摘要
以生物基单体δ-己内酯(δCL)和L-丙交酯(L-LA)为原料,以三羟甲基丙烷或季戊四醇为引发剂,通过一锅法顺序加料方式制备了具有明确结构的(PδCL-b-PLLA)n多臂星形嵌段共聚物。使用小角X射线散射表征了(PδCL-b-PLLA)n的微相分离结构。通过单轴拉伸和循环拉伸实验,研究了拓扑结构对(PδCL-b-PLLA)n多臂星形嵌段共聚物力学性能的影响。结果表明:在分子量相同的情况下,星形嵌段共聚物具有比相应的ABA线形嵌段共聚物更高的断裂强度、弹性回复率以及更低的残留应变;与四臂星形嵌段共聚物相比,三臂星形嵌段共聚物表现出更好的拉伸性和弹性回复性。
The most commonly used thermoplastic elastomers(TPEs)are ABA linear triblock copolymers,which usually suffer from undesirable stress relaxation,poor creep resistance and large residual strain.One of the solutions to address the above problems is to use multi-arm star block copolymers as TPEs.In this contribution,a series of multi-arm star block copolymers(PδCL-b-PLLA)n was prepared by one-pot sequential ring-opening copolymerization of bio-basedδ-caprolactone(δCL)and L-lactide(L-LA)using 1,4-benzenedimethanol,trimethylolpropane or pentaerythritol as the initiators.The welldefined structures of obtained(PδCL-b-PLLA)n copolymers were carefully characterized by 1H-NMR and 13C-NMR spectra.Compared to their linear analogues,the three-arm and four-arm star block copolymers exhibited the improved thermal stabilities.The microphase separation of PδCL soft block and PLLA hard block was supported by the differential scanning calorimetry as well as small-angle X-ray scattering.The effects of molecular weight,volume fraction of hard block(fhard)and topology on the mechanical properties of(PδCL-b-PLLA)n copolymers were investigated using uniaxial and cyclic tensile experiments.The(PδCL-b-PLLA)n copolymers with fhard of 0.45 behaved as thermoplastics while those with fhard of 0.37 behaved as thermoplastic elastomers.The tensile strength of(PδCL-b-PLLA)n copolymers considerably increased as the increase of their molecular weights.When fhard of(PδCL-b-PLLA)n was 0.37,the star block copolymers exhibited higher tensile strength,better elastic recovery as well as lower residual strain than the corresponding ABA linear block copolymers with comparable molecular weights. Remarkably, (PδCL196-b-PLLA100)3 exhibited high tensile strength ((26.8 ± 0.2) MPa), high elastic recovery ((96.7 ± 0.2)%), high resilience ((71.0 ± 0.1)%) as well as low residual strain ((6.4 ± 0.2)%), which were comparable to the commodity styrene based TPEs. Compared to four-arm star block copolymers, three-arm star block copolymers exhibited higher tensile strength and better elastic recovery, which was probably ascribed to the reduced segregation strengths that originated from the lower molar mass of each arm for four-arm star block copolymers.
作者
朱玉玲
王丽颖
沈勇
ZHU Yuling;WANG Liying;SHEN Yong(College of Chemical Engineering,Qingdao University of Science and Technology,Qingdao 266042,Shandong,China)
出处
《功能高分子学报》
CAS
CSCD
北大核心
2024年第3期196-204,共9页
Journal of Functional Polymers
基金
国家自然科学基金(22075160,52322304)。
关键词
热塑性弹性体
嵌段共聚物
星形高分子
聚酯
开环聚合
thermoplastic elastomer
block copolymer
star polymer
polyester
ring-opening polymerization
