Polymeric Quaternary Ammonium-Containing Coatings with Potential Dual Contact-Based and Release-Based Antimicrobial Activity

Abstract

In the present work, reactive blending of copolymers with complementary functional groups was applied to control their antimicrobial activity and antifouling action in real conditions. For this purpose, two series of copolymers, poly(4-vinylbenzyl chloride-co-acrylic acid), P(VBC-co-AAx), and poly(sodium 4-styrenesulfonate-co-glycidyl methacrylate), P(SSNa-co-GMAx), were synthesized via free radical copolymerization and further modified by the incorporation of biocidal units either covalently (4-vinyl benzyl dimethylhexadecylammonium chloride, VBCHAM) or electrostatically bound (cetyltrimethylammonium 4-styrenesulfonate, SSAmC). The cross-linking reaction of the carboxylic group of acrylic acid (AA) with the epoxide group of glycidyl methacrylate (GMA) of these two series of reactive antimicrobial copolymers was explored in blends obtained through solution casting after curing at various temperatures. The combined results from the ATR-FTIR characterization of the membranes, solubility tests, turbidimetry, and TEM suggest that the reaction occurs already at 80 °C, leading mostly to graft samples, while at higher curing temperatures (120 or 150 °C) insoluble cross-linked samples are usually obtained. Controlled release experiments of selected membranes were performed in pure water and aqueous 1 M NaCl solutions for a period of two months. The released material was followed through gravimetry and TOC/TN measurements, while the evolution of the integrity and the morphology of the membranes were followed visually and through SEM, respectively. Antimicrobial tests also revealed that the cross-linked membranes presented strong antimicrobial activity against S. aureus and P. aeruginosa. Finally, a specific blend combination was applied on aquaculture nets and cured at 80 °C. The modified nets, emerged in the sea for 15 and 35 days, exhibited high antifouling action as compared to blank nets.

Polymeric Antimicrobial Coatings Based on Quaternary Ammonium Compounds

“…These copolymers (Table 1) will be denoted as P(VBC-co-AAx) and P(SSNa-co-GMAx), where x is the mole fraction of AA and GMA units in the copolymer, as determined by the 1 H NMR characterization in CDCl 3 and D 2 O, respectively. The experimental procedures for the synthesis and characterization of copolymers have been described previously [31,33]. Table 1.…”

“…Blends of these copolymers, P(SSAmC16-co-GMAx) and P(VBCHAM-co-AAx) were then formed, and were cured at solid state at the desired temperature, leading to the final crosslinked membranes (Scheme 1), as a consequence of the reaction between the carboxylic and the epoxide groups. These membranes presented strong antimicrobial activity against S. aureus and P. Aeruginosa, while when applied as coatings on aquaculture nets exhibited high antifouling action as compared to blank net [33]. An interesting observation in that work was that the observed release in salt solution was maintained in much lower levels than the release in pure water, offering an additional advantage for potential antifouling applications in sea water.…”

“…Recently, we have shown that we can take advantage of the reactive blending concept, in order to prepare self-standing crosslinked membranes containing both released-based hexadecyltrimethylammonium groups and contact-based VBCHAM biocidal units [33]. Thus, polymeric precursors of the two biocidal species with complementary chemical functions, e.g., carboxylic groups of acrylic acid (AA) units and epoxide groups of glycidyl methacrylate (GMA) units, were initially synthesized.…”

Cationic Bottlebrush Polymers from Quaternary Ammonium Macromonomers by Grafting‐Through Ring‐Opening Metathesis Polymerization

“…Quaternary ammonium bottlebrush polymers are interesting materials for antimicrobial applications as their linear counterparts have been explored as antimicrobial materials due to their ionic interaction between ammonium groups and the cell membranes of bacteria 59,60. For example, quaternary ammonium small molecules and polymers with six‐carbon long alkyl groups show antimicrobial behavior with the polymers being more effective antimicrobial agents than the small molecules 61.…”

“…Quaternary ammonium bottlebrush polymers are interesting materials for antimicrobial applications as their linear counterparts have been explored as antimicrobial materials due to their ionic interaction between ammonium groups and the cell membranes of bacteria. [59,60] For example, quaternary ammonium small molecules and polymers with six-carbon long alkyl groups show antimicrobial behavior with the polymers being more effective antimicrobial agents than the small molecules. [61] Quaternary ammonium polymers with different architectures have been produced by direct polymerization of cationic monomers via controlled radical polymerization in aqueous media [62][63][64] or post-quaternization, which can be time-consuming and result in incomplete ammonium functionalization.…”