Formation and Characterization of Silver Nanoparticle Composite with Poly(p-Br/F-phenylsilane).

The one-pot production and structural characterization of composites of silver nanoparticles with poly(p-Br/F-phenylsilane), Br/F-PPS, have been performed. The conversion of Ag+ ions to stable Ag0 nanoparticles is mediated by the copolymer Br/F-PPS having both possibly reactive Si-H bonds in the polymer backbone and C-Br bonds in the substituents along with relatively inert C-F bonds. Transmission electron microscopy and field emission scanning electron microscopy analyses show the formation of the composites where silver nanoparticles (less than 30 nm of size) are well dispersed over the Br/F-PPS matrix. X-ray diffraction patterns are consistent with that for face-centered-cubic typed silver. The polymer solubility in toluene implys that the cleavage of C-Br bond and the Si-F dative bonding may not be occurred appreciably at ambient temperature. Nonetheless, thermogravimetric analysis data suggest that some sort of cross-linking could take place at high temperature. Most of the silver particles undergo macroscopic aggregation without Br/F-PPS, which indicates that the polysilane is necessary for stabilizing the silver nanoparticles.

Synthesis and characterization of phosphine/borane-terminated poly(silole-co-germole) for the evaluation of luminescent polymer light-emitting diode.

Codehydrocoupling (using Red-Al) followed by borane/phosphine-capping (with Ph2BCl and Ph2PCl) of 1,1-dihydrotetraphenylsilole (1) and 1,1-dihydrotetraphenylgermole (2) (9:1 mole ratio) gave electroluminescent poly(silole-co-germole)s containing borane/phosphine-ends (3, 4) in high yield. The borane-terminated copolymer 3 emits at 522 nm and are electroluminescent at 521 nm. The fluorescence quantum yield of 3 in toluene is (1.60±0.30) x 10(-2). The phosphine-terminated copolymer 4 emits at 520 nm and are electroluminescent at 520 nm. The fluorescence quantum yield of 4 in toluene is (1.60±0.20) x 10(-2). 3 and 4 were then mixed in 1:1 ratio. The emission color of 3/4 mixture is green and the maximum brightness of the device is 2,760 cd/m2 with a luminous efficiency of 0.67 lm/W. The borane/phosphine end groups in the 1:1 mixture of 3 and 4 exhibited no appreciable effect on the luminescent properties in spite of possible B-P dative bonding. Ge-132 helped to increase the B-P dative bonding. The electroluminescent copolymers 3 and 4 are good candidates for PLED (polymer light-emitting diode) fabrication.

One-pot synthesis and structural characterization of poly(alkoxysilane)s catalyzed by silver-gold complexes.

Combinative one-pot Si-Si/Si-O dehydrocoupling of hydrosilanes with alcohols (1:1.5 mole ratio), mediated by a mixture of AgNO3-AuCl3 (100/1 mole ratio) rapidly produced poly(alkoxysilane)s in reasonably high yield. The addition of small amount of gold complex to the reaction mixture effectively accelerated the coupling reaction compared to the reaction rate with AgNO3 alone. The hydrosilanes include p-X-C6H4SiH3 (X = H, CH3, OCH3, F), PhCH2SiH3, and (PhSiH2)2. The alcohols include MeOH, EtOH, iPrOH, PhOH, and CF3(CF2)2CH2OH. The weight average molecular weight and polydispersity of the poly(alkoxysilane)s were in the range of 1,600-8,000 Dalton and 1.4-3.5, respectively. The dehydrocoupling reactions of phenylsilane with ethanol (1:3 mole ratio) in the presence of the Ag-Au complexes gave only triethoxyphenylsilane.

One-pot synthesis and characterization of poly(alkoxysilane)s promoted by silver colloidal nanoparticles.

