The recent global energy context has been recognized as evidence for the need to reduce our energy consumption, to prolong fossil fuel supplies and minimize shortage, and to decelerate greenhouse gas transpiration. Over the past few years, using an insulator and decreasing its thermal conductivity have been recognized as the most effective way to reduce energy consumption. Aerogels as superinsulating materials permit reduction of the heat exchange between two environments while producing facile sol−gel and diverse drying routes. Aerogels have intrigued scientists and engineers due to their unique nanocharacteristics, such as low density, fine internal void spaces, and openpore geometry, which originate from sol particles in a 3D random network. Noteworthy are aerogel-based materials that have a supreme potential as thermal insulation owing to their very low thermal conductivity based on trapped air in the meso-/ nanoporous structure. Indeed, aerogels have great appeal in terms of their thermal efficiency, producing simplicity and performance reliability as compared with a traditional insulator. In this work, we will review the main milestones along with the concept of aerogels and then discuss some new trends, strategies, and opportunities in employing various morphological and nanostructural control methods to improve the performance of aerogels, especially enhancing insulation efficiency or decreasing thermal conductivity. The focus will be on (I) tailoring the porous structure of a carbon-based aerogel such as graphene oxide and reduced graphene oxide to accommodate high thermal behavior and (II) designing strategies to achieve intrinsically superinsulating materials in synthesized polymer and bio-based materials, with/without embedding an additional component.

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Acquiring a polymeric nanocomposite with biocompatibility, desirable dynamic‐mechanical‐thermal properties, and piezoelectricity, as well as high loading capacity, is challenging for design polymeric systems with potential applications in tissue engineering and biosensing. In this work, polyvinylidene fluoride (PVDF), poly(ε‐caprolactone) (PCL), and KIT‐6 mesoporous silica particles were used to prepare PVDF/PCL blends and their nanocomposites as potential candidates to meet the characteristics mentioned above. Hence, we deeply investigated the effect of the addition of PCL and KIT‐6 on the compatibility, crystallinity, and engineering properties of immiscible PVDF/PCL blends. PVDF/PCL blends without KIT‐6 particles and 75/25 PVDF/PCL blend containing various amounts of KIT‐6 particles were prepared by solution casting/annealing technique. It was found that PCL decreased the crystallization temperature and melting points of the PVDF component in the blends. The crystallinity and β‐phase content of PVDF reached maximum values for 75/25 PVDF/PCL blend; interestingly, KIT‐6 prevented PVDF crystallization and decreased β‐phase content. The results of thermogravimetric analysis and dynamic‐mechanical thermal analysis revealed that the presence of PCL reduced the thermal stability of the blends. On the other hand, KIT‐6 increased the thermal decomposition temperature and storage modulus of the polymeric matrix.

Polypropylene/polylactic acid (PP/PLA) blends containing 5 wt% of nanoclay in presence and absence of an ethylene‐butylacrylate‐glycidyl methacrylate terpolymer as compatibilizer were prepared by melt‐mixing process. A matrix‐droplet–type morphology confirmed by transmission electron microscope (TEM) and scanning electron microscopy (SEM) studies is formed in presence and absence of the compatibilizer in which the clay platelets were mainly localized in the polylactic acid (PLA) dispersed phase. Degradation studies by means of thermogravimetry analysis (TGA) and analysis of degradation activation energy (Ea), Tmax (maximum degradation temperature), and ΔT (difference between initial and final degradation temperatures) parameters for each polymer component of the system revealed that incorporation of less stable PLA phase to polypropylene (PP) decreases Ea and Tmax parameters, and hence, reduces the thermal stability of PP phase, while incorporation of clay nanoplatelets to the neat blend further reduces its thermal stability attributed to their lack of localization in PP phase. Compatibilization of the filled system results in migration of clay nanoplatelets toward PP and improves Ea and Tmax of PP phase. On the other hand, the Ea and Tmax of PLA phase of the blend were increased with incorporation of clay and its localization within that phase, while compatibilization of the filled system slightly reduces thermal stability of PLA phase due to migration of clay toward PP. A correlation was found between Ea and intensity of the thermogravimetry analysis Fourier‐transform infrared spectroscopy (TGA‐FTIR) peaks of the evolved products. Using the Criado method, a detailed analysis on degradation mechanism of each component was performed, and the changes in the degradation mechanism of the developed systems were determined.

Poly (lactic acid) (PLA)‐based compounds are widely used in thin‐film and food packaging industries. Herein, PLA/ethylene vinyl acetate copolymer (EVA)/nanoclay nanocomposites are prepared in various compositions by melt blending. The gas permeability against N2, CO2, and O2 gases is determined as a function of composition and morphology of the nanocomposites. Inclusion of high aspect ratio of platelet‐like nanoclay to the blend reduces the gas diffusion. The best barrier properties against all gases is observed on introducing 5 wt% poly(ethylene/n‐butyl acrylate glycidyl methacrylate) copolymer as compatibilizer to the PLA/EVA/nanoclay (75/25/5) system. The scanning and transmission electron microscopic analyses and wide‐angle X‐ray scattering studies reveal that inclusion of compatibilizer to the filled‐blends improves the blend morphology, dispersion state, and intercalation level of clay platelets which are preferably localized at the interface of the blend. Analysis of selectivity parameter (α) shows the lowest O2 permeability and the highest αCO2/N2 and αO2/N2 values for the compatibilized filled‐blend (75/25/5/5). In situ aspect ratio of clay and the degree of intercalation are theoretically evaluated based on the permeability data using various empirical models. It is found that the compatibilized filled‐blend has the highest aspect ratio and intercalation level that are responsible for the optimum perm‐selectivity performance.