Green Printing Research Articles

Bio-inspired conductive ink: Harnessing plant based binder for customizing electrochemical, rheological and printing applications

The search for environmentally friendly electronic materials has become more intense in recent years, encouraged by the need to limit the hazards of electronic waste. Conductive inks are crucial in printed electronics. However, challenges like toxic metals, low throughput, and complex fabrication processes hindered their widespread use and spurred the exploration of natural material-based alternatives. This research explores the development of a natural Rosin and Carbon-based Conductive (RoCa) ink, focusing on optimizing the composition and its in-depth electrochemical, rheological, spectroscopic, and morphological characterization. The developed RoCa ink presented shear thinning behavior with a conductivity range between 500 and 1500 S/m and sheet resistance between 14 and 7.82 Ω/sq. The ink coatings were hydrophobic and stable to acid, basic and neutral pHs. The ink was characterized using Raman spectroscopy to understand carbon allotropes and their disordered forms with layers of graphite. FTIR was used to study the functional groups of the ink and XRD and SEM were used to study crystallite size, particle morphology and blending. The customisable electrochemical and mechanical properties of the RoCa ink paved the way towards sustainable and green printing as an environmentally benign alternative to traditional conductive inks in electronic applications.

High-performance color and fluorescence switching of cotton fabrics via light-induced proton transfer strategy of spiropyran sulfonate molecule

Light-responsive color-switching materials have garnered persistent interest recently due to their passive response to external stimuli and manifestation of notable visual color variations. Nonetheless, their development into high-end products has been hindered by unsatisfactory overall performance, characterized by challenges such as the inability to combine color contrast and retention time, poor repeatability, and reliance on a single coloring mode. Herein, we present a negative photochromic cotton fabric (NPCF) capable of real-time dual output of optical signals (color change or fluorescence emission), featuring high color contrast and resolution, excellent reversibility, and facile multicolor printing. These attributes stem from the utilization of a unique photoinduced proton transfer (PPT) strategy exhibited by the designed and synthesized spiropyran sulfonate molecule (MC-NO2). Guided by this strategy, NPCF demonstrates significant color changes and fluorescence switching in a real-time and highly reversible manner, leveraging the remote non-contact and non-destructive nature of visible light. Moreover, direct blending of MC-NO2 with commercially available water-soluble non-stimuli-responsive dyes enables customization of various photosensitive color systems for straightforward multi-color printing, aligning well with the environmental principles of green printing. This study serves as a valuable reference for the advancement and design of diverse high-performance, switchable materials suitable for the production of high-end products.

Sorption‐based treatment of flexographic printing packaging materials ink waste by synthesis of tri‐copolymers via gamma irradiation

AbstractThe treatment or recovery of waste ink constitutes a significant process for the printing and packaging industries, particularly in the flexographic printing of packaging materials. This poses a substantial challenge in the field of waste management science. The application of waste ink recovery, ensuring a safe environment and human health, along with the recovery and sustainability of Earth's resources, has garnered significant global attention. The present research is solely devoted to creating innovative trends without technological barriers for synthesizing a tri‐copolymer to be applied as an effective sorption system for waste ink. The Polyethyleneimine‐Poly Glycidyl methacrylate‐polyethylene glycol diacrylate tri‐polymer (PEI‐PGMA‐PEGDA tri‐polymer) was synthesized and thoroughly investigated using FTIR, TGA, and DSC to confirm its chemical structure, thermal stability, and the shift in melting point affected by radiation dose, respectively. SEM analysis showed significant morphological differences in PEI‐PGMA‐PEGDA tri‐polymer samples before and after treatment with flexographic printing ink waste, offering effective strategies for adsorbing waste printing inks from organic solvents. These findings contribute to a comprehensive understanding of the investigated materials and their potential applications. Additionally, the kinetic study of the sorption efficiency of flexographic ink by two sets of tri‐copolymers with doses of 20 and 40 kGy indicated that 40 kGy has a more efficient capacity. The highest sorption capacity, approximately 97.6%, was observed for a sample of GMA 15% irradiated by 40 kGy with a sorption amount of 2.5 g L−1. This suggests that the current new treatment strategy can be categorized as highly effective waste ink management and should be advocated for in such domains to ensure a safe environment and preserve Earth's resources. The treatment of printing ink for packaging materials is a crucial step towards achieving green printing technology, which must be supported and advanced through research and industrial application.

