• Title/Summary/Keyword: Polymers

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Enhanced stability of NADH/dehydrogenase mixture system by water-soluble phospholipid polymers

  • Fukazawa, Kyoko;Ishihara, Kazuhiko
    • Biomaterials and Biomechanics in Bioengineering
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    • v.3 no.1
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    • pp.37-46
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    • 2016
  • To maintain activity in a coenzyme/enzyme mixture system, such as ${\beta}$-nicotinamide adenine dinucleotide (NADH)/dehydrogenase, the water-soluble 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers as an additive were synthesized and investigated for their stabilizing function. The inhibitor for the NADH/dehydrogenase reaction was spontaneously formed when the NADH was stored in the dehydrogenase solution. Therefore, we hypothesized that if the additive polymer could interact with an inhibitor without any adverse effect on the dehydrogenase, the activity in the NADH/dehydrogenase mixture could be maintained. We selected lactose dehydrogenase (LDH) as the enzyme, and the NADH was dissolved and incubated at $37^{\circ}C$ in the LDH solution containing the polymers. The phospholipid polymers used in this study were poly(MPC) (PMPC), poly(MPC-co-3-trimethylammonium-2-hydroxypropyl methacrylate chloride) (PMQ) and poly[MPC-co-potassium 3-methacryloyloxypropyl sulfonate ($MSO_3$)] ($PMMSO_3$). The poly($MSO_3$) was used as a reference. For the PMQ and $PMSO_3$ aqueous solutions, the activity of the NADH/LDH mixture system decreased with incubation time as the same level or lower than that in the Tris buffered solution in the absence of the polymers. However, for the poly($MPC-co-MSO_3$) ($PMMSO_3$) aqueous solution, the activity of the NADH/LDH mixed system was six times higher than that in the buffered solution even after a 3-days incubation. The LDH activity was 1.5-1.8 times higher in the presence of the $PMMSO_3$ compared with that in the $PMSO_3$ solution. The mixture of two polymers, poly(MPC) and poly($MSO_3$), did not produce any stabilization. Thus, both the MPC and $MSO_3$ units in the polymer chain had important and cooperative effects for stabilizing the NADH/LDH mixture.

Measurement Technologies of Mechanical Properties of Polymers used for Flexible and Stretchable Electronic Packaging (유연/신축성 전자패키징 용 폴리머 재료의 기계적 물성 측정 기술 리뷰)

  • Kim, Cheolgyu;Lee, Tae-Ik;Kim, Taek-Soo
    • Journal of the Microelectronics and Packaging Society
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    • v.23 no.2
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    • pp.19-28
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    • 2016
  • This paper presents an overview of selected advanced measurement technologies for the mechanical properties of polymers used for flexible and stretchable electronic packaging. Over the years, a variety of flexible and stretchable electronics have been developed due to their potential applications for next generation IT industry. To achieve more flexible and wearable devices for practical applications, the usage of polymeric components has been increased significantly. Therefore, accurate measurement of mechanical properties of the polymers is necessary in order to design mechanically reliable devices. However, the measurement has been challenging due to the soft nature and thin applications of polymers. Here, we describe novel measurement technologies of mechanical properties of polymers for flexible and stretchable electronics.

Structural Diversity of Five New Lanthanide Coordination Polymers Tuned by Different Salt Anions

  • Tao, Yinhua;Lou, Yongbing;Li, Yang;Chen, Jinxi
    • Bulletin of the Korean Chemical Society
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    • v.35 no.5
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    • pp.1417-1421
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    • 2014
  • Five new lanthanide coordination polymers, $[Ln_2(1,4-NDC)_2(1,4-HNDC)_2(phen)_2]_n$ (Ln = Er (1), Yb (2)), and $[Ln_2(1,4-NDC)_3(phen)_2(H_2O)_2]_n$ (Ln = Nd (3), Gd (4), Er (5)) ($1,4-H_2NDC$ = 1,4-naphthalenedicarboxylic acid, phen = 1,10-phenanthroline), have been successfully prepared via the reaction of corresponding trivalent lanthanide salt, $1,4-H_2NDC$ and phen in the presence of NaOH and pyridine under hydrothermal condition. Pyridine plays a key role in the synthesis of these lanthanide coordination polymers. Single-crystal X-ray diffraction analyses indicate that compounds 1-5 all form a 2-D network while different salt anions result in the diversity of crystal structures. These lanthanide coordination polymers showed a considerable thermal stability in TGA analyses.

