Local Controllable Laser Patterning of Polymers Induced by Graphene Material

Universal Approach to Integrating Reduced Graphene Oxide into Polymer Electronics

Flexible electronics have sparked significant interest in the development of electrically conductive polymer-based composite materials. While efforts are being made to fabricate these composites through laser integration techniques, a versatile methodology applicable to a broad range of thermoplastic polymers remains elusive. Moreover, the underlying mechanisms driving the formation of such composites are not thoroughly understood. Addressing this knowledge gap, our research focuses on the core processes determining the integration of reduced graphene oxide (rGO) with polymers to engineer coatings that are not only flexible and robust but also exhibit electrical conductivity. Notably, we have identified a particular range of laser power densities (between 0.8 and 1.83 kW/cm2), which enables obtaining graphene polymer composite coatings for a large set of thermoplastic polymers. These laser parameters are primarily defined by the thermal properties of the polymers as confirmed by thermal analysis as well as numerical simulations. Scanning electron microscopy with elemental analysis and X-ray photoelectron spectroscopy showed that conductivity can be achieved by two mechanisms-rGO integration and polymer carbonization. Additionally, high-speed videos allowed us to capture the graphene oxide (GO) modification and melt pool formation during laser processing. The cross-sectional analysis of the laser-processed samples showed that the convective flows are present in the polymer substrate explaining the observed behavior. Moreover, the practical application of our research is exemplified through the successful assembly of a conductive wristband for wearable devices. Our study not only fills a critical knowledge gap but also offers a tangible illustration of the potential impact of laser-induced rGO-polymer integration in materials science and engineering applications.

High-Performance Organic Electrochemical Transistor Based on Photo-annealed Plasmonic Gold Nanoparticle-Doped PEDOT:PSS

Organic electrochemical transistors (OECTs), particularly the ones based on PEDOT:PSS, are excellent candidates for chemical and biological sensing because of their unique advantages. Improving the sensitivity and stability of OECTs is crucially important for practical applications. Herein, the transconductance of OECT is improved by 8-fold to 14.9 mS by doping the PEDOT:PSS channel with plasmonic gold nanoparticles (AuNPs) using a solution-based process followed by photo annealing. In addition, the OECT also possesses high flexibility and cyclic stability. It is revealed that the doping of AuNPs increases the conductivity of PEDOT:PSS and the photo annealing improves the crystallinity of the PEDOT:PSS channel and the interaction between AuNPs and PEDOT:PSS. These changes lead to the increase in transconductance and cyclic stability. The prepared OECTs are also demonstrated to be effective in sensitive detection of glucose within a wide concentration range of 10 nM-1 mM. Our OECTs based on photo-annealed plasmonic AuNP-doped PEDOT:PSS may find great applications in chemical and biological sensing, and this strategy may be extended to prepare many other high-performance OECT-based devices.

Modification of Polymeric Surfaces with Ultrashort Laser Pulses for the Selective Deposition of Homogeneous Metallic Conductive Layers

In recent years, the demand for highly integrated and lightweight components has been rising sharply, especially in plastics processing. One strategy for weight-saving solutions is the development of conductive tracks and layouts directly on the polymer housing parts in order to be able to dispense with the system integration of additional printed circuit boards (PCB). This can be conducted very advantageously and flexibly with laser-based processes for functionalizing polymer surfaces. In this work, a three-step laser-based process for subsequent selective metallization is presented. Conventional injection molded components without special additives serve as the initial substrate. The Laser-Based Selective Activation (LSA) uses picosecond laser pulses to activate the plastic surface to subsequently deposit palladium. The focus is on determining the amount of deposited palladium in correlation to the laser and scan parameters. For the first time, the dependence of the metallization result on the accumulated laser fluence (F_acc) is described. The treated polymer parts are characterized using optical and scanning electron microscopy as well as a contact-type profilometer.

Aramid textile with near-infrared laser-induced graphene for efficient adsorption materials

Porous carbon materials show great application potential in the field of adsorption. However, the preparation process of carbon adsorption materials relies on high temperature, high energy consumption, many steps, and long time. Most of them exist in the form of powder or block, and the practical application scenarios are limited and difficult to recycle. In this study, based on in-situ carbonization of polymer precursor, we directly generated laser-induced graphene (LIG) on the surface of commercial aramid textile using a low-energy near-infrared laser in air, and prospected the application prospect of the prepared aramid/graphene textile in the field of adsorption. Under a certain laser energy, the photothermal reaction promotes the breaking of the CO and CN bonds in the surface layer of the aramid fiber, and reorganizes into a graphene structure at an instantaneous high temperature, while the overall flexible structure of the textile was not destroyed. Further, adsorption materials based on the as-prepared aramid/graphene textiles were also designed, including VOC-adsorbing textile in air and dye-adsorbing textile in water. Using low-energy near-infrared laser to directly achieve LIG writing in commercial textiles under air condition will provide an efficient, environmentally friendly, and designable direction for the large-scale fabrication of textile adsorption products.

