†Center for Biotechnology and Interdisciplinary Studies and Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, New York 12180, United States.
‡Department of Chemical and Biomolecular Engineering, NYU Polytechnic School of Engineering, 6 Metrotech Center, Brooklyn, New York 11201, United States.
Biomacromolecules. 2015 Jun 8;16(6):1818-26. doi: 10.1021/acs.biomac.5b00394. Epub 2015 May 11.
A green manufacturing technique, reactive extrusion (REx), was employed to improve the mechanical properties of polylactide (PLA). To achieve this goal, a fully biosourced PLA based polymer blend was conceived by incorporating small quantities of poly(ω-hydroxytetradecanoic acid) (PC14). PLA/PC14 blends were compatibilized by transesterification reactions promoted by 200 ppm titanium tetrabutoxide (Ti(OBu)4) during REx. REx for 15 min at 150 rpm and 200 °C resulted in enhanced blend mechanical properties while minimizing losses in PLA molecular weight. SEM analysis of the resulting compatibilized phase-separated blends showed good adhesion between dispersed PC14 phases within the continuous PLA phase. Direct evidence for in situ synthesis of PLA-b-PC14 copolymers was obtained by HMBC and HSQC NMR experiments. The size of the dispersed phase was tuned by the screw speed to "tailor" the blend morphology. In the presence of 200 ppm Ti(OBu)4, inclusion of only 5% PC14 increased the elongation at break of PLA from 3 to 140% with only a slight decrease in the tensile modulus (3200 to 2900 MPa). Furthermore, PLA's impact strength was increased by 2.4× that of neat PLA for 20% PC14 blends prepared by REx. Blends of PLA and PC14 are expected to expand the potential uses of PLA-based materials.
采用绿色制造技术——反应挤出（REx）来改善聚乳酸（PLA）的力学性能。为实现这一目标，构想了一种完全生物来源的 PLA 基聚合物共混物，其中掺入了少量的聚（ω-羟基十四烷酸）（PC14）。在 REx 过程中，通过 200ppm 钛酸四丁酯（Ti(OBu)4）促进的酯交换反应，使 PLA/PC14 共混物具有良好的相容性。在 150rpm 和 200°C 下 REx 15min 可提高共混物的力学性能，同时使 PLA 分子量损失最小化。对所得增容相分离共混物的 SEM 分析表明，分散的 PC14 相在连续的 PLA 相中具有良好的附着力。通过 HMBC 和 HSQC NMR 实验获得了 PLA-b-PC14 嵌段共聚物原位合成的直接证据。通过螺杆转速调节分散相的尺寸，“定制”共混物形态。在 200ppm Ti(OBu)4 的存在下，仅加入 5%的 PC14 就可以将 PLA 的断裂伸长率从 3%提高到 140%，而拉伸模量（从 3200MPa 降低到 2900MPa）仅略有下降。此外，与纯 PLA 相比，通过 REx 制备的 20%PC14 共混物的 PLA 冲击强度提高了 2.4 倍。PLA 和 PC14 的共混物有望扩大 PLA 基材料的潜在用途。