Precise ultrasonic coating and controlled release of sirolimus with biodegradable polymers for drug-eluting stent

  • Joung, Yoon Ki;Jang, Bu Nam;Kang, Jong Hee;Han, Dong Keun
    • Biomaterials and Biomechanics in Bioengineering
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    • v.1 no.1
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    • pp.13-25
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    • 2014
  • In the current study, a drug-eluting stent coated with biodegradable polymers and sirolimus was developed by using an ultrasonic nanocoater and characterized in aspects of surface smoothness and coating thickness. In addition, in vitro release profiles of sirolimus by changing top coating layer with different biodegradable polymers were investigated. Smooth surfaces with variable thickness could be fabricated by optimizing polymer concentration, flow rate, nozzle-tip distance, gas pressure, various solvents and ultrasonic power. Smooth surface could be generated by using volatile solvents (acetone, chloroform, and methylene chloride) or post-treating with solvent vapor. Coating thickness could be controlled by varying injection volume or polymer concentration, and higher concentration could reduce the coating time while obtaining the same thickness. The thickness measurement was the most effectively performed by a conventional cutting method among three different methods that were investigated in this study. Release profiles of sirolimus were effectively controlled by changing polymers for top layer. PLGA made the release rate 3 times faster than PDLLA and PLLA and all top layers prevented burst release at the initial phase of profiles. Our results will provide useful and informative knowledge for developing drug-eluting stents, especially coated with biodegradable polymers.

Interactions of methylated $\beta$-cyclodextrin and hydrophobically modified alkali-soluble emulsion (HASE) polymers: a rheological study

  • Gupta, R.K.;Tam, K.C.;Ong, S.H.;Jenkins, R.D.
    • Korea-Australia Rheology Journal
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    • v.12 no.2
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    • pp.93-100
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    • 2000
  • The interactions between methylated $\beta$-cyclodextrin (CD) and hydrophobically modified alkali-soluble associative polymers (HASE) were examined by a rheological technique. The effect of "capping" of hydrophobes by methylated $\beta$-cyclodextrin on the viscosity and modulus was evaluated. Model HASE polymers with $C_1$to $C_{20}$ alkyl hydrophobic groups ethoxylated with~10 moles of ethylene-oxide (EO 10) and at concentrations up to 3 wt% were examined. With the addition of methylated $\beta$-CD, the steady shear viscosity profiles shift from a Newtonian profile to one that display a shear-thinning characteristic. Significant "capping" of the hydrophobes occurs for HASE polymers with $C_{l2}$, $C_{16}$ and $C_{20}$ hydrophobes as reflected by the large reduction in the viscosity. However, the steady shear viscosity remains constant when the concentration of $\beta$-CD exceeds 1 wt%, suggesting that $\beta$-CD is not able to fully encapsulate the hydrophobes of the HASE polymer. The temperature variation plots indicate that the activation energy of the HASE-EO10-$C_{20}$ system and $\beta$-CD is dependent on the magnitude of the applied shear stress. These results further reinforce the hypothesis that $\beta$-CD is not able to completely remove all the hydrophobic associations.phobic associations.

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Linear viscoelastic behavior of acrylonitrile-butadiene-styrene(ABS) polymers in the melt: Interpretation of data with a linear viscoelastic model of matrix/core-shell modifier polymer blends

  • Park, Joong-Hwan;Ryu, Jong-Hoon;Kim, Sang-Yong
    • Korea-Australia Rheology Journal
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    • v.12 no.2
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    • pp.135-141
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    • 2000
  • The linear viscoelastic behavior of acrylonitrile-butadiene-styrene (ABS) polymers with different rubber content has been investigated in the frame of a linear viscoelastic model, which takes into account the inter-connectivity of the dispersed rubber particles. The model developed in our previous work has been shown to properly predict the low frequency plateau for the storage modulus, which is generally observed in polymer blends containing core-shell-type impact modifiers. In the present study, further experiments have been carried out on ABS polymers with different rubber content to verify the validity of our linear viscoelastic model. It has been found that our model describes quite properly the rheological behavior of ABS polymers with different rubber content, especially at low frequencies. The experimental data confirm that our model describes the rheological properties of rubber-modified thermoplastic polymers with strong adhesion at the particle/matrix interface more accurately than the Palierne model.

