Functional metal-porphyrazine derivatives and their polymers, 12. Synthesis and properties of polyimides containing a metalphthalocyanine ring and a pyridyl group

A novel class of polyimides ( 6a – c ) containing Mt(II)-phthalocyanine rings was synthesized by solution condensation in N-methyl-2-pyrrolidone of Mt(II)-[2,9, or 10(or 2,16, or 17)bis(3,4-dicarboxybenzoyl)]phthalocyanine dianhydride [Mt(II)-dahPc: Mt(II) = Co(II), Ni(II), and Cu(II)] with 2,6-diaminopyridine, followed by thermal imidation. The polyimides showed room temperature dc-conductivities in the range of 10^?12 ? 10^?9 Ω^?1 · cm^?1, and, after quaternization of the pyridine group, the conductivities increased by 1 to 3 orders of magnitude.     

Synthesis and properties of aromatic polypyrazoles from bis(β-substituted vinyl ketones) and aromatic dihydrazines

Polycyclocondensations of aromatic dihydrazines 2a and 2b with 1,6-diethoxy-1,5-hexadiene-3,4-dione ( 1a ) in m-cresol and those with bis(3-chloroacryloyl)benzenes 1b and 1c in 1-methyl-2-pyrrolidone (NMP) lead to aromatic polypyrazoles 3a – f having inherent viscosities up to 0,35 dl.g^?1. The polymers are soluble in polar aprotic solvents like NMP and some acidic media including m-cresol. Thermogravimetry shows a loss of 10 wt.-% at ≈ 500°C both in air and nitrogen.     

Photo-oxidative degradation and stabilization of isotactic poly(1-butene) in solid state, 1

The kinetics of photo-oxidative degradation and stabilization of poly(1-butene), [poly(1-ethylethylene), PB-1] at 253, 7 nm and a constant intensity of 2,38·10^?9 Einstein.s^?1·cm^?2 (1,12·10^?3 J·mol^?1·s^?1·cm^?2) was studied in the absence and presence of 0,1 wt.-% 6-(2-hydroxyphenyl)-2,4-diphenyl-1,3,5-triazine ( 1 ) dispersed evenly in the matrix of polymer films in the temperature range of 267 to 313 K. The progress of the reaction was followed by measuring the rate of chain scission of the polymer. It has been confirmed by light scattering and potassium ferrioxalate actinometric measurements that random scission of the polymer chain occurs and 1 acts as a stabilizer to the photo-oxidative degradation processes. Irrespective of the variations in the values of ΔH^≠ and ΔS^≠ the values of ΔF^≠ remain almost constant around 159 kJ·mol^?1 indicating that the rate determining step is the same for both systems.     

Cationic polymerization of α-pinene with aluminium-based binary catalysts, 3. Effects of added base

In the presence of nucleophilic additives such as esters (ethyl benzoate, acetate, and chloroacetate), ethers (diethyl ether and 1,4-dioxane), and ammonium salts (nBu₄NCl), oligomers of α-pinene with relatively high molecular weights (M?_n ≥ 1000) were obtained with the AlCl₃/SbCl₃ binary catalyst in toluene at 0°C ([AlCl₃]₀ = 42,5 mmol · L^?1, Sb/Al = 0,50, [additive]₀ = 10,6 mmol · L^?1). The yield was 80–90 wt.-%, and the dimer content was as low as 6 wt.-%. Also in the polymerization at 25°C, the addition of ethyl benzoate increased the oligomer's average molecular weight (M?_n = 850) and decreased the dimer content (10 wt.-%), in contrast to the low M?_n (350) and the high dimer content (40 wt.-%) in the absence of the additive. The oligomers obtained in the presence of ethyl benzoate contained the repeating unit 1 which has an endo-olefin group, at higher ratio than in the absence of the additive. Phenomenologically, the role of the additives is to retard the polymerization so as to proceed at a moderate rate even at high temperature above 0°C and thereby to suppress the dimer formation.     

Functional metal-porphyrazine derivatives and their polymers, 2. Synthesis and properties of polyimides containing metal-phthalocyanines

A novel class of polyimides (14) containing Mt(II)-phthalocyanine rings has been synthesized by the solution condensation in N-methyl-2-pyrrolidone (NMP) of Mt(II)-[2,9or10(or2, 16or17)bis(3,4-dicarboxybenzoyl)]phthalocyanine dianhydride (Mt(II)-dahPc; Mt(II)=Co(II), Ni(II) and Cu(II); (2–4) ) with aromatic diamines such as 4,4′-methylenebis(aniline), followed by thermal imidization in vacuo at 200°C. The polyamides obtained were soluble in NMP and hexamethylphosphoric triamide, having inherent viscosities up to 0,7 dl·g^?1. The polyimides were stable up to 350°C, and showed room temperature-dc-resistivities in the range of 10¹¹ to 10⁶ Ω·cm.     

