Printable Formulations Research Articles

An overview on potential of novel photoinitiators for vat photopolymerization-based 3D/4D printing formulations

An overview on potential of novel photoinitiators for vat photopolymerization-based 3D/4D printing formulations

The Utilization of Central Composite Design for the Production of Hydrogel Blends for 3D Printing

Central composite design (CCD) is a statistical experimental design technique that utilizes a combination of factorial and axial points to study the effects of multiple variables on a response. This study focused on optimizing hydrogel formulations for 3D printing using CCD. Three biopolymers were selected: sodium alginate (SA), gelatin (GEL), and carboxymethyl cellulose (CMC). The maximum and minimum concentrations of each polymer were established using a Google Scholar search, and CCD was employed to generate various combinations for hydrogel preparation. The hydrogels were characterized in accordance with their swelling degree (SD) in phosphate-buffered saline (PBS) and Dulbecco’s Modified Eagle Medium (DMEM), as well as their printability in 2D and 3D assays. The formulation consisting of 7.5% SA, 7.5% GEL, and 2.5% CMC exhibited the best swelling properties and exceptional printability, surpassing all other tested formulations. This study highlights the effectiveness of design of experiment methodologies in accelerating the development of optimized hydrogel formulations for various applications in 3D printing and suggests avenues for future research to explore their performance in specific biological contexts.

Comparative analysis of ternary blended cement with clay and engineering brick aggregate for high-performance 3D printing

Utilising recycled brick aggregate in cementitious mixtures can decrease the overdependency on limited natural resources and improve the sustainability of concrete. This paper presents a potential solution to lower the amount of waste being landfilled and increase the sustainability of 3D concrete printing technology by combining low-carbon ternary blended cement with recycled aggregates. Hence, the effect of incorporating two types of recycled brick aggregate - clay brick (CBA) and engineering brick (EBA) on the properties of 3D printable ternary blended cement were investigated. The natural aggregate in a pre-existing 3D printable blend was substituted by up to 50 wt.-% with two varieties of recycled brick aggregates available throughout Europe. The recycled brick aggregates underwent characterisation to determine their properties. The fresh property evaluation using the green strength test was used to assess the effect of aggregate replacements on the mixture's shape stability. The mechanical performance of mixtures containing CBA and EBA, both cast and 3D printable mixes, was evaluated and compared to that of the control sample. The results indicated that incorporating recycled brick aggregate enhances green strength and Young's modulus significantly. Mechanical strength performance showed significant enhancement when incorporating RBA, which reached up to 67% and 55% for both cast and 3D printing methods, respectively. The suitability of the developed mix formulations for 3D printing was assessed by printing cylindrical objects.

Extrusion-based 3D food printing - Materials and machines.

To help people with dysphagia increase their food intake, 3D printing can be used to improve the visual appeal of pureed diets. In this review, we have looked at the works done to date on extrusion-based 3D food printing with an emphasis on the edible materials (food inks) and machinery (printers) used. We discuss several methods that researchers have employed to modify conventional food materials into printable formulations. In general, additives such as hydrocolloids may modify the rheological properties and texture of a pureed food to confer printability. Some examples of such additives include starch, pectin, gelatin, nanocellulose, alginate, carrageenan etc. In the second part, we have looked at various food printers that have been developed for both academic and commercial purposes. We identified several common advantages and limitations that these printers shared. Moving forward, future research into food printer development should aim to improve on these strengths, eliminate these limitations and incorporate new capabilities.

Additive Construction Production: Past, Present, Future

An overview of the development of additive construction production from the beginning of the formation of prerequisites to the present moment and future prospects for the development of 3D construction printing in the world is given.The publications of international citation databases, including the results of research in the field of additive construction production for the period from 1972 to 2024, are considered as the basis of the study.The study is divided into several stages, the first of which is devoted to the analysis of search queries and the definition of relevant keywords.It was revealed that the most popular phrases describing the use of additive technologies in construction are “Concrete Printing” and “3D Concrete Printing”, therefore, as part of the subsequent stage of work, abstract samples were formed on their basis to analyze and summarize the results of relevant scientific research. The final stage of the study included a more detailed study of the main results of scientific works characteristic of three time intervals describing past, present and future trends in scientific activity in the subject area under consideration. The results of the study show a significant increase in interest in the technology of construction 3D printing with concrete due to the realization of the potential to increase labor productivity in construction and reduce the negative impact on the environment in comparison with traditional construction production technologies, which can become a driver of sustainable development of the construction industry.The conducted research makes it possible to conclude that there are still unresolved problems on the way of active implementation of the technology, which are constraining factors for the widespread introduction of additive construction production, in particular the issues of printing horizontal structures of floors and coatings of buildings, reinforcement of load-bearing structures printed with a 3D printer. According to the authors, the solution of these problems should be given priority in future research, along with the development of new formulations for 3D printing with concrete.

