Surface initiated RAFT polymerization to synthesize N-heterocyclic block copolymer grafted silica nanofillers for improving PEM properties

Mukherjee, Nilanjan; Das, Anupam; Dhara, Moumita; Jana, Tushar

doi:10.1016/j.polymer.2021.124315

Cited by 23 publications

(27 citation statements)

References 64 publications

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“…The next step of weight loss is observed around 350 °C–400 °C for MMMs which corresponds to the decomposition of organic moieties present in the MOFs. Degradation of the polymeric backbone occurred beyond 550 °C. , …”

Section: Resultsmentioning

confidence: 99%

“…36,41,44,46,49 Poly(4,4′-diphenylether-5,5′-bibenzimidazole) abbreviated as OPBI was synthesized following our earlier reported synthetic strategy (see details in Section S1 in Supporting Information). 16,50 Synthesis of 53-S and 88B-S. The postsynthetic modification of the MOFs, Fe-MIL-53-NH 2 and Fe-MIL-88B-NH 2 , was carried out through the reactions of these MOFs with 1,3-propane sultone.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Degradation of the polymeric backbone occurred beyond 550 °C. 50,55 The TG traces for PA doped OPBI, 88B-S-7.5%, and 53-S-7.5% membranes are shown in Figure 8b and Figure S25b, Supporting Information [magnified TGA plot (100 °C−400 °C)]. The first weight loss step for all the PA doped membranes is observed between 100−200 °C due to the evaporation of absorbed moisture in them.…”

Section: Acs Applied Energy Materialsmentioning

confidence: 99%

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Design of Flexible Metal–Organic Framework-Based Superprotonic Conductors and Their Fabrication with a Polymer into Proton Exchange Membranes

Basu

Das

Jana

et al. 2022

ACS Appl. Energy Mater.

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In recent times, the deployment of metal–organic frameworks (MOFs) to develop efficient proton conductors has gained immense popularity in the arena of sustainable energy research due to the ease of structural and functional tunability in MOFs. In this work, we have focused on developing “flexible MOF”-based proton conductors with Fe-MIL-53-NH 2 and Fe-MIL-88B-NH 2 MOFs using postsynthetic modification (PSM) as the tool. Taking advantage of the porous nature of these frameworks, we have carried out PSM on the primary amine groups present on the MOFs and converted them to −NH(CH2CH2CH2SO3H) groups. The PSM increased the number of labile protons in the channels of the modified MOFs as well as the extent of H-bonded networks inside the framework. The modified Fe-MIL-53-NH 2 and Fe-MIL-88B-NH 2 MOFs, named hereafter as 53-S and 88B-S, respectively, showed proton conductivity of 1.298 × 10–2 and 1.687 × 10–2 S cm–1 at ∼80 °C and 98% relative humidity (RH), respectively. This reflects ∼10-fold and ∼5-fold increases in their proton conductivity than their respective parent MOFs. Since MOFs as such are difficult to make directly into flexible membranes, and these are essential for practical applications as proton conductors, we have incorporated 53-S and 88B-S as fillers into a robust imidazole-based polymer matrix, namely, OPBI [poly(4,4′-diphenylether-5,5′-bibenzimidazole)]. The resulting polymer–MOF mixed matrix membranes (MMMs) after doping with phosphoric acid (PA) performed as flexible proton exchange membranes (PEMs) above 100 °C under anhydrous conditions and were found to be much more efficient and stable than the pristine OPBI membrane (devoid of any filler loading). By optimizing the amount of filler loading in the membrane, we obtained the highest proton conductivity of 0.304 S cm–1 at 160 °C under anhydrous conditions.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: Acs Applied Energy Materialsmentioning

confidence: 99%

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Design of Flexible Metal–Organic Framework-Based Superprotonic Conductors and Their Fabrication with a Polymer into Proton Exchange Membranes

Basu

Das

Jana

et al. 2022

ACS Appl. Energy Mater.

