Volume 45 Issue 10, October 2013

Dilithium diamides of Me₃Si- and i-Pr₃Si-protection were examined as difunctional initiators for polymerization of methyl methacrylate (MMA) in toluene in combination with tributylaluminum. The less sterically demanding Me₃Si-derivative underwent 1,2-addition (carbonyl addition) in the initial stage of polymerization to form type B poly(MMA) (PMMA) as a minor component (26%). The i-Pr₃Si-derivative gave type A PMMA exclusively with the 1,3-xylylenediamine unit in the middle of the chain. H₂/Pd-C-mediated cleavage of the diamine unit yielded PMMA with a half molar mass and narrow molar-mass distribution.

Simultaneous time-dependent measurements of WAXSD, SAXS and Fourier-transform infrared (FTIR) spectra have been performed to study the structural changes in the melt- and cold-crystallization processes of trans-1,4-polyisoprene (TPI). In the melt-isothermal crystallization process, the domains of relatively higher density were formed at first as the intermediate state, which approached each other to form the stacked lamellar structure. In the cold-crystallization process from melt-quenched glass, TPI crystallized to the β-form at −55 °C, which transformed to the α-form at 50 °C via the amorphous phase.

Rubber materials are often used in fluid sealing. Molecular mobility of rubber is one of the important parameter for designing suitable material for rubber seals. Pulsed proton nuclear magnetic resonance (¹H-NMR) results showed that crude acrylonitrile–butadiene rubber has two components with long and short spin–spin relaxation time assigned to the altenatively copolymerized acrylonitrile–butadiene and butadiene block sequences, respectively. We conclude that these components with different mobilities in crude rubber originated from a inhomogeneity in the first-order structure of molecular chains.

We found that the quenched poly(vinylidene fluoride) (PVDF) film in ice-water became transparent by cold-drawing, whereas PVDF that was slowly cooled on a hot plate became opaque. The transmittance of the quenched PVDF measured by ultraviolet–visible spectroscopy increased by up to 30% in the lower wavelength range (200–600 nm), which increased the transparency. The decrease in the density difference between the lamellar crystal and the lamellar amorphous phases might increase the transmittance of the quenched PVDF in the lower wavelength range.

High ordered structure, thermal property and surface wettability of a novel alternated copolymer of vinylidene cyanide and perfluorooctyl ethyl vinyl ether were investigated with wide-angle X-ray diffraction, differential scanning calorimetry, X-ray photoelectron spectroscopy and contact angle measurement. The alternated copolymer showed a smectic liquid crystalline structure and extremely high isotropization temperature of 150 °C, compared with 29.5 °C for the perfluorooctyl ethyl vinyl ether homopolymer. The alternated copolymer also showed large contact angle hysteresis, indicating that surface reorganization of the polar cyano and ether groups occur.

The existence of intramolecular CH/π interaction of four soluble polyfluorenes (PFs) and molecular di-n-octylfluorene in chloroform-d₁ at 20 °C was first revealed by cross-peaks of the ring with several protons of alkyl groups in ¹H–¹H NOESY NMR and marked upfield shift of several alkyl proton signals in ¹H-NMR spectra. Only the PF bearing β-branched chiral groups at 9,9-positions among three chiral PFs in chloroform at 20 °C showed intense circular dichroism bands in the π−π* region because of the intramolecular CH/π interaction. Conflex7 and Gaussian 03 MP2 calculation results supported this idea.

Polymeric pseudo-liquid membrane (PPLM) was constructed from poly(dodecyl methacrylate), which showed rubbery state under membrane transport conditions, as a membrane matrix and dibenzo-18-crown-6 or O-allyl-N-(9-anthracenylmethyl)cinchonidinium bromide as a model transporter. Membrane performance was studied adopting KCl or racemic mixture of phenylglycine as a model substrate. The present results suggest that PPLMs were applicable to not only metal ion transport but also optical resolution.

Biocompatible poly(ɛ-caprolactone) (PCL)/poly((R)-3-hydroxybutyric acid) (PHB)/reduced graphene oxide (RGO) composites with fixed wt% of RGO and different wt% of PHB were prepared using in situ ring-opening polymerization technique of ɛ-caprolactone monomer in the presence of RGO and PHB. The honeycomb-patterned films were fabricated by casting the composite solutions under humid conditions. The films exhibit a semiconducting behavior of the composite materials. The presence of PHB component not only slightly increases the conductivity but also accelerate the biodegradability of the PCL matrix.

Three novel conjugated copolymers containing coplanar bithiophenevinyl-(2-pyran-4-ylidenemalononitrile) unit linked with different electron-donating moieties by a double bond were synthesized by Heck polycondensation reactions. By introducing a double bond between the donor and acceptor unit within the backbone of polymers instead of a single bond, the conjugated length was enhanced, and consequently broader absorption spectral range and reduced band gap. Hence, the polymer can absorb more light to get higher Jsc and power-conversion efficiency.

Polyrotaxane (PR)-protected glycine conjugates with different levels of degrees of substitutions (DS) were successfully prepared by varying reaction temperature, reaction times and stoicheometric ratios of AA to −OH in PR. Variation of the stoicheometric ratios enabled the widest control of DS values. Z-protecting groups of pendant glycine were removable only by trifluoroacetic acid/thioanisole system.

Complex polymeric hollow spheres were made easy. We reported a facile one-pot solvothermal synthesis of anisotropic polyazomethine particles using the in-situ formed Pickering emulsion as templates. Taking advantage of the dynamic nature of imine bonding and the inhomogeneous nature of the particles, these anisotropic particles can further hollow into and result in complex anisotropic yolk-shell and anisotropic hollow spheres, which were heretofore rarely reported in polymeric systems.

This is the first report on synthesis of poly(hydroxyalkanoate)s (PHAs) by various deep-sea bacteria (4 types of Colwellia spp., 11 types of Moritella spp., and 18 types of Shewanella spp.) from glucose, fructose, gluconate, or from one of the several plant oils as the sole source of carbon. The overall results provide important and basic information regarding the production of PHAs by deep-sea bacteria and on the diversity of PHA synthase enzymes in nature.

Mesoporous monolith of poly(vinyl alcohol) (PVA) is successfully prepared by thermally impacted non-solvent induced phase separation without any templates. The pore and skeleton sizes can be controlled by changing the cooling temperature as well as the concentration and molecular weight of PVA. The nitrogen adsorption–desorption isotherms show that the PVA monolith has large surface area and uniform mesopore structure. The crosslinking using glutaraldehyde (GA) as crosslinking agent produces the water-insoluble monolith. By changing the concentration of GA, the crosslinked monolith with different swelling ratios toward water is obtained.