Development of a quaternary photocurable system for 3D printing based on the addition of acrylate monomers to an epoxy/thiol‐Ene system

AbstractThe exothermic nature of acrylate photopolymerizations enables room temperature 3D printing of a quaternary formulation that incorporates an acrylate monomer, and an epoxy/thiol‐ene system (ETES). The latter comprises an epoxy monomer, a multifunctional thiol and a tetraallyl functionalized ditertiary amine curing agent. Pristine ETES necessitates temperatures of 85–95 °C for curing. Several mechanisms operate simultaneously during this process: homopolymerization of acrylates, thiol‐acrylate photopolymerization, thiol‐ene photopolymerization between the double bonds of curing agent and the multifunctional thiol, the Michael addition between thiolates derived from ETES and the double bonds of acrylates, and the anionic polymerization of the epoxy resin via the tertiary amine groups. To optimize the quaternary formulations for printing, parameters, such as reactivity, exothermicity, and viscosity, was explored. Subsequently, the thermal and viscoelastic properties of the printed cross‐linked polymers derived from these formulations were analyzed using Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA) and Thermogravimetric Analysis (TGA). The polymers derived from quaternary formulations exhibited lower crosslinked density compared to those obtained from the pristine acrylates. This reduction in crosslink density contributes to the improved toughness of the hybrid polymers.

3D printing with stabilized earth: Material development and effect of carbon sequestration on engineering performance

This research examines the feasibility of using excavated soil (clay content of 44 %) as 25 % and 50 % replacement of natural sand in 3D printable formulations. A combination of ordinary Portland cement (OPC) and fly ash (FA) are used as binders for stabilization. The development of engineering properties subject to two curing conditions – normal curing and CO2 curing (5 % concentration for 5 h) are investigated. Experimental findings suggest that a combination of FA and clay (mainly kaolinite) in the used soil reduces plastic viscosity and improves flow retention, thus enhancing the extrusion quality and stability. The flocculation of clay at rest accelerates the evolution of static yield stress after extrusion, imparting 18–30 % better thixotropy. As a result, OPC-FA-soil mixes could be stacked to a height of 1.20 m compared to 0.48–0.54 m for OPC-sand and OPC-FA-sand mixes. Carbon sequestration via CO2 curing leads to an increase in wet compressive strength of OPC-25 % soil and OPC-FA-25 % soil by 29–38 % and 26–47 % respectively at 1-day age, which is ascribed to the densification effect of mineral carbonates. This is also reflected in the reduction in water sorptivity through the inter-layer zones and total shrinkage by 20 % and 16 % respectively. Due to reduced shrinkage and capillary sorption, inter-layer bond strengths in CO2-cured OPC-25 % soil are also improved by 20–50 % than the normally cured counterpart. In summary, the research demonstrates a feasible pathway to develop carbon-sequestering earth-based materials (CO2 uptake of 9–11 wt% of OPC) for additive manufacturing of masonry building and infrastructural members.

Optimization of 3D printing formulation of shrimp surimi based on response surface method

The Box-Behnken experimental design is an optimization statistical tool. In this study, shrimp surimi was taken as the research object, Box-Behnken experiment design and regression analysis were used, and the addition of cross-linked starch (CLS), soy protein isolate (SPI) and lard oil (LO) were used as experimental factors. The purpose was to explore the effects of adding different mixed ingredients on the properties of shrimp surimi. The study found that in order to improve the accuracy and stability of 3D printing of shrimp surimi, the material characteristics should meet two conditions at the same time: (i) Water holding capacity is controlled between 89% and 92%; (ii) AF value is controlled between 3500 and 4500 Pa·S1/z. When the addition amount of 3.00% LO, 4.50% CLS, and SPI was controlled between 1.58% and 6.53%, or when the addition amount of 3.00% LO, 4.50% SPI, and CLS was controlled between 1.80% and 6.75%, the above two conditions can be met at the same time, making the material properties of shrimp surimi conducive to 3D printing. This study determined the optimization range of the added amount of mixed ingredients to improve the adaptability of 3D printed shrimp surimi, which could meet the needs of consumers for personalized nutritious diets and improve the added value of shrimp surimi products.

