Jeong Jieun, Ayyoob Muhammad, Kim Ji-Heung, Nam Sung Woo, Kim Young Jun
Department of Chemical Engineering, Sungkyunkwan University Natural Science Campus, 2066, Seobu-ro, Jangan-gu Suwon 16419 Republic of Korea
RSC Adv. 2019 Jul 15;9(38):21748-21759. doi: 10.1039/c9ra03299a. eCollection 2019 Jul 11.
Poly(lactide) (PLA) has received tremendous attention recently from researchers and industrialists due to its ability to solve environmental problems related to plastic pollution. However, PLA's brittleness, poor thermal stability, low elongation at break, and poor melt processing prevent its use in a broader spectrum of applications. Herein, we produced a very tough and thermally more stable PLA stereocomplex by simply mixing PLA with organoalkoxysilane. The stereocomplex PLA/silane (sc-PLA-silane) composite was prepared by simple mixing of three types of organoalkoxysilanes in sc-PLA followed by formation of a silane-based rubbery core with a cross-linked PLA shell. Mechanical and thermal properties were improved by stereocomplexation of PLA with a small amount (1-5 wt%) of PLA-grafted silanes. The addition of organoalkoxysilane with different functional groups resulted in a plasticizer of rubbery silica-PLA core-shell gel through condensation and grafting of long PLA chains at the interface between the stereocomplex and silane particles. The results revealed that the toughness of sc-PLA was improved dramatically with only a small addition (only 2.5%) of 3-(triethoxysilyl)propyl isocyanate (ICPTES). The morphology and mechanical and thermal properties of the toughened stereocomplex films were characterized. The results revealed that elongation at break was increased from 16% to 120%, while other mechanical properties such as tensile strength and modulus were retained. Surface analysis confirmed that this toughness was achieved by formation of a silica-PLA core-shell gel. The mechanical properties of PLA were improved without any significant reduction in modulus and tensile strength using this simple methodology.
聚乳酸（PLA）因其解决与塑料污染相关环境问题的能力，最近受到了研究人员和实业家的极大关注。然而，PLA的脆性、较差的热稳定性、低断裂伸长率和不良的熔体加工性能阻碍了其在更广泛应用领域的使用。在此，我们通过简单地将PLA与有机烷氧基硅烷混合，制备出了一种非常坚韧且热稳定性更高的PLA立体复合物。立体复合物PLA/硅烷（sc-PLA-硅烷）复合材料是通过在sc-PLA中简单混合三种有机烷氧基硅烷，然后形成具有交联PLA壳的硅烷基橡胶核来制备的。通过将PLA与少量（1-5 wt%）的PLA接枝硅烷进行立体复合，机械性能和热性能得到了改善。添加具有不同官能团的有机烷氧基硅烷，通过在立体复合物和硅烷颗粒之间的界面处缩合和接枝长PLA链，形成了橡胶状二氧化硅-PLA核壳凝胶增塑剂。结果表明，仅添加少量（仅2.5%）的3-（三乙氧基甲硅烷基）丙基异氰酸酯（ICPTES）就能显著提高sc-PLA的韧性。对增韧立体复合薄膜的形态、机械性能和热性能进行了表征。结果表明，断裂伸长率从16%提高到了120%，同时保留了拉伸强度和模量等其他机械性能。表面分析证实，这种韧性是通过形成二氧化硅-PLA核壳凝胶实现的。使用这种简单方法，在不显著降低模量和拉伸强度的情况下提高了PLA的机械性能。
