Pitaya-Structured Microspheres with Dual Laser Wavelength Responses for Polymer Laser Direct Writing

Abstract

A unique pitaya-structured graphene/TiO 2 @PS microsphere with dual laser wavelength responses is designed and prepared via a facile approach of polymer melt blending. The graphene/TiO 2 particles ("pitaya seeds") are homogeneously distributed in the polystyrene ("pitaya pulp") of the microspheres with an average size of 1.5 μm. The graphene in microspheres serves not only as a laser absorber that has responses to both 355 nm UV and 1064 nm NIR lasers but also as a reducing agent of TiO 2 during laser direct writing (LDW). As expected, benefiting from the unique pitaya-structured structure, the graphene/ TiO 2 @PS microsphere can remarkably improve the performance of both NIR and UV LDW of polymers. The results of characterizations reveal that the black color caused by NIR LDW is due to the generation of the amorphous carbon and the color change after UV LDW is owing to the formation of black sp/sp 2 carbon compounds. Meanwhile, some TiO 2 in microspheres is reduced into the black/ gray titanium oxides of Ti 2+ and Ti 3+ after NIR and UV LDW, respectively. The above co-contribution endows the graphene/TiO 2 @PS microspheres with an outstanding color-changing ability. This pitayastructured microsphere will have a profound effect on polymers' laser direct writing.

Autocatalytic Laser Activator for Both UV and NIR Lasers: Preparation of Circuits on Polymer Substrates by Selective Metallization

“…Therefore, after NIR laser activation, a complex rough pore-like structure was formed on the surface of the ABS/MoO 3 composites, as shown in Figure 2c, and a deeper depth of action was observed (Figure 2l). By contrast, the thermal effect of the UV laser is relatively much lower, 47 which also explains why the UV laser has a shallower depth of action (Figure 2i) and higher precision (Figure 3j). The limit line width is also related to the thermal effect of lasers.…”

Strategy to Prepare Core–Shell Microspheres for Laser Direct Writing on Polymers: Microemulsion Method

“…During the LDW process, these laser absorbers first absorbed the laser to convert the light energy into heat energy, inducing instant high temperatures. Thus, the nearby polymer resin was immediately carbonized to bring about the color change. , …”

“…A 1064 nm NIR laser was applied to evaluate LDW effects of Sb 2 O 3 @PS, and a QR code with high contrast was fabricated on the PP surface. After that, our group proposed a method for in situ preparation of core–shell microcapsules by melt blending, which is suitable for various common polymers and demonstrated an excellent LDW performance. , …”

“…Thus, the nearby polymer resin was immediately carbonized to bring about the color change. 34,37 In a previous report, Zhong et al melt-blended Bi 2 O 3 with thermoplastic polyurethane (TPU) to prepare TPU@Bi 2 O 3 composites. 38 Since the neat TPU could not absorb the laser, the addition of Bi 2 O 3 played a role in energy conversion, inducing localized pyrolysis and carbonization of TPU to produce clear marks or patterns on the surface.…”

“…After that, our group proposed a method for in situ preparation of core−shell microcapsules by melt blending, which is suitable for various common polymers and demonstrated an excellent LDW performance. 37,46 This work proposes a new one-step microemulsion method of preparing core−shell structure microspheres for LDW. The target microspheres consist of SnO 2 (an effective laser absorber) and easily carbonized polyphenylene oxide (PPO).…”