Ionic conduction of cross-linkable oligo(oxyethylene)-branched poly(phosphazene)

A new cross-linkable polyphosphazene [AEP7] in which allyl groups were introduced at the ends of the etheric side chains of the polymer was prepared. The LiClO₄/AEP7 hybrids showed relatively high ionic conductivity of 7,9·10^?5 S·cm^?1 at 25°C with 6 wt.-% of LiClO₄. The ionic conductivity of the hybrids remained unchanged before and after cross-linking by UV-irradiation. The dimensional stability or the mechanical strength of the hybrids was improved upon cross-linking. Additionally, the cross-linked AEP7(29)/propylene carbonate (PC)(60)/LiClO₄(11) (wt.-%) hybrids, in which PC was used as a plasticizer, showed an ionic conductivity as high as 3,1·10^?3 S·cm^?1 at 25°C.     

Autoxidation reactions of polystyrene derivatives

p-Isopropylstyrene was homopolymerized or copolymerized with styrene using AIBN as initiator in benzene at 50°C. The resulting polymers were easily oxidized by oxygen to produce polymers having hydroperoxy groups. The oxidized polymer was found to have considerably different solubility from the original polymer. Kinetic evaluation of the oxidation reactions of poly(p-isopropylstyrene) showed that the tertiary hydrogen of the isopropyl group present at the pendant aromatic ring was more susceptible to the oxidation reaction than the main chain methine hydrogen. The rate constants of these two oxidation reactions were found to be 4,0 · 10^?4 mol^?1/2 · l^1/2 · s^{Autoxidation reactions of polystyrene derivatives1/2} and 2,5 · 10^?4 mol^?1/2 · l^1/2 · s^?1/2, respectively. These values were much smaller than that for the tertiary hydrogen atom of the isopropyl group of cumene (3,21 · 10^?3 mol^?1/2 · l^1/2 · s^?1/2, at 68°C), a low molecular weight model compound.     

Mixed (electronic and ionic) conductive solid polymer matrix, 1. Synthesis and properties of poly(2,5,8,11,14,17,20,23-octaoxapentacosyl methacrylate)-block-poly(4-vinylpyridine)

Poly(2,5,8,11,14,17,20,23-octaoxapentacosyl methacrylate)-block-poly(4-vinylpyridine) semicomb polymers were synthesized using anionic living polymerization techniques. The polymers are white, powdery materials and were characterized by ¹H and ¹³C nuclear magnetic resonance spectroscopy and gel-permeation chromatography. The polymers display monomodal molecular weight distributions which are relatively narrow. The block copolymers show microphase separation as indicated by the presence of two glass transition temperatures (T_g), a soft (oxyethylene) phase T_g is observed between ?60°C and ?45°C and a hard (4-vinylpyridine) phase T_g is observed between 135°C and 150°C. The soft oxyethylene phase has been doped with LiClO₄ to obtain ionic conductors with electrical conductivities around 5 · 10^?6 S · cm^?1 at 25°C and the hard 4-vinylpyridine phase has been complexed with 7,7,8,8-tetracyano-1,4-quinodimethane (TCNQ, 2,5-cyclohexadiene-1,4-diylidenedimalonitrile) to obtain electronic conductivities around 10^?6 S · cm^?1 at 25°C. The mixed (electronic and ionic) conductivities are intermediate between the ionic and electronic conductivities. Higher electronic conductivities (≈ 10^?5 S · cm^?1 at 30°C) are obtained for the polycation TCNQ^?/TCNQ⁰ complexes.     

Synthesis of high-molecular-weight poly(L-lactide) initiated with tin 2-ethylhexanoate

The bulk polymerization of L ,L -dilactide was studied as a function of polymerization temperature (T_p), time and concentration of catalyst (tin 2-ethylhexanoate). Poly(L -lactide) (PLLA), with the highest value of intrinsic viscosity ([η] = 13 dl · g^?1; M?_v ≈ 1 · 10⁶) and heat of fusion (ΔH_m = 64,7 J · g^?1), was synthesized at a low catalyst concentration (0,015 wt.-%) and at the lowest T_p studied (100°C), just above the melting point of L ,L -dilactide (98°C). The ceiling temperature of PLLA was found to be 275°C, as deduced from an M?_{v max.} ? T_p curve. The M?_w/M?_n ratios of as-polymerized PLLA samples ranged from 2 to 3. Fractions of PLLA with M?_{v max.} were already present at 50% conversion. The experimental results support a proposed nonionic insertion polymerization mechanism. Polymerization at 100–140°C resulted in early crystallization of PLLA leading to a rather untangled polymer and microporous (pores up to 100 nm) sample texture.     

