(496a) Elucidating the Structure-Property-Performance Relationship of Incorporating Waste Polymethyl Methacrylate in Polyvinylidene Fluoride Membrane Fabrication

With an annual production of ~4 million metric tons, polymethyl methacrylate (PMMA) is a widely used polymer due to its optical properties, biocompatibility, and hardness. Estimates indicate that only 10% of waste PMMA is recycled, while the majority is disposed by conventional means. Furthermore, current recycling processes are typically energy intensive and/or produce inferior materials, which presents an opportunity to develop alternative methods to address these downfalls. A promising strategy involves solution blending, where additional polymer(s) are dissolved with PMMA to form a miscible blend. Previously, researchers have identified polyvinylidene fluoride (PVDF) as a compatible polymer to improve the mechanical properties of PMMA for membrane fabrication. This study probes the structure-property-performance relationship of PVDF/PMMA blends to understand how different additive and molecular weight compositions in waste PMMA sources affect PVDF ultrafiltration/microfiltration (UF/MF) membrane properties. Laboratory cuvettes and fiber-optic cables were used as sources of PMMA waste. 16 wt% PVDF/PMMA blends were prepared with two greener solvents, dimethyl sulfoxide (DMSO) and triethyl phosphate (TEP), to produce flat-sheet UF/MF membranes using nonsolvent-induced phase separation (NIPS). Waste plastics were evaluated with spectroscopic and chromatographic techniques to characterize polymer properties and to determine if processing additives or co-polymers were present. Scanning electron microscopy (SEM) was used to evaluate the cross-sectional and top surface morphologies of fabricated membranes. Pure water permeance and polyethylene oxide (PEO) rejection were quantified with dead-end filtration. We found that increasing the PMMA loading from 0 to 8 wt% decreased the permeance and surface porosity from 768 ± 64 to 37 ± 4 LMH/bar and 34 ± 5 to 6 ± 1%, respectively. However, PEO (MW = 100,000 Da) rejection exhibited the opposite trend, increasing from 67 ± 6 to 95 ± 3%. These results indicate that incorporating waste PMMA into PVDF membranes produces distinctly different membranes with tailorable separation properties.