Bentonite clay/poly(vinyl alcohol) (PVA) inorganic/organic hybrid nanocomposite membranes were prepared via solvent casting method. A series of PVA nanocomposite membranes have been prepared by varying the concentration of the bentonite clay. Nanoscale dispersion of bentonite clay affected the properties of PVA. PVA with 5 wt % clay showed better enhancement in the properties. Both X-ray diffration and transmission electron microscopy showed uniform dispersion and exfoliated structure of the bentonite in the PVA membranes. The effective separation of azeotropic composition of isopropanol (IPA) and water mixtures was also carried out by using these membranes. The flux and separation factor of the membranes were increased with 1 wt % clay loading and followed by a decrease. The intrinsic properties of the membranes have been calculated using membrane permeance and selectivity. The 1 wt % clay loaded membrane showed enhanced membrane permeance with a water permeance of 6500 gpu and a selectivity value of 46. The effective membrane area for transport has been analyzed from atomic force microscopy analysis. Finally, it is important to mention that the minimum nanoscale filler loading gave rise to the maximum separation efficiency for the azeotropic composition of IPA and water mixtures.

Nanocomposite membranes based on poly-(ethylene-co-vinyl acetate) copolymer (18% vinyl acetate content) and two different organomodified clays have been prepared by mechanical mixing using two roll mill method. The morphology of the nanocomposites was investigated using small angle X-ray scattering, scanning electron microscopy, and transmission electron microscopy. The mechanical and thermal studies were also performed using universal testing machine and differential scanning calorimeter, respectively. Samples with low filler content showed excellent dispersion of layered silicates resulting in a partially exfoliated structure. The diffusion and transport of organic solvents through the membranes have been investigated in detail as a function of clay content, nature of solvent and clay, and temperature in the temperature range of 28−70 °C. The influence of free volume on the transport properties of the membranes was studied using positron annihilation lifetime spectroscopy. The solvent uptake was minimum for composites with 3 wt % of filler, and it get increased with increasing filler content, which is presumably due to aggregation of clay filler at higher loading. The transport phenomenon was found to follow an anomalous mode. Activation parameters were estimated, and the molar mass between cross-links was calculated. Finally, the experimental transport data were compared with theoretical predictions.

Poly (ethylene-co-vinyl acetate) (EVA)/clay nanocomposites containing two different organoclays with different clay loadings were prepared. The transport of gases (oxygen and nitrogen) through the composite membranes was investigated and the results were compared. These studies revealed that the incorporation of nanoclays in the polymer increased the efficiency of the membranes toward barrier properties. It was also found that the barrier properties of the membranes decreased with clay loadings. This is mainly due to the aggregation of clay at higher loadings. The morphology of the nanocomposites was studied by scanning electron microscopy, transmission electron microscopy and X-ray scattering. Small angle X-ray scattering results showed significant intercalation of the polymer chains between the organo-modified silicate layers in all cases. Better dispersed silicate layer stacking and more homogeneous membranes were obtained for Cloisite V R 25A based nanocomposites compared with Cloisite V R 20A samples. Microscopic observations (SEM and TEM) were coherent with those results. The dispersion of clay platelets seemed to be maximized for 3 wt % of clay and agglomeration increased with higher clay loading. Wide angle X-ray scattering results showed no significant modifications in the crystalline structure of the EVA matrix because of the presence of the clays. The effect of free volume on the transport behavior was studied using positron annihilation spectroscopy. The permeability results have been correlated with various permeation models.

The mushrooming utilization of electronic devices in the current era produces electromagnetic interference (EMI) capable of disabling commercial and military electronic appliances on a level like never before. Due to this, the development of advanced materials for effectively shielding electromagnetic radiation has now become a pressing priority for the scientific world. This paper reviews the current research status of polymer nanocomposite-based EMI shielding materials, with a special focus on those with hybrid fillers and MXenes. A discussion on the theory of EMI shielding followed by a brief account of the most popular synthesis methods of EMI shielding polymer nanocomposites is included in this review. Emphasis is given to unravelling the connection between microstructures of the composites, their physical properties, filler type, and EMI shielding efficiency (EMI SE). Along with EMI shielding efficiency and conductivity, mechanical properties reported for EMI shielding polymer nanocomposites are also reviewed. An elaborate discussion on the gap areas in various fields where EMI shielding materials have potential applications is reported, and future directions of research are proposed to overcome the existing technological obstacles.

Fabrication of PP/in situ reduced GO nanocomposites with excellent EMI shielding capability realized via a facile and green route.

Poly(glycerol sebacate) (PGS), produced from renewable monomers such as sebacic acid and glycerol, has been explored extensively for various biomedical applications. However, relatively less attention has been paid to explore PGS as sustainable materials in applications such as elastomers and rigid plastics, primarily because of serious deficiencies in physical properties of PGS. Here, we present two new approaches for enhancing the properties of PGS; (i) synthesizing block copolymers of PGS with poly(tetramethylene oxide)glycol (PTMO) and (ii) preparing a blend of PGS-b-PTMO with a poly(ester–ether) thermoplastic elastomer. The consequence of molar ratio (hard and soft segments) and Mn of soft segment on tensile properties of the material was investigated. The PGS-b-PTMO with 25:75 mole ratios of hard and soft segments and having a medium Mn soft segment (5350 g mol–1) exhibits an appreciable increase in percentage of elongation that is from 32% for PGS to 737%. Blends of PGS-b-PTMO and a thermoplastic polyester elastomer, Hytrel 3078, form a semi-interpenetrated polymer network, which exhibits increased tensile strength to 2.11 MPa and percentage of elongation to 2574. An elongation of such magnitude is unprecedented in the literature for predominantly aliphatic polyesters and demonstrates that the simple polyester can be tailored for superior performance.

Poly(ethylene-co-vinyl acetate)/organically modified clay nanocomposites were prepared using different clay loadings and by varying the amount of organic modifier. The morphology of the nanocomposites was investigated using small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). SAXS results displayed intercalation of polymeric chains between the silicate layers in all the cases. The interlayer distance varies slightly between the series. TEM images showed a better dispersion of the clay platelets at lower loading for both series of samples. The pervaporation performances of membranes were analyzed using a chloroform/acetone mixture. Membranes displayed high selectivity. The influence of feed composition on pervaporation was analyzed. The nanoclay content and the influence of free volume on pervaporation performance were also investigated in detail. A drop in selectivity and an increase in permeation rate were observed at higher clay loadings.

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