writer：Jin Feng, Jihai Zhang, Zhuo Zheng, and Tao Zhou*
keywords：laser direct writing; near-infrared pulsed laser; polymer; microcapsule; core-shell structure; carbonization
source：期刊
specific source：ACS Applied Materials & Interfaces, 2019, 11, 41688?41700
Issue time：2020年
This paper proposed an efficient and environmentally friendly strategy to prepare a new color-changing microcapsule with core-shell structure for laser direct writing of polymers, and only the physical melt blending of polymers was employed. The laser absorber (SnO2) and the easily carbonized polymer (PC) were designed as the “core” and the “shell” of the microcapsule, respectively. The microcapsules were in situ formed during melt blending. SEM, TEM, and EDS confirmed the successful preparation of SnO2/PC microcapsules with core-shell structure. Its average diameter was 2.2 μm, and the “shell” thickness was 0.21?0.24 μm. As expected, this SnO2/PC microcapsule endowed polymers with an outstanding performance of NIR laser direct writing. The Raman spectroscopy and XPS indicated that the color change ascribed to the polymer carbonization due to the instantaneous high temperature caused by the SnO2 absorption of NIR laser energy. Optical microscopy observed a thick carbonization layer of 234 μm. Moreover, Raman depth imaging revealed the carbonization distribution, confirming that the amorphous carbon produced by the carbonization of the PC “shell” is the key factor of SnO2/PC microcapsules to provide polymers an outstanding performance of laser direct writing. This color-changing microcapsule has no selectivity to polymers due to providing a black color source (the carbonization of PC) itself, ensuring the high contrast and precision of patterns or texts after laser direct writing for all general-purpose polymers. We believe that this novel strategy to achieve laser direct writing of polymers will have broad application prospects.