29 Oct Polymer-based antimicrobial coatings

Since 2019, the world is facing one of the most significant pandemic in its history and there is an increasing need to develop innovative antimicrobial, antiviral and/or antibacterial coatings. These coatings prevent microbial growth as well as the proliferation of harmful bacteria and viruses on surfaces in medical, food and other industries [1].

Different materials have been elaborated over the years based [2] on organic molecules, polymers, or inorganic particles. Two different approaches have been implemented: (i) Passive strategies that consist in imparting repellent properties to limit the pathogens and virus adhesion and biofilm formation and (ii) Active strategies where biocide components are introduced into the coating. SPECIFIC POLYMERS is developing functional monomers, polymers or building-blocks of interest within this area and has the ability to develop innovative anti-microbial coatings while respecting other specifications linked to the application (mechanical properties, adhesion, optical properties, process compatibility, etc.).

Active Antimicrobial Coatings

Another strategy, named as active coatings, consists in adding biocide substances that will damage the bacteria membrane and eventually inactivate the virus or the bacteria, into the coating formulation.

Metal-based antimicrobial coatings

One of the most efficient technologies implemented so far is the introduction of inorganic particles such as silver, copper, or zinc into the coating material. These particles slowly release metal ions that eradicate the virus for a long time period. These compounds can already be found in different anti-microbial applications and more specifically in biomedical coatings. Moreover, Reactive Oxygen Species (ROS) can be generated with metal oxides, killing the bacteria thanks to the oxidizing effect of the radical groups. Interestingly, the biocide performances of such particles can be enhanced by grafting cationic surfactants on their surfaces.[5] Within this approach, SPECIFIC POLYMERS can provide functional polymers of interest for the design of metallic core-shell nanoparticles, for instance methacrylic copolymers bearing phosphonic acid to ensure the adhesion of the metallic surfaces and well-selected co-monomers to provide satisfying thermo-mechanical properties to the final layer.

Cationic polymeric layer

The second active strategy is based on the development of cationic polymeric layer. This technique hinders the growth of pathogens mostly by contact killing mechanism. The cationic and amphiphilic moieties of these materials attract the bacteria cell walls by electrostatic force of attraction and disrupt their membranes. Some cationic polymers are available on the market but can also be custom designed. For instance, a free radical copolymerization in between monomers bearing quaternary ammonium functional groups (ADAM-Quat, APTAC, VIm-Quat, or 4VP-Quat) and well selected co-monomers can be performed to combine different properties.

Other active materials have been described in the literature for the development of antimicrobial coatings. N-alkyl polyethylene imine, cinnamaldehyde, green tea or grape seed extract have been demonstrated to be efficient in killing virus and bacteria.[6-8]