Papers by Keyword: Diblock Copolymer

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Authors: Min Young Lee, Chan Park, Seong Soo Hong, Yeong Soon Gal, Kwon Taek Lim
Abstract: Well-defined block copolymers consisting of a hydrophilic poly (ethylene oxide) (PEO) and lipophobic poly (1H,1H-perfluorooctyl methacrylate) (PFOMA) were synthesized with controlled molecular weight via atom transfer radical polymerization (ATRP). The block copolymers formed stable micelles where PEO is the shell and PFOMA is the core in chloroform. The micellar morphology of PEO5K-b-PFOMA5K was found to be spherical with average diameter of ca. 12 nm, while meandering cylindrical with average diameter of ca. 13 nm was observed for PEO5K-b-PFOMA13K by TEM analysis. The self-assembled structures were reorganized to thermodynamically stable morphologies upon annealing above glass transition temperature (Tg). For example, spherical shape of PEO5K-b-PFOMA5K and cylindrical domain of PFOMA block in PEO5K-b-PFOMA5K became ordered cylindrical and continuous phase, respectively.
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Authors: Pongsaton Amornpitoksuk, Sumetha Suwanboon, Nantakan Muensit, Jonas Baltrusaitis
Abstract: Ag/ZnO powders were synthesized through a precipitation method, using poly(ethylene oxide)-block-poly(propylene oxide) as stabilizer. X-ray diffraction patterns of all prepared powders showed a mixed phase of Ag and ZnO. The existence of metallic Ag on the surface of all prepared ZnO powders was confirmed by X-ray photoelectron spectroscopy. Their photocatalytic activities were investigated through the degradation of a methylene blue solution under blacklight illumination. The Ag/ZnO prepared from the Zn2+ solution containing 7 mol% of Ag+ had the highest photocatalytic activity and this also showed better photocatalytic activity than a commercial ZnO powder.
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Authors: Miftakhul Huda, Zulfakri bin Mohamad, Takuya Komori, You Yin, Sumio Hosaka
Abstract: The progress of information technology has increased the demand of the capacity of storage media. Bit patterned media (BPM) has been known as a promising method to achieve the magnetic-data-storage capability of more than 1 Tb/in.2. In this work, we demonstrated fabrication of magnetic nanodot array of CoPt with a pitch of 33 nm using a pattern-transfer method of block copolymer (BCP) self-assembly. Carbon hard mask (CHM) was adopted as a mask to pattern-transfer self-assembled nanodot array formed from poly (styrene)-b-poly (dimethyl siloxane) (PS-PDMS) with a molecular weight of 30,000-7,500 mol/g. According to our experiment results, CHM showed its high selectivity against CoPt in Ar ion milling. Therefore, this result boosted the potential of BCP self-assembly technique to fabricate magnetic nanodot array for the next generation of hard disk drive (HDD) due to the ease of large-area fabrication, and low cost.
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Authors: Miftakhul Huda, Takuro Tamura, You Yin, Sumio Hosaka
Abstract: In this work, we studied the fabrication of 12-nm-size nanodot pattern by self-assembly technique using high-etching-selectivity poly (styrene)-poly (dimethyl-siloxane) (PS-PDMS) block copolymers. The necessary etching duration for removing the very thin top PDMS layer is unexpectedly longer when the used molecular weight of PS-PDMS is 13.5-4.0 kg/mol (17.5 kg/mol total molecular weight) than that of 30.0-7.5 kg/mol (37.5 kg/mol total molecular weight). From this experimental result, it was clear that PS-PDMS with lower molecular weight forms thicker PDMS layer on the air/polymer interface of PS-PDMS film after microphase separation process. The 22-nm pitch of nanodot pattern by self-assembly holds the promise for the low-cost and high-throughput fabrication of 1.3 Tbit/inch2 storage device. Nanodot size of 12 nm also further enhances the quantum-dot effect in quantum-dot solar cell.
