摘要:

AbstractThe polymerization rate of 1‐methylazacyclotridecan‐2‐one (N‐methyldodecanelactam) (1) initiated with dodecanoic acid (2) can be described within the whole range of conversions in terms of the simple relation In ([1]0/[1]) =k[2]0t, in spite of the complexity of the overall reaction scheme. The rate constants (k) determined for 240, 260, and 280°C are 0,32, 1,21, and 3,4 kg · mol−1h−1, respectively, and the constants of the Arrhenius equation areA= 6,6 · 1013kg · mol−1h−1,E= 140 kJ · mol−1. The resulting poly(N‐methyldodecaneamide) (3) is a semicrystalline polymer (m.p. 65°C), soluble in polar organic solvents. The following constants of the Mark‐Houwink equation were determined for solutions of this polyamide: for 5000

ISSN:0025-116X    

DOI:10.1002/macp.1983.021841001

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe copolymerization parameters ofN‐methyl‐N‐phenyl‐2‐aminoethyl methacrylate (MPAM) and 2‐acryloyloxybenzoic (AOB), 2‐methacryloyloxybenzoic (MOB), and methacrylic acid (MAA) with styrene in DMSO solution at 50°C were determined and used in the calculation of the Alfrey‐Price copolymerization constantseandQfor MPAM, AOB, MOB, and MAA. From theeandQconstants of the monomers thus determined, the copolymerization parameters of the pairs MPAM‐AOB, MPAM‐MOB, MPAM‐MAA were calculated and compared with those determined by the copolymerization of the corre

ISSN:0025-116X    

DOI:10.1002/macp.1983.021841002

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractFour intrinsically different methods for the determination of the number of active centers were employed in propylene polymerization catalyzed by the typical heterogeneous system TiCl3/AlEt2Cl: (i) determination of M̄n(GPC method) and calculation of number of macromolecules therefrom; (ii) quenching with BuOT and determination of tritium in the polymer; (iii) quenching with CO or CO2and determination of carbonyl groups in the polymer (IR spectroscopy); (iv) quenching with SO2and determination of sulfur in the polymer. The first two methods exhibited a reasonable agreement for the number of active centers. Method (iii) gave much lower values, whereas method (iv) was found to be virtually unsuitable due to a high extent of side reactions of SO2with the polymer. A similar comparison of the methods was made in ethylene polymerization catalyzed by the typical homogeneous systems Cp2TiEtCl/AlEtCl2and Cp2TiEtCl/alumoxane. Method (ii) gave a much lower number of active centers than method (i), due perhaps to a low extent of alcoholysis of the TiC bond or to a high kinetic isotope effect. CO2appeared to be entirely inert as a quenching agent and CO had been reported to show side reactions. It follows that none of the above quenching methods have universal application and thus literature data should be considered with cauti

ISSN:0025-116X    

DOI:10.1002/macp.1983.021841003

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe effect of addition of quaternary ammonium halides was studied in the nonactivated polymerization of 2‐pyrrolidone (1) initiated with the potassium salt of 2‐pyrrolidone (2‐oxo‐1‐pyrrolidinylpotassium) (2). The polymerization was accelerated upon small additions of Me4NCl, whereas addition of Et4NBr and Bu4NBr rather had a retardation effect and reduced the molecular weight of polymer. The formation of the corresponding quaternary ammonium salts of 2‐pyrrolidone in situ is analogous to the formation of the pure salts in their synthesis from the ammonium halides. The nonactivated polymerization of1initiated with the pure tetramethylammonium salt of 2‐pyrrolidone (3) showed all kinetic features of other nonactivated polymerizations of1. High yields and molecular weights of poly(2‐pyrrolidone) and a higher number of growth centers during polymerization are evidence of a higher dissociation of3dissolved in1in comparison with2as the initiator. The activation energy of polymerization activated with3(47,9 kJ · mol−1in the range 35 to 55°C) and the reaction order with respect to3(1,3 at 45

ISSN:0025-116X    

DOI:10.1002/macp.1983.021841004

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractN‐(2‐Hydroxypropyl)methacrylamide copolymers are considered to be a potential drug delivery system. To fulfil this role the drug‐polymer linkage must be susceptible to intralysosomal hydrolysis. Takingp‐nitroanilide as a drug analogue, copolymers were synthesized bearing oligopeptidyl‐p‐nitroanilide side‐chains designed to match known specificities of the lysosomal enzymes cathepsin L or cathepsin D. Degradation of side‐chains by rat liver lysosomal enzymes (measured by monitoring terminalp‐nitroaniline release) occurred only in the presence of reduced glutathione (5 mmol/l) and was effectively inhibited by leupeptin, indicating the involvement of thiol‐proteinases in every case. Depending on side‐chain composition, between 20 and more than 50% of the terminalp‐nitroaniline residues were liberated during a 5 h incubation. It has also been shown that 1) a polymer molecule may contain side‐chains of a single type that are nevertheless differentially susceptible to lysosomal hydrolysis; 2) two of the side‐chains studied liberate only ap‐nitroaniline residue, whereas the others also release amino‐acyl‐p‐nitroanilides; 3) the cleavage of all side‐chains displays a broad pH optimum pH 5 to pH 7; 4) the Michaelis‐Menten constantKmfor side‐chain cleavage varied between 26,1 and 143,2 mg/ml, depending on

