• Title, Summary, Keyword: copolymer

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A Pathway to Microdomain Alignment in Block Copolymer/Nanoparticle Thin Films under Electric Field

  • Bae, Joonwon
    • Bulletin of the Korean Chemical Society
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    • v.35 no.9
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    • pp.2689-2693
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    • 2014
  • The control over microstructure in block copolymer thin films using external electric fields has become an interesting research topic. In this article, the effect of nanoparticle on the microdomain alignments in block copolymer (polystyrene-b-poly(2-vinylpyridine)/nanoparticle (Au) thin films under electric fields has been examined with transmission electron microscopy. The homogeneous dispersion of Au nanoparticles into the block copolymer matrix was achieved by surface modification of nanoparticles with compatible ligands. Compared with the phenomenon seen in the pristine block copolymer thin films, a peculiar alignment behavior was observed in the block copolymer/nanoparticle hybrid thin films under electric fields. In addition, the different pathways observed in the pristine and nanoparticle incorporated block copolymer thin films were also monitored as a function of exposure time. This work can provide the fundamental information for understanding microdomain alignment in block copolymer/nanoparticle thin films under external electric fields.

Cure Reactions of Epoxy/Anhydride/(Polyamide Copolymer) Blends

  • Youngson Choe;Kim, Wonho
    • Macromolecular Research
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    • v.10 no.5
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    • pp.259-265
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    • 2002
  • The cure kinetics of blends of epoxy (DGEBA, diglycidyl ether of bisphenol A)/anhydride resin with polyamide copolymer, poly(dimmer acid-co-alkyl polyamine), were studied using differential scanning calorimetry (DSC) under isothermal condition. On increasing the amount of polyamide copolymer in the blends, the reaction rate was increased and the final cure conversion was decreased. Lower values of final cure conversions in the epoxy/(polyamide copolymer) blends indicate that polyamide hinders the cure reaction between the epoxy and the curing agent. The value of the reaction order, m, for the initial autocatalytic reaction was not affected by blending polyamide copolymer with epoxy resin, and the value was approximately 1.3, whereas the reaction order, n, for the general n-th order of reaction was increased by increasing the amount of polyamide copolymer in the blends, and the value increased from 1.6 to 4.0. A diffusion-controlled reaction was observed as the cure conversion increased and the rate equation was successfully analyzed by incorporating the diffusion control term for the epoxy/anhydride/(polyamide copolymer) blends. Complete miscibility was observed in the uncured blends of epoxy/(polyamide copolymer) up to 120 $^{\circ}C$, but phase separations occurred in the early stages of the curing process at higher temperatures than 120 "C. During the curing process, the cure reaction involving the functional group in polyamide copolymer was detected on a DSC thermogram.gram.

Swelling Controlled Drug Release from Acrylamide-Styrene Copolymer Hydrogels (Acrylamide-Styrene Copolymer 하이드로겔로부터의 수팽윤 속도조절에 의한 약물 방출)

  • Kim, Min-Kyoung;Lee, Seung-Jin
    • Journal of Pharmaceutical Investigation
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    • v.19 no.4
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    • pp.173-178
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    • 1989
  • Drug release rates from copolymer hydrogels were controlled by their hydrophilic-hydrophobic balances. As a model copolymer hydrogel, poly(acrylamide-co-styrene) was synthesized at different monomer composition. Release mechanisms of propranolol-HCI from the copolymer matrices were investisated. Swelling rates of the copolymer hydrogels retarded as their hydrophobicity increased. Swelling kinetics of the copolymer hydrogels regulated drug release rates via polymer relaxation controlled release mechanisms. Zero order drug release could thus be achieved within certain periods.

