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

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Scale-up Polymerization of L -Lactide in Supercritical Fluid (초임계 유체에서 L-Lactide의 Scale-up 중합)

  • Prabowo, Benedictus;Kim, Se-Yoon;Choi, Dong-Hoon;Kim, Sao-Hyun
    • Polymer Korea
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    • v.35 no.4
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    • pp.284-288
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    • 2011
  • For the purpose of the pre-industry production of poly(L-lactide) (PLLA) and full understanding of the supercritical polymerization system, large scale polymerization of L-iactide initiated by 1-dodecano/stannous 2-ethyl-hexanoate (DoOH/Sn(Oct)$_2$) was carried out in supercritical chlorodifluoromethane under various reaction conditions (time, temperature and pressure)and reactants (monomer and supercritical solvent) concentrations. A 3 L sized-reactor system was used throughout this study. The monomer conversion increased to 72% on increasing reaction time to 5 h. The molecular weight of PLLA product also increased to 68000 g/moi over the same period. An increase in monomer concentration resulted in a higher molecular weight, up to 144000 g/mol and 97% of monomer conversion. Raising the reaction pressure from 130 to 240 bar also resulted in an increased monomer conversion and molecular weight. To increase heat resistivity of PLLA, methanol treatment and heat-vacuum methods were evaluated. Both of them successfully improved the heat resistivity property of PLLA.

Synthesis of Methoxy Poly(ethylene glycol)/Polyesters Diblock Copolymers and Evaluation of Micellar Characterization as Drug Carrier (메톡시 폴리(에틸렌 글리콜)/폴리에스테르 블록공중합체의 합성 및 미셀 특성 비교)

  • Hyun, Hoon;Yang, Jae-Chan;Kim, Moon-Suk;Lee, Hai-Bang;Khang, Gil-Son
    • Polymer Korea
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    • v.30 no.6
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    • pp.464-470
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    • 2006
  • Diblock copolymers consisting of methoxy Poly (ethylene glycol) (MPEG) and poly (${\epsilon}-ca$ prolactone) (PCL), poly(${\delta}-valerolactone$) (PVL), poly(L-lactide) (PLLA), or poly(L-lactide-co-glycolide) (PLGA) were prepared to compare the characterization of diblock copolymers as a drug carrier. MPEG-PCL, MPEG-PVL, MPEG-PLLA, and MPEG-PLGA diblock copolymers were synthesized by the ring-opening polymerization of ${\epsilon}$-caprolactone or ${\delta}$-valerolactone in the presence of $HCl{\cdot}Et_2O$ as a monomer activator at room temperature and by the ring-opening polymerization of L-lactide or a mixture of L-lactide and glycolide in the presence of stannous octoate at $130^{\circ}C$, respectively. The synthesized diblock copolymers were characterized with $^1H-NMR$, GPC, DSC, and XRD. The micellar characterization of MPEG-polyester diblock copolymers in an aqueous phase was carried out by using NMR, dynamic light scattering, AFM, and fluorescence techniques. Most micelles exhibited a spherical shape in AFM. Thus, ore confirmed that the micelles formed with MPEG-polyester diblock copolymers have possibility as a potential hydrophobic drug delivery vehicle because a hydrophobic drug could be preferentially distributed in the micelle core.

Synthesis and Physical Properties of New Biodegradable Polyester-Polypeptide Copolymer

  • Yong Kiel Sung;Chu
    • Journal of Biomedical Engineering Research
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    • v.13 no.2
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    • pp.147-154
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    • 1992
  • Poly (glycolic aclu-co-glycine-L-lactic aclu) has been prepared by rlng opening polymerlzation. The monomer 6-methyl morpholine-2, 5-dlone was synthe-slzed by bromoproplonylation of 2 bromopropionyl bromide with glycine. Glycolide and 6-methyl morpholine-2, 5-dione have been used as starling materials for polydepsipeptides. The synthesized copolymers have been Identlrled by NMR and FT-lR spectrophotometer. The Tg value of poly(glycollc aclu-co glycine-L-tactic acld ) Is In creased with increasing mole fraction of 6-methylmorpholine-2, 5-dlone(60-$84^{\circ}C$). The glass trasltion temperature of poly(glycolic acid-co-glycine-L-lactic-acid) (62-$86^{\circ}C$) is lower than that of poly (L-lactic acrid-co-glycine-L-lactic acid ). The thermal degradation of poly( L-lactic acid-co- glycine-L-lactic acid ) Is decreased with increasing mole fraction of L-lactide. The thermal degrada pion of poly(glycolic acrid-co-91ycine-L-lactic aclu ) is increased with increasing mole Fraction of glycolide.

