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Poly(glycolide-co-${\varepsilon}$-caprolactone) 블록 공중합체의 합성과 비등온 결정화 거동 분석
최송연,지민호,박남집,송승호,최교창,백두현,Choi, Song-Yeon,Jee, Min-Ho,Park, Nam-Jib,Song, Seung-Ho,Choi, Kyo-Chang,Baik, Doo-Hyun 한국섬유공학회 2011 한국섬유공학회지 Vol.48 No.1
Poly(glycolide-co-${\varepsilon}$-caprolactone)(PGCL) block copolymers were synthesized by two step polymerization using glycolide and ${\varepsilon}$-caprolactone as starting materials. The chain-microstructures of the resulting block copolymers were characterized by $^1H-NMR$. The structure and thermal properties of the PGCL block copolymer were strongly affected by the chain-microstructure of the prepolymer. The non-isothermal crystallization behavior of the PGCL block copolymers was examined at various cooling rates and analyzed with modified-Avrami and Ziabicki equations. The PGCL block copolymer with a lower degree of randomness in the prepolymer block had a higher crystallization temperature and faster crystallization rate, which suggests that differences in chain-microstructure of the PGCL prepolymer can affect the crystallization characteristics, such as crystallinity and crystallization rate.
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지민호,최송연,강찬솔,백두현 한국섬유공학회 2023 Fibers and polymers Vol.24 No.9
In this study, as a first step toward the development of novel candidate for absorbable suture materials based on poly(glycolide-co-ɛ-caprolactone), we synthesized a poly(glycolide-co-ɛ-caprolactone-co-L-lactide) block copolymer with ABA block structure via a two-step polymerization process and prepared the final PGCLA suture using a pilot-scale melt spinning machine. Then, to understand the mechanism on the early degradation stage of the PGCLA suture, we systematically investigated the mechanical, morphological properties and microstructural changes of the PGCLA suture through in vitro degradation. As a result, it was observed that, during the in vitro degradation process, the mechanical properties of PGCLA sutures exhibited an overall linear decrease and retained only 32% of its initial strength at 2 weeks of degradation. In addition, it was confirmed that, from FE-SEM analysis, internal degradation and structural changes, including longitudinal cracks on the suture surface, were noticeably appeared at 2 weeks of degradation. Interestingly, the results obtained from 1H-NMR and WAXS analyses exhibited clearly that PGCLA sutures undergo simultaneous degradation of glycolide units and L-lactide units present in the amorphous region during in vitro degradation. Therefore, based on these findings, we concluded that in the early stage of in vitro degradation of PGCLA suture, simultaneous degradation of glycolide units and L-lactide units in the amorphous region occurs, leading to chemical and structural changes such as erosion and cracking of the suture, as well as a decrease in its mechanical properties.
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지민호,박지희,최송연,백두현 한국섬유공학회 2022 Fibers and polymers Vol.23 No.10
In this study, poly(glycolide-co-ε-caprolactone) (PGCL) block copolymers, which have an ABA block structure, were prepared by a two-step polymerization process, and their microstructures, thermal properties and in vitro degradation properties according to introducing a small amount of L-lactide as a comonomer in the first step of the polymerization process were systematically investigated. Through our study, it was confirmed that the introduction of L-lactide in the first step of the polymerization process had a great effect on the microstructure of the random PGCL prepolymer (B block) as well as the final PGCL block copolymer (ABA block). Specifically, with the introduction of L-lactide, the average sequence length of glycolide segments on the PGCL prepolymer decreased from 3.32 to 2.40. In addition, it was observed that there is a relatively large difference in the average sequence length of glycolide segments in the final PGCL block copolymers. As a result, these microstructural changes of the PGCL prepolymer originated from the L-lactide comonomer affected significantly the thermal properties and in vitro degradation properties on the final PGCL block copolymers. Compared with the PGCL block copolymer without L-lactide, melting temperature and crystallization temperature of the PGCL block copolymer with L-lactide decreased, as well as their thermal degradation temperature. In addition, the introduction of a small amount of L-lactide comonomer accelerated the hydrolytic degradation of the PGCL block copolymer. Overall, by introducing L-lactide copolymer in the first step of the two-step manufacturing process for the PGCL block copolymer, changes of various properties on the PGCL block copolymer originated from the changes in the microstructure of random PGCL prepolymer were confirmed.
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