Grafting of sulfonated monomer onto an amino-silane functionalized 2-aminoterephthalate metal − organic framework via surface-initiated redox polymerization: proton-conducting solid electrolytes

A post-polymerization method for metal–organic frameworks (MOFs) has been developed to produce super-acidic solid nanoparticles. Thus, the NH2MIL-53(Al) MOF was functionalized with (3-aminopropyl)triethoxysilane (APTES) from amine groups to yield active site anchored MOF nanoparticles. Then, sulfonated polymer/MOF hybrid nanoparticles were prepared by redox polymerization of 2-acrylamido-2-methyl-1-propane sulfonic acid (MOF-g-PAMPS), initiated onto the surfaces of aminopropyl-functionalized NH2MIL-53(Al) nanoparticles. The synthesis and modification of NH2MIL-53(Al) nanoparticles were characterized by Fourier transform infrared (FTIR) spectroscopy and TGA. FTIR and TGA results indicated that APTES modifier agent and AMPS monomer were successfully grafted onto the MOF nanoparticles. The grafting efficiency of PAMPS polymer onto the MOF nanoparticles was estimated from TGA thermograms to be 33%. Also, sulfonated polymer/MOF hybrid nanoparticles showed a proton conductivity as high as 4.9 × 10−5 S cm−1. Nitrogen adsorption of modified NH2MIL-53(Al) showed also a decrease in pore volume. The morphology and crystalline structure of MOF nanoparticles before and after the modification processes were studied by SEM and XRD, respectively. © 2015 Society of Chemical Industry