Volume 42 Issue 11, November 2010

Hyperbranched polycarbonates (HBPCs) were synthesized by A₂+B₃ polymerization, particularly using di-tert-butyl tricarbonate (DBTC) as A₂ monomer and 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) as B₃ monomer. The terminal functionalized HBPCs with Boc and phenol were obtained by using 1-pot or 2-pot synthesis.

Arm-replaceable star-like nanogels consisting of poly(methyl methacrylate) arms and poly(divinylbenzene) cores with alkoxyamine units at their branching points were synthesized by a combination of atom transfer radical polymerization and nitroxide-mediated radical polymerization. The arms of the star-like nanogels were replaced by means of dynamic covalent exchange processes, and arm detachment and arm exchange reactions were successfully accomplished. The structural changes were confirmed by gel permeation chromatography–multiangle light scattering measurements, small-angle X-ray scattering measurements and scanning force microscopic observation.

Isotactic (it-) and syndiotactic (st-) uniform poly(methyl methacrylate)s (PMMAs) with hydroxyl end group, isolated by supercritical fluid chromatography (SFC), were reacted with benzene-1,3,5-tricarbonyl trichloride, and two types of uniform three-arm star-PMMAs with different stereoregular arms, [it/it/st]- and [it/st/st]-3-star-PMMAs, were isolated by SFC from the product mixture. The stereocomplex formation of these stereostar PMMAs was examined in acetone. Although both stereostar PMMAs formed intramolecular stereocomplexes, the [it/st/st]-3-star-PMMA, in particular, was found to form two types of intramolecular stereocomplexes with different hydrodynamic volumes because of different compositions of it- and st-PMMA arms involved in the stereocomplexes.

Three types of poly(4-diphenylaminostyrene) (PDAS) having different polymer chain structures were prepared by living anionic polymerization, and the electroluminescence of PDAS/tris(8-hydroxyquinoline) aluminum (Alq₃) blend films was examined. The hole drift mobility of PDAS increased with an increase in the syndiotactic configuration. The current density, turn-on voltage and brightness were also improved with an increase in the syndiotactic configuration of PDAS.

A series of novel fluorinated crosslinkable poly(phthalazinone ether)s, bearing tetrafluorostyrene groups (FSt-FPPEs), have been prepared by polycondensation. The structures were identified using ¹H-NMR and infrared spectroscopy measurements. The resulting polymers could be thermally crosslinked either at 160 °C in the presence of a free radical initiator dicumyl peroxide under vacuum or at 280 °C in the absence of any initiator under vacuum. The refractive indices of the crosslinked polymers could be well controlled over a wide range; crosslinked polymers also show low optical losses at 1550 nm. These results indicate that the application of FSt-FPPE in the field of optical waveguide seems feasible and promising.

Distinct skin-core structured PET X(a) proved notch sensitive as shown in Y(a) when 5–60 μm-deep hairline cracks were introduced. PET was annealed in hot edible oil to alter its morphology and remove internal stresses [PET X(b)] in order to improve toughness. Results showed significant reduction in its notch sensitivity, as shown in Y(b). Therefore, annealing in hot oil proved to be effective in achieving more dispersed skin-core morphology, thus improving the toughness of PET.

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.