Antibacterial and Hemolytic Activities of Quaternary Pyridinium Functionalized Polynorbornenes

In this study, amphiphilic polyoxanorbornene with different quaternary alkyl pyridinium side chains were synthesized. The biological efficiencies of these polymers, with various alkyl substituents, were determined by bacterial growth inhibition assays and hemolytic activity (HC₅₀) against human red blood cells (RBCs) to provide selectivity of these polymers for bacterial over mammalian cells. A series of polymers with different alkyl substituents (ethyl, butyl, hexyl, octyl, decyl and phenylethyl) and two different molecular weights (3 and 10 kDa) were prepared. The impact of alkyl chain length divided the biological activity into two different cases: those with an alkyl substituent containing four or fewer carbons had a minimum inhibitory concentration (MIC) of 200 µg · mL^?1 and a HC₅₀ greater than 1 650 µg · mL^?1, while those with six or more carbons had lower MICs ≤ 12.5 µg · mL^?1 and HC₅₀ ≤ 250 µg · mL^?1. Using MSI‐78, the potent Magainin derivative which has an MIC = 12.0 µg · mL^?1 and HC₅₀ = 120 µg · mL^?1, as a comparison, the polymers with alkyl substituents ≤C₄ (four carbons) were not very potent, but did show selectivity values greater than or equal to MSI‐78. In contrast, those with alkyl substituents ≥C₆ were as potent, or more potent, than MSI‐78 and in three specific cases demonstrated selectivity values similar to, or better than, MSI‐78. To understand if these polymers were membrane active, polymer induced lipid membrane disruption activities were evaluated by dye leakage experiments. Lipid composition and polymer hydrophobicity were found to be important factors for dye release.

     

Expression,purification, and characterization of a novel laccase from Setosphaeria turcica in Eschericha coli

Laccases are multicopper oxidases (E.C. 1.10.3.2) that catalyze the oxidation of many phenolic compounds. In this study, a novel laccase, Stlac4, from Setosphaeria turcica was cloned and expressed in Escherichia coli by insertion into the pET‐30a expression plasmid. The recombinant laccase was purified and visualized on SDS–PAGE as a single band with an apparent molecular weight of 71.5 KDa, and confirmed by Western blot. The maximum activity of the purified laccase was 127.78 U · mg^?1, the optimum temperature and pH value were 60 °C and 4.0 respectively, measured by oxidation of 2,2′‐Azinobis‐(3‐ethylbenzthiazoline‐6‐sulphonate) (ABTS). Purified laccase activity under different metal ions and an inhibitor were tested, revealing that laccase activity increased by approximately 434.8% with Fe³⁺, and 217.4% with Cu²⁺ at 10 mmol · L^?1 concentrations, Mn²⁺ increased the laccase activity only at 5 mmol · L^?1, while Na⁺ increased activity at 1 mmol · L^?1 but inhibited activity at 5 and 10 mmol · L^?1. SDS increased laccase activity at 1 mmol · L^?1, and inhibited activity at 5 and 10 mmol · L^?1.     

Polyurethanes containing binaphthyl groups

Polyurethanes containing binaphthyl groups were synthesized by reaction of diisocyanates – 4,4'-diphenylmethane diisocyanate (MDI), 2,4-toluylene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) – with 2,2'-(1,1'-binaphthyl-4,4'-ylenedioxy)diethanol ( 3 ). The polyurethane obtained from 3 with MDI has an intrinsic viscosity [η]⁹⁰_DMSO^90°C of 0,14 dl · g⁻¹ and a melting point of 244 – 260°C, that from 3 with TDI has an [η]^90°C_DMSO of 0,12 dl · g⁻¹ and a melting point of 181 – 191°C, and that from 3 with HDI has an [η]^90°C_DMSO of 0,11 dl · g⁻¹ and a melting point of 222 – 241°C. These polymers were found to be crystalline. Segmented polyurethanes (SPU) from 3 with prepolymers of poly(tetramethylene glycol) (PTG), (M = 1079) and MDI or HDI (mole ratio PTG:MDI (or HDI) = 1:2) were also synthesized. The SPU from MDI has an intrinsic viscosity [η]^90°C_DMSO of 0,56 dl · g⁻¹ and a melting point of 260–275°C, and that from HDI has an [η]^90°C_DMSO of 0,50 dl · g⁻¹ and a melting point of 231 – 253°C. These polymers show slight crystallinity.     

