Fabrication and Characterization of Poly (L-lactic acid) ' Aluminum based Metal Organic Frameworks Mixed Matrix Membranes

Abstract

Poly (L-lactic acid) (PLLA) and Aluminum based Metal Organic Frameworks (MOFs) mixed matrix membranes (MMMs) were prepared by solvent casting PLLA with 1, 5, 10 and 20% w/w of MIL-53(Al). PLLA and PLLA-MOF MMMs were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). DSC studies indicate that the addition of MOF particles in the PLA polymer matrix reduces the polymeric chain mobility, which affects the crystallization process. The percent crystallinity of neat PLLA was found to be 3.23% and decreased by around 4% for PLLA-1% MOF and 85% for PLLA-5% MOF as compared to neat PLLA. PLLA-10% MOF and PLLA-20% MOF compositions were completely amorphous. TGA results show that PLLA-MOF MMMs are thermally less stable than neat PLLA suggesting that MOF particles act as a depolymerization catalyst for PLLA. An average of 14% volatile compounds originated from trapped chloroform was found in neat PLLA and PLLA-MOF compounds. The variable wt% of MOF in the samples for the different PLLA-MOF ratios indicated that the MOF particles were not well dispersed in the PLLA matrix. This was confirmed by SEM analysis showing that MOF particles have the tendency to accumulate within the PLLA matrix. In this study non-homogeneous MMMs containing chloroform were fabricated. Future work can be focused on improving the synthesis technique and the impact of MOF particles on permeability of PLLA'MOF MMMs for different compounds.