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Synthesis and Characterization of Biodegradable MethoxyPoly(ethylene glycol)-Poly$(\varepsilon-caprolactone-co-L-lactide)$ Block Copolymers (메톡시폴리(에틸렌 글리콜)-폴리(카프로락톤-co-L-락타이드) 공중합체의 합성 및 특성 분석)

  • Hyun Hoon;Cho Young Ho;Jeong Sung Chan;Lee Bong;Kim Moon Suk;Khang Gilson;Lee Hai Bang
    • Polymer Korea
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    • v.30 no.1
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    • pp.28-34
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    • 2006
  • A series of methoxypoly(ethylene glycol) $(MPEG)-poly(\varepsilon-co-L-lactide)$ (PCLA) diblock copolymers were synthesized by ring-opening polymerization of a mixture of $\varepsilon-caprolactone$ and L-lactide with different ratios in the presence of $Sn(Oct)_2$. The characterization of MPEG-PCLA diblock copolymers were examined by $^1H-NMR$, GPC, DSC, and XRD. Kinetic study on ring-opening polymerization of monomer mixtures was carried out in various conditions such as a variation with polymerization time, amount of catalyst, and temperature. The highest conversion obtained in 1.2 ratic of initiator venn catalyst at $110\;^{\circ}C$. The biodegradable characterization of MPEG-PCLA diblock copolymers in aqueous solution was carried out by using GPC for $1\~14$ weeks. The biodegradability of MPEG-PCLA diblock copolymers increased as the L-lactide content of diblock copolymers increased. In conclusion, we confirmed the dependence of polymerization rate according to various conditions. In addition, we can control the biodegradability of MPEC-PCLA diblock copolymers by changing the ratio of PCL and PLA block segment.

Control of Hydrolytic Degradation of Polylactide Mixtures Using Optical Isomers (광학이성질체를 이용한 폴리락타이드 혼합물의 가수분해성 조절)

  • Lee, Won-Ki
    • Polymer Korea
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    • v.36 no.3
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    • pp.309-314
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    • 2012
  • To control degradation rate of biodegradable poly(lactide)s (PLA), the stereochemical PLAs with different ratios of $d$-lactide and $l$-lactide units were synthesized by the ring open polymerization and a degradation behavior was measured by a Langmuir film balance. Degradation rates of mixture monolayers on alkaline subphase were investigated as a function of optical purity of mixture component, 100, 99, 97 and 95%. As increasing their optical purity, melting temperatures of mixtures from stereocomplexation increased. The degradation rate of mixture monolayer with 100% optical purity was much slower than that of each homopolymer one and the others showed 2 step degradation behaviors. In the first step, the degradation which is faster than that of each homopolymer occurs in the uncomplexed region, and secondly, the degradation occurred in the complexed region which showed similar degradation rate to that of 100% optical purity. These results indicate that the alkaline degradation of stereochemical PLAs could be controlled by stereochemistry and stereocomplexation between enantiomer PLAs.

Preparation and In Vitro Release of DNA-Loaded Poly(D,L-lactic-co-glycolic acid) Microspheres (DNA가 봉입된 Poly(D,L-lactic-co-glycolic acid) 미립구의 제조 및 시험관내 방출)

  • Son, Hye-Jung;Kim, Jin-Seok
    • Polymer Korea
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    • v.29 no.1
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    • pp.69-73
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    • 2005
  • To overcome the main disadvantages of non-viral gene delivery systems such as repeated administration due to the low transfection efficiency, poly(D,L-lactide-co-glycolide) was applied to encapsulate pDNA in its microsphere formulation. Free pDNA or various ratios (w/w) of chitosan/pDNA complexes was used for encapsulation, with the resulting encapsulation efficiency of 44%, 5%, and 8% for free pDNA, 0.7:1 and 1:1 ratios, respectively. Scanning electron micrographs of poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres encapsulating pDNA or chitosan-condensed pDNA revealed a smooth spherical shape immediately after microsphere preparation and a collapsed porous shape in 41 days due to the degradation of PLGA. In vitro release profile showed that the 0.7:1 (w/w) ratio formulation exerted 47% release in 26 days, whereas free pDNA or 1:1 (w/w) ratio formulation did only 15% or 32%, respectively.