Exploring Effective Ways of Green Printing to Reduce Harmful Volatile Organic Compounds Emissions

This paper delves into the transformative shift in the printing industry from traditional petroleum-based inks to sustainable alternatives, focusing on soy ink. Initially, it examines the environmental and health hazards associated with conventional printing, highlighting the detrimental impact of volatile organic compounds (VOCs) and toxic substances in inks. The emergence of soy ink as an eco-friendly solution is then explored. Derived from soybeans, soy ink significantly reduces the release of harmful VOCs and enhances the recyclability of printed materials. The paper discusses not only the environmental benefits of soy ink but also its operational and economic advantages, such as improved deinking capabilities and waste reduction. A notable development in soy ink technology is the use of soy methyl ester, which addresses the challenges of slow drying and penetration associated with traditional inks. The paper concludes by emphasizing the need for continued innovation in sustainable practices within the printing industry, positioning soy ink as a key player in aligning economic goals with environmental responsibility. The shift to soy-based inks exemplifies a broader trend towards sustainability, pivotal for the future health of the planet.

Green Printing for Scalable Organic Photovoltaic Modules by Controlling the Gradient Marangoni Flow.

Despite the rapid development in the performances of organic solar cells (OSCs), high-performance OSC modules based on green printing are still limited. The severe Coffee-ring effect (CRE) is considered to be the primary reason for the nonuniform distribution of active layer films. To solve this key printing problem, the cosolvent strategy is presented to deposit the active layer films. The guest solvent Mesitylene with a higher boiling point and a lower surface tension is incorporated into the host solvent o-XY to optimize the rheological properties, such as surface tension and viscosity of the active layer solutions. And the synergistic effect of inward Marangoni flow generation and solution thickening caused by the cosolvent strategy can effectively restrain CRE, resulting in highly homogeneous large-area active layer films. In addition, the optimized crystallization and phase separation of active layer films effectively accelerate the charge transport and exciton dissociation of devices. Consequently, based on PM6:BTP-eC9 system, the device prepared with the co-solvent strategy shows the a power conversion efficiency of 17.80%. Moreover, as the effective area scales to 1 and 16.94 cm2, the recorded performances are altered to 16.71% and 14.58%. This study provides a universal pathway for the development of green-printed high-efficiency organic photovoltaics.

Stimuli-fluorochromic smart organic materials.

Smart materials based on stimuli-fluorochromic π-conjugated solids (SFCSs) have aroused significant interest due to their versatile and exciting properties, leading to advanced applications. In this review, we highlight the recent developments in SFCS-based smart materials, expanding beyond organometallic compounds and light-responsive organic luminescent materials, with a discussion on the design strategies, exciting properties and stimuli-fluorochromic mechanisms along with their potential applications in the exciting fields of encryption, sensors, data storage, display, green printing, etc. The review comprehensively covers single-component and multi-component SFCSs as well as their stimuli-fluorochromic behaviors under external stimuli. We also provide insights into current achievements, limitations, and major challenges as well as future opportunities, aiming to inspire further investigation in this field in the near future. We expect this review to inspire more innovative research on SFCSs and their advanced applications so as to promote further development of smart materials and devices.

Thermal/UV Respond Polydiacetylene /Ni2+ Thermal Paper with Reusability

AbstractPolydiacetylenes (PDAs) are a family of highly conjugated polymers that generate optical response sensitively if exposed to stimuli, the color would change from blue to red. PDAs with reusability and color reversibility are at the central of current research efforts generously. They enhance the electrostatic interaction between cations and the negatively charged carboxylate head groups to increase the rigidity and decrease the energy barrier by introducing Ni2+ into the side chains of PDAs. The amphiphilic 10,12‐pentacosadiynoic acid (PCDA) molecules with the hydrophilic and hydrophobic group are dispersed into Ni2+ aqueous solution and self‐assembled in situ into nanoparticles. Transferring the solution onto a paper base to yield a precisely controlled thickness of PDAs thermal paper. The thermal paper undergoes UV‐induced topological chemical polymerization and further cross‐linking to form stably blue. Because of the reduced energy barrier, red thermal paper after thermal stimulation can undergo color reduction under UV light irradiation. Increasing the photopolymerization time from 5 s to 600 s leads to the rising of the color change temperature from approximately 76.4 °C to 105.4 °C. The polydiacetylene/Ni2+ (PDA/Ni2+) thermal paper can be available for green printing, thermal history recording, and temperature visualization.