ISSN:0025-116X    

DOI:10.1002/macp.1983.021841005

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThree types of copolymers ofN‐(2‐hydroxypropyl)methacrylamide(HPMA) were prepared which contain oligopeptide sequences: (a) HPMA copolymers containing oligopeptide side‐chains terminated withp‐nitroaniline; (b) soluble HPMA copolymers containing oligopeptide sequences in crosslinks connecting two poly(HPMA) chains; (c) a hydrophilic gel, i.e. a three dimensional copolymer of HPMA containing an oligopeptide sequence in the crosslinks. These polymeric substrates (suitable as drug carriers) containing potentially degradable oligopeptide sequences were incubated with an intracellular proteolytic enzyme, bovine spleen cathespin B. The degradation process of the substrates made it possible to reveal the relationship between the structure of oligopeptide sequences and their degradability. The results suggest an important role played by cathepsin B in the degradation of polymeric substrates investigated in this study under physiological con

ISSN:0025-116X    

DOI:10.1002/macp.1983.021841006

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractIn continuation of a preceding study, the course of the reaction between methyl methacrylate(2)and methyl 2‐sodioisobutyrate (1) was investigated, applying reaction times between 0,02 and 1,4 s, as a function of the following conditions: character of the solvent, effect of the addition of sodiumtert‐butoxide, mole ratio2/1, concentration of the reactants, and temperature. Under all conditions used, the reaction between2and1was very fast and gave rise, along with other compounds, to a mixture of oligomers of2with the average molecular weight obeying the ratio [2]:[1]eff.. The balance of products showed that in some cases only a part of1has reacted with2, giving rise to the expected oligomers. The efficiency of1varied in the range from 24 to 100%, being mainly dependent on the character of the solvent (efficiency in THF>in toluene). Moreover, it was higher in the presence of sodiumtert‐butoxide and with a higher2/1mole ratio. In experiments with a low efficiency of1a certain part of it remained unreacted, in spite of the presence of2, for reasons not yet clear. The resulting oligomers undergo consecutive reactions. Starting with the trimer3b, cyclizing selfcondensation was the most important of the consecutive reactions and could be easily investigated in the case of the trimer. The rate of this cyclization was much higher in THF than in other solvents used, and it was, therefore, difficult to obtain the linear trimer at room temperature. On the contrary, the addition of sodiumtert‐butoxide or lowering the temperature suppressed the cyclization, which was especially easy to perceive in THF. Using the experience described in the study, it is possible to choose such conditions of the reaction between1and2, under which the required oligomers are formed in goo

ISSN:0025-116X    

DOI:10.1002/macp.1983.021841007

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractRadical, cationic, and Ziegler‐Natta polymerizations of 9‐allylanthracene (1) were carried out. The radical polymerization was found to be an inefficient method leading to oligomers with complex structure. Reaction of initiator radicals and growing macroradicals with the anthryl group or with the allylic hydrogen leads to resonance stabilized radicals which stop the polymerization. The cationic and Ziegler‐Natta polymerizations gave a copolymer with 9‐anthrylmethylethylene units (8) (from normal 1,2 addition) and 9,10‐anthrylenepropylene units (11) (from the electrophilic attack of carbocations at the aromatic nucleus). Low polymerization temperatures lead to a preference for the alkylation

ISSN:0025-116X    

DOI:10.1002/macp.1983.021841008

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe alternating copolymer, poly(N‐vinylimidazole‐co‐maleic acid) (4), and the random copolymer, poly(N‐vinylimidazole‐co‐acrylic acid) (5), with nearly the same ratio of carboxyl groups to imidazolyl groups, were found to catalyze the hydrolysis of 3‐acetoxy‐N‐trimethyl‐anilinium iodide (1), 4‐nitrophenyl acetate (2), and 4‐acetoxy‐3‐nitrobenzoic acid (3). For these esters, the catalytic activity of4at pH>9 was found to be in the following order:3>2>1that for1being a retarding one. Copolymer5shows a reverse catalytic activity of the order1>2>3. The catalytic site of the alternating copolymer4is the free imidazolyl group, and the reaction rate is enhanced by the carboxylate anion, whereas the reaction rate in the presence of the random copolymer5is controlled predominantly by electrostatic interaction forces between the substrate and se

ISSN:0025-116X    

DOI:10.1002/macp.1983.021841009

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY

摘要:

AbstractThe association of two‐block copolymers polystyrene‐block‐poly(2‐vinylpyridine) has been studied in toluene (a solvent selective for polystyrene) by osmometry, viscometry, and light scattering. Polystyrene‐block‐poly(2‐vinylpyridine) in toluene forms polymolecular micelles having a poly(2‐vinylpyridine) core and a polystyrene shell, and micellization conforms to the model of closed association. The phenomenon of so‐called anomalous micellization has been observed within a certain temperature interval where unusually large par

ISSN:0025-116X    

DOI:10.1002/macp.1983.021841010

出版商:Hüthig&Wepf Verlag    

年代:1983

数据来源: WILEY