Bio-Materials and Technology Lab, Department of Grain Science and Industry, Kansas State University, Manhattan, Kansas 66506, USA.
Biomacromolecules. 2010 Jul 12;11(7):1847-55. doi: 10.1021/bm100320q.
Compared with pristine polymers, bionanocomposites derived from biopolymers and inorganic nanoparticles have significantly improved electrical/magnetic properties, mechanical properties, thermal stability, gas barrier properties, and fire retardance. In this study, poly(lactic acid) (PLA) nanocomposites were prepared by in situ melt polycondensation of L-lactic acid with different loading ratios of surface-hydroxylated magnesium oxide (MgO) nanocrystals. Molecular weight, structure, morphology, and thermal properties of the nanocomposites were characterized. PLA-grafted MgO (PLA-g-MgO) was isolated from free PLA for the nanocomposite with 3% MgO via repeated dispersion/centrifugation processes and characterized. The weight-average molecular weight of the PLA-0.01%MgO nanocomposite was 55500, which was 30% higher than that of pure PLA. Discoloration of PLA was obviously depressed in the presence of MgO nanocrystals. Formation of hydrogen bonding between PLA chains and surface -OH groups from MgO was detected by Fourier transform infrared spectroscopy. Morphological images showed uniform dispersion of MgO nanocrystals in the PLA matrix and demonstrated a strong interfacial interaction between the PLA matrix and MgO nanocrystals. PLA-MgO nanocomposites exhibited improved thermal stability compared with pure PLA. Calculations based on thermogravimetric analysis revealed that more than 42.5% PLA was successfully grafted into PLA-g-MgO.
与原始聚合物相比，由生物聚合物和无机纳米粒子衍生的生物纳米复合材料具有显著改善的电/磁性能、机械性能、热稳定性、气体阻隔性能和阻燃性。在这项研究中，通过 L-乳酸的原位熔融缩聚制备了聚乳酸（PLA）纳米复合材料，其负载比为不同的表面羟基化氧化镁（MgO）纳米晶。对纳米复合材料的分子量、结构、形态和热性能进行了表征。通过重复的分散/离心过程从含有 3%MgO 的纳米复合材料中分离出 PLA 接枝 MgO（PLA-g-MgO），并对其进行了表征。PLA-0.01%MgO 纳米复合材料的重均分子量为 55500，比纯 PLA 高 30%。在 MgO 纳米晶的存在下，PLA 的变色明显受到抑制。通过傅里叶变换红外光谱检测到 PLA 链与 MgO 表面-OH 基团之间形成氢键。形貌图像显示 MgO 纳米晶在 PLA 基体中均匀分散，并证明 PLA 基体与 MgO 纳米晶之间具有强的界面相互作用。与纯 PLA 相比，PLA-MgO 纳米复合材料表现出更好的热稳定性。基于热重分析的计算表明，超过 42.5%的 PLA 成功接枝到 PLA-g-MgO 上。