Numerical Simulation of Impinging Jet Drying Multiphase Flow in Gravure Printing Water-Based Ink Based on the Volume of Fluid Method

Gravure printing is widely used in food, pharmaceutical, and other packaging industries. As a green printing material, water-based ink has problems such as non-volatile and poor drying on non-absorbent packaging substrates, which has a great impact on its application. To solve these difficulties, this study adopts the volume of fluid (VOF) method and user-defined function (UDF) to establish a multiphase flow impinging air jets drying model of water-based ink in the gravure printing process, taking a water-based ink droplet as an example. The model was used to simulate the ink drying state in the impinging air jets region and analyze the effects of impinging air jets’ temperature and velocity, as well as ink viscosity and thickness, on the ink drying efficiency. Meanwhile, the heat and mass transfer mechanism between impinging air jets and water-based ink was investigated. The results show that the higher impinging air jet temperature and velocity, the faster the drying rate of the ink; a lower viscosity and thinner thickness of ink can also enhance the drying efficiency of the ink. The multiphase impinging air jets drying model based on the computational fluid dynamics (CFD) method provides a new research idea for the analysis of drying characteristics of water-based ink on non-absorbent substrates, and the research results provide theoretical support to promote its application.

Structural color modulation by laser post-processing on metal-coated colloidal crystals.

A method to use a pulsed solid-state laser to create structural color modulation on metal-coated colloidal crystal surfaces by changing the scanning speed has been proposed. Vivid colors as cyan, orange, yellow, and magenta are obtained with different predefined stringent geometrical and structural parameters. The effect of laser scanning speeds and polystyrene (PS) particle sizes on the optical properties is studied, and the angle-dependent property of the samples is also discussed. As a result, the reflectance peak is progressively red shifted along with increasing the scanning speed from 4mm/s to 200mm/s with 300nm PS microspheres. Moreover, the influence of the microsphere particle sizes and incident angle are also experimentally investigated. For 420 and 600nm PS colloidal crystals, along with a gradual decrease in the scanning speed of the laser pulse from 100mm/s to 10mm/s and an increase in the incident angle from 15° to 45°, there was a blue shift for two reflection peak positions. This research is a key, low-cost step toward applications in green printing, anti-counterfeiting, and other related fields.

Overcoming Disordered Preaggregation in Liquid State for Highly Efficient Organic Solar Cells Printed from Nonhalogenated Solvents

AbstractThe current power conversion efficiencies of laboratory‐sized organic solar cells (OSCs), based on the spin‐coating process with halogenated solvents, have exceeded 19%. Environmentally friendly printing is needed to bridge the gap between laboratory and industrialization by being compatible with roll‐to‐roll large‐area production. Here, the molecular design rules are revealed for enhancing the green printing potential of the state‐of‐the‐art photovoltaic martial systems by investigating the detailed structure formation dynamic and the key determining factors. By comparing two model systems based on D18:Y6 and D18:BTP‐eC9, it is found that disordered preaggregation in liquid state can result in over‐sized domains with reduced crystallinity and disordered molecular orientation, which significantly limits device performance. By systematically tuning the length of the inner alkyl side chains with multiple Y‐series materials, the authors demonstrate that molecular side‐chain engineering can effectively supress the detrimental disordered preaggregation in liquid state during environmentally friendly printing process, leading to enhanced crystallization with preferential faceon molecular orientation, more efficient exciton dissociation and charge carrier transport, and finally high upscaling potential. The work provides deeper insights into molecular engineering and structure formation dynamics toward environmentally friendly production of OSCs.

Advances in the device design and printing technology for eco-friendly organic photovoltaics

This perspective systematically discusses strategies of optimization of active layer films in the preparation of organic photovoltaic (OPV) devices by green printing.

Novel green printing of cotton, wool and polyester fabrics with natural madder dye nanoparticles

In this study, madder dye nanoparticles have been successfully prepared by using a simple ball milling technique. Madder dye nanoparticles are characterized by using UV-vis. absorption, XRD, TEM, FTIR spectroscopy and SEM. The prepared madder dye nanoparticles are used as an active ingredient for printing cotton, wool, and polyester fabrics via dye printing technique and pigment printing technique. Factors of printing process, such as substrates mordanting, thickeners type, urea concentration and p H of printing paste, urea concentration of first paste and binder concentration of second paste, are studied. Results show that fabrics printed with madder dye nanoparticles via mentioned two methods show very good to excellent fastness properties with a full green method. These data indicate that printed samples have high quality for colour strength without any environmental hazards as compared to other conventual and nanotechnological aspects.

Research on the Development Path of Green Printing Industry under the Background of Bi-carbon Goal

Carbon peak and carbon neutrality is a major strategic decision made by China in the face of climate problems. This paper starts from the definition of double carbon, introduces the progress of double carbon work in China, clarifies the necessity and urgency of promoting the green development of the printing industry, organizes the technical strategies for the green development of the printing industry under the background of "double carbon", and proposes a model of collaboration among the government, industry and enterprises. The aim is to explore the prospect of green development in the printing industry under the background of "double carbon".

