• Fibers and Polymers
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• v.3 no.4
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• pp.153-158
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• 2002

A series of waterborne polyurethanes (WBPU) were prepared from 4,4-dicyclohexylmethane diisocyanate ($H_{12}$MDI),2,2-bis(hydroxylmethyl) propionic acid (DMPA), othylenediarnine (EDA), triethylamine (TEA), and triblock glycol [TBG, ($\varepsilon$-caprolactone)$_{4.5}$-poly(tetramethylene ether) glycol (MW= 2000)-($\varepsilon$-caprolactone)$_{4.5}$: $(CL)_{4.5}$-PTMG-$(CL)_{4.5}$, MW=3000] as a soft segment. Two melting peaks of TBG at about 14$^{\circ}C$ and 38$^{\circ}C$ were observed indicating the presence of two different crystalline domains composed of CL and PTMG dominant component. The effect of soft segment content (60-75 wt%) on the colloidal properties of dispersion, and thermal and mechanical properties of WBPU films, the water vapor permeability (WVP) and water resistance (WR) of WBPU-coated Nylon fabrics, and the adhesive strength of WBPU- coated layer and Nylon fabrics was investigated. As soft segment contents increased, the water vapor permeability of WBPU- coated Nylon fabrics increased from 3615 to 4502 g/$m^2$day, however, the water resistances decreased from 1300 to 500 mm$H_2$O.O.

• YAKHAK HOEJI
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• v.39 no.1
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• pp.31-35
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• 1995

An unusual 10-membered lactone possesing ring-olefin at 7, 8-position has been efficiently synthesized. The $\omega$-hydroxy acid as a cyclization precusor was derived from $\varepsilon$-caprolactone in 41% overall yield of 7 steps and efficiently cyclized by Mukaiyama procedure.

• Fibers and Polymers
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• v.6 no.1
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• pp.13-18
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• 2005

PLA/LPCL/HPCL blend fibers composed of poly (lactic acid) (PLA), low molecular weight poly ($\varepsilon$-caprolactone) (LPCL), and high molecular weight poly ($\varepsilon$-caprolactone) (HPCL) were prepared by melt blending and spinning for bioab­sorbable filament sutures. The effects of blending time and blend composition on the X-ray diffraction patterns and tensile properties of PLA/LPCL/HPCL blend fibers were characterized by WAXD and UTM. In addition, the effect of in vitro degra­dation on the weight loss and tensile properties of the blend fibers hydrolyzed during immersion in a phosphate buffer solu­tion at pH 7.4 and 37$^{\circ}C$ for 1-8 weeks was investigated. The peak intensities of PLA/LPCL/HPCL blend fibers in X-ray diffraction patterns decreased with an increase of blending time and LPCL contents in the blend fibers. The weight loss of PLA/LPCL/HPCL blend fibers increased with an increase of blending time, LPCL contents, and hydrolysis time while the tensile strength and modulus of the blend fibers decreased. The tensile strength and modulus of the blend fibers were also found to be increased with an increase of HPCL contents in the blend fibers. The optimum conditions to prepare PLA/LPCL/HPCL blend fibers for bioabsorbable sutures are LPCL contents of $5 wt\%, HPCL contents of $35 wt\%, and blending time of 30 min. The strength retention of the PLA/LPCL/HPCL blend fiber prepared under optimum conditions was about $93.5\% even at hydrolysis time of 2 weeks.

• Polymer(Korea)
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• v.34 no.6
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• pp.574-578
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• 2010

In this study, the caprolactone modified hydroxy acrylates (CHAs) were synthesized by ring-opening reaction of caprolactone and 2-hydroxyethyl acrylate (2-HEA) as initiator. Also, the caprolactone modified urethane acrylate (UA) oligomers were synthesized by condensation reaction of previously synthesized CHAs, 2-hydroxyethyl acrylate (2-HEA) and hexamethylene diisocyanate trimer (HDT). Using the hydroxy number of CHAs, the molecular weights of the CHAs were calculated easily and their molecular weight was similar to the theoretical molecular weight of them. The viscosity of UA oligomers decreased as increasing a content of CHA in the UA oligomer. Cure films were prepared from UA oligomer, reactive diluents, and UV initiator to investigate their physical properties. The thermal stability and color difference on high temperature for the cured film were improved as increasing the crosslinking density. Their surface hardness was also increased as increasing crosslinking density of the cured films, but their elongation at break was decreased.

