Note in 2010

The structural relaxation of glassy, spin-cast thin polymer films was investigated using spectroscopic ellipsometry. Results from poly(tertiary-butyl methacrylate) (P(tert-BMA)) and poly(normal-butyl methacrylate) (P(norm-BMA)) polymers and also blends of P(tert-BMA) and poly(methyl methacrylate) (PMMA) are compared. It is found that P(tert-BMA) films exhibit almost no relaxation over a period of several days, compared with PMMA-rich films, which exhibit significant amounts of relaxation. Blends show intermediate amounts of relaxation.

To increase the tenacity of poly L-lactic acid (PLLA), we have developed self-assembling siloxane nanoparticles with three phases: a high-density crosslinked siloxane phase (plural cores), an elastomeric silicone phase and a caprolactone oligomer phase with a high affinity for the PLLA matrix. These nanoparticles self-assemble by aggregation and condensation of an organosiloxane with three units, which respectively form each phase. Adding the nanoparticles (5 wt%) to PLLA improved the tenacity (elongation) of the PLLA without degrading its high breaking strength.

Polyethylene glycol-containing hematin (PEGylated hematin) was prepared using the Mitsunobu reaction as a water-soluble biomimetic catalyst for polymerization of arbutin in a phosphate buffer solution of pH 7.0. The structure of polyarbutin obtained was characterized by ¹H nuclear magnetic resonance and infrared spectroscopy. PEGylated hematin showed high catalytic activity for arbutin polymerization, indicating that it is a better catalyst compared with horseradish peroxidase.

Addition-type poly(norbornene)s with siloxane substituents were synthesized using the (η³-Allyl)(η⁵-cyclopentadienyl)palladium/tricyclohexylphosphine/[Ph₃C][B(C₆F₅)₄] system. The obtained polymers had very high glass transition temperature of up to 255 °C, and their films displayed high mechanical flexibility. The incorporation of siloxane groups in the chain resulted in significant increase in the gas permeability of their films, and the polymers with branched siloxane groups showed high oxygen permeability (P(O₂)=66–360 Barrer). In addition, poly(norbornene) membranes with a unique porous structure were prepared.

Hydroxyl-group-alkoxylated lignophenols (LPs) with various types of alkyl halides were prepared by Williamson ether synthesis to reutilize lignin, an industrial waste material, and make it processable. As compared with raw LP, alkoxylated LPs exhibited good organosolubility and thermal stability (temperatures at 5% loss in weight were estimated to be more than 330 °C by thermogravimetric analyses). Alkoxylated LPs could also form transparent thin films; in particular, films of hexyloxyl LPs exhibited high refractive indices (≈1.55) similar to that of bisphenol A-based poly(carbonate) (PC). Furthermore, these films had lower birefringence (<0.001) than that of PC; therefore, alkoxylated LPs can be utilized as natural-polymer-based optical materials.

Permeation of model drugs with different molecular weights through a bioconjugated membrane having antigen–antibody complexes as reversible crosslinks was investigated in the absence and presence of a target antigen. The bioconjugated membrane regulated the drug permeation in response to the concentration of a target antigen. This paper focuses on the effect of the molecular size of the drugs on controlled permeability of the antigen-responsive membrane.

Poly(fluorene) composed of alternating structures are considered to assume an ordered macrostructure involving lamellar and π–π stacking in the film state. The ordered structure gives rise to perfect interpolymer excimeric luminescence, which can be used as a luminescence layer in an electroluminescent device.

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.

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 effects of the degree of hydrolysis (DH) of poly(vinyl alcohol) (PVA) on electrospinning and water resistance of electrospun PVA/poly(acrylic acid) (PAA) composite fibers were explored. At a constant concentration of PVA solution (∼8wt%), the average diameter of electrospun PVA fibers increased with increasing DH. The water resistance of heat-treated PVA/ PAA composite fibers was dramatically enhanced, and was also affected by PAA weight fractions (φPAA) in PVA/PAA blend solutions.

The synthesis of well-defined poly(4-(2-(tert-butyldimethylsiloxy)ethyl)-styrene-b-isobutylene-b-4-(2-(tert-butyldimethylsiloxy)ethyl)styrene)(PTBDMES-b-PIB-b-PTBDMES) triblock copolymers was accomplished by cationic sequential block copolymerization of isobutylene (IB) and 4-(2-(tert-butyldimethylsiloxy)ethyl)styrene (TBDMES) using the capping-tuning technique in a one-pot procedure in methylcyclohexane/CH₃Cl at −80 °C. Deprotection of the precursor triblock copolymer with tetrabutylammonium fluoride yielded poly(4-(2-hydroxyethyl)styrene-b-isobutylene-b-4-(2-hydroxyethyl)styrene) (PHOES-b-PIB-b-PHOES), with pendant hydroxyl groups along the hydrophilic backbone chains. FT-IR, NMR confirmed that hydrolysis was complete.

A methacrylate monomer, having an N-(2-methoxyethyl)methylamino group and urea bond, was newly prepared. The methacrylate monomer was used for graft polymerization from polysilsesquioxane containing the dimethyl dithiocarbamate group as the initiator specie to provide thermoresponsive property. The grafted product showed hydrophobic aggregation at 30 °C in an aqueous solution. Copolymerization with 2-hydroxyethyl methacrylate was also examined to introduce the additional functional group.