The Impact of Selected Laser-Marking Parameters and Surface Conditions on White Polypropylene Moldings

Laser marking of polymer materials is a technology that is increasingly used in industry. Polypropylene (PP) shows a low ability to absorb electromagnetic radiation in the near-infrared range (λ = 1064 nm). The paper presents the influence of the surface condition of white-colored polypropylene moldings on the efficiency of their marking with a laser beam. In addition, the operation of the commercial laser marking additive (LMA) Lifolas M 117009 UN, intended to support the process of laser marking of polyolefin surfaces, was verified. The study is an attempt to combine laser operating parameters, material, and geometric properties of PP moldings to obtain the expected quality of graphic symbols. The test samples were made by injection molding method with the use of a specially designed modular injection mold. The molding cavities were prepared with various methods of metal processing, thanks to which obtained moldings differed in surface condition. The marking effects were assessed based on colorimetric tests and digital image analysis. The 0.5 wt% LMA content resulted in obtaining a graphic sign with high contrast in comparison to the background. The gradual increase in the modifier content resulted in a further increase in contrast. These values depended on the degree of surface finish of the samples, and therefore on the roughness parameters. Samples with a rough surface finish showed higher contrast compared to surfaces with a high surface finish. It was also found that for the analyzed moldings, the laser-marking process should be performed with the use of a low head velocity (450–750 mm/s) and a high concentration of the laser beam (0.03–0.05 mm).

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

A unique pitaya-structured graphene/TiO₂@PS microsphere with dual laser wavelength responses is designed and prepared via a facile approach of polymer melt blending. The graphene/TiO₂ 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 TiO₂ during laser direct writing (LDW). As expected, benefiting from the unique pitaya-structured structure, the graphene/TiO₂@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/sp² carbon compounds. Meanwhile, some TiO₂ in microspheres is reduced into the black/gray titanium oxides of Ti²⁺ and Ti³⁺ after NIR and UV LDW, respectively. The above co-contribution endows the graphene/TiO₂@PS microspheres with an outstanding color-changing ability. This pitaya-structured microsphere will have a profound effect on polymers' laser direct writing.

Modification of Laser Marking Ability and Properties of Polypropylene Using Silica Waste as a Filler

Polypropylene (PP) belongs to the group of polymers characterized by low susceptibility to absorption of electromagnetic radiation in the infrared range (λ = 1064 nm). This research consisted of assessing the possibility of using silica waste from the metallurgic industry as an additive for PP laser marking. The modifier was introduced into the polymer matrix in the range from 1 to 10 wt%. The effects of laser radiation were assessed based on colorimetric tests and microscopic surface analysis. The mechanical properties of the composites were determined during the static tensile tests. The thermal properties were investigated via differential scanning calorimetry. It was found that the introduction of silica waste into polypropylene allows for the effective marking of sample surfaces with the use of a laser beam. The greatest contrast between the graphic symbol and the background was obtained for silica contents of 3 and 5 wt%, with the use of a low-speed laser head and a strong concentration of the laser beam. The application of silica caused an increase in the modulus of elasticity and the tensile strength of the composite samples. Increases in the crystallization temperature and the degree of crystallinity of the polymer matrix were also observed. It was found that silica waste can act as multifunctional additive for polypropylene.

Preparation and Laser Marking Properties of Poly(propylene)/Molybdenum Sulfide Composite Materials

