Flexible Composites Based on Thermoplastic Elastomers for Laser Direct Writing: Porous Structures

Laser direct writing (LDW) has been widely applied to rigid plastics, but its application to soft elastomers has rarely been reported. In this study, we designed and prepared a flexible thermoplastic polyurethane (TPU) material containing multilayer graphene (MLG). Based on the strong absorption of the MLG for the NIR laser, light-colored patterns can be conveniently produced on the TPU/MLG composite by directly writing with a near-infrared (NIR) laser of 1064 nm. For the light-colored patterns, the results of characterizations show that a cell layer with a depth of 113.3 μm was produced on the surface of the composite, consisting of many irregular close-cell cells with an average diameter of 27.7 μm. The light color produced by the LDW is actually a structural color from these newly formed cells. TG revealed that the gases that cause foaming during LDW were mainly caused by the thermal decomposition of TPU by an NIR laser. Due to the high precision of LDW, personalized patterns can be accurately written on 2D flat or complex 3D parts of TPU/MLG composites, exhibiting excellent stability and flexibility. Thus, this TPU/MLG composite has good application prospects. This work also provides ideas for developing soft elastomer materials that lasers can directly write.