• Title, Summary, Keyword: Poly(l-lactide)

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A Study on the Interfacial Properties of Bioabsorbable Fibers/PoIy-L-Lactide Composites using Micromechanical Tests and Surface Wettability Measurement (Micromechanical 시험법과 표면 젖음성 측정을 이용한 생흡수성 섬유 강화 Poly-L-Lactide 복합재료의 계면물성 연구)

  • Park, Joung-Man;Kim, Dae-Sik;Kim, Sung-Ryong
    • Journal of Adhesion and Interface
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    • v.3 no.2
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    • pp.17-29
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    • 2002
  • Interfacial properties and microfailure degradation mechanisms of the bioabsorbable composites for implant materials were investigated using micromechanical technique and measurement of surface wettability. As hydrolysis time increased, the tensile strength, the modulus and the elongation of poly(ester-amide) (PEA) and bioactive glass fibers decreased, whereas those of chitosan fiber almost did not change. Interfacial shear strength (IFSS) between bioactive glass fiber and poly-L-lactide (PLLA) was much higher than PEA or chitosan fiber/PLLA systems using dual matrix composite (DMC) specimen. The decreasing rate of IFSS was the fastest in bioactive glass fiber/PLLA composites whereas that of chitosan fiber/PLLA composites was the slowest. Work of adhesion, $W_a$ between bioactive glass fiber and PLLA was the highest, and the wettability results were consistent with the IFSS. Interfacial properties and microfailure degradation mechanisms can be important factors to control bioabsorbable composite performance.

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Encapsulation of CdSe/ZnS Quantum Dots in Poly(ethylene glycol)-Poly(D,L-lactide) Micelle for Biomedical Imaging and Detection

  • Lee, Yong-Kyu;Hong, Suk-Min;Kim, Jin-Su;Im, Jeong-Hyuk;Min, Hyun-Su;Subramanyam, Elango;Huh, Kang-Moo;Park, Sung-Woo
    • Macromolecular research
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    • v.15 no.4
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    • pp.330-336
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    • 2007
  • Luminescent CdSe/ZnS QDs, with emission in the red region of the spectrum, were synthesized and encapsulated in poly(ethylene glycol)-poly(D,L-lactide) diblock copolymer micelles, to prepare water-soluble, bio-compatible QD micelles. PEG-PLA diblock copolymers were synthesized by ring opening polymerization of D,L-lactide, in the presence of methoxy PEG as a macro initiator. QDs were encapsulated with PEG-PLA polymers using a solid dispersion method in chloroform. The resultant polymer micelles, with encapsulated QDs, were characterized using various analytical techniques, such as UV- Vis measurement, light scattering, fluorescence spectroscopy, transmission electron microscopy (TEM) and atomic forced microscopy (AFM). The polymer micelles, with encapsulated QDs, were spherical and showed diameters in the range of 20-150 nm. The encapsulated QDs were highly luminescent, and have high potential for applications in biomedical imaging and detection.

Synthesis and Characterization of Biocompatible Block Copoly (L-Lactde-$\gamma$-Benzyl-L-Glutamate) (생체적합성 공중합체의 합성과 물성에 관한 연구 -Block Copoly (L-Lactde-$\gamma$-Benzyl-L-Glutamate)-)

  • Sung, Yong-Kiel;Kim, Hoon;Song, Dae-Kyung;Kim, Young-Soon;Paek, U-Hyun
    • Journal of Biomedical Engineering Research
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    • v.9 no.2
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    • pp.215-224
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    • 1988
  • Block copoly(L-lactide-${\gamma}$-benzyl-L-glutamate)was synthesized from L-lactide by cationic ring opening polymerization and ${\gamma}$-benzyl-L-glutamate N-carboxy anhydride by introducing amino group terminated poly(L-lactide). L-lactide was polymerized in the presence of stannous octate at $110^{\circ}C$ and ${\gamma}$-benzyl- L-glutamate was polymerized in the presence of NaH at room temperature. The synthesized monomers and copolymers were identified by IR and NMR. The Itermal properties of the copolymers were characterized by differential scanning calorimetry and thermogravimetry. The thermal stability and melting temperature(Tm) of the block copolymers were measured and discussed. The activation energies of thermal decomposition for the block copoly(L-lactide-${\gamma}$ benzyl-L-glutamate) were evaluated from the thermogravimetric data by Freeman and Carroll method.