Behaviour of ring-shaped polymers in dilute solution. Quantitative calculation and experimental verification for molecular dimensions and second virial coefficient

Relationships between the ratios of the mean-square radii of gyration g_s and the second virial coefficients g_A2 of ring-shaped and linear polymers with the degree of polymerization P of the polymer and its Peterlin exponent ε in dilute solution were derived theoretically and numerical values calculated. The second virial coefficients of ring-shaped and of linear polystyrene at 25°C in toluene were determined using light scattering. By verifying the theoretical calculation based on the experimental determination of this polymer-solvent system with light scattering and other methods reported in the literature, the agreement between theoretical calculation and experimental results is shown. The correlation equations for linear (l) and ring-shaped (r) polystyrene in toluene at 25°C A_{2, 1} = 8,06 · 10^?3 · M^0,224 and A_2,r = 6,68 · 10^?3 · M^0,218 were obtained using light scattering.     

Preparation of polyimide/polydimethylsiloxane graft copolymer and its permeabilities for gases and liquids

Polyimide/polydimethylsiloxane (PI/PDMS) graft copolymers with various PDMS contents were prepared by polycondensation of PDMS macromonomer 1 with aromatic diamines and pyromellitic dianhydride followed by heating at 220°C. The PDMS content of the grafts copolymers was controlled by changing the average degree of polymerization of the PDMS macromonomer in the range between 4 and 21. Graft copolymer membranes were prepared by casting films in the poly(amic acid) stage 2 and subsequent imidation upon heating. PI/PDMS membranes thus obtained are insoluble. The permeability coefficients towards nitrogen, oxygen, hydrogen, methane and carbon dioxide were evaluated. In the region of a PDMS content above 50 wt.-%, the oxygen permeability coefficient of a PI/PDMS graft copolymer membrane is > 10^?8 cm³(STP) · cm · cm^?2 · s^?1 · cmHg^?1. In addition, the permeability coefficient of methane is remarkably enhanced in comparison with a PI membrane. Preferential permeation of ethanol was observed through the graft copolymer membrane in the case of pervaporation of aqueous ethanol solution. Furthermore, acetone, acetonitrile and tetrahydrofuran were efficiently separated from water at any solvent/water ratio in the mixture.     

Synthesis and characterization of metal containing polychloranilamides

2,5-Diamino-3,6-dichloro-1,4-benzoquinone (chloranilamide) condensates, under generation of HCl, above 300°C to form polychloranilamide. The reaction was studied by thermovolumetric measurements, especially in the presence of different metal salts (cobalt, iron and manganese). The composition of the brittle black polymers is as expected, and the IR spectra resemble to those of the corresponding model compounds based on 5,8-dihydroxyquinoxaline. Their electrical conductivity is 10^?8 – 10^?5 S · cm^?1. Metal contents of up to 25 wt.-% were achieved corresponding to 80% of the theoretical value. The metal complexes are not stable against acids, and the compounds are not very resistant in a strongly alkaline milieu. Nevertheless, they could be promising, e.g., as ion exchangers, as precursors for organic materials with high metal contents such as catalysts, or as model compounds for similar polymers.     

Effect of circulatory occlusion on human muscle metabolism during exercise and recovery

To assess muscle metabolism and inorganic phosphate (P_i) peak splitting during exercise, 31-phosphorus nuclear magnetic resonance spectroscopy was performed during ramp incremental and submaximal step exercise with and without circulatory occlusion. Seven healthy men performed calf flexion in a superconducting magnet. There was no P_i splitting during ramp incremental exercise with the circulation present and phosphocreatine (PCr) decreased linearly by 0.07 (SEM 0.01) mmol?·?l^?1?·?s^?1, while exercise with the circulation occluded caused the P_i peak to split into a high and a low pH peak. The rate of PCr decrease during exercise with the circulation occluded was 0.15 (SEM 0.03) mmol?·?l^?1?·?s^?1 which with the efficiency of the adenosine 5′-triphosphate (ATP) hydrolysis reaction corresponded well to the mechanical energy. Both with and without occlusion of the circulation PCr decreased with some time lag which may reflect the consumption of residual oxygen. In submaximal step exercise PCr decreased exponentially at the onset of exercise with the circulation open whereas it decreased linearly by 0.15?mmol?·?l^?1?·?s^?1 when the circulation was occluded. After exercise, occlusion of the circulation was maintained for 1 min more and there was no PCr resynthesis. It is suggested that ATP synthesis was limited by the availability of oxygen.     

