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PMMA/High-k Self-assembled TiO2 /PMMA Multi-layer Gate Dielectric for P3HT Organic Field Effect Transistors
(2022-01-01)
Inpor, Kroekchai
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Houngkamhang, Nongluck
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Thanachayanont, Chanchana
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Prichanont, Seeroong
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Kayunkid, Navaphun
In this work, a multi-layer structure of poly (methyl methacrylate)/ titanium dioxide/poly (methyl methacrylate) (PMMA/TiO₂ /PMMA; PTP) was proposed as a top-gate insulator for P3HT-based organic field-effect transistors (OFETs). Adding a TiO₂ interlayer as a high dielectric constant (high-k) material into PMMA film enables the modification of the dielectric constant of the multi-layers PTP film. The content of TiO₂ in the PTP film, which can be varied by changing the number of soaking cycles in TiO₂ solution, plays a crucial rule in modifying the dielectric constant of the PTP film. The higher the TiO₂ content used in the PTP film, the higher the dielectric constant of PTP film can be obtained. However, using high TiO₂ content led to a reduction in the dielectric constant of the PTP film due to leakage current induced by the agglomeration of TiO₂. The utilization of the top-gate insulator containing TiO₂ significantly enhanced several P3HT-OFETs characteristics, e.g., an increase in the I<inf>on</inf>/I<inf>off</inf> ratio, and a decrease in the threshold voltage. However, the use of the PTP top-gate insulator with a high content of TiO₂ resulted in regressions in the OFETs characteristics, such as a decrease in carrier mobility and reduction in the I<inf>on</inf>/I<inf>off</inf> ratio. OFETs operating at the optimum conditions of the PTP gate-insulator, with PTP thickness of 225 nm and RMS roughness of 20.0 nm, provided a dielectric constant of 7.13, a threshold voltage of-8.49 V, a saturation mobility of 2.2× 10-4 cm²V-1s-1, I<inf>on</inf>/I<inf>off</inf> ratio of 37.9, and a subthreshold slope of 0.39 V/decade.
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Preparation and characterization of PEG bis(amine) grafted PMMA/SPION composite nanoparticles
(2016-03-01)
Wanna, Yongyuth
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Pui-ngam, Rachineewan
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Nukeaw, Jitti
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Chindaduang, Anon
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Tumcharern, Gamolwan
We report novel magnetic composite nanoparticles for heavy metal ion separation. Superparamagnetic iron oxide nanoparticles (SPIONs) and were coated with poly(methylmethacrylate) (PMMA) by emulsion polymerization process in the aqueous suspension of SPIONs. In addition, the hydrolysis of carboxylic functional groups onto the PMMA-coated SPIONs was grafted with Polyethylene glycol bis(amine). Then, the functional group structures were investigated by Fourier transforms infrared spectroscopy (FTIR). The morphology of PMMA/SPIONs was determined by transmission electron microscopy (TEM) and atomic force microscope (AFM). The magnetic property was investigated by the vibrating sample magnetometer (VSM). The metal concentration in the solution after separation using the nanoparticles was determined by inductivity coupled plasma optical emission spectrometer (ICP-OES). Furthermore, we demonstrate that the efficiencies of the heavy metal ion removal for Cu(II), Mn(II), Zn(II), Cd(II), Pb(II), Co(II) and Ni(II) are 80.0%, 57.7%, 54.3%, 40.0%, 34.8%, 32.5% and 30.2% by weight, respectively. The nanoparticles also exhibit some selectivity for copper, manganese and zinc. The results show that the composite nanoparticles are extremely promising for heavy metal ion separation.
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PMMA-N,N,N-trimethyl chitosan nanoparticles for fabrication of antibacterial natural rubber latex gloves
(2014-08-30)
Arpornwichanop, Thanida
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Polpanich, Duangporn
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Thiramanas, Raweewan
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Suteewong, Teeraporn
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Tangboriboonrat, Pramuan
This paper presents one-pot synthesis of N,N,N-trimethyl chitosan (TMC) stabilized poly(methyl methacrylate) (PMMA) latex particles via the miniemulsion polymerization technique. From 1H NMR, synthesized TMC contains 52% degree of quaternization. Compared to native biopolymer chitosan, TMC possesses permanently positive charges as well as provides greater antibacterial activity. Combining properties of PMMA and TMC, PMMA-TMC latex nanoparticles hydrodynamic size.© 2014 Elsevier Ltd. All rights reserved.
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The effects of solvents on the properties of ultra-thin poly (methyl methacrylate) films prepared by spin coating
(2013-11-01)
Tippo, T.
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Thanachayanont, C.
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Muthitamongkol, P.
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Junin, C.
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Hietschold, M.
Poly (methyl methacrylate) (PMMA) is extensively used as an insulating layer in organic electronic devices. In this study, spin coating method was used to cast thin layers of PMMA for dielectric application from solutions in three different solvents, namely dimethylformamide (DMF), n-butyl acetate and toluene. The solvent's vapor pressure causes the solvent to vaporize at different rates leading to layer's distortion and different surface roughnesses. Preparation of suitable surface morphologies, for example, pinhole-free and crack-freewas studied. A step profilometer was used to measure the film thicknesses. Alternatively an equation correlating final film thickness to spin speed and solution concentration was proposed. A metal/insulator/metal parallel plate capacitor structurewas fabricated and the current density dependence on the applied electric fieldwas measured. The resulting low surface roughness, low leakage currents, high breakdown voltage, and high dielectric constant were obtained for the 100 nm-thick PMMA film prepared with DMF. © 2013 Elsevier B.V.
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Effect of Tio 2 compact layer on optical absorpt+ion and fluorescence performance of R6G/PMMA composite light-guided films
(2012-10-29)
Mukdachacharoenchai, P.
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Mekprasart, W.
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Sritharathikhun, J.
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Pecharapa, W.
Rhodamine 6G (R6G) and Poly(methyl methacrylate) (PMMA) light-guided films accompanied with titanium dioxide thin layer were prepared by spin-coating process onto on glass substrate. Dichloromethane was used as disperser for blending R6G and PMMA. The TiO <inf>2</inf> layer thickness was varied by controlling spinning speed. The effects of TiO <inf>2</inf> layer with different thickness on optical absorption and florescence performance of the films were investigated and the results exhibited strong absorption of TiO <inf>2</inf> in UV region and the enhancement in florescence efficiency with increasing TiO <inf>2</inf> film thickness. © (2012) Trans Tech Publications, Switzerland.

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