Towards Sustainable Material: Optimizing Geopolymer Mortar Formulations for 3D Printing: A Life Cycle Assessment Approach

Geopolymer-based concretes have been elaborated among others for their potential to lower the environmental impact of the construction sector. The rheology and workability of fresh geopolymers make them suitable for new applications such as 3D printing. In this paper, we aim to develop a potassium silicate- and metakaolin-based geopolymer mortar with sand and local earth additions suited for 3D printing and an environmental assessment framework for this material. The methodology aims at the optimization of both the granular skeleton and the geopolymer matrix for the development of a low-environmental-impact material suited for 3D printing. Using this approach, various metakaolin/earth geopolymer mortars are explored from a mechanical and environmental point of view. The environmental assessment of the lab-scale process shows an improvement for the climate change category but a degradation of other indicators, compared to Portland-cement-based concrete. Several promising options exist to further optimize the process and decrease its environmental impacts. This constitutes the main research perspective of this work.

Sustainable 3D printed poly (lactic acid) (PLA)/Hazelnut shell powder bio composites for design applications

In the context of seeking sustainable solutions for developing innovative materials and products by an efficient use of natural resources and recycling waste, with an increasing focus on circular economy and mitigating environmental impact, the presents research aims to use biomass and agricultural residues as raw materials for bio composite production. Specifically, valorizing European hazelnut waste presents a unique opportunity to devise innovative formulations for 3D printing, leveraging both the mechanical properties and aesthetic appeal of lignocellulosic bio composites. In detail, this work aimed at the investigation of new poly(lactic acid) (PLA)/Hazelnut Shell Powder formulations for 3D printing design applications exploiting the woody aesthetic effect of these bio composites. A pellet 3D printer was used to bypass the filament production. Three different Hazelnut Shell Powder content (from 10 up to 30 wt%) were investigated and a design of experiment was carried out to generate response surfaces able to identify the best printing conditions to optimize flexural, tensile and impact properties. Finally, the effect of three different raster angles (0°, ±45° and 90°) on the mechanical properties was investigated. The best configuration was: 220 °C of nozzle temperature, 25 mm/s of printing speed and ±45° of raster angle. With this configuration, prototypes of ornamental pots, jewellery and home furniture were produced as demonstrators.

Methodology for formulating low-carbon printable mortar through particles packing optimization

High packing density is one of the key factors for obtaining ultra-high-performance cementitious materials in the hardened state. Packing density also plays a role in the fresh state, influencing various properties of dense suspensions, including rheological properties and stability, which are highly important in 3d printing applications. The maximum packing density of a specific mixture can be estimated by considering the geometrical properties and proportions of each component using the compressive packing model (CPM). This paper aims to utilize the CPM as an efficient tool for designing cementitious materials specifically tailored for large-scale 3D printing of mortar in bi-component printing systems, with a focus on maximizing the performance-to-environmental impact ratio. Two different sets of mixtures were prepared for this study. Set A consisted of cement, sand, and silica fume, while Set B utilized cement, multiple sands, and multiple limestone fillers. Within each group, various mixtures were tested on a small scale to validate their rheological properties, particularly the yield stress. Pumpability, extrudabilty and buildability were evaluated by utilizing these mixtures in different printing sessions. Additionally, the compressive strengths of these mixtures were characterized. Finally, a method for designing a printable mixture is presented, and efficient and printable formulations with low cement ratio are proposed and printed.

Improvement of jelly 3D printing using ultrasound treatment and calcium chloride.

This study investigated the effects of ultrasound treatment or calcium chloride (CaCl2) addition on the physical properties of jelly formulations. Elastic modulus (G'), loss modulus (G"), tan δ, shear modulus, yield stress (τ0), phase angle (δ), and gel strength were the parameters selected to describe the requirements of jelly printing, such as fidelity, shape retention, and extrudability. Ultrasound treatment of the jelly formulation without pectin increased the G' and shear moduli values, while decreasing the δ and gel strength. The addition of CaCl2 to the jelly formulation with pectin increased the G', G", shear modulus, τ0, and gel strength but lowered the tan δ and δ values. Both ultrasound treatment and CaCl2 addition improved the jelly printing requirements and demonstrated the potential to control the physical properties of jelly formulations for 3D printing using fused deposition modeling.

