Polymer Bulletin

Ni(II)-α-diimine catalyst [(2,6-i-Pr)2C6H3-DAB(An)]NiBr2 plus methylaluminoxane was successfully used in the homopolymerization of ethylene, 1-hexene, and 1-octene and the copolymerization of ethylene with 1-hexene and 1-octene in n-hexane. The polymerization of 1-octene was conducted in a controlled manner with a narrow molecular weight distribution (M w/M n = 1.2–1.5) and with the weight-average molecular weight increasing linearly with the monomer conversion. The molecular weights, T g, T m, branching degree, and density of the obtained (co)polymers were greatly controlled by ethylene pressure and polymerization temperature. Compared with that of ethylene homopolymer, the branching degree of the copolymers prepared by the copolymerization of ethylene with 1-hexene or 1-octene increased, whereas the molecular weight, density, T m, and catalyst activity decreased. However, compared with those of the homopolymer of 1-hexene or 1-octene, the copolymer density, T m, and catalyst activity increased, whereas the branching degree declined.

Mixed polar-nonpolar urethane networks have been prepared by crosslinking various mixtures of polyisobutylene diols (HO-PIB-OH) and polar polytetrahydrofuran diols (HO-PTHF-OH) with stoichiometric quantities of a triisocyanate. Essentially complete crosslinking was demonstrated by very low (<4%) sol fractions in benzene and THF. The mixed networks were biocompatible and had less tissue response than pure PIB as evaluated by bacterial and histological analysis after 11 weeks of implantation at the following sites: dorsal neck muscle, abdominal cavity and near the abdominal aorta.

Spherical support was produced using melt quenching method. Scanning electron microscopy (SEM) images showed that support particles have a rough surface morphology with small pore sizes. The size of primary particles determined to be about 50 nm. Produced particles were dealcoholated using hot nitrogen flow. In this study, the dealcoholation apparatus was similar to a fluidized bed reactor. It consists of three main zones: heating zone, bed zone, and expansion zone. This apparatus is capable to dealcoholate and elutriate support particles at the same time. Results showed a significant increase in specific pore volume and surface area of support particles during the dealcoholation. According to the obtained results, two mechanisms were proposed to explain effect of the dealcoholation on the morphology of support particles. Three dealcoholated samples of different alcohol contents were used in the catalyst preparation. Results showed that by decrease in alcohol content of support particles, specific surface area, and pore volume of catalysts increased. Moreover, titanium content of final catalysts increased slightly. Polymerization of propylene was carried out using obtained catalysts in slurry phase. An increase in catalyst activity and enhancement of polypropylene powder morphology were observed as the alcohol content of support particles decreased.

We report the improved oscillation frequency of the organic complementary ring oscillators by balancing mobilities of p- and n-type organic field-effect transistors (OFETs) with a functional polymer interfacial layer. By employing poly (methyl methacrylate) (PMMA) as the interfacial layer, the balanced performance of the p- and n-type OFETs was achieved, which resulted in the improved performance of the complementary inverters. With the PMMA interfacial layer, the noise margin was increased from 35 % to 80 % of 1/2 supply voltage, and the maximum gain was 1.5 times higher than the one of the complementary inverter without the interfacial layer. The oscillation frequency of the organic complementary ring oscillators was remarkably improved from 106.7 Hz to 1.4 kHz. The polymer interfacial layer to balance the performance of p- and n-type OFETs is found to be a simple and efficient way to facilitate the operation of the organic complementary ring oscillators.

Polyurethane ionomers with reduced flammability were obtained by incorporating a brominated chain extender (dibromoneophentyl glycol-DBNPG) into the ionomers based on isophoronediisocyanate, polyoxytetramethylene glycol and 2,2-bis(hydroxymethyl)propionic acid. To examine the influence of brominated diol on the characteristics of the synthesized polymers, model polyurethane compounds containing various amounts of brominated and nonbrominated chain extenders (1,4-butanediol and neopenthyl glycol) were prepared, as well. The products were studied by FTIR, DSC and TGA methods. Hydrolytic stability of the ionomers in water was controlled by FTIR; their flammability was examined by oxygen index measurements.

Metal complexes of hybrid copolymers (HC) and amino acid lysine were prepared by complex formation with salts in aqueous (VOSO4·5H2O, Na2MoO4·2H2O, FeCl2·4H2O, CoCl2·6H2O, CuCl2·2H2O) and organic [VO(acac)2 and MoO2Cl2] solutions. The optimal conditions for the formation of complexes between the hybrid copolymers and heavy metal ions were established. The studies carried out by FT-IR spectroscopy and electron paramagnetic resonance proved the formation of metal complexes. The one of their possible applications as catalysts for the oxidation of cyclohexene with organic hydroperoxides was shown. Good results from epoxidation were obtained using metal complexes with VO2+ and MoO2 2+. The activities of the complexes obtained toward cyclohexene epoxidation can be arranged in order: HC-MoO2 2+ > HC-VO2+. It was found out that only cyclohexene oxide is selectively obtained in this reaction. The contents of cyclohexene oxide and 2-cyclohexene-1-ol reached 38.5 and 10.4 %, respectively. In the future, new approaches should be sought for the preparation of polymer carriers with suitable amphiphilic properties.

POE-graft-methyl methacrylate and acrylonitrile (POE-g-MAN) was prepared by suspension graft copolymerization of methyl methacrylate (MMA) and acrylonitrile (AN) onto polyethylene-octene copolymers (POE). POE-g-MAN/SAN resin blends (AOMS) were prepared by blending POE-g-MAN with styrene-acrylonitrile copolymer (SAN resin). The effects of reaction conditions on the graft copolymerization and the toughening effect of POE-g-MAN on SAN resin were discussed. The results showed that the optimized reaction conditions were AN/(MMA + AN) ratio of 15 wt%, POE/(POE + MM − AN) ratio of 60 wt%, BPO/(POE + MMA − AN) ratio of 1 wt%, toluene dosage of 44.4 wt%, PVA dosage of 0.4 wt%, SDS dosage of 0.07 wt%, aqueous phase/oil phase mass ratio of 1.5, at 80 °C for 20 h, and when the POE/AOMS mass ratio was 25 wt% under the optimized reaction conditions, the notched Izod impact strength of AOMS reached 54.0 kJ/m2. Fourier transform infrared spectroscopy provided substantial evidence of grafting of MMA and AN onto POE chains, and differential scanning calorimetry showed that the graft branches affected the crystallization of POE chains and made the melt temperature and the fusion heat be lower. Transmission electron microscopy analysis showed that the highest toughness occured when the size of POE-g-MAN particles and the surface to surface interparticle distance were proper. Scanning electron microscopy analysis indicated that the AOMS fracture surface had plastic flow visible which looked like a fibril morphology when POE content was 25 wt% with the AN/(MMA + AN) ratio (f AN) of POE-g-MAN of 15 wt%. The toughening mechanism of AOMS was shear yielding of matrix, which endowed AOMS with remarkable toughness. Dynamic mechanical thermal analysis showed that the compatibility of the POE phase and SAN phase improved after graft copolymerization of MMA and AN onto POE.