Volume 44 Issue 4, April 2012

We demonstrated that a method based on the analysis of both orientational birefringence and photoelastic birefringence is effective for designing polymers that are processed in a molten state and used in a glassy state. The designed polymer exhibits no birefringence for any orientation of the polymer main chains or under elastic deformation. Birefringence is close to zero even in injection-molded plates of the polymer. We have also shown that it is possible to compensate and control the birefringence of polymers using inorganic nanocrystals, and we have obtained valuable information on the optimal size of nanocrystals for compensation and control of birefringence.

Pd-catalyzed Suzuki coupling polymerization of macrocycle-containing monomer with diboric acid pinacol esters afforded aromatic poly(ether ketone)s with optically active macrocycles. The resulting aromatic poly(ether ketone)s have high glass transition temperatures (T_g: 220–257°C), large molar rotations ([Φ]_D²⁵: +1906–1976 deg) and excellent solubility to typical solvents such as CHCl₃ and DMF.

We found that isopropyl and tert-butyl propargyl carbonates (1b and 1c) afforded high-molecular-weight polyethers compared with methyl propargyl carbonate (1a) in the polycondensation with bisphenols. The molecular weight (M_n) of the obtained polyethers 3 increased in the order of methyl carbonate 1a<isopropyl carbonate 1b<tert-butyl carbonate 1c.

A series of racemic helical or achiral poly(phenylacetylene)s were prepared, and the preferential helical sense of the polymers was induced by transformation in chiral solvents, even if the interaction between the chiral molecule and the polymer was weak such as solvent–solute interaction. The enantioenriched helical poly(phenylacetylene)s possessing no chiral moieties except for helicity were obtained by removal of chiral solvents. In particular, one of them retained the induced helical sense even in an achiral solvent.

Transmission electron microscopy of epoxy nanocomposites with process parameters of clay loading of 2.0 wt%, magnetic stirring time of 120 min and sonication time of 30 min showed good intercalation morphology. The glass fiber-based composites containing epoxy and clay mixture with these parameters produced maximum Young's modulus.

The star- and dumbbell-shaped isobutyl-substituted POSS derivatives were synthesized. The star and dumbbell structures of the obtained compounds were confirmed by ¹H-, ¹³C-, and ²⁹Si-NMR and MALDI-TOF-MS analysis. The star-shaped POSS compound formed the optical transparent film, and showed T_g and T_m at 24 and 96 °C, respectively. All the dumbbell-shaped POSS compounds, however, formed opaque whitish films, and showed no T_g and high T_m over 230 °C. The lower T_m and appearenace of T_g in the star-shaped POSS suggested its lower crystallinity, which promoted formation of the transparent film.

Poly(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[def]phenanthrene)) (PCPP) is a stable blue light emitting conjugated polymer even after annealing at 150 °C or operation of the device in air. The polymers, BC-PCPP, CO-PCPP and BO-PCPP, have been synthesized by Yamamoto polymerization. The photoluminescence (PL) emission spectra of the BC-PCPP, CO-PCPP and BO-PCPP in chloroform solution show maximum peaks at 398, 387 and 384 nm, respectively. The polymer films show maximum peaks at 419, 425 and 425 and additional peaks at around 530 nm in PL spectra.

Imidazole-terminated first- and second-generations poly(amidoamine)-typed POSS-core dendrimers denoted as POSS-Im16 and POSS-Im32, respectively, were synthesized. The results of pH titrations for the dendrimers showed well-defined one-step titration curves as same as that of 1-methylimidazole as a monomeric imidazole compound. Spectrophotometric titrations of the dendrimer aqueous solutions with Cu²⁺ ions indicated variation of the coordination modes of POSS-Im16 from the Cu²⁺–N₂O₂ complex to the Cu²⁺–N₄ complex and the existence of the only one complexation mode of Cu²⁺–N₄ between Cu²⁺ ion and POSS-Im32 with increasing concentrations of the dendrimers.

Liquid crystal polymer (LCP) nanofibers were prepared by electrospinning from isotropic and biphasic poly(γ-benzyl-L-glutamate) (PBLG)/dichloromethane-pyridine solutions. The as-spun PBLG fiber from the isotropic solutions had an undulating orientation of closed packed α-helices like a serpentine trajectory. The as-spun fibers from the biphasic solutions containing the LC phase, on the other hand, had uniaxially oriented hexagonal lattices of α-helices along the fiber axis. These results indicated that the orientation of the ordered structure of the electrospun lyotropic LCP fibers can be controlled by the initial microstructure of the spinning solution.

Biologically identified peptides that bind to the surfaces of isotactic poly(methyl methacrylate) (PMMA), syndiotactic PMMA, and their assembled stereocomplex films were used as noncovalent surface modifiers. Each peptide was biotinylated and immobilized onto the PMMA films to function as a linker for the subsequent immobilization of streptavidin. We demonstrated that the PMMA species had a great impact on the peptides' abilities to functionally modify the film surfaces.