly (CnBr)s prepared in water and dimethylformamide (DMF). Most of polymers produced here conformed to Bernoullian propagation statistics and a definite difference was not found in the tacticities between the polymers prepared in isotropic and anisotropic media. From the results obtained here it was deduced that the micellar aggregation has little influence upon the stereochemistry in the polymerization of the quaternary monomers. © 1994 John Wiley&Sons, I

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320305

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractLoss of diamine and distinct transition phenomena from the solid to the melt state restrain solid‐state polymerization (SSP) of nylon salts from industrial application. To depress these phenomena temperatures well below the melting point of the starting material are employed, resulting however in low reaction rates. The need to use catalysts arises and accordingly in this study hexamethylenediammonium adipate (HMA) particles were polymerized containing a strictly controlled amount of uniformly distributed catalyst. The catalysts included boric, sulphuric, and phosphoric acids with boric acid being the most effective in accelerating the reaction while eliminating the tendency to agglomeration. In general, catalyst concentration up to a critical value plays a considerable role in the overall behavior. Furthermore, in agreement with non catalytic processes, the reaction temperature remains an influential parameter. © 1994 John Wiley&Sons, I

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320306

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractCationic cyclopolymerization of (E, E)‐[6.2]‐(2,5) thiophenophane‐1,5‐diene (2) gave polymer3which has bridged thiophene rings pendant to the polymer backbone. The structural, thermal, and electronic properties of polymer3were compared to those of its benzene analogue (1) and its nonbridged analogue poly (2‐vinylthiophene) (5). The onsets of thermal degradation for polymers3and5under helium were 425 and 382°C, respectively. Polymer3exhibited conductivity in the 10−3−10−4S/cm range when exposed to iodine vapor, four orders of magnitude higher than for5treated in the same manner. Apparent energies of activation for conductivity in iodine saturated polymers3(0.57 eV) and5(0.61 eV) were calculated from conductivity temperature dependence measurements. Conductivity parameters for iodine saturated3show both a higher level of conductivity and weaker temperature dependence than for the corresponding cyclopolymer1which has benzene rather than thiophene moieties, suggesting that greater charge generation occurs in3, due to the lower oxidation potential of the thiophenophane repeat units. Differences in conductivity behavior for iodine saturated polymers1, 3, and5are discussed in terms of both charge generation and mobility. © 1994 Joh

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320307

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe synthesis of various phosphoranimines including (CH3OCH2CH2O) (CF3CH2O)2PNSi(CH3)3, (CH3OCH2CH2OCH2CH2O) (CF3CH2O)2PNSi (CH3)3, (CH3OCH2CH2O)2(CF3CH2O) PNSi(CH3)3, and (CH3OCH2CH2OCH2CH2O) 2 −(CF3CH2O) PNSi(CH3)3via the Staudinger reaction of (CH3)3SiN3with the suitably substituted phosphite is reported. These monomers were polymerized using tetra‐n‐butylammonium fluoride andN‐methylimidazole in various solvents at several temperatures.In situ31P‐NMR kinetic studies andMnversus time studies were also performed for the monomers to understand the propagation mechanism

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320308

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractA polyaddition of phenylphosphine (PH) to 1,4‐divinylbenzene (DVB) or 1,4‐diisopropenylbenzene (DIPB) was carried out by radical initiations or UV irradiation at 60–80°C in toluene under a nitrogen atmosphere. The soluble polymer with higher molecular weight ($\[ \bar M_w = 2 \times 10^4 \]$) was obtained in a high yield with AIBN initiator for 95 h in the presence of 5% excess of PH to DVB (monomer feed ratio [DVB]0/[PH]0= 1/1.05). On the other hand, a polyaddition of PH to DIPB proceeded much slower than the case of DVB, but the high polymer was obtained in a high yield by choosing polyaddition conditions such as polyaddition temperature and initiator concentration. From1H‐NMR, IR analyses, and phosphorus content of the polymers, it was characterized that both polymers have the alternating structure consisting of PH and DVB or DIPB units in 1 : 1 ratio. The glass transition and decomposition temperatures of both polymers under a nitrogen atmosphere were almost similar: 15–30°C and 380–385°C, respectively; but, the polymers were oxidized by heating under an atmosphere of air. The polymers had a self‐extinguishing property and the polymer blend of the flammable polymers such as polystyrene and polyethylene with the phosphorus‐containing polymers exhibited an excellent flame resistance. © 1994 J

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320309

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe photo‐ and thermooxidative degradation of different grades of high‐impact polystyrene (HIPS) has been studied by FT‐IR spectroscopy. The oxidized films were treated with NH3and SF4for the rapid identification and resolution of the various carbonyl species, alcohols, and hydroperoxides. All the sample gave similar oxidation products, but in varying quantities. The heterogenity in the film was also determined by micro‐FT‐IR spectroscopy. The thermal degradation processes at different temperature were compared. © 1994 John Wiley

ISSN:0887-624X    

DOI:10.1002/pola.1994.080320310

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY