Diffusivity enhancement of water vapor in poly(vinyl alcohol)–fumed silica nano-composite membranes: Correlation with polymer crystallinity and free-volume properties

Surfactant-Assisted Perovskite Nanofillers Incorporated in Quaternized Poly (Vinyl Alcohol) Composite Membrane as an Effective Hydroxide-Conducting Electrolyte

“…Incorporating 0.1% of LaFeO 3 nanofillers in the polymeric matrix prevented the polymer chain from unfolding, which resulted in lower water solubility. We have found similar results for PVA/fumed silica nanocomposites [53]. The improved stability is likely attributable to the physical cross-linking between the nanofillers and polymer chains [55].…”

“…As more nanoparticles were added to the PVA, the same 0.1% load of amorphous or crystalline LaFeO 3 in the membrane did not render significantly different conductivity values (as shown in the last two rows in Table S3): both had 220-300% increases compared to the PVA sample. This implies that the nanoparticles improved the ionic conductivity due to physical factors; higher filler loads had more pronounced effects [53]. Now, if the PVA sample containing 0.1% CTAB-coated LaFeO 3 has similarly increased conductivity comparable to the combined conductivity increase values of 0.05% CTAB and 0.05% LaFeO 3 composites, an additive effect from both the chemical and physical factors is confirmed.…”

“…Therefore, the QPVA nanocomposite membranes showed a semicrystalline structure with an XRD peak at 2θ of 20°, corresponding to the (101) plane of the PVA crystal structure [17,[53][54][55]. The nanocomposite membrane intensity decreased compared with pristine PVA, as described in our previous study [53], yet the QPVA composites retained good film structure [17,18,23]. This result implies that the addition of nanofiller to the polymeric matrix greatly suppressed the crystalline domains [18,23].…”

“…The QPVA membrane had a quarterisation efficiency of 3-4% [10], and the other 96-97% of the polymeric matrix retained the PVA structure [53][54][55]. Therefore, the QPVA nanocomposite membranes showed a semi-crystalline structure with an XRD peak at 2θ of 20 • , corresponding to the (101) plane of the PVA crystal structure [17,[53][54][55]. The nanocomposite membrane intensity decreased compared with pristine PVA, as described in our previous study [53], yet the QPVA composites retained good film structure [17,18,23].…”

“…The phase purity and crystallinity of the QPVA/CTAB-coated LaFeO3 and QPVA/annealed LaFeO3 membranes were analysed using XRD analysis, as shown in Figure 4a. The QPVA membrane had a quarterisation efficiency of 3-4% [10], and the other 96-97% of the polymeric matrix retained the PVA structure [53][54][55]. Therefore, the QPVA nanocomposite membranes showed a semicrystalline structure with an XRD peak at 2θ of 20°, corresponding to the (101) plane of the PVA crystal structure [17,[53][54][55].…”