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“…PXRD plots shown in Figure A suggest that both PGNT1 and the pristine OPBI are amorphous in nature. OPBI exhibits a broad peak in the 2θ range of 20° to 30° which attributes to the amorphous halo of the polymer . MWCNT shows an intense peak at 2θ = 26° and low intensity peak at 43° corresponds to (002), (100) diffraction pattern of a typical graphite type material, respectively .…”

Section: Resultsmentioning

confidence: 99%

“…A number of interesting articles were published in recent years exploring the effect of surface functionalization of CNTs. − But no report is found to grow block copolymer chains on the CNT surface. In a series of studies, we found that the surface initiated grafting from RAFT polymerization approach allows the in situ formation of the polymer chains on the modified solid surface effectively − and hence we have chosen this technique in the current work, so that we can control the gradual growth of the block copolymer chain at the molecular level, on the surface of the CNT with better precision and check their properties. Our objective here is to grow block copolymer consisting of pNVT and pNVI chains on MWCNT in such a way so that the pNVI portion of the chain, which has p K a 7.05, resides near to the nanotube walls, while the pNVT part, which has p K a 2.33 and high hydrolysis stability, resides away from the nanotube walls.…”

Section: Introductionmentioning

confidence: 99%

Poly(N-vinyl triazole-b-N-vinyl imidazole) Grafted on MWCNTs as Nanofillers to Improve Proton Conducting Membranes

Mukherjee

Das

Jana

2022

ACS Appl. Nano Mater.

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Carbon nanotubes (CNTs) are of particular interest because of their ability to enhance the mechanical strength in the material; however, processing difficulties of CNTs often restrict utilization up to its full potential. To resolve this, in the current study, we have developed a simple and efficient method to functionalize the surface of a multiwalled carbon nanotube (MWCNT) with precise functional polymer chains, which were covalently graf ted on the surface of the MWCNT, and delved into an application to demonstrate this material as an efficient nanofiller in developing a proton conducting membrane (PEM) from polybenzimidazole (PBI). At first, the MWCNT surface was converted to a polymerizable surface by attaching a trithiocarbonate based chain transfer agent (CTA). Then, a N-heterocyclic block copolymer, namely poly-N-vinyl-1,2,4-triazole-b-poly-N-vinyl imidazole (pNVT-b-pNVI), was grown from the CTA anchored surface with a one-pot surface initiated reversible addition−fragmentation chain transfer (SI-RAFT) technique. Graf ting of block copolymer chain was confirmed by GPC, NMR, TGA, TEM, FESEM, and EDX studies. To the best of our knowledge, this will be the first report of a growing block copolymer structure graf ted covalently on the surface of the MWCNT. The novelty of the work was further enhanced by incorporating pNVT-b-pNVI-g-MWCNT as a nanofiller into the oxypolybenzimidazole (OPBI) membrane to obtain homogeneous nanocomposite membranes with excellent thermomechanical and tensile properties, thermal stability, superior proton conduction when doped with phosphoric acid (PA), and PA holding capacity. The nanocomposite membrane with 2.5 wt % nanofiller loading displayed a tensile stress of 1.8 MPa and a strain of 176% at break. The basic N-heterocyclic rings dangling from the block copolymer chains graf ted on the MWCNT surface allowed formation of strong H-bonding, acid−base interaction with PA, which is responsible for high acid uptake and superior PA retention, and also exhibited proton conductivity as high as 0.164 S cm −1 at 180 °C, which is a 2.6-fold increment when compared with a pristine OPBI membrane. This significant increase in conductivity is attributed to the proton conducting nanochannel pathway generated along the polymer-g-MWCNT surface.

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Improved proton conductivity and mechanical performance of phosphoric acid doped aminated PAF-1 reinforced OPBI for high temperature proton exchange membranes

Wang¹,

Mi²,

Wang³

et al. 2023

Composites Communications

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Surface initiated RAFT polymerization to synthesize N-heterocyclic block copolymer grafted silica nanofillers for improving PEM properties

Cited by 23 publications

References 64 publications

Design of Flexible Metal–Organic Framework-Based Superprotonic Conductors and Their Fabrication with a Polymer into Proton Exchange Membranes

Design of Flexible Metal–Organic Framework-Based Superprotonic Conductors and Their Fabrication with a Polymer into Proton Exchange Membranes

Poly(N-vinyl triazole-b-N-vinyl imidazole) Grafted on MWCNTs as Nanofillers to Improve Proton Conducting Membranes

Improved proton conductivity and mechanical performance of phosphoric acid doped aminated PAF-1 reinforced OPBI for high temperature proton exchange membranes

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