A one-step method of in situ polymerization of nylon 66/reduced graphene oxide (PA66/rGO) nanocomposites is first proposed, simply by introducing graphene oxide (GO) into PA66 salt with the existence of ammonium hydroxide. The GO is prereduced by the ammonium hydroxide at an early stage of the polymerization process and then grafted on the PA66 chains, accompanied with the thermal reduction of GO. The PA66 chains were grafted onto the GO nanosheets through the condensation between the oxygen-containing functional groups of the GO and the terminal amino ends of the PA66 chains. The effect of GO on the mechanical properties, especially tensile strength, of nanocomposites was investigated. The results revealed that the incorporation of a very small amount (about 1 wt%) of GO caused a significant improvement in ultimate tensile strength (about 17%). The SEM of the fracture surface of composites indicated a good dispersion of rGO in the matrix. Raman spectroscopy, thermogravimetric analysis (TGA), scanning electron microscope (SEM), Fourier transformed infrared spectroscopy (FTIR), and XRD patterns of rGO, which was isolated from nanocomposites, revealed that the GO nanolayers were simultaneously reduced and PA66 chains were grafted on the rGO nanosheet during the polymerization process. The rGO grafted with the PA66 chain increases its compatibility in the PA66 matrix and effectively enhanced the interfacial energy of the composites.

A mesoporous silica-coated Fe3O4 nanoprobe exhibiting a high photothermal conversion efficiency was synthesized by a facile and green approach.

significant attention. However, their practical application is seriously restricted by their poor flexibility and fragility, which result from inefficient structure continuity and the loose connections between the socalled "pearl necklace-like" strings of inorganic nanoparticles. [24] As an alternative to inorganic aerogels, an organic aerogel was produced from resorcinol formaldehyde in 1987. [25] This was followed by the production of various other polymer aerogels (polyimide, polyurethane, polybenzoxazine, polyurea, and polystyrene), which reportedly had excellent mechanical properties, ultralow density, favorable thermal insulation properties, and diverse molecular designs. The preparation of these polymer aerogels often starts with their monomers or precursors and is followed by a supercritical drying process, which involves a sophisticated, expensive, and time-consuming synthesis process. Moreover, the use of toxic organic solvents is often inevitable. Therefore, a simple, feasible, and environmentally friendly method of preparing advanced aerogels with satisfying mechanical property and multifunctionality from widely available low-cost raw materials remains desirable.Poly(vinyl alcohol) (PVA) is a widely available and inexpensive polymer that is an attractive material for the fabrication of aerogels because it is biocompatible, chemically stable, has excellent mechanical properties, and is nontoxic. [26,27] To date, a variety of aerogels based on PVA have been successfully fabricated. However, such PVA aerogels are usually prepared by freeze-drying a modified PVA solution directly, [28][29][30][31] which results in a higher aerogel density. Moreover, to improve their mechanical properties, crosslinking agents-such as glutaraldehyde, [32] melamine formaldehyde, [33] and divinyl sulfone, [34] which have recognized disadvantages including potential toxic effects-are commonly used in the fabrication of PVA-based aerogels. [27] This greatly hinders the quantification of aerogels and their practical application. Therefore, it is an important challenge to develop a simple, low-cost, nontoxic, and green route for PVA aerogel synthesis.In recent years, new aerogels based on polymer nanofibers have been developed. [35][36][37][38] The nanofibers serve as building blocks to form a chemically crosslinked and/or physically entangled 3D network, unlike the interconnected framework of colloidal particles in inorganic aerogels. [38,39] Nanofiberbased aerogels do not have "necks" in their skeletons. This Polymer nanofiber aerogels are highly flexible and elastic. However, their preparation in a simple, low-cost, and environmentally friendly manner remains challenging. Herein, a green strategy for preparing an ultralight poly(vinyl alcohol) (PVA) nanofiber aerogel by electrospinning and freezedrying is reported. A simple thermal crosslinking method is used to make a mechanically robust material that can withstand up to 1000 times its own weight, i.e., no toxic crosslinking agents or organic solvents are used in any part of ...