A general enlarging shear impulse approach to green printing large-area and efficient organic photovoltaics

The shear impulse strategy is an effective strategy that optimizes the morphology of the active layer by varying the MGC speed, resulting in a remarkable PCE of 17.15%.

An alloy small molecule acceptor for green printing organic solar cells overcoming the scaling lag of efficiency

The BTP-F3Cl-based ternary system can overcome the scaling lag of device efficiency more effectively than the PM1:L8-BO host system, which can guide the lab-to-manufacturing translation of green printing organic solar cells.

Green and Eco-Friendly Indigo Printing using New Smart Nano-Colorants and Their Application in Combined Printing and Antibacterial Finishing

Green and Eco-Friendly Indigo Printing using New Smart Nano-Colorants and Their Application in Combined Printing and Antibacterial Finishing

Second-harmonic generation from green printed selenium structures

Plenary large-scale efficient second-harmonic generation sources remains a challenge in micro-/nanoscale research. In this work, we demonstrate the strong second-harmonic generation in arrays of selenium particles fabricated by green printing method at the pumping wavelength of 1047 nm. Second-harmonic generation mapping shows the strong signal over the whole area of selenium particle. We propose, that such structures can be a perspective platform for efficient frequency conversion systems and nonlinear sensing applications.

Light drive reversible color switching for rewritable media and encoding

Nowadays, photo reversible color switching systems (PCSS) are always limited by some requirements, such as good stability, low toxicity, fast light response, long cycling performance and low production cost, therefore, it is a huge challenge to develop such a system that integrates beneficial features. Herein, a new type of PCSS have been demonstrated, which integrated reducing agent of triethanolamine (TEOA), catalyst of β-FeOOH nanorods and the redox driven color conversion characteristics of redox dyes. The system has the advantages of high switching rate, high reversibility (>10 cycles), wavelength selective response, safety and less light damage, which can be widely used in rewritable paper. As-prepared rewritable paper has high contrast, high resolution, suitable printing time and good reversibility, which is in line with the environmental protection concept of green printing. Rewritable paper is a kind of self-erasable rewritable medium which is highly suitable for printing. Environmental protection film has the advantages of low cost, convenient preparation and recycling. It is expected to replace the traditional writing, printing paper, existing systems and make a big step forward to practical application. Even more surprising, it also can be applied for a data encoding and reading strategy.

Printing Wool Fabrics with Natural Dyes Curcuma and Alkanet (A Critique)

Green printing of wool textiles utilizing green print Paste with natural alkanet dye nanoparticles. The ball-milling technique provides an effective way of generating alkanet-nano particles dye at room temperature and pressure in one step. In this research, we study the effect of alkanet alone and Curcuma dye alone on wool fabric in natural size and nano size and comparing among them. studying K/s of the samples and the properties of fastness. we study the ball milling method to get nanoparticles of alkanet dye. we study the effect of mordants that are attached to fibers before or post-printing of wool fabrics. Regardless of the textile used, nano samples have a K/S value greater than the basic samples. Nano-Curcuma can be replaced for alum mordant with normal Curcuma. K/S values of pre-mordant gained values that were above the simultaneous mordant, regardless of the fabric or size of dye or the quantities of Curcuma in the usage of tannic acid mordant.

Noniridescent structural color from enhanced electromagnetic resonances of particle aggregations and its applications for reconfigurable patterns

Hypothesis: The conventional noniridescent structural colors refer to the coherent scattering of visible light by the short-range ordered structures assembled from the small colloids (100–250 nm). Our hypothesis is that noniridescent structural color can be generated by the random aggregations of large silica particles through the enhanced electromagnetic resonances.Experiments: The random aggregations of large silica particles (350–475 nm) were prepared through the infiltration of silica particles solution with the porous substrate. The mechanism of the structural color is investigated. Reconfigurable patterns are prepared.Findings: Dissimilar to the conventional noniridescent colors, the angle-independent colors of silica aggregations originate from the enhanced electromagnetic resonances due to the random aggregation of the particles. The colors (blue, green, and red) and corresponding reflection peak positions of the particle aggregations can be well controlled by simply altering the size of the silica particles. Compared to the traditional prints with permanent patterns, reconfigurable patterns with large-area and multicolor can be fabricated by the repeatedly selective spray of water on the substrate pre-coated with noniridescent colors. This work provides new insight and greenway for the fabrication of noniridescent structural colors and reconfigurable patterns, and will promote their applications in soft display, green printing, and anti-counterfeiting.