PDLA-b-PEG-b-PDLA嵌段共聚物的链结构对聚左旋乳酸性能的影响
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摘要
采用不同聚右旋乳酸(PDLA)分子量的PDLA-b-PEG-b-PDLA嵌段共聚物改性聚左旋乳酸(PLLA),系统探究不同链结构的PDLA-b-PEG-b-PDLA嵌段共聚物对PLLA的热行为、结晶行为和拉伸性能的影响。结果表明,在降温过程中,PDLA_(1k)-PEG_(2k)-PDLA_(1k)嵌段共聚物对PLLA均聚物晶体(α晶)的结晶温度影响较小,PDLA_(5k)-PEG_(2k)-PDLA_(5k)嵌段共聚物使α晶的结晶温度从纯PLLA的96℃提高至130℃。130℃等温结晶结果显示,嵌段共聚物的加入均能降低α晶的结晶时间和球晶尺寸,PDLA_(5k)-PEG_(2k)-PDLA_(5k)共聚物对PLLA中α晶形成的促进作用明显优于PDLA_(1k)-PEG_(2k)-PDLA_(1k)共聚物。在室温下拉伸,随着PDLA_(1k)-PEG_(2k)-PDLA_(1k)含量提高,共混物由脆性向韧性断裂转变;而在实验比例范围内,PLLA/PDLA_(5k)-PEG_(2k)-PDLA_(5k)共混物均呈现脆性断裂,这与PLLA/PDLA_(5k)-PEG_(2k)-PDLA_(5k)共混物中含有较多立构晶相关。
The PDLA-b-PEG-b-PDLA block copolymers with different PDLA molecular weights were used to modify poly(L-lactic acid)(PLLA). The effect of different chain structures of PDLA-b-PEG-b-PDLA on the properties of PLLA was investigated. The results indicate that the crystallization behavior of α crystal in the PLLA/PDLA_(1 k)-PEG_(2 k)-PDLA_(1 k) blends is the same as in PLLA during the cooling process. However, the PDLA_(5 k)-PEG_(2 k)-PDLA_(5 k) copolymers increases the crystallization temperature of α crystal from 96 ℃ to 130 ℃. Both of the crystallization time and spherulite size of α crystal of PLLA crystallized at 130 ℃ are reduced with addition of the block copolymers, while the decline level varied with the different chain structure. It shows a better promotion of the crystallization of α crystal for the specimen with PDLA_(5 k)-PEG_(2 k)-PDLA_(5 k) copolymer. When stretched at room temperature, the blends display a changing from brittle to ductile fracture with the amount of PDLA_(1 k)-PEG_(2 k)-PDLA_(1 k) copolymer increased. However, the addition of PDLA_(5 k)-PEG_(2 k)-PDLA_(5 k) has little effect on the tensile properties of PLLA in our experiments, showing brittle fracture of all the samples. It is thought to be related to the more stereocomplex crystallites in the PLLA/PDLA_(5 k)-PEG_(2 k)-PDLA_(5 k) blends.
The PDLA-b-PEG-b-PDLA block copolymers with different PDLA molecular weights were used to modify poly(L-lactic acid)(PLLA). The effect of different chain structures of PDLA-b-PEG-b-PDLA on the properties of PLLA was investigated. The results indicate that the crystallization behavior of α crystal in the PLLA/PDLA_(1 k)-PEG_(2 k)-PDLA_(1 k) blends is the same as in PLLA during the cooling process. However, the PDLA_(5 k)-PEG_(2 k)-PDLA_(5 k) copolymers increases the crystallization temperature of α crystal from 96 ℃ to 130 ℃. Both of the crystallization time and spherulite size of α crystal of PLLA crystallized at 130 ℃ are reduced with addition of the block copolymers, while the decline level varied with the different chain structure. It shows a better promotion of the crystallization of α crystal for the specimen with PDLA_(5 k)-PEG_(2 k)-PDLA_(5 k) copolymer. When stretched at room temperature, the blends display a changing from brittle to ductile fracture with the amount of PDLA_(1 k)-PEG_(2 k)-PDLA_(1 k) copolymer increased. However, the addition of PDLA_(5 k)-PEG_(2 k)-PDLA_(5 k) has little effect on the tensile properties of PLLA in our experiments, showing brittle fracture of all the samples. It is thought to be related to the more stereocomplex crystallites in the PLLA/PDLA_(5 k)-PEG_(2 k)-PDLA_(5 k) blends.
引文
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[10] 张秀芹, 熊祖江, 刘国明,等. 取向对聚左旋乳酸/聚右旋乳酸复合物纤维结晶性能的影响[J]. 高分子学报, 2014(8): 1048-1055. Zhang X Q, Xiong Z J, Liu G M,et al. Effect of orientation on the crystallization behavior of poly( L-lactic acid) /poly( D-lactic acid) fibers [J]. Acta Polymerica Sinica, 2014(8): 1048-1055.
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[12] Yin Y A, Song Y, Xiong Z J. Effect of the melting temperature on the crystallization behavior of a poly(L-lactide)/poly(D-lactide) equimolar mixture [J]. J. Appl. Polym. Sci.,2016, 133: DOI:10.1002/app.43015.
[13] 李楠, 史学涛, 张广成. 聚乳酸立构复合物的结晶行为[J]. 高分子材料科学与工程, 2014, 30(8): 48-53. Li N, Shi X T, Zhang G C. Crystallization behavior of poly(lactic acid) stereocomplex [J]. Polymer Materials Science & Engineering, 2014, 30(8): 48-53.
[14] Yin Y A, Liu G M. Formation of stereocomplex in enantiomeric poly(lactide)s via recrystallization of homocrystals: an in-situ X-ray scattering study [J]. Eur. Polym. J., 2016, 82: 46-56.