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Development of In situ PCR Method Using Primer Polymers (프라이머 중합체를 이용한 원위치 중합효소 연쇄반응 In situ PCR 방법의 개발)

  • 장진수;이재영
    • Korean Journal of Microbiology
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    • v.40 no.2
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    • pp.167-171
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    • 2004
  • Reduction in the leakage of the amplified PCR product out of cell is required for effective in situ PCR. For this purpose, primers with complementary tail sequences at their 5' sides were utilized to synthesize high molecular weight PCR products, but it is time-consuming and causes deterioration of cellular appearance with many PCR cycles. Therefore, it is required to optimize the PCR condition with minimal PCR cycles. To achieve the pur-pose, primer polymers were made without the target DNA in tube from nonspecific amplification with tailed primers and treated onto the fixed Molt/LAV cells on the glass slide for the 20 cycle-in situ PCR, in which the appropriate target signals were observed for the possible use of primer polymers in in situ PCR.

Study on Phase Separation of Carbon Dioxide-reducible Polymer Blends (이산화탄소 저감형 고분자 블렌드의 상 분리 특성연구)

  • Cho, Yong-Kwang;Kim, Yeong-Woo;Lee, Hak Yong;Park, Sang-Bo;Park, Chan-Young;Lee, Won-Ki
    • Journal of Environmental Science International
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    • v.24 no.1
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    • pp.9-15
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    • 2015
  • Sustainable and eco-friendly polymers, natural polymers, bio-based polymers, and degradable polyesters, are of growing interest because of environmental concerns associated with waste plastics and emissions of carbon dioxide from preparation of petroleum-based polymers. Degradable polymers, poly(butylene adipate-co-terephthalate) (PBAT), poly(propylene carbonate) (PPC), and poly(L-lactic acid) (PLLA), are related to reduction of carbon dioxide in processing. To improve a weak mechanical property of a degradable polymer, a blending method is widely used. This study was forced on the component separation of degradable polymer blends for effective recycling. The melt-mixed blend films in a specific solvent were separated by two layers. Each layer was analysed by FT-IR, DSC, and contact angle measurements. The results showed that each component in the PPC/PLLA and PPC/PBAT blends was successfully separated by a solvent.

A Study on the Characterization of Intrinsic Flame Retardant and Heat Resistant Sulfur-Bridged Heterocyclic Polymers (본질적 난연 및 내열성 헤테로환식 폴리머의 특성에 관한 연구)

  • Young-Goo Kang;Hong Kim;Ho-Suk Ryu
    • Journal of the Korean Society of Safety
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    • v.12 no.3
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    • pp.173-178
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    • 1997
  • The intrinsic flame retardant and heat resistant polymers such as PQXS [poly( quinoxaline )sulfide], PIQS [poly(isoquinoline)sulfide] and PQS [poly(quinoline)sulfide] were synthesized from 2, 3-dichloroquinoxaline, 1, 3-dichloroisoquinoline and 4, 7-dichloroquinoline. They were characterized by FT-IR, UV/Vis spectroscopy, DTA and elemental analysis. The melting point above $350^{\circ}C$ of the polymers show higher than that of the heat resistant PPS polymer(mp. $295^{\circ}C$), In the LOI test, the polymers exhibit an intrinsically high flame retardant property having the LOI values in the range of 41~42. The vertical burning test for the polymers also show an UL 94 V-0 performance.

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NMR Microimaging for Noninvasive Investigation of Polymers (고분자의 비파괴 연구를 위한 핵자기 공명 현미영상법)

  • Lee, D.H.;Ko, R.K.;Moon, C.H.;Cho, Z.H.
    • Proceedings of the KOSOMBE Conference
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    • v.1995 no.11
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    • pp.253-256
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    • 1995
  • Polymers have been one of the emerging biomedical materials in the area of biomedical research which are applicable to the human body. For human applications, noninvasive characterization of the biomedical polymers has been one of the important topics, and is valuable information. Among others, the swelling rate is one of the important measurements needed for the hydrophilic polymers. NMR imaging has been a suitable method for the noninvasive study of such a material since it is sensitive to many physical and biochemical changes of the specimens. In addition, NMR techniques possess many useful intrinsic properties such as the relaxation and diffusion effects. The present study has provided a noble and noninvasive method of measuring the process of swelling as well as volumetric changes occurred in polymers and drug delivery processes in a drug delivery system (DDS) together with changes of released drug. This gives information, relating with both water ingress process, volumetric changes of polymer specimens and the visualization of sequential drug delivery process. Also, this study provides more reliable method to ascertain the time dependent swelling process compared to the conventional method. The important aspects is that the proposed method is truly noninvasive and is able to ascertain time dependent processes.

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