• Journal of Biomedical Engineering Research
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• v.40 no.1
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• pp.7-14
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• 2019

The microencapsulation of nifedipine (NF) with 4 wt% of poly(${\varepsilon}-caprolactone$) (PCL)/polyvinylpyrollidone (PVP) or PCL/polyethylene glycol (PEG) was carried out by solvent evaporation method in oil in water emulsion system to investigate the effect of PVP and PEG addition on drug release behavior of the microcapsules. The PVA (emulsifier) concentration of 1.0 wt% was chosen for the formation of PCL capsule having an average size of $154{\pm}25{\mu}m$ due to nearly spherical shape with a narrow size distribution. As PCL/PVP and PCL/PEG ratios were raised from 10/0 to 6/4, the capsule size increased gradually from $154{\pm}25{\mu}m$ to $236{\pm}32{\mu}m$ and $248{\pm}56{\mu}m$, respectively. The drug release rate of PCL/PVP and PCL/PEG capsules increased dramatically from 0 to 4 h at the beginning and then reached the plateau region from 20 h. As the concentration of PVP or PEG increased, the amount of drug release increased, suggesting that the larger capsule size was attributed to the higher drug content. However, the drug release behavior remained almost constant. The PCL capsules exhibited no evidence of causing cell lysis or toxicity regardless of NF loading, implying that the microcapsules are clinically suitable for use as drug delivery systems.

• Polymer(Korea)
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• v.30 no.2
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• pp.146-151
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• 2006

Linear and branched copolymers consisting of poly(ethylene glycol) (PEG) and $Poly({\varepsilon}-caprolactone)$ (PCL) were prepared to compare the characterization of star-shaped copolymers with various molecular architecture. Linear and branched PEG-PCL (1-arm, 2-arm, 4-arm, and 8-arm) copolymers were synthesized by the ring-opening polymerization of ${\varepsilon}-caprolactone$ in the presence of HCl $Et_2O$ as a monomer activator at room temperature. The synthesized copolymers were characterized with $^1H-NMR$, GPC, DSC, and XRD. As a result of the DSC and XRD, each copolymers showed different thermal properties and crystallinity according to the number of ms. The micellar characterization of linear and branched copolymers in an aqueous phase was carried out by using NMR, dynamic light scattering, AM, and fluorescence techniques. The critical micelle concentration (CMC) and diameters of micelles depended on the number of arms. Most micelles exhibited a spherical shape in AFM. In this study, we characterized star-shaped PEG-PCL copolymers and investigated their molecular architecture effect on the various properties. Furthermore, we confirmed that the micelles termed with linear and branched PEG-PCL copolymers have possibility as a potential hydrophobic drug delivery vehicle.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.531-532
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• 2012

• Polymer(Korea)
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• v.38 no.4
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• pp.477-483
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• 2014

Poly(lactic acid) (PLA) and poly(${\varepsilon}$-caprolactone) (PCL) blends with various components for melt-blown non-wovens were prepared by a twin-screw extruder. Tributyl citrate (TBC) was added in order to improve the miscibility between PLA and PCL. The results showed that small circular particles of PCL were dispersed in PLA matrix uniformly. The addition of PCL had the heterogeneous nucleation effect on the crystallization of PLA and decreased thermal stability of PLA. The flow of pure PLA and blends approached to Newtonian liquid at a low shear rate and expressed more obvious viscoelasticity at a high shear rate.

• Journal of Radiation Industry
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• v.5 no.4
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• pp.365-370
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• 2011

Electrospun nanofibers prepared with synthetic biodegradable polymer have some limitations in regulating adhesion, proliferation, and spreading of cells because of their surface hydrophobicity and absence of cell-interaction. In this study, we functionalized the electrospun poly(L-lactide-co-${\varepsilon}$-caprolactone) (PLCL) nanofibers with acrylic acid (AAc) to modulate their surface hydrophilicity using electron-beam irradiation method and then measured grafting ratio of AAc, water contact angle, and ATR-FTIR of AAc-grafted nanofibers. A grafting ratio of AAc on the nanofibers was increased as irradiation dose and AAc concentration were increased. AAc-grafted nanofibers also have higher wettability than non-modified nanofibers. In conclusion, those surface-modified nanofibers may be an essential candidate to regulate cell attachment in tissue engineering applications.

• Polymer(Korea)
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• v.27 no.5
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• pp.464-469
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• 2003

In this work, the fragrant oil release behavior of poly($\varepsilon$-caprolactone) (PCL) microcapsules containing SiO$_2$ was investigated. The SiO$_2$ was chemically treated in 10, 20, and 30 wt% hydrochloric acid and sodium hydroxide. The acid and base values were determined by Boehm's titration technique and $N_2$/77 K adsorption isotherm characteristics, the specific surface area and total pore volume were studied by BET. The PCL microcapsules containing SiO$_2$ and fragrant oil were prepared by oil-in-water (o/w) emulsion solvent evaporation method. The shape and surface of PCL microcapsules were observed using image analyzer and scanning electron microscope (SEM). The fragrant oil release behavior of PCL microcapsules was characterized using UV/vis. spectra. The average diameters of PCL microcapsules were decreased from 35 to 21 $\mu$m with increasing stirring rate. It was found that in the case of acidic treatment the fragrant oil adsorption capacity and release rate were increased due to the increase of specific surface area and acid value. In the case of basic treatment, the fragrant oil adsorption capacity and release rate were decreased due to the decrease of sp ecific surface area and the increase of acid-base interactions between SiO$_2$-NaOH and fragrant oil with increasing base value of SiO$_2$.