Copolymerization of L-Lactide and ${\varepsilon}$-Caprolactone in Supercritical Fluid

  • Prabowo, Benedictus;Choi, Dong-Hoon;Kim, Soo-Hyun
    • Macromolecular research
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    • v.17 no.8
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    • pp.575-579
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    • 2009
  • Copolymerization of L-lactide and s-caprolactone initiated by tin (II) octoate (Sn(Oct)$_2$) was carried out in supercritical chlorodifluoromethane (R22) with varying reaction conditions (time and temperature) and amounts of monomer and catalyst, under a pressure of 250 bar. The optimum conditions were a reaction time of 10 h and a temperature of 130 $^{\circ}C$, which is similar to the temperature used in bulk copolymerization system. The conversion increased from 56% to 76% by increasing the reaction time from 1 to 10 h. The molecular weight also increased to 75,900 g.mol$^{-1}$ over the same period, while the increased monomer concentration resulted in a high molecular weight of 86,400 g.mol$^{-1}$ and a monomer conversion of 84%. Raising the reaction temperature from 90 to 130 $^{\circ}C$ increased the monomer conversion as well as the poly-L-lactide-co-${\varepsilon}$-caprolactone (PLCL) molecular weight. The variation on the stannous octoate catalyst suggested that less catalyst would decrease the caprolactone content of the polymer.

Effect of Biodegradable Polymer Coating on the Corrosion Rates and Mechanical Properties of Biliary Magnesium Alloy Stents (생분해성 고분자 코팅이 담관용 마그네슘 합금 스텐트의 분해 속도와 기계적 물성에 미치는 영향)

  • Kim, Hyun Wook;Lee, Woo-Yiel;Song, Ki Chang
    • Korean Chemical Engineering Research
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    • v.58 no.1
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    • pp.36-43
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    • 2020
  • A biliant stent was fabricated using a magnesium alloy wire, a biodegradable metal. In order to control the fast decomposition and corrosion of magnesium alloys in vivo, magnesium alloy wires were coated with biodegradable polymers such as polycaprolactone (PCL), poly(propylene carbonate) (PPC), poly (L-lactic acid) (PLLA), and poly (D, L-lactide-co-glycolide) (PLGA). In the case of PPC, which is a surface erosion polymer, there is no crack or peeling compared to other polymers (PCL, PLLA, and PLGA) that exhibit bulk erosion behavior. Also, the effect of biodegradable polymer coating on the axial force, which is the mechanical property of magnesium alloy stents, was investigated. Stents coated with most biodegradable polymers (PCL, PLLA, PLGA) increased axial forces compared to the uncoated stent, reducing the flexibility of the stent. However, the stent coated with PPC showed the axial force similar to uncoated stent, which did not reduce the flexibility. From the above results, PPC is considered to be the most efficient biodegradable polymer.

Evaluation of In Vitro Release Profiles of Fentanyl-Loaded PLGA Oligomer Microspheres

  • Gilson Khang;Seo, Sun-Ah;Park, Hak-Soo;John M. Rhee;Lee, Hai-Bang
    • Macromolecular research
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    • v.10 no.5
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    • pp.246-252
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    • 2002
  • In order to the development of the delivery device of long-acting local anesthetics for postoperative analgesia and control of chronic pain of cancer patient, fentnyl-loaded poly (L-lactide-co-glycolido) (PLGA, molecular weight, 5,000 g/mole; 50 : 50 mole ratio by lactide to glycolide) microspheres (FMS) were studied. FMS were prepared by an emulsion solvent-evaporation method. The influence of several preparation parameters such as initial drug loading, PLGA concentration, emulsifier concentration, oil phase volume, and fabrication temperature has been investigated on the fentanyl release profiles. Generally, the drug showed the biphasic release patterns, with an initial diffusion followed by a lag period before the onset of the degradation phase, but there was no lag time in our system. Fentanyl was slowly released from FMS over 10 days in vitro with a quasi-zero order property. The release rate increased with increasing drug loading as well as decreasing polymer concentration with relatively small initial burst effect. From the results, FMS may be a good formulation to deliver the anesthetic for the treatment of chronic pain.

Poly(l-lactide) membranes with biomimetic nanolayer for bone induction for tissue regeneration

  • Chung , Ji-Eun;Lee, Jue-Yeon;Kim, Kyung-Hwa;Baek, Hyun-Jin;Ku , Young;Chung, Chong-Pyung;Lee, Seung-Jin
    • Proceedings of the PSK Conference
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    • pp.226.2-226
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    • 2003
  • .The healing of a bone defect is complex, and involves a wide range of cellular, molecular, physiological, and biological processes. The main effect of bone substitute is to promote wound healing by induce cell proliferation. Bone defect sites usually are localized below the original bone surface; therefore, space production and maintenance between the membrane and the original bone surface is essential. As a result, membranes must have proper mechanical strength to prevent the collapse of the soft tissue and maintain wound space that permits membranes of poly (L-lactide) (PLLA) were fabricated to provide and maintain sufficient space for bone growth. (omitted)

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