Plasma surface engineering for manmade soft materials: a review

Abstract

Manmade soft materials are important in a wide range of technological applications and play a key role in the development of future technologies, mainly at the interface of synthetic and biological components. They include gels and hydrogels, elastomers, structural and packaging materials, micro and nanoparticles as well as biological materials. Soft materials can be distinguished from liquids owing to their defined shape and from hard materials by the deformability of their shape. This review article provides an overview of recent progress on the plasma engineering and processing of softer materials, especially in the area of synthesis, surface modification, etching, and deposition. The article aims to demonstrate the extensive range of plasma surface engineering as used to form, modify, and coat soft materials focusing on material properties and potential applications. In general, the plasma provides highly energetic, non-equilibrium conditions at material surfaces requiring to adjust the conditions for plasma-surface interaction to account for the specifics of soft matter, which holds independent of the used plasma source. Plasma-induced crosslinking and polymerization of liquids is discussed to transform them into gel-like materials as well as to modify the surface region of viscous liquids. A major field covers the plasma surface engineering of manmade soft materials with the help of gaseous reactive species yielding ablation, nanostructuring, functionalization, crosslinking, stiffening, and/or deposition to obtain demanded surface properties or adhesion to dissimilar materials. Finally, plasma engineering of rigid materials is considered to induce surface softening for the enhanced contact with tissues, to allow interaction in aqueous media, and to support bonding to soft matter. The potential and future perspectives of plasma engineering will be discussed in this review to contribute to a higher knowledge of plasma interaction with sensitive materials such as soft matter.

Nanoporous SiOx plasma polymer films as carrier for liquid‐infused surfaces

“…In addition to their lubricating properties, surfaces decorated with hydrogels by means of plasma surface engineering are an emerging research topic for a broad field of applications. [ 90 ]…”

Plasma‐deposited AgOx‐doped TiOx coatings enable rapid antibacterial activity based on ROS generation

“…[ 68,69 ] To some extent, also water penetration occurs to a film depth of ~10 nm. [ 33,70–72 ] Water might also find access to the catalyst surface through defects and phase boundaries in the hydrophobic cover layer caused by the growth conditions on the Ag nano islet‐decorated TiO x surface (Figure 13a).…”

Melimine-Modified 3D-Printed Polycaprolactone Scaffolds for the Prevention of Biofilm-Related Biomaterial Infections

“…At the surface, these ions transfer their kinetic and potential energy to the surface in the form of increased temperature and can leave the surface as neutral species. , It is important to stress that not all of the reactive oxygen and argon ions that approach the surface are able to interact with it, as ions can encounter other particles and undergo elastic collisions that will reflect them back to the gaseous plasma. These interactions between particles lower the probabilities of positively charged ions reaching and modifying the polymer surface . This is even more significant in the case of 3D samples, where the deeper layers are less exposed to the plasma than the top layers, and therefore, the probability of ions reaching them is much lower.…”

“…Particularly, the use of O 2 plasma promotes etching of the polymer surface by causing the bond cleavage and ablation of weaker polymer chains. Prolonged exposure to plasma etching can result in strong nanostructuring of the polymer surface along with a reduction in mechanical properties . This is congruent with other studies showing that the use of O 2 plasma for long exposure times can lead to polymer chain scission and loss of mechanical properties. , …”