Syntheses and Physical Characterization of New Aliphatic Triblock Poly(L-lactide-b-butylene succinate-b-L-lactide)s Bearing Soft and Hard Bi
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- 作者：Chaoyi Ba ; Jing Yang ; Qinghui Hao ; Xiaoyun Liu ; and Amin Cao
- 刊名：Biomacromolecules
- 出版年：2003
- 出版时间：November 2003
- 年：2003
- 卷：4
- 期：6
- 页码：1827 - 1834
- 全文大小：143K
- 年卷期：v.4,no.6(November 2003)
- ISSN：1526-4602
文摘
This study presents chemical syntheses and physical characterization of a new aliphatic poly(L-lactide-b-butylene succinate-b-L-lactide) triblock copolyester with soft and hard biodegradable building blocks. First,poly(butylene succinate) (PBS) prepolymers terminated with hydroxyl functional groups were synthesizedthrough melt polycondensation from succinic acid and 1,4-butanediol. Further, a series of new PLLA-b-PBS-b-PLLA triblock copolyesters bearing various average PLLA block lengths were prepared via ringopening polymerization of L-lactide with the synthesized hydroxyl capped PBS prepolymer (
n = 4.9 KDa)and stannous octanoate as the macroinitiator and catalyst, respectively. By means of GPC, NMR, FTIR,DSC, TGA, and wide-angle X-ray diffractometer (WAXD), the macromolecular structures and physicalproperties were intensively studied for these synthesized PBS prepolymer and PLLA-b-PBS-b-PLLA triblockcopolyesters. 13C NMR and GPC experimental results confirmed the formation of sequential block structureswithout any detectable transesterification under the present experimental conditions, and the molecular weightsof triblock copolyesters could be readily regulated by adjusting the feeding molar ratio of L-lactide monomerto the PBS macroinitiator. DSC measurements showed all single glass transitions, and their glass transitiontemperatures were found to be between those of PLLA and PBS, depending on the lengths of PLLA blocks.It was noteworthy that the segmental flexibilities of the hard PLLA blocks were found to be remarkablyenhanced by the more flexible PBS block partner, and the PBS and PLLA building blocks were well mixedin the amorphous regions. Results of TGA analyses indicated that thermal degradation and stabilities of thePLLA blocks strongly depended on the average PLLA block lengths of triblock copolyesters. In addition,FTIR and WAXD results showed the coexistence of the assemblied PLLA and PBS crystal structures whenthe average PLLA block length became larger than 7.8. These results may be beneficial for this newbiodegradable aliphatic triblock copolyester to be applied as a potential biomaterial.
n = 4.9 KDa)and stannous octanoate as the macroinitiator and catalyst, respectively. By means of GPC, NMR, FTIR,DSC, TGA, and wide-angle X-ray diffractometer (WAXD), the macromolecular structures and physicalproperties were intensively studied for these synthesized PBS prepolymer and PLLA-b-PBS-b-PLLA triblockcopolyesters. 13C NMR and GPC experimental results confirmed the formation of sequential block structureswithout any detectable transesterification under the present experimental conditions, and the molecular weightsof triblock copolyesters could be readily regulated by adjusting the feeding molar ratio of L-lactide monomerto the PBS macroinitiator. DSC measurements showed all single glass transitions, and their glass transitiontemperatures were found to be between those of PLLA and PBS, depending on the lengths of PLLA blocks.It was noteworthy that the segmental flexibilities of the hard PLLA blocks were found to be remarkablyenhanced by the more flexible PBS block partner, and the PBS and PLLA building blocks were well mixedin the amorphous regions. Results of TGA analyses indicated that thermal degradation and stabilities of thePLLA blocks strongly depended on the average PLLA block lengths of triblock copolyesters. In addition,FTIR and WAXD results showed the coexistence of the assemblied PLLA and PBS crystal structures whenthe average PLLA block length became larger than 7.8. These results may be beneficial for this newbiodegradable aliphatic triblock copolyester to be applied as a potential biomaterial.