• Macromolecular Research
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• v.16 no.7
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• pp.609-613
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• 2008

Poly($\varepsilon$-caprolactone)-poly(ethylene glycol)-poly($\varepsilon$-caprolactone) (PCL-PEG-PCL) multiblock copolymers at various hydrophobic-hydrophilic ratios were successfully synthesized by the chain extension of triblock copolymers through isocyanate (hexamethylene diisocyanate). Biodegradable films were prepared from the resulting multiblock copolymers using the casting method. The mechanical properties of the films were improved by chain extension of the triblock copolymers, whereas the films prepared by the triblock copolymers were weak and brittle. Atomic force microscopy (AFM) of the multiblock copolymer film showed that the hydrophilic PEG had segregated on the film surface. This is consistent with the observed contact angle of the films.

• Polymer(Korea)
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• v.25 no.3
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• pp.421-426
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• 2001

11-Aminododecanoic acid, to insert the functional group of -COOH reacted with the end group of poly($\varepsilon$-caprolactone) diol, and cetyltrimethylammonium bromide (CTMA), to increase the d-spacing of Montmorillonite (MMT), were intercalated into $Na^+;_-$MMT. The modified MMT was reacted with poly(${varepsilon}-caprolactone$) diol ($M_n{=2000$) in THF solution at $80^{\circ}C$ for 4 hrs. After reaction, poly(${varepsilon}-caprolactone$) ($M_n{=80000$) was mixed into the solution for 12 hrs. To prepare the PCL/clay nanocomposite film this solution was cast into the silicon mold at $60^{\circ}C$ in vacuum oven for 6 hrs. From the results of XRD and TEM, it was found that the exfoliated PCL/clay nanocomposite were prepared. The effects of the amount of MMT on the mechanical properties and thermal properties of PCL/clay nanocomposites have been investigated by tensile tester and DSC. Because the MMT was dispersed homogeneously in PCL matrix, the Young's modulus of the nanocomposite were found to be excellent. However, MMT dispersed in PCL matrix had almost no effect on the tensile strength of the composites. The crystallization temperature of PCL increased in proportion to 3 wt% MMT in the PCL matrix.

• Macromolecular Research
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• v.15 no.7
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• pp.623-632
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• 2007

Thermosensitive nanoparticles were prepared via the self-assembly of two different $poly({\varepsilon}-caprolactone)$-based block copolymers of poly(N-isopropylacrylamide)-b-$poly({\varepsilon}-caprolactone)$ (PNPCL) and poly(ethylene glycol)-b-$poly({\varepsilon}-caprolactone)$ (PEGCL). The self-aggregation and thermosensitive behaviors of the mixed nanoparticles were investigated using $^1H-NMR$, turbidimetry, differential scanning microcalorimetry (micro-DSC), dynamic light scattering (DLS), and fluorescence spectroscopy. The copolymer mixtures (mixed nanoparticles, M1-M5, with different PNPCL content) formed nano-sized self-aggregates in an aqueous environment via the intra- and/or intermolecular association of hydrophobic PCL chains. The microscopic investigation of the mixed nanoparticles showed that the critical aggregation concentration (cac), the partition equilibrium constants $(K_v)$ of pyrene, and the aggregation number of PCL chains per one hydrophobic microdomain varied in accordance with the compositions of the mixed nanoparticles. Furthermore, the PNPCL harboring mixed nanoparticles evidenced phase transition behavior, originated by coil to the globule transition of PNiPAAm block upon heating, thereby resulting in the turbidity change, endothermic heat exchange, and particle size reduction upon heating. The drug release tests showed that the formation of the thermosensitive hydrogel layer enhanced the sustained drug release patterns by functioning as an additional diffusion barrier.

• Archives of Pharmacal Research
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• v.26 no.6
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• pp.504-510
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• 2003

The aim of this study is to prepare biodegradable microspheres without the use of surfactants or emulsifiers for a novel sustained delivery carriers of protein drugs. A poly($\varepsilon$-caprolactone)/poly(ethylene glycol)/poly($\varepsilon$-caprolactone) (CEC) triblock copolymer was synthesized by the ring-opening of $\varepsilon$-caprolactone with dihydroxy poly (ethylene glycol) to prepare surfactant-free microspheres. When dichloromethane (DCM) or ethyl formate (EF) was used as a solvent, the formation of microspheres did not occur. Although the microspheres could be formed prior to lyophilization under certain conditions, the morphology of microspheres was not maintained during the filtration and lyophilization process. Surfactant-free microspheres were only formed when ethyl acetate (EA) was used as the organic solvent and showed good spherical micro-spheres although the surfaces appeared irregular. The content of the protein in the micro-sphere was lower than expected, probably because of the presence of water channels and pores. The protein release kinetics showed a burst release until 2 days and after that sustained release pattern was showed. Therefore, these observations indicated that the formation of microsphere without the use of surfactant is feasible, and, this the improved process, the protein is readily incorporated in the microsphere.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.374-375
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• 2003

