Volume 47 Issue 7, July 2015

We report a formal aryne/ethylene copolymerization using [2.2.1]oxabicyclic alkenes as aryne equivalents. A palladium-catalyzed copolymerization of [2.2.1]oxabicyclic alkenes with ethylene followed by acid-promoted dehydration produced novel aryne/ethylene copolymers. The use of a bulky phosphine–sulfonate ligand was essential to obtain the desired copolymers with high molecular weight. The present study provides a useful method for the introduction of o-arylene units into the main chains of polyethylene.

The melt memory of isotactic polystyrene spherulites from the melt is investigated using optical microscopy. When the melting–recrystallization processes are repeated by raising and lowering the temperature after the reset of the melt and the subsequent seeding process, the number of the spherulites is found to decrease with the cumulative melting time. The spherulites appear at the same positions as the original ones, and the higher the melt temperature is, the faster their number decreases. At the initial stage, the number density of spherulites rapidly decreases with the cumulative melting time. After the initial stage, the number density of spherulites exponentially decays with the cumulative melting time and approaches a finite value. This asymptotic value decreases with the melt temperature.

The intrinsic viscosity [η] of the Kratky–Porod (KP) wormlike rings is evaluated by Monte Carlo simulations. The behavior of the ratio of [η] of the rings of the trivial knot ([η]_t.k.) to that of the rings without the topological constraint ([η]_mix) is examined as a function of the reduced contour length λL, where λ⁻¹ is the stiffness parameter of the KP ring and L is the total contour length.

The crystallization behavior of the ethylene, propylene and carbon monoxide/thermoplastic elastomer (EPCO/HY) blends in the static and dynamic states revealed that immiscible HY retarded the crystallization of EPCO without changing its crystal structure. The large difference in the elastic moduli of the two polymers at the crystallization temperature was the principal reason for the retardation process. The retardation of crystallization could be explained by steric hindrance or a shield effect of the HY phase on the growth of EPCO spherulites at a temperature near the crystallization temperature (T_c).

Periodic lamellar nanostructures have been created in polymer blend thin films composed of poly(L-lactide) (PLLA) and poly(vinyl phenol) (PVPh) via directional solidification and epitaxial crystallization. The obtained morphology was strongly dependent on annealing condition and blending ratio. These processing parameters closely correlate to the strength of the hydrogen bonding between PLLA and PVPh, hence it was highlighted that the noncovalent interaction between polymers affects the pattern formation.

Poly(lactic acid) (PLA) with titanium oxide (TiO_x) composite films were successfully prepared using a simple sol–gel method. Once TiO_x was incorporated into the PLA surface, initial cell adhesion and proliferation on the scaffolds were enhanced due to the high biocompatibility of TiO_x derivatives.

We developed the donor–acceptor (D-A) type π-conjugated polymers including the 1,3,4-thiadiazole unit (TDz) with dodecyl side chains for the polymer solar cell application (PSC). The PSC using TDz polymers showed high open-circuit voltage up to 0.965 V based on the deep highest occupied molecular orbital energy levels in the range −5.50 to −5.20 eV. Especially, the D-A polymer with the thienylene vinylene unit yielded the highest J_sc and power conversion efficiency of 0.529% among all the polymers.

The flexible and electroconducting composite films were prepared from poly(3,4-ethylenedioxythiophene) poly(4-styrenesulfonate) (PEDOT-PSS) and xylitol, although the PEDOT-PSS films themselves were stiff and brittle. The thermoelectric properties of the composite films were measured and found to be improved in electroconductivity by application of the stretching technique to the composite films owing to improving the polymer chain alignment, and in addition by treatment of the composite films with DMSO (N,N-dimethyl sulfoxide) and/or water owing to losing the excess insulating PSS.