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Novel cross-linkable, highly fluorinated poly(arylene ether ketones/sulfones) have been prepared by copolycondensation reactions of perfluorinated aromatic ketone/sulfone with 4,4‘-(hexafluoroisopr...

Random and alternating fluorene/carbazole (F/Cz) copolymers with various carbazole contents (20−50 mol %) have been designed and synthesized for use as the hole-transporting as well as light-emitting layer in blue light-emitting diodes (LEDs). DSC analysis has indicated the complete suppression of the crystallizability of these polymers by the introduction of 3,6-carbazole linkages into the polymer backbone, which also results in changes in their optical properties. The absorption maximum has been blue-shifted with an increase in the carbazole content due to the interruption in the main chain conjugation. Meanwhile, the photoluminescent properties have been influenced by the sequence distribution of the fluorene segments as well as the carbazole content. The emission maxima and vibronic features of the alternating copolymers have changed with carbazole content, reflecting the differences in the electronic structures of the repeat units. However, in the case of the random copolymers, the emission spectra r...

Thermal dehydration of boronic acid groups to form six-membered boronic acid anhydride (boroxine) was employed as a means of immobilizing oligofluorenes. This approach appears to improve the photoluminescenct stability of the cross-linked films compared to polyfluorenes. The emergence of long-wavelength emission upon thermal treatment usually observed in polyfluorenes has been prevented in this system. Initially the fluorene dimer (F2BA), trimer (F3BA), and tetramer (F4BA) containing boronic acid groups were prepared. These compounds were found to be readily soluble in common solvents such as THF, acetone, and DMF. Transparent thin films of these materials could be easily prepared by casting their solutions in THF onto KBr disks or glass substrates. Using mild reaction conditions (60−130 °C under vacuum for 2 h), these oligomers in the solid sate readily undergo cross-linking reactions by the dehydration of boronic acid groups as evidenced by FT-IR spectroscopy and DSC/TGA studies. The resulting cross-lin...

A poly(tert-butyl acrylate)-block-poly(2-cinnamoylethyl methacrylate), PtBA-b-PCEMA, sample was synthesized and characterized. After annealing at 105 ± 2 °C, the PtBA block formed densely packed cylinders inside the PCEMA matrix. Thin films of the diblock were obtained by microtomy. After PCEMA photo-cross-linking, the tert-butyl groups of PtBA were hydrolyzed, leaving poly(acrylic acid) chains in the loosely packed nanometer-sized cylinders. The permeability of water across such films varied by several orders of magnitude, depending on the pH of the aqueous medium or the types of cations in it. The possibility of using such nanochannels as templates for making further nanostructures was tested by filling the nanochannels with CdS or Fe2O3 nanoparticles.

A polyisoprene-block-poly(2-cinnamoylethyl methacrylate) (PI-b-PCEMA) sample formed vesicles in THF/hexanes with a THF volume fraction of 20%. In such vesicles, PCEMA made up the essentially-solvent-free spherical shell and the PI chains stretched into the solution phase from both the inner and outer PCEMA surfaces. Hairy hollow nanospheres were prepared by photo-cross-linking the PCEMA shell. Treating the cross-linked vesicles with ozone for a short period selectively degraded the outer PI chains to yield semi-shaved hollow nanospheres. Fully shaved hollow nanospheres were prepared by degrading both the inner and outer PI chains using long ozonolysis times. Due to the poor solubility of the fully shaved hollow nanospheres in common organic solvents, they may be useful as macroporous resins in chemical separations.

Graft polymers of well-defined structure consisting of monodisperse poly(sodium styrene sulfonate) graft chains and a polystyrene backbone have been synthesized by stable free radical polymerization. Proton-exchange membranes prepared from these polymers possess phase-separated nanochannels of ionic domains and exhibit larger proton conductivity compared to analogous membranes prepared from random copolymers of sodium styrene sulfonate and styrene.