Volume 42 Issue 5, May 2010

Polymer reactions of poly(p-phenylene–ethynylene) based on addition reaction of decaborane to the carbon–carbon triple bond were successfully carried out. The platform polymer was synthesized through Sonogashira–Hagihara coupling polymerization. The effective introduction of boron cluster was supported by ¹H and ¹¹B NMR spectroscopies. UV-vis absorption and photoluminescence studies illustrate the shortening of an effective p-conjugation length caused by the introduction of carborane clusters. Furthermore, the introduction of the boron cluster by the polymer reaction efficiently enhanced the heat resistance of poly(p-phenylene–ethynylene).

Poly(ethylene glycol) with a molecular weight of 400 (PEG400) as an environmentally benign and highly viscous polymeric solvent was found to effectively accelerate the free radical polymerization of methyl methacrylate and to afford a high-molecular-weight polymer. The polymerization rate and the polymer molecular weight increase linearly with the square root of the viscosity η of the polymerization media. The kinetic study has shown that the highly viscous PEG400 solvent largely suppresses diffusion-controlled bimolecular termination.

The network aggregates of poly(2,5-benzimidazole) nanofibers were prepared by the polymerization of phenyl 3,4-diaminobenzoate at 350 °C in a mixture of dibenzyltoluene isomers. The average diameter of the fibers was ∼60 nm. These fibers were formed by the crystallization of oligoimidazoles and the subsequent polymerization in them.

The mean square end-to-end distance 〈R²〉 is dependent on the polymer-surface interaction ɛ. It reaches minimum near critical adsorption point (CAP) ɛ_c≈−0.29. The result provides an alternate method to determine ɛ_c.

The second and third virial coefficients (A₂ and A₃, respectively) for benzyl-end polystyrene in toluene at 15 °C are determined by light scattering. The figure shows that A₂ data for benzyl-end (unfilled circles) and butyl-end (filled circles, literature data) polystyrenes can be fitted by the theoretical curves (solid and dashed curves) when the chain-end effect is incorporated into the theory without that effect (dotted curve).

The amorphous phase and crystalline morphology of the poly(vinyl methyl ether) (PVME)/poly(1,6-hexamethylene adipate) (PHA) blend were compared with those of the classical PVME/poly(ɛ-caprolactone) (PCL) system, isomeric to the former. Both blend systems’ amorphous phases are similarly miscible with χ₁₂=−0.2. In contrast, the crystalline phases of these two blends differ significantly. When crystallized at high T_c (46 °C or above), the PVME/PCL (20/80) blend assumes fluffy feather-like dendrites (Graph-a), which are dramatically different from straight-stalk dendrites in the PVME/PHA (20/80) blend (Graph-b).

Novel anionic polymerizable surfactants were prepared by reacting maleic anhydride with different benzyl alcohols. These surfmers were evaluated in the emulsion polymerization of styrene in the presence of potassium persulfate as the initiator. Special attention was focused on the effect of the concentration of surfmers on the polymerization kinetic and the final particle size through polymerization conversion particle size and size distribution determination.

Optically pure and helical poly(quinoxaline-2,3-diyl)s prepared by asymmetric living polymerization of 1,2-diisocyano-3,6-dimethyl-4,5-di(propoxymethyl)ben zene with an optically pure organopalladium initiator were found to take highly ordered and stable monolayer formation at the air/water interface, providing well-defined multilayer structures with 1.5 nm monolayer thickness.

Poly(butylene succinate) (PBS) copolymers including 1 mol% of amino acid were produced at high molecular weights and good break strain. Preparation of PBS copolymer including L-aspartic acid (3) was found to be quite different compared with the preparation of the copolymer produced using other amino acids. The reaction time was found to decrease in proportion to the amount of 3. A similar effect due to the inclusion of 3 was observed in other PBS copolymers.

Syndiotactic polystyrene (sPS) end-capped with an isotactic rich block was obtained by using the Ni(η²-CH₃COCHCOCH₃)₂/[η⁵-(CH₃)₅C₅]TiCl₃/methylaluminoxane or Ni(η²-CH₃COCHCOCH₃)₂/[η⁵-(CH₃)₅C₅]TiCl₃/methyl-aluminoxane/triisobutylaluminum catalytic system. The formation of the stereoblock structure, in the mixture containing also syndiotactic, atactic and isotactic-rich polystyrene, was evidenced by exhaustive solvent extraction, ¹³C-nuclear magnetic resonance spectroscopy, differential scanning calorimetry and size exclusion chromatography measurements.

The in situ dielectric relaxation measurement of crystallized PVDF under CO₂ revealed that the shape and frequency of the peak maximum for the α_c relaxation of the crystalline chain did not change under pressurized CO₂, suggesting that CO₂ is not dissolved inside the crystalline region and the crystalline chain motion is not accelerated under CO₂.