Intrinsic Benign Functional Polyacrylates for Transpicuous-Cum Antifouling Applications

Abstract

Protein attachment, cell adhesion and the development of microorganisms are serious some issues of the equipment being used underwater while antifouling is considered as the best remedy to those issues. However, development of new intrinsic antifouling materials and investigation of their structure-antifouling activity relationship are important and currently an area to provide many challenges including optimize benign, intrinsic and transpicuous performances. In consideration of these challenges, present work accessible to the design of a series of amphiphilic polyacrylate copolymers to control bacterial and algal biofilm development on material’s surface. In present research endeavor, the facile synthesis, bioassay of functional antifouling polymers and characterization are included. In the first series amphiphilic copolymers were synthesized by 2-dimethylaminoethylmethacrylate (DMAEMA), hydrophilic monomer and methyl methacrylate (MMA), hydrophobic monomer. These amphiphilic copolymers were characterized by FTIR, 1HNMR and gel permeation chromatography techniques. These copolymers P(DMAEMA-co MMA), with different concentrations of DMAEMA were explored to inhibit the biofouling causing bacterial adhesion. The main objective of current study was to elucidate antifouling activity of synthesized copolymers and to investigate the mode of antifouling action. Antibacterial activities were performed against Gram-positive Staphylococcus aureus (ATCC 6538) and Gram negative Escherichia coli (ATCC 8739) by disk diffusion method and zones of inhibition were calculated. Among these, PDM1 copolymer has furnished highest zones of inhibition i.e. 19 ± 0.33 mm and 20 ± 0.33 mm for E. coli and S. aureus. Copolymers, PDM1 and PDM2 have showed substantial control on bacterial adhesion and biofilm formations. Bacterial biofilm formation has visualized and analyzed by SEM and these synthetic copolymers perform in a same fashion like cationic biocide. The antialgal activity of the copolymers has determined through suspension assay at 25 oC for seven days. Adhesion of Dictyosphaerium sp. algae on different compositions of copolymers with different surface energy was tested by measuring chlorophyll A content. The copolymer (P1), poly(DMAEMA-co-MMA) with 35 % DMAEMA has lowest surface energy, 50 ± 1 mJ/m2 and smaller chlorophyll A content of 0.5 μg/cm2. Algal adhesion on the surface of polymers was observed by optical microscopy. P1 copolymer with greater content of DMAEMA showed low adhesion of Dictyosphaerium algae due to stronger hydration and wettability. In the second series, the copolymers of 3-sulfopropyl methacrylate (SPMA) and methyl methacrylate (MMA) were synthesized by free radical polymerization in different compositions. Samples PSM20, PSM30, PSM40, PSM50 and PSM60 contain 20%, 30%, 40%, 50% and 60% SPMA by weight respectively. Resultant copolymers were characterized by FTIR and 1H-NMR spectroscopy for their structure and compositional analyses. The synthesized copolymers have exhibited excellent transparency in the range of 75% to 88% as resolute by the UV-Vis spectroscopy. In this series of copolymers, transmittance was reduced from 6% to 2% by changing the concentration of 3-sulfopropyl methacrylate from 20% to 50% owing to bacterial and algal biofilm formation. The contact angle values by using water as solvent were in the range of 18o to 63o and reduced with rise in the polarity of copolymers. Surface energies were found from the lowest value 58 mJ/m2 to the highest value 72 mJ/m2 for PSM20 and PSM50 respectively that was calculated by the Chibowski approach. PSM50, copolymer has exhibited the highest antibacterial activity of 18 mm and 19 mm against Escherichia coli and Staphylococcus aureus that was measured by disk diffusion method. The copolymer PSM50 has presented minimum algal adhesion for Dictyosphaerium algae as observed by optical microscopy. This lesser bacterial and algal adhesion is endorsed to higher concentrations of the anionic SPMA monomer that origin electrostatic repulsion between functional groups of the polymer and microorganisms. Thus copolymer PSM50 is a promising candidate material for many applications including healthcare, biotechnology, medical diagnostics, energy, and aquatic medium that exhibited good potential for optronic shielding due to good transparency and high antifouling activity. Both series of amphiphilic acrylate copolymers have crystallinity and thermal stability that were improved with increasing concentrations of DMAEMA and SPMA with MMA. Optimized concentrations from both antimicrobial polymers p(MMA-co-DMAEMA) and p(MMA-co-SPMA) were further tested for thermal stability and BSA adsorption. Here kinetics showed that BSA adsorption on the surface of polymers is physiosortion and pMMA showed maximum adsorption capacity 100 mg g-1 at 7.4 pH and 25 oC. These copolymers pMD1 and pMS1 with -56.6 and -72.6 mV charge had thermal stability at 100 oC and with Tg 82 and 132 oC respectively.