최근 나노섬유기술의 중요성이 증가함에 따라 나노섬유를 제조할 수 있는 여러 방법들 중에 상용화의 가능성, 적용 고분자의 다양성, 제조 공정의 단순성, 다양한 제품기술 응용성을 고려할 때 전기방사는 가장 기대되는 방법으로 현재, 다양한 분야의 연구들이 활발히 진행되고 있다[1,3]. 본 연구는 전기 방사 방법을 이용하여 다공성의 Poly($\varepsilon$-caprolactone) 필라멘트를 제조하고, 제조한 필라멘트를 수직기를 이용하여 평직 직물을 제조하여 그 응용 가능성을 확인하는 것이다[2]. (중략)

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.408.2-409
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• 2002

The aim of this study is to prepare biodegradable microspheres without use of any kind of surfactants or emulsifiers for a novel sustained delivery carriers of protein drugs. Poly(e-caprolactone)/poly(ethylene glycol)/poly(e-caprolactone) (CEC) triblock copolymer was synthesized by ring-opening of e-caprolactone with dihydroxy poly(ethylene glycol) and was used to make surfactant-free microspheres. (omitted)

• Polymer(Korea)
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• v.24 no.5
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• pp.664-672
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• 2000

It is generally agreed that transesterification provides the, copolymer in the melt blending of poly(ethylene naphthalate) (PEN) and poly($\varepsilon$-caprolactone) (PCL). Effects of the conditions of transesterification reaction and catalyst on the degree of randomness and average sequence length of PEN/PCL blends were investigated and results were used to interpret the biodegradability of PEN/PCL blends. It was found that degree of randomness values of obtained copolymer lied between 0 and 1, and it indicated that this blend consisted with physical blends of PEN/PCL and PEN/PCL block copolymers. The degree of randomness reached almost 1 which is the theoretical value of random copolymers and the average sequence length became shorter by the further transesterification reaction. In additions, it was found that the increase of copolymers, especially random copolymers reduced the biodegradability in PEN/PCL blends.

• Macromolecular Research
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• v.16 no.3
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• pp.231-237
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• 2008

Biodegradable poly($\varepsilon$-caprolactone-co-L-lactide)-b-poly(ethylene glycol) (PCLA-b-PEG) copolymers were synthesized via solution polymerization by varying the feed composition of $\varepsilon$-caprolactone ($\varepsilon$-CL) and L-lactide (LLA) ($\varepsilon$-CL: LLA= 10:0, 7:3, 5:5, 3:7, 0: 10). The feed ratio based on weight is in accordance with the copolymer composition except for the case of $\varepsilon$-CL: LLA=3:7 (C3L7), which was verified by $^1H$-NMR. Two different approaches were used for the exceptional case, which is an extension of the reaction time or the sequential introduction of the monomer. A copolymer composition of $\varepsilon$-CL: LLA=3:7 could be obtained in either case. The chemical microstructure of PCLA-b-PEG was determined using the $^{13}C$-NMR spectra and the effect of the sequential structure on the thermal properties and crystallinity were examined. Despite the same composition ratio of the copolymer, the microstructure can differ according to the reaction conditions.

• Polymer(Korea)
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• v.25 no.4
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• pp.486-495
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• 2001

Degradable poly(butylene succinate) (PBS)/poly(TEX>${\varepsilon}$-caprolactone) (PCL) copolyesters were prepared by using transesterification between poly(butylene succinate) and poly(TEX>${\varepsilon}$-caprolactone). The thermal and mechanical properties of copolyesters were investigated using differential scanning calorimetry and tensile testing. Interchange reaction between PBS and PCL molecules could be identified from proton NMR spectra. The reduced viscosity of the PBS/PCL copolyesters increased with reaction time except for a series of PBS/PCL (50/50 wt%) copolyesters. For all the compositions, the melting point and crystallization temperature of high-$T_m$ component (PBS) decreased as reaction time increased. From the results of tensile testing, it was found that stress and strain at break of the PBS/PCL copolymers containing less than 40 wt% PCL improved as compared to those of pure PBS, but at 50 wt% PCL stress at break of PBS/PCL copolymers was lowered due to decrease of crystallinity. On the other hand, Young's moduli of all the copolyesters decreased with both reaction time and PCL content.

• Polymer(Korea)
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• v.34 no.3
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• pp.185-190
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• 2010

Recently, an electrospinning process, which is one of various nanotechnologies, has been used in fabricating micro/nanosized fibers. The fabricated electrospun micro/nanofibers has been widely applied in biomedical applications, specially in tissue regeneration. In this study, we fabricated highly aligned electrospun biodegradable and biocompatible poly(${\varepsilon}$-caprolactone)(PCL) micro/nanofibers by using a modified electrospinning process supplemented with a complex electric field. From this process, we can attain highly aligned electrospun nanofibers compared to that fabricated with the normal electrospinning process. To observe the feasibility of the highly aligned electrospun mat as a biomedical scaffold, nerve cells(PC-12) was cultured and it was found that the cells those were well oriented to the direction of aligned fibers.