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A Study on Fabrication of Polyester Copolymers (IV) - Physical Properties of PET/BPA Copolymer - (폴리에스테르 공중합체의 Fabrication 연구(IV) - PET/BPA 공중합체의 물리적 특성 -)

  • 현은재;이소화;제갈영순;장상희;최현국
    • Polymer(Korea)
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    • v.25 no.2
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    • pp.208-217
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    • 2001
  • PET/BPA copolymer of terephthalic acid, bisphenol-A and ethylene glycol was melt-pressed and quenched in ice water. This copolymer film was drawn by capillary rheometer. Shrinkage, crystallinity, morphology, thermal, dynamic mechanical, and mechanical properties of these copolymer films were investigated. The PET/BPA copolymer film exhibited T$_{m}$ lower than that of PET film. The crystallinity and density of these drawn copolymer films increased with draw ratio and draw rate but decreased with draw temperature. The tensile strength and tensile modulus of the copolymer films increased with draw ratio but decreased with draw temperature. Shrinkage of the drawn copolymer film decreased with draw ratio and draw rate.e.

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Suspension Polymerization and Characterization of Transparent Poly(methyl methacrylate-co-isobornyl methacrylate)

  • Park, Sung-Il;Lee, Sang-In;Hong, Soon-Jik;Cho, Kuk-Young
    • Macromolecular Research
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    • v.15 no.5
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    • pp.418-423
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    • 2007
  • A methacrylate copolymer based on isobornyl methacrylate (IBMA) and methyl methacrylate (MMA) was synthesized in an aqueous suspension via free-radical polymerization. The potential of this copolymer as a heat-resistant optical polymer is also discussed. 1,1,3,3-tetramethylbutyl peroxy-2-ethyl hexanoate and n-octyl mercaptan were used as the initiator and chain transfer agents, respectively. The effect of IBMA on the properties of the copolymer was investigated. The composition of the copolymer was analyzed using $^1H-NMR$, and the heat resistance by measuring the glass transition temperature, which exhibited a linear dependency on the IBMA content in the copolymer. Variation of the chain transfer content used in the synthesis step was effective for the optimization of the copolymer for practical use.

Synthesis and Thermal Properties of Poly(cyclohexylene dimethylene terephthalate-co-butylene terephthalate

  • Lee, Sang-Won;Wansoo Huh;Hong, Yoo-Seok;Lee, Kyung-Mi
    • Macromolecular Research
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    • v.8 no.6
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    • pp.261-267
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    • 2000
  • It is well known that poly(cyclohexylene dimethylene terephthalate) (PCT) is used as the engineering plastics with high melting temperature and fast crystallization rate compared with poly(butylene terephthalate)(PBT). However, poor thermal stability of PCT has limited its practical application due to the drastic decrease of molecular weight during the processing temperature. In order to improve the thermal stability of PCT homopolymer, the copolymer of PCT and PBT was synthesized and the thermal properties of the copolymer have been studied. P(CT/BT) copolymer was obtained by condensation polymerization of DMT, CHDM, and 1,4-butanediol. The chemical structure and composition of the copolymer was investigated by FTIR and NMR analysis. The thermal behavior of copolymer was studied using DSC and it was found that the crystallization-melting behavior of the copolymer was observed for the whole composition range. TGA analysis exhibited that P(CT/BT) copolymer is more stable at the initial stage of thermal decomposition compared with PCT and PBT homopolymers.

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Damping Properties and Transmlission Loss of Polyurethane. II. PU Layer and Copolymer Effect

  • Yoon, kwan-Han;Kim, Ji-Gon;Bang, Dae-Suk
    • Fibers and Polymers
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    • v.4 no.2
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    • pp.49-53
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    • 2003
  • Polyurethane (PU) layer and copolymer consisted of the different molecular weights (1000 and 2000 g/mol) of poly(propylene glycol) (PPG) were prepared. The damping and mechanical properties of these materials were compared with PU 1000 made by PPG having the molecular weight of 1000 g/mol. The optimum composition of PU2000 used for PU layer and copolymer was diphenylmethane diioscynate (MDI)/propylene glycol (PPG)/butanediol (BD) (1/0.3/0.7) based on the damping and mechanical properties. The damping peak of PU copolymer was higher than those of PU layer and PUI 1000 in low temperature range (-30- $10^{\circ}C$). For application in noise reduction, the transmission loss of the mechanical vibration through solid structure was measured. PU layer and copolymer were used as a damping layer. The transmission loss of PU copolymer was more effective than those of PU layer and PU 1000 in the experimental frequency range.