In this study, using molybdenum sulfide (MoS₂) as laser-sensitive particles and poly(propylene) (PP) as the matrix resin, laser-markable PP/MoS₂ composite materials with different MoS₂ contents ranging from 0.005 to 0.2% were prepared by melt-blending. A comprehensive analysis of the laser marking performance of PP/MoS₂ composites was carried out by controlling the content of laser additives, laser current intensity, and the scanning speed of laser marking. The color difference test shows that the best laser marking performance of the composite can be obtained at the MoS₂ content of 0.02 wt %. The surface morphology of the PP/MoS₂ composite material was observed after laser marking using a metallographic microscope, an optical microscope, and a scanning electron microscope (SEM). During the laser marking process, the laser energy was absorbed and converted into heat energy to cause high-temperature melting, pyrolysis, and carbonization of PP on the surface of the PP/MoS₂ composite material. The black marking from carbonized materials was formed in contrast to the white matrix. Using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and Raman spectroscopy, the composite materials before and after laser marking were tested and characterized. The PP/MoS₂ composite material was pyrolyzed to form amorphous carbonized materials. The effect of the laser-sensitive MoS₂ additive on the mechanical properties of composite materials was investigated. The results show that the PP/MoS₂ composite has the best laser marking property when the MoS₂ loading content is 0.02 wt %, the laser marking current intensity is 11 A, and the laser marking speed is 800 mm/s, leading to a clear and high-contrast marking pattern.

Laser irradiation method to prepare polyethylene porous fiber membrane with ultrahigh xylene gas filtration capacity

In recent years, volatile organic compound (VOC) gases have caused potential harm to people's health. This study reveals the preparation of polyethylene porous fiber membrane with excellent low-concentration VOCs filtration performance via laser irradiation technology. A neodymium-doped yttrium aluminum garnet (Nd:YAG) pulsed laser beam was used to scan the laser-sensitive low-density polyethylene/carbon black (LDPE/CB) fibers prepared by nanolayer coextrusion in the air. The controllable thermal energy generated by laser irradiation makes the surface of the fiber membrane to produce a porous carbon layer in situ. Laser power and scanning speed are important parameters for controlling laser-induced carbonization. The results indicate that the rich "fluffy" carbon structures on the surface of the porous fiber membrane can efficiently adsorb xylene gas. This study can provide a positive reference for the large-scale preparation of polyolefin porous fiber membrane with VOCs filtration by simple and efficient laser irradiation method.

Laser induced porous electrospun fibers for enhanced filtration of xylene gas

With the development of industry, the harm caused by volatile organic compound (VOC) gases to the human body has received much attention. This study reveals as the first attempt to apply laser irradiation technique to the preparation of porous electrospun fibers with excellent low-concentration VOC gases adsorption properties. The laser-sensitive polycarbonate (PC) fibers prepared from electrospinning was treated in air by scanning with a neodymium-doped yttrium aluminum garnet (Nd: YAG) pulsed laser beam to achieve porous structure. During the laser irradiation process, a series of changes such as melting, thermal degradation, and carbonization of the polymer fibers can change the surface structure. The morphology of the porous structure is related to the degree of laser-induced carbonization, and the laser current is an important parameter for determining the degree of laser-induced carbonization of a particular polymer. The results indicate that porous carbon structures can be created on the surface of the fiber membrane by controlling the degree of laser-induced carbonization, and a highly xylene gas adsorption efficiency is exhibited. This study may provide useful insights for developing electrospun porous fibers with VOC adsorption by simple, effective and environmentally friendly laser post-processing process.

Surface Laser-Marking and Mechanical Properties of Acrylonitrile-Butadiene-Styrene Copolymer Composites with Organically Modified Montmorillonite

In this study, organically modified montmorillonite (OMMT) was prepared by modifying MMT with a cationic surfactant cetyltrimethylammonium bromide (CTAB). The obtained OMMT of different loading contents (1, 2, 4, 6, and 8 wt %) was melt-blended with poly(acrylonitrile-co-butadiene-co-styrene) (ABS) to prepare a series of ABS/OMMT composites, which were laser marked using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser beam of 1064 nm under different laser current processes. X-ray diffraction (XRD), color difference spectrometer, optical microscope, water contact angle tests, scanning electron microscope (SEM), and Raman spectroscopy were carried out to characterize the morphology, structure, and properties of the laser-patterned ABS composites. The effects of the addition of OMMT and the laser marking process on the mechanical properties of ABS/OMMT composites were investigated through mechanical property tests. The results show that the obtained ABS/OMMT composites have enhanced laser marking performance, compared to the ABS. When the OMMT content is 2 wt % and the laser current intensity is 9 A, the marking on ABS composites has the highest contrast (ΔE = 36.38) and sharpness, and the quick response (QR) code fabricated can be scanned and identified with a mobile app. SEM and water contact angle tests showed that the holes, narrow cracks, and irregular protrusion are formed on the composite surface after laser marking, resulting in a more hydrophobic surface and an increased water contact angle. Raman spectroscopy and XRD indicate that OMMT can absorb the near-infrared laser energy, undergo photo thermal conversion, and cause the pyrolysis and carbonization of ABS to form black marking, and the crystal structure itself does not change significantly. When the 2 wt % of OMMT is loaded, the tensile strength, elongation at break, and impact strength of ABS/OMMT are increased by 15, 20, and 14%, respectively, compared to ABS. Compared with the unmarked ABS/OMMT, the defects including holes and cracks generated on the surface of the marked one lead to the decreased mechanical property. The desirable combination of high contrast laser marking performance and mechanical properties can be achieved at an OMMT loading content of 2 wt % and a laser current intensity of 9 A. This research work provides a simple, economical, and environmentally friendly method for laser marking of engineering materials such as ABS.