Artificial intelligence generates novel 3D printing formulations

Formulation development is a critical step in the development of medicines. The process requires human creativity, ingenuity and in-depth knowledge of formulation development and processing optimization, which can be time-consuming. Herein, we tested the ability of artificial intelligence (AI) to create de novo formulations for three-dimensional (3D) printing. Specifically, conditional generative adversarial networks (cGANs), which are generative models known for their creativity, were trained on a dataset consisting of 1437 fused deposition modelling (FDM) printed formulations that were extracted from both the literature and in-house data. In total, 27 different cGANs architectures were explored with varying learning rate, batch size and number of hidden layers parameters to generate 270 formulations. After a comparison between the characteristics of AI-generated and human-generated formulations, it was discovered that cGANs with a medium learning rate (10−4) could strike a balance in generating formulations that are both novel and realistic. Four of these formulations were fabricated using an FDM printer, of which the first AI-generated formulation was successfully printed. Our study represents a milestone, highlighting the capacity of AI to undertake creative tasks and its potential to revolutionize the drug development process.

Thiol-ene-based degradable 3D printed network from bio resource derived monomers ethyl-lactate and isosorbide

A polymeric ene-based thiol-ene network is reported that was demonstrated for light-based 3D printing. Allyl poly (acrylate ethyl lactate) (PAEL) was synthesized starting from ethyl lactate in an efficient and scalable manner. Ethyl lactate is a biobased material obtained naturally or chemically in high yields in the form of ethyl ester of lactic acid. Isosorbide, which is also a bio based resource was converted into thiol derivative and was used along with Pentaerythritol tetrakis(3-mercaptopropionate) (PETMP) as multifunctional thiol. The polymeric nature of the ene (i.e. PAEL) imparted exceptionally high mechanical properties like Young's modulus of 1.75 GPa as well as high thermal stability with a decomposition temperature (Td,10%) exceeding 350 °C for all the networks studied. The properties could also be customized by fine tuning the type and stoichiometric ratio of the thiol crosslinked employed. For instance, the Young's modulus range from 1.75 GPa to 1.03 GPa and glass transition temperature range from 44 °C to 54 °C could be achieved. DLP 3D printing was used to demonstrate the printability of the resins with high resolution and structural fidelity. The study also highlights the base-mediated rapid hydrolytic degradation efficiency of the 3D printed parts, demonstrating the applicability of these novel polymeric ene based thiol-ene for sustainable and eco-friendly 3D printable formulations.

Chitosan/Nanohydroxyapatite/Hydroxyethyl-cellulose-based printable formulations for local alendronate drug delivery in osteoporosis treatment

Osteoporosis is a silent bone disease and a growing health issue. Despite recent progress in diagnosis and treatment, effective therapeutic strategies are still needed. One of the possible solutions is the implantation of engineered drug-releasing scaffolds at the disease site. To boost this approach further, we aimed to develop printable materials (the inks) for the construction of patient-specific 3D scaffolds with drug-release capability. The inks were composed of chitosan – a natural osteoinductive polysaccharide, nanohydroxyapatite – a natural bone matrix ingredient improving mechanical properties, sodium alendronate – a bioactive drug, and hydroxyethyl-cellulose – a filler improving the printability. Printed scaffolds were crosslinked with citric acid or KOH. After coating with collagen and gelatin, they demonstrated biocompatibility with the adipose-derived mesenchymal stem cells and MG-63 cell line. They also showed a sustained release of alendronate for 50 days, causing a significant reduction in the expression of Cathepsin K, an osteoclast-specific gene marker, which indicates the osteoclast-inhibiting capacity of the coated scaffolds. This work demonstrates the potential of developed printable materials to find applications as cell and drug carriers for the treatment of osteoporosis.

