• Title, Summary, Keyword: polar functionalization

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Functionalization of Multi-walled Carbon Nanotube by Treatment with Dry Ozone Gas for the Enhanced Dispersion and Adhesion in Polymeric Composites

  • Kim, Jung-Hwan;Min, Byung-Gil
    • Carbon letters
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    • v.11 no.4
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    • pp.298-303
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    • 2010
  • A method of functionalization of multi-walled carbon nanotube (MWNT) at room temperature using dry ozone gas is described. The resulting MWNT were characterized by Fourier transform infrared, x-ray photoelectron spectroscopy, and scanning electron microscopy. Combined to these analyses and solubility in liquids, it could be concluded that the dry ozone gas exposure introduces polar functional groups such as carboxylic groups to MWNT similar to acidic modification of MWNT. Particularly, the stable dispersion of MWNT in water after ozone treatment above a critical level could be obtained, implying potential bio-application. The hydrophilic functional groups on the MWNT introduced by ozone oxidation were helpful in improving the interaction with functional groups in PA6 such as $-NH_2$ and -CONH- resulting in improved mechanical properties.

Separation of Non-covalently Functionalized Graphene Nanoplatelets via Salting-out Process (염석법을 이용한 비공유 기능기화된 그래핀 나노플레이트렛의 분리 공정 연구)

  • Kim, Joonhui;Yoo, Sung Chan;Cha, Jaemin;Ryu, Hojin;Hong, Soon Hyung
    • Composites Research
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    • v.32 no.3
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    • pp.134-140
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    • 2019
  • Graphene nanoplatelets (GNP), one of the graphene derivatives is famous as the most proper candidate for industrial applications. However, current performance of GNPs as reinforcing filler in composites is limited by their agglomeration and physicochemical heterogeneity. Herein, an approach to produce non-covalently functionalized GNPs (F-GNPs) is reported which possesses potential to be extended as the industrial level of mass production. The one-step functionalization process uses melamine, a low-cost chemical, to prevent agglomeration and dispersion in polar solvents. Furthermore, a purification strategy called salting-out process based on differences in the dispersibility of the individual F-GNP flakes is reported to separate F-GNPs. The functionalization and separation process developed in this paper provides a strategy to use GNPs at the industrial level in composite applications.

Functionalization of polyethylene by graft copolymerization for separation processes

  • Kaur, Inderjeet;Gupta, Nitika;Kumari, Vandna
    • Advances in materials Research
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    • v.2 no.1
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    • pp.15-36
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    • 2013
  • Incorporation of polar functional moieties into polyethylene (PE) film has been achieved by graft copolymerization of polar monomers such as methacrylic acid (MAAc) and acrylamide (AAm) on to PE film, preirradiated with ${\gamma}$-rays from $^{60}Co$ source, using benzoyl peroxide (BPO) as initiator in aqueous medium. Percentage of grafting of MAAc and AAm was determined as a function of irradiation dose, monomer and initiator concentration, temperature, reaction time and amount of water. Maximum percentage of grafting of MAAc (1453%) and AAm (21.28%) was obtained at [MAAc] = $235.3{\times}10^{-2}$ mol/L, [AAm] = $23.4{\times}10^{-2}$ mol/L, [BPO] = $5.5{\times}10^{-2}$ mol/L and $16.5{\times}10^{-2}$ mol/L at $80^{\circ}C$, $90^{\circ}C$ in 180 min and 90 min respectively. The grafted PE films were characterized by FTIR, Thermogravimetric analysis (TGA) Scanning Electron Micrography (SEM) and X-ray diffraction methods. Some selective properties of grafted films such as swelling behavior, ion and metal uptake have been carried out. The biodegradation studies of the grafted PE films have also been investigated. The grafted films developed superior swelling behavior with maximum swelling (480%) in water as compared to pristine PE (13.55%), better thermal stability and ion and metal uptake studies showed promising results that can be effectively used for desalination of brackish water and separation of metals from the industrial effluents.

Study on the controlled preparation of polyolefin based block or graft copolymers (폴리올레핀 기반 블록 또는 그라프트 공중합체의 정밀 제조에 대한 고찰)

  • Lee, Jong Heon;Hong, Sung Chul
    • Elastomers and Composites
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    • v.48 no.1
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    • pp.30-38
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    • 2013
  • Polyolefin is one of the most important commodity polymers having excellent physical properties and cost competitiveness, which has continuously broadened their market in response to a heavy demand from industry. However, the lack of polarity in polyolefin has limited its applications, especially where interactions with other materials are important. In view of the above, the incorporation of polar functional groups in polyolefin has been widely attempted. Especially, the preparations of segmented modified polyolefin copolymers, such as block and graft copolymers have been extensively investigated, since the loss of the original properties of polyolefin can be minimized while the polar segments can endow interactions with other materials. Living radical polymerization (LRP) method can be one of the most attractive synthetic tools for the preparation of the modified polyolefin block or graft copolymers. In this review, progress on the preparation of the polyolefin based block or graft copolymers through LRP technique is briefly summarized.

