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We report here a facile and reproducible strategy for fabricating highly dispersible silver nanowires (AgNWs) in organic solvents using poly(methyl methacrylate)-b-poly(acrylic acid) (PMMA-b-PAA) diblock copolymers as the dispersant. The copolymers could be assembled into spherical micelles with PMMA as the core and the solvated PAA block as the corona in methanol. Interestingly, when the copolymer micelle solution was mixed with an AgNW dispersion in methanol, the AgNWs precipitated out within no more than a few minutes depending on the concentration of the micelle solution. The precipitate could readily be redispersed in common organic solvents such as chloroform, toluene, etc., which are good solvents for the PMMA block. The mechanism study revealed that while the PAA block served as an anchor that became chemically attached onto the surfaces of the AgNWs, the PMMA block formed a solvated “buoy” to allow the AgNWs to remain dispersed in the solvent. Transparent conductive glass (TCG) from the modified AgNWs and PMMA was also produced, suggesting that the modified AgNWs could also be well dispersed within the polymer matrix. Although there are reports on the preparation of dispersible inorganic particles using copolymers as a dispersant, the strategy reported in this article is believed to be novel, facile, and quite simple, and can be used as a concept and a universal tool for surface modification of other inorganic nanoparticles from specifically designed and prepared copolymers. [ABSTRACT FROM AUTHOR]

A photochromic polymer film has been fabricated by the layer-by-layer (LBL) self-assembly through alternating the deposition of poly(acrylic acid) bearing a naphthopyran copolymer and poly(4-vinylpyridine) in an organic solvent. The multilayer assembly process is monitored via UV-vis spectroscopy by measuring the increase in absorbance at 380 nm, and the results reveal that the multilayer films grow in a uniform way in each deposition. Atomic force microscopy (AFM) images prove that the surface of the film was relatively smooth. The photochromic properties of the naphthopyran in the LBL films are investigated and the kinetic results confirm that the colored merocyanine in the LBL films show a significant slow fading speed (critical T1/2 decoloration time increased to 64 min in the 3-bilayer film) and are more stable than those in previous reports. [ABSTRACT FROM AUTHOR]

A new low band gap copolymer containing dialkylfluorene and 4,7-dithienyl-2,1,3-benzothiadiazole (TBT), poly(fluorenevinylene-alt-4,7-dithienyl-2,1,3-benzothiadiazole) (PF-TBT) was synthesized by Heck cross-coupling polymerization. The copolymer is soluble in common organic solvents such as chloroform, tetrahydrofuran and chlorobenzene. The TGA result indicated that the copolymer possesses good thermal stability. The absorption, electrochemical and photovoltaic properties of PF-TBT were investigated and compared with those of poly(fluorenevinylene-alt-4,7-diphenyl-2,1,3-benzothiadiazole) (PF-DBT) whose structure is similar to PF-TBT. The copolymer exhibited a broad absorption band with an absorption edge close to 700 nm and an optical band gap of 1.82 eV. Cyclic voltammetry studies indicated that the relatively low HOMO energy level assured a higher open circuit voltage (Voc) when PF-TBT is used as the donor material in a photovoltaic cell. The bulk heterojunction (BHJ) solar cell using PF-TBT as the donor and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) as the acceptor with the structure of ITO/PEDOT : PSS/copolymer : PCBM/LiF/Al, exhibited a Vocof 0.86 V, short-circuit current density (Jsc) of 3.97 mA cm−2, fill factor (FF) of 0.35, and a power conversion efficiency (PCE) of 1.18% under one sun of AM 1.5 solar simulator illumination (100 mW cm−2). [ABSTRACT FROM AUTHOR]