Tailoring Morphology and Size of Silver Nanoparticles Prepared by Polyol Method by Changing the Structure of Silver Carboxylate Precursor

AbstractSilver nanoparticles are synthesized by reducing silver alkyl carboxylates at their high concentrations with ethylene and propylene glycol without a common use of polymeric dispersants and stabilizers. The effects of alkyl chain structure on the morphology and size of silver particles have been studied by scanning electron microscopy, transmission electron microscopy, powder X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analyses. The carboxylates that have been investigated are silver caprylate, laurate, 2‐butyloctanoate, and 2‐ethylhexanoate. It was found that the reduction temperature of straight‐chain alkyl carboxylates is in the 110–120 °C range. The particles prepared under these conditions are perfectly spherical in shape and their average size varies from 20 to 40 nm. In the case of the branched structure, the reduction process starts at around 80 °C and produces irregularly shaped silver particles with a size of 150 to 450 nm. Possible ways of controlling the parameters of the synthesized nanoparticles are proposed. This study proposes a simple and easily scalable method to prepare silver nanoparticles stabilized by a non‐polymeric stabilizer. The as‐synthesized silver particles may have applications as metallic fillers in ink and paste formulations for 2D and 3D printing to fabricate functional components and devices.

Research Progress in Printing Formulation for 3D Printing of Healthy Future Foods

Research Progress in Printing Formulation for 3D Printing of Healthy Future Foods

Additive construction using enhanced earthen-based composites: Improvement of the mechanical strength and water durability using chitosan and agave fibers

3D printing has emerged as a revolutionary technology with potential applications in the construction industry. However, the prevalent use of ordinary cement in most 3D printing formulations results in significant greenhouse gas emissions during 3D printing construction. In contrast, earthen-based composites are an eco-friendly alternative for building materials. However, as a construction material, earth presents poor mechanical strength and low durability against water erosion. This study aims to obtain earthen-based composites with suitable mechanical and durability properties to investigate their extrudability and buildability in tests. It also explores the effects of incorporating short sisal fibers (l/d ratio = 138.7) and chitosan (DD = 91%, Mw = 598 kDa) to improve strength and water durability in earthen-based composites for 3D printing purposes. Chitosan is a natural macromolecule derived from a waste product from the food industry, whereas sisal fibers are obtained from the Agave sisalana plant. The change in compressive strength was analyzed through uniaxial compression. Water durability was evaluated by measuring the water contact angle, total and capillary water absorption, and accelerated erosion tests. The results indicate that the use of 3.0% (w/v) aqueous solution of chitosan and 1.0% (w/w) of sisal fibers have an important effect on the hardening and water durability properties of earthen-based composites. This study suggests that these materials could serve as natural additives to enhance the mechanical properties and water durability of new eco-friendly construction materials for 3D printing. In conclusion, this study demonstrates that appropriate formulations with natural and eco-friendly additives can lead to stabilized earthen-based composites with suitable printing, mechanical and durability properties for 3D printing applications in construction materials.

Quality attributes for printable emulsion gels and 3D-printed tablets: Towards production of personalized dosage forms

3D-printing technology offers a flexible manufacturing platform with the potential to address the need of personalized dosage forms. However, quality aspects of such small-scale, on-demand production of pharmaceutical products intended for personalization is still limited. The aim of this study was therefore to study critical quality control attributes of lipid tablets produced by semi-solid extrusion (SSE) 3D printing from emulsion gels incorporating a poorly water-soluble drug. Quality attributes for both the printable emulsion gel and the printed dosage forms were assessed. The emulsion gel was shown to be printable with accurate dosing for at least one month of storage at 4 °C. Tablets were 3D printed in different sizes and a correlation, R2 value of 0.99, was found between the weight and the drug content. The 3D-printed tablets complied with the mass and drug content uniformity requirements described in the European Pharmacopoeia.. Solid-state characterization of the tablets during short-term storage revealed no signs of crystallinity of the drug. Lastly, the lipid digestion and drug release were unchanged after short-term storage of the tablets. This study demonstrates the potential of SSE 3D printing for personalized dosing of a lipid-based formulation strategy and discusses central quality attributes for the printable formulation and the 3D-printed dosage form.

The selection and design of earthen materials for 3D printing

Significant efforts are being made to reform the construction industry using 3D printing. Among an extensive variety of printing materials, eco-friendly earth materials have recently received increased attention. Nonetheless, corresponding research is limited, particularly in assessing the availability of earthen mixture and printing performance. This study presents a methodical and effective procedure for selecting earthen formulations for 3D printing. Four different soils were identified based on their characteristics, including granularity, clay behavior, and linear shrinkage, in order to select suitable construction materials. In addition, the rheological behavior (yield stress) of the earthen mixture was investigated so that printing formulations could be selected effectively. Finally, the printing performance was evaluated for establishing recommendations for selecting appropriate mixtures, and an analytical model of mass transfer based on the drying process for predicting the occurrence of plastic collapse was also proposed.