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생분해성 고분자 합성을 위한 락티드 합성에서 열분해 공정의 개선

  • No, Won-Gyun;Ryu, Hwa-Won
    • 한국생물공학회:학술대회논문집
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    • pp.622-624
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    • 2003
  • Poly(lactic acid) is a biodegradable themoplastic based on the renewable resources to substitute for petrochemical plastics. Most of PLA is produced by ring opening polymerization from lactide. However, pyrolysis process in the lactide synthesis is expensive, we studied lactide synthetic process for more economical preparation of PLA. In this research was tried to minimize the pyrolysis time, and obtained L-lactide from lactic acid without any catalyst.

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Introduction of Specific Interaction of Hydroxyapatite/Polylactide Composites (수산화인회석과 폴리락타이드 복합체에서 상호작용력의 도입)

  • Kang, Jin-Kyu;Lim, Jun-Heok;Moon, Myong-Jun;Lee, Won-Ki;Kim, Mi-Ra;Lee, Jin-Kook
    • Polymer Korea
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    • v.33 no.1
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    • pp.13-18
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    • 2009
  • To increase mechanical properties of the hydroxyapatite/poly (L-lactide) (HA/PLLA) composite which was a potential bone substitute material, HA was modified by the surface grafting with D-lactide (DLA) and the formation of stereocomplexes between components was introduced. The composite films were prepared by the solvent-nonsolvent technique to minimize the precipitation of HA during drying. The structure and properties of the composites were investigated by thermal gravimetric analysis (TGA), differential scanning calorimeter, and scanning electron microscopy, and mechanical property measurements. TGA results showed that the amount of DLA grafted on the HA surfaces (g-HA) was 6 wt%. The obtained g-HA exhibited better dispersity in an organic solvent than HA. The formation of stereocomplexes in the composites was confirmed by the change in melting temperature. The mechanical properties of g-HA/PLLA composites were increased, compared to the HA/PLLA composites.

Polymerization of L-lactide Using Methylalumionxane (Methylaluminoxane을 이용한 L-lactide 중합)

  • Yim, Jin-Heong;Kim, Da Hee;Ko, Young Soo
    • Polymer Korea
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    • v.39 no.3
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    • pp.365-369
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    • 2015
  • In this study, the bulk and solution polymerizations of L-lactide using an aluminium compound, methylaluminoxane (MAO), were performed. In the bulk polymerization, the conversion of polymerization was increased with increasing the amount of catalyst in feed. The largest molecular weight (Mw), 60800 g/mol, was shown at the MAO amount in feed of 0.15 mmol, and Mw was decreased above 0.15 mmol of MAO in feed. At the 0.15 mmol of MAO in feed, turn of frequency (TOF) was the highest, and it was decreased with increasing MAO amount in feed. In the solution polymerization, the induction time of 30 min was shown. The conversion of polymerization was linearly increased with the polymerization time, and the highest Mw, 54700 g/mol, was achieved at the polymerization time of 6 h.

Characterization of Poly(ethylene oxide)-b-Poly(L-lactide) Block Copolymer by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

  • Jeongmin Hong;Donghyun Cho;Taihyun Chang;Shim, Woo-Sun;Lee, Doo-Sung
    • Macromolecular research
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    • v.11 no.5
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    • pp.341-346
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    • 2003
  • A poly(ethylene oxide)-b-poly(L-lactide) diblock copolymer (PEO-b-PLLA) is characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and a block length distribution map is constructed. Although the MALDI- TOF mass spectrum of PEO-b-PLLA is very complicated, most of the polymer species were identified by isolating the overlapped isotope patterns and by fitting the overlapped peaks to the Schulz-Zimm distribution function. Reconstructed MALDI-TOF MS spectrum was nearly identical to the measured spectrum and this method shows its potential to be developed as an easy and fast analysis method of low molecular weight block copolymers.