Surface modification for block copolymer nanolithographyon gold surface

  • Hwang, In-Chan;Bang, Seong-Hwan;Lee, Byeong-Ju;LeeHan, Bo-Ram;Kim, Hyeong-Jun
    • Proceedings of the Materials Research Society of Korea Conference
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    • pp.33.2-33.2
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    • 2009
  • Block copolymer lithography has attracted great attention for emerging nanolithography since nanoscaleperiodic patterns can be easily obtained through self-assembly process without conventional top-down patterning process. Since the morphologies of self-assembled block copolymer patterns are strongly dependent on surface energy of a substrate, suitable surface modification is required. Until now, the surface modification has been studied by using random copolymer or self-assembled mono layers (SAMs). However, the research on surface modifications has been limited within several substrates such as Si-based materials. In present study, we investigated the formation of block copolymer on Au substrate by $O_2$ plasma treatment with the SAM of 3-(p-methoxy-phenyl)propyltrichloro-silane [MPTS, $CH_3OPh(CH_2)_3SiCl_3$]. After $O_2$ plasma treatment, the chemical bonding states of the surface were analyzed by X-ray photoelectron spectroscopy (XPS). The static contact angle measurement was performed to study the effects of $O_2$ plasma treatment on the formation of MPTS monolayer. The block copolymer nanotemplates formed on Au surface were analyzed by scanning electron microscopy. The results showed that the ordering of self-assembled block copolymer pattern and the formation of cylindrical nano hole arrays were enhanced dramatically by oxygen plasma treatment. Thus, the oxidation of gold surface by $O_2$ plasma treatment enables the MPTS to form the monolayer assembly leading to surface neutralization of gold substrates.

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Fabrication of Free-Standing Three-Dimensional Block Copolymer Patterns on Substrate (블록 공중합체 3차원 패턴의 제조 방법 및 그 구조 특성)

  • Choi, Hong Kyoon
    • Korean Journal of Materials Research
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    • v.29 no.12
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    • pp.804-811
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    • 2019
  • As the importance of three-dimensiona (3D) nano patterns and structures has recently emerged, interest in the study of 3D structures of block copolymers has increased. However, most existing studies on block copolymer 3D patterns on substrates are limited to simple 3D structures such as a multi-layered forms. In this study, we propose an experimental method for realizing free-standing 3D block copolymer patterns on substrates using an e-beam lithographic template and film transfer method. The block copolymer 3D structure formed in wide hole templates are similar to simple multi-layered structures; however, as the width of the hole template become narrower, more complex block copolymer 3D structures are formed in which the upper and lower layer structures are interconnected. Furthermore, we introduce a method to fabricate novel block copolymer structures in which the 2D planar structures are connected to 3D complex structures. Proposed 3D block copolymer fabrication method provides a framework for generation of unconventional 3D structures of block copolymer, which can be useful for next generation 3D devices.

Synthesis and Characteristics of Polymer Electroluminescent Device Using PPV-Copolymer (PPV-Copolymer를 이용한 고분자 EL소자의 제작 및 특성연구)

  • Kim, H.Y.;Lim, D.J.;Lim, S.B.;Moon, H.D.;Kim, E.O.;Gil, S.K.;Kim, Y.H.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.984-987
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    • 2002
  • In this study, It is to synthesize PPV-copolymer and to make polymer electroluminesence device in single layer of ITO/PPV -copolymer/metal. and then it has been realized basic characteristics for display device through analysis and recognized application possibility by luminous material. PPV-copolymer is used spin coating method and electrode is evaporated of vacuum deposition method by changing materials. The result of experiment, The PPV-copolymer used this study emitted blue color, could be discovered a change of emttion characteristic by electrode material.

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