This study presents synthesis and characterization of antibacterial and antifouling polymers containing plant-based cardanol moiety, and their applications for water treatment and coating applications. Firstly, polymers containing a renewable cardanol moiety were prepared via radical polymerization of 2-hydroxy-3-cardanylpropyl methacrylate (HCPM) and methyl methacrylate (MMA), where HCPM was synthesized by a reaction of cardanol with glycidyl methacrylate in the presence of a base catalyst. Incorporation of the cardanol moiety into PMMA was found to increase the thermal and mechanical stability of the brittle PMMA. When the cardanol based polymers were irradiated with UV light, the mechanical stability increased further because cross-linked networks were formed between the double bonds in the cardanol moieties. Cross-linked polymer films containing the cardanol moiety exhibited high gloss and transparency to visible light. Cardanol-containing polymers with and without the cross-linked networks and other cardanol-based polymers such as poly(cardanyl acrylate) and poly(2-acetoxy-3-cardanylpropyl methacrylate) all showed high antibacterial activity against Escherichia coli (E. coli), indicating that the disappearance of double bonds and/or the structure changes of connecting groups do not diminish the intrinsic bactericidal properties of the cardanol moieties.
Secondly, a series of copolymers [PCD#s, where # is the weight percentage of dopamine methacrylamide (DMA) in polymers] containing mussel-inspired hydrophilic dopamine and plant-based hydrophobic cardanol moieties was prepared via radical polymerization using DMA and 2-hydroxy-3-cardanylpropyl methacrylate (HCPM) as the monomers. PCD#s were used as coating materials to prevent flux decline of the membranes caused by the adhesion of biofoulants and oil-foulants. Polysulfone (PSf) ultrafiltration membranes coated with PCD#s showed higher biofouling resistance than the bare PSf membrane, and the bactericidal properties of the membranes increased upon increasing the content of HCPM units in the PCD#s. Serendipitously, the PSf membranes coated with the more or less amphiphilic PCD54 and PCD74, having the optimum amount of both hydrophilic DMA and hydrophobic HCPM moieties, showed noticeably higher oil-fouling resistance than the more hydrophilic PCD91-coated membrane, the more hydrophobic PCD0-coated membrane, and the bare PSf membrane. Therefore, multifunctional coating materials having biofouling- and oil-fouling-resistant and bactericidal properties could be prepared from the monomers containing mussel-inspired dopamine and plant-based cardanol groups.
Finally, A new series of ABA-triblock copolymers (PHCPMF#s, where # is the number of repeating unit of HCPM at each side of the A block) containing perfluoropolyether (PFPE) as B block and cardanol based polymer as A block was prepared via atom transfer radical polymerization using modified PFPE as macroinitiator (Br-PFPE-Br) and 2-hydroxy-3-cardanylpropyl methacrylate (HCPM) as a monomer. Stable PHCPMF# films were prepared on the silicon wafer using spin coating method, followed by UV irradiation to form a crosslinked structure. Cross-linked PHCPMF# (C-PHCPMF#) films showed bactericidal properties much better than the bare PMMA, and bacterial adhesion resistance of the films increased with decreasing the content of HCPM units in the PHCPMF#s. Moreover, bacterial adhesion resistance of the PHCPMF# films closely correlated with low surface energy and water contact angle hysteresis (CAH). Additionally, C-PHCPMF# films showed excellent cell viability on their surfaces but still didn’t show any cytotoxicity due to the biocompatible property of the PFPE block. Therefore, PHCPMF#s are new ABA-triblock copolymers with PFPE and cardanol moieties, and they can be used as multifunctional coating materials having bactericidal properties, bacterial adhesion resistance, and biocompatibility in a variety of coating application.