Controlled Synthesis, Optical And Electric Performances Of Silver Nanowires/Polymer Composite Materials

It is urgently needed to develop novel flexible transparent conductive thin films with high transparency and low sheet resistance as the flexible electronics grows rapidly. Herein, we firstly synthesized silver nanowires through reduction of silver nitrate by ethylene glycol in the presence of polyvinylpyrrolidone (PVP), and studied the morphology control agent, the precursor inducing agent, reaction temperature, dropping speed on the influence of the preparation of high concentration and high uniform of silver nanowires. When silver ions concentration is 0.049 M, the molar ratio of AgNO3 and PVP is 1.4:1 of the system, uniform silver nanowires with a diameter of 70-110 nm and length of 20 to 40 um, yield of over 80% could be obtained with good crystallinity. Silver nanomaterials with the highest length to diameter ratio of 470 while the systems is at 30 μM FeCl3. However, with the same adding molarity, Cu2+, Na+ and Pt4+ is bad for the synthesis of silver nanowires, a large amount of heterogeneous nanowires or nanorods is gotten. Under the condition of the same PVP/AgNO3 molar ratio (1.4:1), the higher the molecular weight of PVP, the silver nanowires length to diameter ratio is higher. The best temperature of preparation silver nanowires is 140℃ whether the control agent type and concentration changed or not. The proper way of adding silver nitrate and morphology control agent will resulted in high uniform and high length to diameter ratio of silver nanowires.We then deposited silver nanowires with diameters of 20,35,70 and 100 nm on the poly(ethylene terephthalate) films, respectively, and formed silver conductive thin films. The effects of deposition density and nanowire diameter on the film transmittance and sheet resistance were investigated. It was indicated that both transparence and sheet resistance decreased when the deposition density increased, while the Figure of Merit for these films increased up to 410, and high length to diameter ratio of silver nanowires produced more migration resistance to avoid the occurrence of "the coffee ring "We next deposited silver nanowires on the polyethylene glycol (PVA) films and formed silver conductive thin films. The adhesion, transmittance, sheet resistance and stability of the film were investigated. It was indicated that both transparence and sheet resistance decreased when the deposition density increased. The conductive films based on the silver nanowires afforded a relatively low sheet resistance of 1.3 Ω/□ while the F.O.M for these films increased up to 760, more than 350 of the ITO,410 of PET/silver nanowires composite film. Compared with PET/silver nanowires composite film, the surface adhesion is higher, after tape test about 10 times, the sheet resistance of PVA/silver nanowires composite film has remained at about 20 Ω/□.Lastly we deposited silver nanowires on the photopolymerisable acrylate films and formed silver conductive thin films. The effects of UV intensity, average functionality of monomer on photopolymerization kinetics and the effects of deposition density and nanowire diameter on the film transmittance and sheet resistance were investigated. It was indicated that photopolymerization is faster than the traditional polymerizations, and polymerization process for 30 seconds. The polymerization rate and apparent kinetic constant meet the maximum in the polymerization process. With UV light intensity increased, Rpmax and final conversion rate were significantly promoted, and the threshold value of UV intensity is about 4 mW/cm2, with the increase of the average functionality of monomer, Rpmax and the final conversion rate showed a trend of decline. The photopolymerisable acrylate films based on the silver nanowires with diameters of 35 and 70 nm afforded a relatively low sheet resistance of 132 Ω/□ at the transparency of 80%. The conductive films afforded a relatively low sheet resistance of 2.3 Ω/□ while the F.O.M for these films increased up to 451, more than 350 of the ITO film.Through the study of the above,we provide an optimized process for the controllable synthesis of high uniform silver nanowires and lay the foundation for the preparation of high performance silver nanowires/polymer composite materials, and these will rich polymer/silver nanowires composite material in optical, electrical application prospect.