Marcott Curtis, Kansiz Mustafa, Dillon Eoghan, Cook Debra, Mang Michael N, Noda Isao
University of Delaware, Newark, DE 19716, USA.
Light Light Solutions, Athens, GA 30698, USA.
J Mol Struct. 2020 Jun 15;1210. doi: 10.1016/j.molstruc.2020.128045. Epub 2020 Mar 10.
Optical photothermal infrared (O-PTIR) and Raman spectroscopy and imaging was used to explore the spatial distributions of molecular constituents of a laminate sample consisting of the bioplastics, polyhydroxyalkanoate (PHA) and polylactic acid (PLA), near the interfacial boundary. Highly spatially resolved simultaneous IR and Raman spectra were sequentially collected at 100 nm increments along a line traversing the interface. The set of spectra were subjected to 2D-COS analysis to extract the detailed nature of the spatial distribution of the laminate constituents. It was revealed that the laminate is not a simple binary system of two non-interacting polymers, but consists of different constituents with more complex spatial distributions. Some portion of PLA seems to penetrate into the PHA layer. The crystallinity of PHA near the interface is reduced compared to the rest of the PHA layer. The result suggests the existence of some partial molecular mixing even for these seemingly immiscible polymer pairs. The mixing probably occurs at the segmental level confined to only several hundred nanometers of space at the interface. Such partial mixing may explain the high compatibility between the two bioplastics.
利用光热红外（O-PTIR）和拉曼光谱及成像技术，研究了由生物塑料、聚羟基脂肪酸酯（PHA）和聚乳酸（PLA）组成的层压样品在界面边界附近分子成分的空间分布。沿着穿过界面的一条线，以100 nm的增量依次收集高空间分辨率的同步红外和拉曼光谱。对这组光谱进行二维相关光谱（2D-COS）分析，以提取层压材料成分空间分布的详细特征。结果表明，该层压材料不是由两种不相互作用的聚合物组成的简单二元体系，而是由具有更复杂空间分布的不同成分组成。PLA的一部分似乎渗透到PHA层中。与PHA层的其余部分相比，界面附近PHA的结晶度降低。该结果表明，即使对于这些看似不相容的聚合物对，也存在一定程度的分子部分混合。这种混合可能发生在仅限于界面处几百纳米空间的链段水平上。这种部分混合可能解释了这两种生物塑料之间的高相容性。
