A new class of multifunctional polymers based on poly(l,6heptadiyne) derivatives with various functional groups such as carbazole unit for photoconductive polymers and nonlinear optical (NLO) chromophores for NLO polymers were synthesized by metathesis polymerization. The polymerizations were carried out with MoCI,-and WCI,-based catalysts. The catalytic activity of MoCI, was found to be greater than that of WCI , . The resulting polymers exhibited photoconductivity and large optical nonlinearity. These conjugated polymers have good solubility in common organic solvents, long-term stability toward air oxidation, and high electrical conductivity.

SynopsisPolycondensations of N,N'bis(hydroxyalky1)pyromellitic diimides, N,N'-bis(hydroxypheny1)pyromellitic diimides, N,N'bis( hydroxyalkyl)-3,3',4,4'-benzophenonetetracarboxylic diimides and N,N'-bis(hydroxyphenyl)-3,3'-4,4'-benzophenonetetracarboxylic diimides with aromatic disulfonyl chlorides were carried out in pyridine to produce poly(imide-su1fonate)s. The resulting polymers had inherent viscosities in the range of 0.25-0.38 dL/g. These poly(imide-su1fonate)s were insoluble in common organic solvents and had relatively good thermal stability. The TGA data showed 10% weight losses at 253-365OC and residual weights a t 50OOC were 22-72% in nitrogen.a Observed in TGA in nitrogen (5"Wmin).Residual weight.

The thermally stable second-order nonlinear optic (NLO) hybrid materials were successfully prepared by a sol-gel process using dye-attached sol-gel monomers (ormosils) of difunctionalized or trifunctionalized second-order NLO chromophores attached to silicon atoms. The dye-attached sol-gel monomers were synthesized by the coupling reaction of 3-isocyanatopropyltriethoxysilane with the corresponding functionalized NLO chromophores in DMAc. The dye-attached sol-gel monomers were homopolymerized and copolymerized with TEOS by hydrolysis and polycondensation in the presence of a slight excess amount of acidified water (pH 3), yielding the hybrid precusors (or a homogeneous solution). The hybrid precursors were spin-coated on various substrates such as ITO glass and NaCl disk. Hybrid films were further polycondensed by curing at 170°C for 3 h. The cured hybrid materials existed in monohydroxy (T 2 , Q 3 ) and nonhydroxy (T 3 , Q 4 ) states, indicating the formation of a highly cross-linked silicon-oxygen polymeric network. All of the cured organic/SiO 2 hybrid films are transparent. The organic/SiO 2 hybrid materials were quite stable at elevated temperatures above 250°C. The hybrid films were poled by corona discharge technique or dc contact electrode. The values of electro-optic coefficient for the organic/SiO 2 hybrid materials were in the range of 3.7 to 16 pm/V at the wavelength of 1.3 µm, depending on dye-attached sol-gel monomers and poling conditions. The SG-DANS (1:2:2) film shows excellent temporal stability. The r 33 signal remained at 80% of its initial value after heating even at 150°C for 3 h. Also, the second-order nonlinear optical coefficient d 31 of 72 pm/V for the SG-DANS (1:2:0) hybrid film measured by the Maker fringe technique was obtained. The refractive index was decreased after photobleaching. Using the hybrid film, a singlemode channel waveguide was also fabricated by the photobleaching method. The mode pattern confirmed that a channel waveguide was single-mode, and the optical propagation loss was measured to be less than 1 dB/cm.

No abstract

The formation of galaxies, clusters and superclusters (SCs) is discussed based on a cosmic string model, and the constrain& are given for the corresponding loops which form these structures by the accretion of the loops. Only those loops that came into horizon after teq (the time of equal matter and radiation) may be the seeds of clusters and SCs. &BComic s t r i n g s are one-dimensional t o p o l o g i c a l d e f e c t s formed i n cert a i n p r o c e s s of GUT(grand u n i f i e d t h e o r y ) d u r i n g a phase t r a n s i t i o n i n t h e e a r l y u n i v e r s e .Zeldovich' and V i l e n k i n 2 f i r s t r e a l i z e d t h a t e n e r g y

No abstract

No abstract

The preparation and cyclopolymerization of dipropargyl sulfoxide were studied. The polymerization of dipropargyl sulfoxide was carried out by various transition metal catalysts. WCl6–EtAlCl2, MoCl5, and PdCl2 catalyst systems were very effective. The resulting poly(dipropargyl sulfoxide) structures were characterized by NMR (1H and 13C), IR, and elemental analysis to have conjugated polyene units. Poly(dipropargyl sulfoxide) prepared by PdCl2 was mostly soluble in organic solvents such as DMF and DMSO. Thermal and oxidative properties of poly(dipropargyl sulfoxide) were also studied. The electrical conductivity of iodine‐doped poly(dipropargyl sulfoxide) was 5.2 × 10−2 Ω−1 cm−1. Comparisons of poly(dipropargyl sulfoxide) properties with other similar polymers from dipropargyl sulfur derivatives such as dipropargyl sulfide and dipropargyl sulfone were also carried out. © 1993 John Wiley & Sons, Inc.