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Authors: Yang Yang, Chun Cheng Zuo, Yu Xin Zuo, Ying Yu
Abstract: We use molecular dynamics simulations method to investigate the behavior characteristics of AB diblock copolymers that are adsorbed on a planar surface. Adsorption density has been distinguished, depending on the adsorption manner of A-block on the (100) surface and formation of brushes. It is examined in detail that conformational behavior of the brushes affects the adsorption density. In addition, we make a comparison of linear brush with length ratio of the A-block to the chain, in the cases of the fixed length of chain and the fixed length of A-block, respectively. The result shows that the adsorption density is strongly affected by the length ratio of the A-block to the chain. And our findings can be used as a guide for fabrication and preparation of actual synthetic polymer brushes on a solid surface by the approach of physical adsorption.
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Authors: H. Brown
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Authors: Ying Yu, Yu Xin Zuo, Zhao Zhang, Chun Cheng Zuo
Abstract: Coarse-grained molecular dynamics simulations on self-assembly behavior of diblock copolymers (DCP) with nanoparticles confined in cylindrical nanopores are perfomed to study the morphology transition of DCP affected by the confined ratio of the cylindrical confinement diameter to the block copolymer domain spacing, the wall-polymer interactions, the particle-polymer interaction potential and the component concentration. The simulation results show that nanoparticles have a pronounced effect on the morphology transition of DCP and can therefore be considered as an important aspect in controlling the confined self-assembly in cylindrical confinement. Besides, the phase diagram indicates the process of morphology transition.
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Authors: N. Niamsa, M. Srisa-ard, Y. Srisuwan, N. Kotsaeng, Y. Baimark, N. Narkkong, W. Simchuer
Abstract: Nanocomposite chitosan-based films incorporated with drug-loaded methoxy poly(ethylene glycol)-b-poly(D,L-lactide-co-glycolide) diblock copolymers (MPEG-b-PDLLG) nanoparticles were prepared by forming drug-loaded nanoparticles in chitosan solution before suspension-solution film casting. Salicylic acid was used as a poorly-water soluble model drug. The nanocomposite films with DLL/G ratios of 100/0 and 85/15 mol% and chitosan/diblock copolymer/drug ratios of 80/1/1, 80/2/2 and 80/4/4 (w/w) were prepared and investigated. The sizes of drug-loaded nanoparticles into the chitosan films were approximate or less than 100 nm. Nanopores were observed in the resulted chitosan films incorporated with drug-loaded nanoparticles when the diblock copolymer ratio was increased up to 2. Number and size of the nanopores increased as increasing the diblock copolymer ratio. Only the nanocomposite films with chitosan/diblock copolymer/drug ratio of 80/1/1 (w/w) showed slower drug release than the chitosan film.
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Authors: Miftakhul Huda, You Yin, Sumio Hosaka
Abstract: In this study, we investigate self-assembled large-area nanodot fabrication on a silicon substrate using poly(styrene)-poly(dimethyl-siloxane) (PS-PDMS) for the application to quantum dot solar cell. By optimizing the PS-PDMS concentration by 2% and the volume of PS-PDMS solutions by 20 μL/cm2 dropped to silicon substrate, nanodots with a pitch size of 33 nm and a diameter of 23 nm are achieved with the molecular weight of 30,000-7,500. It is found that the dropped volume of PS-PDMS solution correlated to the thickness of spin-coated PS-PDMS layer has a great effect on the size and the pattern morphology.
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Authors: Yu Xin Zuo, Guo Qiang Wang, Ying Yu, Chun Cheng Zuo, Yi Rui Wang
Abstract: We present molecular dynamic (MD) simulations to model and simulate the self-assembly of asymmetrical diblock copolymers (DCP) confined in carbon nanotube (CNT). The strength of the attractive interaction is systemically varied to examine effects on the self-assembled morphologies. The aim of our study is to understand how the surface energy and cohesive energy affect the structure. The dependence of the chain conformation on the strength of the surface preference is reasonably explained. The energetics is discussed qualitatively and used to account for the appearance of the complex morphological transition.
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