Phthalate doped PVC membranes for the inhibition of fouling

Four phthalate plasticizers, each with different structural characteristics were assessed within a poly (vinylchloride) (PVC) matrix for their potential as an antifouling material. The materials contained phthalic ester compounds: dimethyl phthalate (DMP), diethyl phthalate (DEP), butyloctyl phthalate (BOP) and di-(2-ethylhexyl) phthalate (DEHP) and were prepared at 5% w/v concentration. The phthalates all possess the same phthalic ester C6H4COCO moiety with structural differences of chain length and branching across the four plasticizer compounds. This poses a question as to whether alkyl chain length does affect microorganism attachment and subsequent fouling. In order to determine the antifouling capacity of the materials, the polymer coatings underwent a series of analyses for biomass determination, biological assessment, glycocalyx production, contact angle determination, surface roughness using atomic force microscopy (AFM) and topological characterisation through scanning electron microscopy (SEM). It was found that using a 7-day fresh water tank study, the increased branched and longer chain phthalic esters, in DEHP and BOP gave rise to better antifouling performance. A pure culture study involving the test membranes in Staphylococcus aureus and Escherichia coli cell suspensions, displayed less cellular attachment on the DEHP and BOP doped PVC matrices, once again showing potential in preventing cellular attachment and biofouling.

Research highlights▶ Plasticizers incorporated with a PVC matrix afford different anti-fouling response. ▶ Di-(2-ethylhexyl) phthalate (DEHP) presents higher toxicity. ▶ DEHP when doped in PVC has outperformed the lesser molecular branched plasticizers in developed biofouling assays.