The propagation rate-constants for the cationic polymerisation of acenaphthylene and styrene in nitrobenzene

Rate measurements of the polymerisation of acenaphthylene in nitrobenzene at 298 K by PhCO⁺ SbF₆^? gave k_p⁺ = 23,2 ± 2 dm³ · mol^?1 · s^?1 which confirmed our previous value with yet another initiator. Under the same conditions we obtained k_p⁺ = 188 ± 9 dm³ · mol^?1 · s^?1 for styrene. The completeness of initiation was indicated by a count of carbonyl groups by spectroscopy. The conductivity measurements indicated that [P_n⁺] is independent of time and that there is no ion-pairing. The DPD of the polymers was unimodal and the DP independent of m₀ and c₀. Exploratory experiments showed that HClO₄ and CF₃SO₃H in nitrobenzene are not useful for k_p⁺ determinations. In an Appendix a detailed treatment is given of how the impurity content of solvent and monomer can be determined by kinetic measurements.     

Role of bulky α-substituent in free-radical polymerization and copolymerization of methyl α-(alkoxymethyl)acrylates

Methyl α-(alkoxymethyl)acrylates were prepared from methyl α-(bromomethyl)acrylate in 80–90% yield. The monomers homopolymerize fast to yield low-molecular-weight polymers. The monomers bearing a linear alkoxymethyl group except for the ethoxymethyl group are characterized by a relatively low ceiling temperature. The rate constants for propagation k_p and termination k_t of methyl α-(butoxymethyl)acrylate were evaluated to be k_p = 298 dm³ · mol^?1 · s^?1 and k_t = 8 · 10⁶ dm³ · mol^?1 · s^?1 at 60°C, respectively. The α-(alkoxymethyl)acrylates are more reactive than methyl methacrylate toward polystyrene radical, except for the α-(dodecyloxymethyl)acrylate which is slightly less reactive, indicating that an increase in the reactivity by the electron-withdrawing character of the alkoxy group prevails over the steric hindrance against addition of the polymer radical, except for the large dodecyloxymethyl group.     

The structure and time evolution of a cellulose sheet in the nascent fibril produced by acetobacter xylinum

Structure and time evolution of a nascent cellulose sheet, produced by Acetobacter xylinum, were examined regarding the resistance of the nascent fibrils to alkali. It became clear that the never-air-dried cellulose, obtained after an incubation period of 5 min, changes its morphology after an alkali treatment at very low concentrations (ranging from 1,0 · 10^?3 to 1,0 · 10^?2 wt.-%). It is subsequently transformed into cellulose II. On the other hand, although the fibril after an incubation period of 30 min seems to be in a stainable state toward sodium tungstophosphate when it was treated with 4,6 wt.-% alkali, 70–80% of it maintains the fibrous shape. Electron diffraction experiments, involving the fibrils, indicate a cellulose I structure. Even when the sample after an incubation period of 30 min was treated with 9,6 wt.-% alkali, about 30% of it still maintains the fibrous shape. Electron diffraction experiments, involving the fibrils, also indicate a cellulose I structure. The shape of a cellulose sheet, just after its extrusion from a cell, seems to be maintained by hydrophobic bonds. The enhancement of the resistance of cellulose toward alkali with time must be due to the development of inter-and intramolecular hydrogen bonds in each cellulose sheet.     

Influence of chemical structure on glass transition temperatures of poly(propylene terephthalate) and poly(propylene isophthalate)

Poly(propylene terephthalate)

1 Systematic IUPAC name: poly(oxypropyleneoxyterephthaloyl).

(PPTP) and poly(propylene isophthalate)

2 Systematic IUPAC name: poly(oxypropyleneoxyisophthaloyl).

(PPIP) were prepared by melt polycondensation. Different fractions with number-average molar masses in the range 5 000 ? 20 000 g·mol^?1 were obtained and their respective glass transition temperatures (T_g) determined by calorimetry. The solubility parameters of the polymers were obtained by viscosity measurements in different solvents and were found to be 9,4 and 9,5 cal^1/2·cm^?3/2 (19,2·10³ and 19,4·10³ J^1/2·m^?3/2) for PPIP and PPTP, respectively. The glass transition temperatures were compared with those reported for analogous polyesters and it was shown that intramolecular interactions highly influence the T_g of these polyesters, whereas the effect of intermolecular interactions seems to be less important.