The actual situation of microorganisms resistant to antibiotics and pandemics caused by a virus makes research in the area of antimicrobial and antiviral materials and surfaces more urgent than ever. Several strategies can be pursued to attain such properties using different classes of materials. This review focuses on polymeric materials that are applied as coatings onto pre-existing components/parts mainly to inhibit microbial activity, but polymer surfaces with biocidal properties can be reported. Among the several approaches that can be done when addressing polymeric coatings, this review will be divided in two: antimicrobial activities due to the topographic cues, and one based on the chemistry of the surface. Some future perspectives on this topic will be given together with the conclusions of the literature survey.

With the advances in new materials, equipment, and processes, additive manufacturing (AM) has gained increased importance for producing the final parts that are used in several industrial areas, such as automotive, aeronautics, and health. The constant development of 3D-printing equipment allows for printing multi-material systems as sandwich specimens using, for example, double-nozzle configurations. The present study aimed to compare the mechanical behavior of multi-material specimens that were produced using a double-nozzle 3D printer. The materials that were included in this study were the copolymer acrylonitrile-butadiene-styrene (ABS), high-impact polystyrene (HIPS), poly(methyl methacrylate) (PMMA), and thermoplastic polyurethane (TPU). The configuration of the sandwich structures consisted of a core of TPU and the outer skins made of one of the other three materials. The mechanical behavior was evaluated through three-point bending (3PB) and transverse impact tests and compared with mono-material printed specimens. The effect of aging in artificial saliva was evaluated for all the processed materials. The main conclusion of this study was that the aging process did not significantly alter the mechanical properties for mono-materials, except for PMMA, where the maximum flexural stress decreased. In the sandwich structures, the TPU core had a softening effect, inducing a significant increase in the resilience and resistance to transverse impact. The obtained results are quite promising for applications in biomedical devices, such as protective mouthguards or teeth aligners. In these specific applications, the changes in the mechanical properties with time and with the contact of saliva assume particular importance.