Si-Si/Si-O dehydrocoupling of hydrosilanes with alcohols (1:1.5 mole ratio), catalyzed by AgNO3 which converted to Ag(0) colloidal nanoparticles, gave poly(alkoxysilane)s in one-pot in moderate to high yield. The hydrosilanes include p-X-C6H4SiH3 (X = H, CH3, OCH3, F), PhCH2SiH3, and (PhSiH2)2. The alcohols include MeOH, EtOH, (i)PrOH, PhOH, and CF3(CF2)2CH2OH. The weight average molecular weight and polydispersity of the poly(alkoxysilane)s were in the range of 1,600 approximately 8,000 Dalton and 1.4 approximately 3.5. The dehydrocoupling reactions of phenylsilane with ethanol (1:3 mole ratio) in the presence of the silver nanocolloid catalyst produced only triethoxyphenylsilane as product.

Catalytic sol-gel co-polycondensation of para-substituted phenylsilanes and bis(silyl)phenylene to robust organosilicas using colloidal nickel nanoparticles.

The dry sol-gel co-polycondensation at toluene in ambient air atmosphere of p-X-C6H4SiH3 (X = H, CH3, CH3O, F, Cl) and p-H3Si-C6H4SiH3 (9:1 mole ratio) to co-silicas (p-X-C6H4SiO1.5)9(p-O1.5Si-C6H4SiO1.5)1 in high yield, catalyzed by colloidal nickel nanoparticles in-situ generated from nickelocene(II) is described. The co-gels (p-X-C6H4SiO1.5)9(p-O1.5Si-C6H4SiO1.5)1 with higher molecular weights and TGA residue yield were obtained when compared to the homogels p-X-C6H4SiO1.5 Some degree of unreacted Si-H bonds still remained in the gel matrix because of steric bulkiness. All the insoluble gels adopt an amorphous structure with a smooth surface. A plausible mechanism for the dry sol-gel reaction was provided.

Convenient synthesis and characterization of silver/poly(p-Cl-phenylsilane) nanocomposites.

The one-pot preparation and structural characterization of silver/poly(p-Cl-phenylsilane) nanocomposites have been performed. The one-step transformation of silver(I) salt to stable silver(0) nanoparticles is mediated by poly(p-Cl-phenylsilane), Cl-PPS having both reactive Si-H bonds in the polymer backbone and C-Cl bonds in the substituents. XRD, TEM, and FE-SEM, and solid-state UV-vis analytical techniques were used to analyze the interesting metal/inorganic polymer hybrid nanocomposites. TEM and FE-SEM data show the formation of hybrid composites in which large number of silver nanoparticles (less than 30 nm of size) are dispersed throughout the Cl-PPS matrix. XRD patterns are consistent with that for fcc-typed silver. The elemental analysis for Cl atom and the polymer solubility confirm that the appreciable cleavage of C-Cl bond and the Si-Cl dative bonding were not occurred. The size and processability of such nanoparticles depend on the ratio of metal to Cl-PPS. In the absence of Cl-PPS, most of the silver particles undergo macroscopic aggregation, which indicates that the polysilane is absolutely necessary for stabilizing the silver nanoparticles.

Synthesis and characterization of germane/stannane-capped polysiloles for the fabrication of luminescent OLED.

Dehydropolymerization (with various inorganic hydrides) and subsequent germane/stannane-capping (with Me2GeHCI and Ph2SnHCI) of 1,1-dihydrotetraphenylsilole (1) give electroluminescent germane/stannane-capped polysiloles (2) in high yield. The polymerization yield and molecular weight with Selectride increase in the order L-Selectride < N-Selectride < K-Selectride. The molecular weights increase in the order Red-Al < K-Selectride < Super Hydride. The germane/stannane-capped polysiloles 2 emit at 521 nm and are electroluminescent at 522 nm. The fluorescence quantum yield of 2 in toluene is (1.66 +/- 0.26) x 10(-2). The emission color is green and the maximum brightness of the device is 2,800 cd/m2 with a luminous efficiency of 0.68 lm/W. The type of end group exhibited no appreciable effect on the luminescent properties of polysilole backbone. Thus, the germane/stannane-capped polysiloles are found to be a good material for OLED fabrication.