Effect of Collector Temperature on the Porous Structure of Electrospun Fibers

  • Kim Chi Hun;Jung Yoon Ho;Kim Hak Yong;Lee Douk Rae;Dharmaraj Nallasamy;Choi Kyung Eun
    • Macromolecular research
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    • v.14 no.1
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    • pp.59-65
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    • 2006
  • We report a new approach to fabricate electrospun polymer nonwoven mats with porous surface morphology by varying the collector temperature during electrospinning. Polymers such as poly(L-lactide) (PLLA), polystyrene (PS), and poly(vinyl acetate) (PVAc) were dissolved in volatile solvents, namely methylene chloride (Me) and tetrahydrofuran (THF), and subjected to electrospinning. The temperature of the collector in the electrospinning device was varied by a heating system. The resulting nonwoven mats were characterized by using scanning electron microscopy (SEM), field emission SEM (FESEM), and atomic force microscopy (AFM). We observed that the surface morphology, porous structure, and the properties such as pore size, depth, shape, and distribution of the nonwoven mats were greatly influenced by the collector temperature.

Microfailure Degradation Mechanisms and Interfacial Properties of Bioabsorbable Composites for Implant Materials using Micromechanical Technique and Acoustic Emission (Micromechanical 시험법과 음향방출을 이용한 Implant용 Bioabsorbable 복합재료의 미세파괴 분해메커니즘과 계면물성)

  • 박종만;김대식
    • Composites Research
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    • v.14 no.4
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    • pp.15-26
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    • 2001
  • Interfacial properties and microfailure degradation mechanisms of the bioabsorbable composites fur implant materials were investigated using micromechanical technique and nondestructive acoustic emission (AE). As hydrolysis time increased, the tensile strength, the modulus and the elongation of poly(ester-amide) (PEA) and bioactive glass fibers decreased, whereas these of chitosan fiber almost did not change. Interfacial shear strength (IFSS) between bioactive glass fiber and poly-L-lactide (PLLA) was much higher than PEA or chitosan fiber/PLLA systems using dual matrix composite (DMC) specimen. The decreasing rate of IFSS was the fastest in bioactive glass fiber/PLLA composites whereas that of chitosan fiber/PLLA composites was the slowest. AE amplitude and AE energy of PEA fiber decreased gradually, and their distributions became narrower than those in the initial state with hydrolysis time. In case of bioactive glass fiber, AE amplitude and AE energy in tensile failure were much higher than in compression. In addition, AE parameters at the initial state were much higher than those after degradation under both tensile and compressive tests. In this work, interfacial properties and microfailure degradation mechanisms can be important factors to control bioabsorbable composite performance.

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Characteristics of Nifedipine Loaded PLGA Wafer (니페디핀을 함유한 생분해성 PLGA 웨이퍼의 제조와 특성분석)

  • 서선아;최학수;이동헌;강길선;이해방
    • Polymer Korea
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    • v.25 no.6
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    • pp.884-892
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    • 2001
  • Biodegradable wafers were prepared with poly (L-lactide-co-glycolide) (50 : 50 mole ratio of lactide to glycolide, molecular weight:5000 g/mole) by direct compression method for the sustained release of nifedipine to investigate the possibility of the treatment of hypertension. PLGA wafers were prepared by altering initial drug/polymer loading ratio, wafer thickness, and hydroxypropyl methylcellulose (HPMC) content. These wafers showed new zero-order release patterns for 11 days, and various biphasic release patterns could be obtained by altering the composition of wafers such as addition of matrix binder as HPMC to the PLGA wafer to reduce release rate of initial phase. The onset of polymer mass loss only occured after 4 days and about 40% of mass loss was observed after 11 days nifedipine release. This system had advantages in terms of simplicity in design and obviousness of drug release rate and may be useful as an implantable dosage form.

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