Volume 45 Issue 4, April 2013

The lipophilic triazole ligand 1 (C₁₂OC₃Trz) has been designed such that an ether linkage exists in the alkyl chain moiety. This flexible ether linkage enhances the solubility of various complexes of this ligand (including [Co^II(1)₃]Cl₂ and [Fe^II(1)₃]Cl₂) in organic media and also improves the packing efficiency of the alkyl chains. Such lipophilic modifications of 1D coordination systems can result in dynamic structural transformations leading to unique solution properties, including heat-set gel-like networks, guest-induced structural changes, electrochemical transformations and spin crossover state switching.

Vapor phase polymerization of polyterthiophene using iron (III) para-toluenesulfonate showed c.a. 2.3 times the expected yield of polyterthiophene based on the amount of iron (III). This is explained through a mechanism where part of the para-toluenesulfonate is gradually converted to SO₃ and toluene, and that the reduction of SO₃ is driving the oxidation of the additional terthiophene. This finding opens a possible polymerization route for conducting polymers where the oxidant is leaving no trace in the end product.

Poly(carbazole-3,6-diyl-alt-9,9-dihexylfluorene-2,7-diyl)s bearing the functional groups such as imine, 1,3-oxazoline and pyridine at the 1,8-positions of the carbazole unit were synthesized by the Suzuki coupling polymerization to examine the structure–properties relationship. The formation of an intramolecular hydrogen bonding between the carbazole NH proton and the functional group influenced the UV–Vis and PL spectra, and generally decreased the fluorescence quantum yield. The chelate coordination of metal ions also had an impact on the optical properties.

Nanosized palladium species, which were prepared in situ from Pd(OAc)₂, PPh₃ and Bu₄NOAc in 1,4-dioxane, were suitable for the synthesis of 1,1′-binaphthyl-2,2′-dioxy-bearing aromatic poly(ether ketone)s. The resulting poly(ether ketone)s are soluble in typical organic solvents, such as CHCl₃, tetrahydrofuran and dimethylformamide. Glass transition temperatures (T_g′s) of the poly(ether ketone)s are high in the range of 188–224 °C. Temperatures where 10% weight losses of the poly(ether ketone)s occur under N₂ flow are in the range of 445–480 °C

Random copolymer of poly(lactic acid-co-glycidyl methacrylate), P(LLA-co-GMA) was systematically synthesized by ring-opening polymerization. Synthesis parameters, that is, catalyst type, comonomer ratio and polymerization time and temperature were studied. The incorporated GMA content strongly affected physical and thermal properties of the obtained copolymers, which varied from semi-crystalline to completely amorphous polymer. Curing behaviors of the copolymers were assessed by employing thermo- and photo-crosslinking processes, where the crosslink density was evaluated via their gel content and solvent swelling ratio.

Curing studies and reaction mechanism of MF resin was studied by thermal and spectroscopic tools comparing DSC and FTIR studies explains the two-stage thermal curing mechanism. The first step of thermal curing at temperature range of 140–160 °C is the reverse reaction of methylol groups to melamine and second step occurring at temperature >160 °C is the crosslinking of methylol groups to the final product, methylene bridge. Hence, by the mutual agreement of DSC and FTIR studies, a possible reaction route was derived for the thermal curing process. The DSC–TGA thermogram supports the two-step process of the cure reaction by exhibiting two peaks in the same temperature region.

Poly(ɛ-caprolactone)₂-b-poly(L-lactide)₂ miktoarm block copolymers were successfully synthesized via ring-opening polymerization with protection–deprotection procedure, using pentaerythritol as initiator. The degradation behavior of (PCL)₂-b-(PLLA)₂ microspheres, which were produced by oil-in-water emulsion solvent extraction/evaporation method, showed that the degradation occurred from the surface to the interior as a combined degradation model with surface erosion and bulk degradation.

The stereo diblock (d-sb-PLA: PDLA-PLLA) and triblock (t-sb-PLA: PDLA-PLLA-PDLA) were synthesized by terminal Diels-Alder coupling of anthracene-terminated PLLA and maleimide-terminated PDLA. The d-sb-PLA and t-sb-PLA were found to form the stereocomplex crystals of PLLA and PDLA showing excellent thermo-mechanical properties.

We investigated the crystallization behavior and crystal orientation of poly(ɛ-caprolactone) (PCL) blocks confined in the polyethylene (PE) lamellar morphology of PCL-block-PE (PCL-b-PE) with different PE crystallinities χ_PE and PCL layer thicknesses d_PCL. We found that the crystallization behavior of PCL blocks in PCL-b-PE with higher χ_PE and smaller d_PCL was different from that in other PCL-b-PE copolymers. In addition, the orientation of PCL crystals significantly changed with changing crystallization temperature in PCL-b-PE with higher χ_PE and smaller d_PCL, whereas it did not change in PCL-b-PE with lower χ_PE or larger d_PCL.

We performed molecular dynamics simulation of liquid-crystalline epoxy resin. For the simulation, one molecule is modeled as a diamine ends of which are connected to derivatives of diepoxy mesogens. Molecular ends were drawn by external force in order to generate well-aligned initial structure. After removing the external force, equilibrated results expressed an even–odd effect for number of methylene units of mesogenic structures. Finally we propose a recipe to use the present simulation for a screening to obtain epoxy molecules of higher thermal conductivity.

We investigated the effect of carbon fiber (CF) on the capillary flow behavior of high-density polyethylene (PE). The presence of CF was found to have much great effect on reducing of the die swell of PE. CF could prevent the helical distortion of PE. The helical distortion of PE also changed to the sharkskin failure by adding CF. The extrusion behavior can be controlled by the addition of a small amount of CF.

Triblock copolymers comprising multifunctional poly(oxyethylene) (PEO) central block with various regularly distributed side functionalities and poly(D,L-lactide) outer blocks were synthesized. In the first step, an acetal-linked, in-chain multifunctional PEO was used as a macroinitiator for the metal-free controlled ring-opening polymerization of D,L-lactide. The amphiphilic biodegradable triblock copolymers provide a platform for further multifunctionalization through efficient quaternization and ‘click’ reactions. Thus, zwitterionic, fluorophilic, alkyne and alkyl pendant functionalities were introduced into the central PEO-block.

Chemical oxidative polymerization (COP) of 3-hexylthiophene in polar solvents, such as CH₃CN and CH₂Cl₂, smoothly proceeded at temperatures below 0 °C to afford regio-controlled poly(3-hexylthiophene-2,5-diyl) (P3HexTh) with a head-to-tail (HT) content of higher than 80%. Use of CH₃CN at −40 °C gave P3HexTh with 83% HT content, M_n (number-average molecular weight) of 42 000, and a relatively narrow polydispersity of 1.6. Obtained P3HexTh formed an ordered structure in solid, and NOBF₄-treated film of P3HexTh with the HT content of 83% showed electrical conductivity of 3.0 S cm⁻¹.