Preserving precision of inkjet-printed features with solvents of different volatilities

Joint Experimental and Theoretical Study on Deposition Morphologies in Polymer Sessile Droplets

Although past experimental and theoretical research has made substantial progress in understanding evaporation behaviors in various suspensions, the fundamental mechanism for polymer sessile droplets is still lacking. One critical effect is the molecular weight on the evaporation behaviors. Here, systematic experiments are carried out to investigate the evaporation behavior of polymer droplets under the effects of polymer concentration, evaporation rate, and especially molecular weight. We obtain polymer films with various morphologies with molecular weights ranging from 2 orders of magnitude to 4 orders of magnitude and polymer concentration across 4 orders of magnitude. We further develop a theoretical model based on the Onsager principle to explain the evaporation mechanism from a dynamic perspective. Analysis indicates that increasing molecular weight or polymer concentration enhances the contact angle hysteresis and slows down the evaporation, resulting in the transition from multiring to coffee ring and eventually to uniform films. The findings offer a guideline for achieving the desired deposition patterns via droplet processing techniques.

Two-dimensional printing of nanoparticles as a promising therapeutic method for personalized drug administration

The necessity for personalized patient treatment has drastically increased since the contribution of genes to the differences in physiological and metabolic state of individuals have been exposed. Different approaches have been considered so far in order to satisfy all of the diversities in patient needs, yet none of them have been fully implemented thus far. In this framework, various types of 2D printing technologies have been identified to offer some potential solutions for personalized medication, which development is increasing rapidly. Accurate drug-on-demand deposition, the possibility of consuming multiple drug substances in one product and adjusting individual drug concentration are just some of the few benefits over existing bulk pharmaceuticals manufacture, which printing technologies brings. With inclusion of nanotechnology by printing nanoparticles from its dispersions some further opportunities such as controlled and stimuli-responsive drug release or targeted and dose depending on drug delivery were highlighted. Yet, there are still some challenges to be solved before such products can reach the pharmaceutical market. In those terms mostly chemical, physical as well as microbiological stability concerns should be answered, with which 2D printing technology could meet the treatment needs of every individual and fulfill some existing drawbacks of large-scale batch production of pharmaceuticals we possess today.

Inkjet Printing of Drug-Loaded Mesoporous Silica Nanoparticles-A Platform for Drug Development

Mesoporous silica nanoparticles (MSNs) have shown great potential in improving drug delivery of poorly water soluble (BCS class II, IV) and poorly permeable (BCS class III, IV) drugs, as well as facilitating successful delivery of unstable compounds. The nanoparticle technology would allow improved treatment by reducing adverse reactions of currently approved drugs and possibly reintroducing previously discarded compounds from the drug development pipeline. This study aims to highlight important aspects in mesoporous silica nanoparticle (MSN) ink formulation development for digital inkjet printing technology and to advice on choosing a method (2D/3D) for nanoparticle print deposit characterization. The results show that both unfunctionalized and polyethyeleneimine (PEI) surface functionalized MSNs, as well as drug-free and drug-loaded MSN-PEI suspensions, can be successfully inkjet-printed. Furthermore, the model BCS class IV drug remained incorporated in the MSNs and the suspension remained physically stable during the processing time and steps. This proof-of-concept study suggests that inkjet printing technology would be a flexible deposition method of pharmaceutical MSN suspensions to generate patterns according to predefined designs. The concept could be utilized as a versatile drug screening platform in the future due to the possibility of accurately depositing controlled volumes of MSN suspensions on various materials.

Tailoring Ink-Substrate Interactions via Thin Polymeric Layers for High-Resolution Printing

The surface properties of a substrate are among the most important parameters in the printing technology of functional materials, determining not only the printing resolution but also the stability of the printed features. This paper addresses the wetting difficulties encountered during inkjet printing on homogeneous substrates as a result of improper surface properties. We show that the wetting of a substrate and, consequently, the quality of the printed pattern, can be mediated through the deposition of polymeric layers that are a few nanometers thick. The chemical nature of the polymers determines the surface energy and polarity of the thin layer. Some applications, however, require a rigorous adjustment of the surface properties. We propose a simple and precise method of surface-energy tailoring based on the thermal decomposition of poly(methyl methacrylate) (PMMA) layers. A smooth transition in the wetting occurs when the thickness of the PMMA layer approaches zero, probably due to percolation of the underlying surface of the substrate, which enables the inkjet printing of complex structures with a high resolution. In particular, the wetting of three substrate-ink systems was successfully adjusted using the thin polymeric layer: (i) a tantalum-oxide-based ink on indium-tin-oxide-coated glass, (ii) a ferroelectric lead zirconate titanate ink on a platinized silicon substrate, and (iii) a silver nanoparticle ink on an alumina substrate.

Inkjet printing of nanocellulose–silver ink onto nanocellulose coated cardboard

Conductive inkjet printed cellulose nanocrystals (CNC)–silver based lines.

Hansen solubility parameters of surfactant-capped silver nanoparticles for ink and printing technologies

Optimal ink formulations, inclusive of nanoparticles, are often limited to matching the nanoparticle's capping agent or surface degree of polarity to the solvent of choice. Rather than relying on this single attribute, nanoparticle dispersibility was optimized by identifying the Hansen solubility parameters (HSPs) of decanoic-acid-capped 5 nm silver nanoparticles (AgNPs) by broad spectrum dispersion testing and a more specific binary solvent gradient dispersion method. From the HSPs, solvents were chosen to disperse poly(methyl methacrylate) (PMMA) and nanoparticles, give uniform evaporation profiles, and yield a phase-separated microstructure of nanoparticles on PMMA via film formation by solvent evaporation. The goal of this research was to yield a film that is reflective or transparent depending on the angle of incident light (i.e., optically variable). The nanoparticle HSPs were very close to alkanes with added small polar and hydrogen-bonding components. This led to two ink formulations: one of 90:10 vol % toluene/methyl benzoate and one containing 80:10:10 vol % toluene/p-xylene/mesitylene, both of which yielded the desired final microstructure of a nanoparticle layer on a PMMA film. This approach to nanoparticle ink formulation allows one to obtain an ink that has desirable dispersive qualities, rheology, and evaporation to give a desired printed structure.