Facile Fabrication of High-Contrast and Light-Colored Marking on Dark Thermoplastic Polyurethane Materials

In this work, using ferroferric oxide (Fe₃O₄) and zirconium oxide (ZrO₂) as laser-sensitive particles and thermoplastic polyurethane (TPU) as the matrix resin, a series of TPU/Fe₃O₄/ZrO₂ composites were prepared by melt blending, and the effect of the laser marking additive content, composition, and laser marking parameters on the laser marking properties of composites was investigated. The laser marking mechanism of Fe₃O₄/ZrO₂ additives and the role of each component in TPU laser marking were studied by metallographic microscopy, color difference test, scanning electron microscopy, and Raman spectroscopy. Fe₃O₄ nanoparticles as a laser sensitizer component, on the one hand, can act as a pigment to make the TPU substrate black and, on the other hand, can absorb laser energy to contribute to the formation of laser markings on TPU composite surfaces. In addition, the introduction of ZrO₂ nanoparticles can help absorb the laser energy, while the contrast can be improved to enhance the laser marking performance of the TPU composite. Through thermogravimetric analysis, the changes in the thermally stable properties of TPU composites before and after laser marking were investigated, and the results indicated that Fe₃O₄/ZrO₂ nanoparticles can absorb the laser energy, causing melting and pyrolysis of the TPU backbone at a high temperature, to produce a gaseous product resulting in foaming. Finally, the high-contrast and light-colored markings were formed on the black TPU composite surface. This work provides a facile method for producing high-contrast and light-colored markings on the dark TPU composite surface.

New Strategy to Achieve Laser Direct Writing of Polymers: Fabrication of the Color-Changing Microcapsule with a Core-Shell Structure

This paper proposed an efficient and environmentally friendly strategy to prepare a new color-changing microcapsule with a 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. Scanning electron microscopy, transmission electron microscopy, and energy-dispersive spectrometry confirmed the successful preparation of SnO₂/PC microcapsules with a core-shell structure. Their average diameter was 2.2 μm, and the "shell" thickness was 0.21-0.24 μm. As expected, these SnO₂/PC microcapsules endowed polymers with an outstanding performance of near-infrared (NIR) laser direct writing. Raman spectroscopy and X-ray photoelectron spectroscopy indicated that the color change was ascribed to the polymer carbonization because of 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 because of 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.

Laser-Induced Selective Metallization on Polymer Substrates Using Organocopper for Portable Electronics

Our work proposed a facile strategy for selective fabrication of the precise metalized patterns onto polymer substrates through the laser direct structuring (LDS) technology using organocopper compounds. Copper oxalate (CuC₂O₄) and copper acetylacetonate [Cu(acac)₂] which can be used as laser sensitizers were first introduced into an acrylonitrile-butadiene-styrene (ABS) matrix for preparing LDS materials. After the activation with 1064 nm pulsed near-infrared laser, the Cu⁰ (metal copper) was generated from CuC₂O₄ and Cu(acac)₂ and then served as catalyst species for the electroless copper plating (ECP). A series of characterizations were conducted to investigate the morphology and analyze the surface chemistry of ABS/CuC₂O₄ and ABS/Cu(acac)₂ composites. Specially, the X-ray photoelectron spectroscopy analysis indicated that 58.3% Cu²⁺ in ABS/CuC₂O₄ was reduced to Cu⁰, while this value was 63.9% for ABS/Cu(acac)₂. After 30 min ECP, the conductivities of copper circuit on ABS/CuC₂O₄ and ABS/Cu(acac)₂ composites were 1.22 × 10⁷ and 1.58 × 10⁷ Ω^-1·m^-1, respectively. Moreover, the decorated patterns and near-field communication circuit were demonstrated by this LDS technology. We believe that this study paves the way for developing organocopper-based LDS materials, which have the potential for industrial applications.