Papers by Keyword: Polyacetylene

Abstract: Expanded graphite (EG) is a promising conducting filler to enhance the conductivity of the polyacetylene (PA)/EG composites and also an ideal support to catalyst PA to polymerize on the surface of EG. The expanded interlayers of EG prepared by chemical oxidation is between 100 and 1500 nm. Diameters of the Fe (naph)₃ nanoparticles deposited on the external surface and internal surface (i.e. surface of the expanded graphitic layers) of EG range from 7 to15 nm. PA/EG composites were prepared by heterogeneous polymerization. PA catalyzed by Fe (naph)₃ nanoparticles supported on the external surface and at the edge of the expanded layers was inclined to form bigger aggregation, while PA grown between the interlayers exhibit smaller size. The bulk conductivity of the prepared composites is 5.78×10³ S·m^-1.

Abstract: Electrical measurements under increasing hydrostatic pressure (1–4000 [bar]) have shown that electrical conductivity is closely related to the iodine doping rate (0–14%) of polyacetylene (PA) films. In pristine PA, conductivity increases with pressure while in 14% iodinedoped PA it decreases. A most important result is noticed for an intermediate doping rate (1.5%). In fact, for sweeping of the range of pressure, conductivity decreases in the beginning and then increases with pressure augmentation. This change is located at a critical pressure Pc. An empirical formula was proposed to describe this behaviour. The aim of this work is to contribute to the greater understanding of the pressure effect on the transport mechanism and/or the nature of charge carriers.

Abstract: The new comb-copolymers [polyacetylene–MPEG (polyethylene glycol monomethyl ether)] were synthesized with (nbd)Rh⁺[η⁶-C₆H₅B^- (C₆H₅)₃] as catalyst. The copolymers with moderate molecular weights (Mn) (13000-170000) and yields (31.6-47.3%) exhibited higher optical activities compared with chiral monomer, which accorded with the “Chiral Amplification” effect. The optical activity of the copolymers gradually decreased as the amount of MPEG increased. The maximum amounts of MPEG for successful copolymerization and optical activity of copolymers were 40%, 30%, 20%(mol%) as the Mn of MPEG was 350, 750,1900, respectively. The optical activity of copolymers could change at external environmental stimulation, e.g., decreased as methanol content increased.