[15] Rahman N , Kawai T , Matsuba G, et al. Effect of polylactide stereocomplex on the crystallization behavior of poly(L-lactic acid) [J]. Macromolecules, 2009, 42: 4739-4745.
[16] Song Y, Wang D J, Jiang N. Role of PEG segment in stereocomplex crystallization for PLLA/PDLA-b-PEG-b-PDLA blends [J]. Sustain. Chem. Eng., 2015, 3: 1492-1500.
[17] Zhang X Q, Konrad S. Structure variation of tensile-deformed amorphous poly(L-lactic acid): effects of deformation rate and strain [J]. Polymer, 2011, 52: 4141-4149.
[2] 李玉洁,姚军燕,陈明河.聚乳酸静电纺丝纳米纤维及其药物缓释体系[J].高分子材料科学与工程, 2014,30(6): 147-151. Li Y J, Yao J Y, Chen M H. Electrospun poly( lactic acid) nanofibers and application in drug delivery system[J]. Polymer Materials Science & Engineering, 2014, 30(6): 147-151.
[3] Ikada Y, Jamshidi K, Tsuji H. Stereocomplex formation between enantiomeric poly(lactides)[J]. Macromolecules, 1987, 20: 904-906.
[4] Zhang C Z. Inducing stereocomplex crystals by template effect of residual stereocomplex crystals during thermal annealing of injection molded polylactide [J]. Ind. Eng. Chem. Res., 2016, 55: 10896-10905.
[5] 李琦,熊祖江,王锐.右旋聚乳酸-己内酯无规共聚物改性左旋聚乳酸的结构与性能[J].高分子材料科学与工程, 2018, 34(3): 43-53.Li Q, Xiong Z J, Wang R. Structure and properties of toughened poly(L-lactide) by poly(D-lactide)-r-poly(ε-caprolactone) random copolymer[J]. Polymer Materials Science &Engineering, 2018, 34(3): 43-53.
[6] Liu Y L, Shao J. Toughening effect of poly(d-lactide)-b-poly(butylene succinate)-b-poly(d-lactide) copolymers on poly(l-lactic acid) by solution casting method [J]. Mater. Lett., 2015, 155: 94-96.
[7] Jing Z X, Shi X T, Zhang G C. Competitive stereocomplexation and homocrystallization behaviors in the poly(lactide) blends of PLLA and PDLA-PEG-PDLA with controlled block length [J]. Polymers, 2017, 9: 107.
[8] 李晓露, 王锐, 杨春芳,等. 含柔性链段聚右旋乳酸嵌段共聚物对聚左旋乳酸拉伸行为的影响[J].高分子学报, 2018(5): 598-606. Li X L, Wang R, Yang C F,et al. Effect of poly (D - lactic acid) block copolymers with soft chains on the tensile behavior of poly (L-lactic acid) [J]. Acta Polymerica Sinica, 2018(5): 598-606.
[9] 杨春芳, 熊祖江, 王锐,等. 左旋聚乳酸右旋聚乳酸嵌段共物的共混物及其纤维的结构与性能[J]. 高分子材料科学与工程, 2017, 33(7): 59-64. Yang C F, Xiong Z J, Wang R, et al. Preparation and properties of poly(L-lactic acid)/poly(D-lactide) block copolymer blends and its fibers [J]. Polymer Materials Science & Engineering, 2017, 33(7): 59-64.
[10] 张秀芹, 熊祖江, 刘国明,等. 取向对聚左旋乳酸/聚右旋乳酸复合物纤维结晶性能的影响[J]. 高分子学报, 2014(8): 1048-1055. Zhang X Q, Xiong Z J, Liu G M,et al. Effect of orientation on the crystallization behavior of poly( L-lactic acid) /poly( D-lactic acid) fibers [J]. Acta Polymerica Sinica, 2014(8): 1048-1055.
[11] Kim S I, Lee B R, et al. Preparation of topographically modified poly(L-lactic acid)-b-poly(epsilon-caprolactone)-b-poly(L-lactic acid) tri-block copolymer film surfaces and its blood compatibility [J]. Macromol. Res., 2014, 22: 1229-1237.
[12] Yin Y A, Song Y, Xiong Z J. Effect of the melting temperature on the crystallization behavior of a poly(L-lactide)/poly(D-lactide) equimolar mixture [J]. J. Appl. Polym. Sci.,2016, 133: DOI:10.1002/app.43015.
[13] 李楠, 史学涛, 张广成. 聚乳酸立构复合物的结晶行为[J]. 高分子材料科学与工程, 2014, 30(8): 48-53. Li N, Shi X T, Zhang G C. Crystallization behavior of poly(lactic acid) stereocomplex [J]. Polymer Materials Science & Engineering, 2014, 30(8): 48-53.
[14] Yin Y A, Liu G M. Formation of stereocomplex in enantiomeric poly(lactide)s via recrystallization of homocrystals: an in-situ X-ray scattering study [J]. Eur. Polym. J., 2016, 82: 46-56.
[15] Rahman N , Kawai T , Matsuba G, et al. Effect of polylactide stereocomplex on the crystallization behavior of poly(L-lactic acid) [J]. Macromolecules, 2009, 42: 4739-4745.
[16] Song Y, Wang D J, Jiang N. Role of PEG segment in stereocomplex crystallization for PLLA/PDLA-b-PEG-b-PDLA blends [J]. Sustain. Chem. Eng., 2015, 3: 1492-1500.
[17] Zhang X Q, Konrad S. Structure variation of tensile-deformed amorphous poly(L-lactic acid): effects of deformation rate and strain [J]. Polymer, 2011, 52: 4141-4149.