Catalytic Si-Si/Si-O dehydrocoupling of 1,1-dihydrotetraphenylsilole to optoelectronic polysiloles with colloidal silver nanoparticles.

The combinative Si-Si/Si-O dehydrocoupling at ambient air atmosphere of 1,1-dihydrotetraphenylsilole 1 with 2 mol% of AgNO3 and Ag2SO4 in toluene at 90 degrees C produces optoelectronic polysiloles 2 in high yield. The complexes such as Cp2Co, Cp2Ni, Cp2ZrCl2/Red-Al, and AgCl were found to be ineffective for the dehydrocoupling of 1. The polysiloles mainly have Si-Si bonds along with the small portion of Si-O bonds in the polymer backbone chain. Interestingly, the Si-O linkage increased with increasing the concentration of catalyst AgNO3, implying that while Ag(0) species catalyze the Si-Si dehydrocoupling, Ag(I) species catalyze the Si-O dehydrocoupling along with the simultaneous oxidation of NO3 ion to NO2. The silver complexes transformed to colloidal silver nanoparticles during the catalytic reaction. The Si-Si/Si-O dehydrocoupling of 1 with AgNO3 even at dry nitrogen atmosphere is occurred, supporting that the oxidation of NO3- ion to NO2 is only the possible oxygen source, but not from the adventitious moisture in air. sigma-, beta-, and gamma-Cyclodextrins considerably deteriorated the dehydrocoupling of 1 probably due to both the formation of insoluble inclusion complexes in toluene and the encapsulation of SiH2 moiety. The resulting silole polymer 2 emits green light at 520 nm and is electroluminescent at 520 nm.

Dry sol-gel polycondensation of hydrosilanes to organosilicas catalyzed by colloidal nickel nanoparticles.

The dry sol-gel polycondensation at toluene in ambient air atmosphere of p-X-C6H4SiH3 (X = H, CH3, CH3O, F, Cl) to silica p-X-C6H4SiO15 in high yield, catalyzed by colloidal nickel nanoparticles in-situ generated from nickelocene(II), nickel(II) acetate, and bis(1,5-cyclooctadiene)nickel(0), is described. Similar catalytic activities were observed for the catalysts. Similarly, the dry sol-gel polyco-condensation p-X-C6H4SiH3 (X = CH3, CH3O, F, Cl):C6H4SiH3 (9:1 mole ratio) at toluene in ambient air atmosphere of was performed to yield co-silicas (p-X-C6H4SiO1.5)9(p-X-C6H4SiO1.5)1 in high yield using nickelocene. The co-gels with higher molecular weights and TGA residue yield were obtained when compared to the homogels. The highest yield, molecular weight, polydispersity index, and TGA residue yield were obtained for p-Cl-C6H4SiH3. Some degree of unreacted Si-H bonds still remained in the gel matrix because of steric bulkiness. All the insoluble gels adopt an amorphous structure with a smooth surface. A plausible mechanism for the dry sol-gel reaction was suggested.

Dry sol-gel condensation of p-X-C6H4SiH3 (X = H, CH3, CH3O, F, Cl) to organosilica p-X-C6H4SiO3 using nickelocene.

The dry sol-gel reaction at toluene in ambient air atmosphere of p-X-C6H4SiH3 (X = H, CH3, CH3O, F, Cl) to p-C6H4SiO3 in high yield, catalyzed by nickelocene, is reported. The highest yield, molecular weight, polydispersity index, and TGA residue yield were obtained for p-Cl-C6H4SiH3. Some degree of unreacted Si-H bonds still remained in the gel because of steric reason. All the insoluble gels adopt an amorphous structure with a smooth surface. A plausible mechanism for the dry sol-gel reaction was suggested.