Beryllium(II) Recognition by Allosteric Effects in 1,2-Ethylenedioxybenzene Based Ditopic Receptors

  • Kim, Dong-Wan;Kim, Jung-Hwan;Hwang, Jae-Young;Choi, Myong-Yong;Kim, Jae-Sang
    • Bulletin of the Korean Chemical Society
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    • v.32 no.8
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    • pp.2643-2647
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    • 2011
  • Efficient ditopic receptor, uranyl(II) N,N'-(ethylenedioxy)benzenebis(salicylideneimine) (3) for beryllium ion has been obtained upon functionalization of 1,2-ethylenedioxybenzene (1) with a uranyl-salphen (salphen = N,N'-phenylenebis(salicylideneimine)) unit. Binding affinities of the receptor, 3 in AN-DMSO (v/v 95:5) solution have been measured for alkali and alkaline earth metal ions by conductometry comparing 1. The results showed that both monotopic 1 and ditopic receptor 3 were selective for $Be^{2+}$ ions over other cations, while especially 3 that can complex both with cations (coordinated to basic oxygen of ethylenedioxybenzene) and anions (coordinated to the Lewis acidic uranyl center) results in an increase of the stability constants by a factor of $10^{2.42}$ with respect to 1. Furthermore, the $Be^{2+}$-3 interactions are demonstrated by $^1H$ NMR experiments in highly polar solvent medium, DMSO-$d_6$. Higher selectivities were also observed for $Be^{2+}$ when the ditopic receptor, 3 was incorporated into PVC membranes and tested as ion selective electrodes at neutral pH.

Study on Morphology Control of Polymeric Membrane with Clathrochelate Metal Complex (Clathrochelate계 금속 착물을 이용한 고분자 멤브레인 구조 제어)

  • Kim, Nowon;Jung, Boram
    • Membrane Journal
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    • v.24 no.6
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    • pp.472-483
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    • 2014
  • This study is preparation of microporous membranes by using macrocyclic metal ion complexes and extended cage complexes. It is a more favorable way to existing methods because polymer and metal ion-ligand complex system provides a fine control over the phase transition behavior. Chemical functionalization of the polar surface can be obtained. Metal-templated condensation of cyclohexanedione dioxime, hydroxyphenylboronic acid in the presence of metal salts proceeds cleanly in methanol to furnish the metal clathrochelate complexes. Organic/inorganic hybrid membranes were prepared with polyethersulfone (PES), polyvinylpyrrolidone (PVP), ethyleneglycol butyl ether (BE), metal clathrochelate s and DMF by using nonsolvent induced phase inversion method. The structure of membranes was characterized with scanning electron microscopy (SEM) and microflow permporometer. The addition of Fe(II) clathrochelate complex with p-hydroxyphenyl group leads to changes of membrane morphology such as narrow mean pore size distribution, increase of surface pore density and decrease of the largest pore size.

Synthesis of High Functionalized Anion Exchange Fibers Using Hybrid Polyolefine by $\gamma-Ray$ Mutual Radiation (방사선 동시조사법을 이용한 고관능성 Hybrid Polyolefine 음이온교환섬유의 합성)

  • Cho In-Hee;Kwak Noh-Seok;Kang Phil-Hyun;Nho Young-Chang;Hwang Taek-Sung
    • Polymer(Korea)
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    • v.30 no.3
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    • pp.217-223
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    • 2006
  • Ion exchange fibers, high functionalized onto hybrid polyolefine fiber's surface, were synthesized by $\gamma-ray$ mutual radiation. Degree of grafting (DG) of copolymer increased with increasing GMA monomer concentration and the maximum rate of DG was 355% at 50 GMA. The graft reaction occurred in polar solvent and DG was 190% maximum value in $1.0\times10^{-3}$ Mohr's salt and 0.1 M sulfuric acid, respectively. The amination for graft copolymers varied depending on amine reagents, and the reactivity for copolymers was highest for methylamine, and that of triethylamine lowest. It was shown that water uptake and ion exchange capacities increased with increase in the rate of amination while surface area decreased rapidly as proceeding for graft reaction and amination.

Preparation and Characterization of Grafted Maleic Anhydride onto Polypropylene by Reactive Extrusion (반응 압출을 통한 PP-g-MA 제조 및 특성평가)

  • Kang, Dong-Jin;Lee, Sung-Hyo;Pal, Kaushik;Park, Chan-Young;Zhang, Zhen Xiu;Bang, Dae-Suk;Kim, Jin-Kuk
    • Polymer(Korea)
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    • v.33 no.4
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    • pp.358-363
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    • 2009
  • Maleic anhydride-grafted polypropylene has been widely used to improve the interfacial interaction between the components in PP/polar polymer blends and PP/filler composites and to maximize the physical properties and thermal properties. In this paper. the maleic anhydride (MAH)-grafted polypropylene (co-PP) was fabricated through reactive extrusion process with di-cumyl peroxide (DCP) as an initiator. The grafting degree of MAH depending on the contents of DCP and MAH was investigated by FT-IR spectra and chemical titration. The grafting degree increased with increasing MAH concentration and also showed maximum value at 0.06 wt% of DCP concentration. Melt flow index (MFI) of the grafted copolymer was increased with increasing the contents of MAH. The DSC and TGA analysis data indicate the melting temperature and thermal degradation of PP depending on the grafting degree of MAH.