Jing Zhanxin, Li Jin, Xiao Weiyu, Xu Hefeng, Hong Pengzhi, Li Yong
Department of Applied Chemistry, College of Chemistry and Environment, Guangdong Ocean University Zhanjiang Guangdong 524088 China
RSC Adv. 2019 Aug 20;9(45):26067-26079. doi: 10.1039/c9ra04283k. eCollection 2019 Aug 19.
In this study, we investigated the blending of poly(l-lactide) (PLLA) with supramolecular polymers based on poly(d-lactide)-poly(ε-caprolactone--δ-valerolactone)-poly(d-lactide) (PDLA-PCVL-PDLA) triblock copolymers as an efficient way to modify PLLA. The supramolecular polymers (SMP) were synthesized by the terminal functionalization of the PDLA-PCVL-PDLA copolymers with 2-ureido-4[1]-pyrimidinone (UPy). The structure, thermal properties and rheological behavior of the synthesized supramolecular polymers were studied; we found that the formation of the UPy dimers expanded the molecular chain of the polymer and the incorporation of the UPy groups suppressed the crystallization of polymers. In addition, the synthesized supramolecular polymers had a low glass transition temperature of about -50 °C, showing the characteristics of elastomers. On this basis, superior properties such as a fast crystallization rate, high melt strength, and toughness of fully bio-based, , PLA-based materials were achieved simultaneously by blending PLLA with the synthesized supramolecular polymers. In the PLLA/SMP blends, PLLA could form a stereocomplex with its enantiomeric PDLA blocks of supramolecular polymers, and the stereocomplex crystals with the cross-linking networks reinforced the melt strength of the PLLA/SMP blends. The influences of the SMP composition and the SMP content in the PLLA matrix on crystallization and mechanical properties were analyzed. The supramolecular polymers SMP0.49 and SMP1.04 showed a reverse effect on the crystallization of PLLA. Tensile tests revealed that the lower content of the synthesized supramolecular polymers could achieve toughening of the PLLA matrix. Therefore, the introduction of supramolecular polymers based on PDLA-PCVL-PDLA is an effective way to control the crystallization, rheology and mechanical properties of PLLA.
在本研究中，我们研究了聚（L-丙交酯）（PLLA）与基于聚（D-丙交酯）-聚（ε-己内酯-δ-戊内酯）-聚（D-丙交酯）（PDLA-PCVL-PDLA）三嵌段共聚物的超分子聚合物共混，作为改性PLLA的有效方法。超分子聚合物（SMP）通过用2-脲基-4[1]-嘧啶酮（UPy）对PDLA-PCVL-PDLA共聚物进行末端功能化合成。研究了合成的超分子聚合物的结构、热性能和流变行为；我们发现UPy二聚体的形成扩展了聚合物的分子链，并且UPy基团的引入抑制了聚合物的结晶。此外，合成的超分子聚合物具有约-50°C的低玻璃化转变温度，显示出弹性体的特性。在此基础上，通过将PLLA与合成的超分子聚合物共混，同时实现了全生物基、基于PLA的材料的快速结晶速率、高熔体强度和韧性等优异性能。在PLLA/SMP共混物中，PLLA可以与其超分子聚合物的对映体PDLA嵌段形成立体复合物，并且具有交联网络的立体复合物晶体增强了PLLA/SMP共混物的熔体强度。分析了PLLA基体中SMP组成和SMP含量对结晶和力学性能的影响。超分子聚合物SMP0.49和SMP1.04对PLLA的结晶表现出相反的影响。拉伸试验表明，较低含量的合成超分子聚合物可以实现PLLA基体的增韧。因此，引入基于PDLA-PCVL-PDLA的超分子聚合物是控制PLLA结晶、流变学和力学性能的有效方法。
