A series of ABA type triblock copolymers based on biodegradable poly(butylene carbonate) (PBC) and poly(l-lactide) (PLLA) were synthesized with PBC as the core and varying the PLLA chain length. A significant reduction in the crystallinity of the PBC component is observed in the block copolymers as evidenced by DSC and wide angle X-ray diffraction. A systematic increase in the crystallinity of the PLLA blocks is also observed with increasing chain length of PLLA. The block copolymers undergo a transition from micro-phase separated lamellar morphology to macro-phase separated unstable morphology in the composition domain of ∼45–55 wt% of PLLA. A pseudo-ductile to quasi-brittle transition was observed in the composition range of ∼45–55 wt% of PLLA corresponding to a change in morphology as confirmed by Atomic Force Microscopy and Small Angle X-ray Scattering. This study demonstrates a green path for PLLA toughening by using another biodegradable aliphatic polymer.

以PBC为核心，改变PLLA链长，合成了一系列基于可生物降解的聚碳酸亚丁酯（PBC）和聚（1-丙交酯）（PLLA）的ABA型三嵌段共聚物。DSC和广角X射线衍射证明，在嵌段共聚物中PBC组分的结晶度明显降低。随着PLLA链长度的增加，还观察到PLLA嵌段的结晶度的系统性增加。在PLLA的约45-55 wt％的组成范围内，嵌段共聚物经历了从微相分离的层状形态到大相分离的不稳定形态的转变。一个伪-ductile到准原子力显微镜和小角X射线散射证实，在约45–55 wt％的PLLA组成范围内观察到脆性转变，这与形态变化相对应。这项研究表明通过使用另一种可生物降解的脂肪族聚合物，PLLA增韧的绿色道路。