Electrospun (e-spun) nanofiber materials have emerged as a prominent research focus owing to their extensive and promising potential applications across biomedical, energy, and environmental domains. Polyacrylonitrile (PAN) is a commonly used polymer for electrospinning (e-spinning). Due to insufficient hydrophilic properties of nitrile groups of PAN, its e-spun nonwoven membranes had low water absorption and moisture absorption, which limited application in medical and health fields. In this study, it was investigated that the hydrophilic modification of e-spun PAN nanofiber membrane (NFM) was conducted via Ritter reaction to convert nitrile groups into hydrophilic amide ones, thereby improving the hydrophilicity of PAN NFMs. The surface morphologies and structure of the modified e-spun fibers were characterized and verified by SEM, FTIR and XPS. After 60–90 min of Ritter reaction, the fiber diameter of the PAN NFM became thicker, transforming from a hydrophobic membrane to a hydrophilic one, and the water contact angle decreased from 124.2 to 40.7°. The amidated PAN obtained membrane was post-treatment with sodium hypochlorite to make some amide groups change to N-halamine, which took the PAN NFM antibacterial activity or bacteriostasis. This work suggested a strategy that the espun PAN NFMs modified would have a promising application in medical dressings, air filtration, etc.

The augmented demand for sustainable nanocomposites has paved the way to explore naturally derived materials. Nanocellulose, with its bountiful sources and inherent properties, ranks top in the list of biofillers with a perspective of reducing the carbon footprint. A systematic study is required to understand the reinforcing effect of various types of nanocellulose. In the present work, we selected three types of nanocellulose, i.e., cellulose nanocrystal (CNC), cellulose nanofiber (CNF) and microfibrillated cellulose (MFC), to investigate the effect of geometrical structure on the properties of unvulcanized natural rubber (NR). Incorporating these fillers improved the tensile strength and modulus of natural rubber films significantly through reinforcement via filler network structure. The reinforcing effect of CNF was found to be higher compared to CNC and MFC, where an increase of 3.85 MPa in tensile strength from the neat sample was obtained. More uniform dispersion was evident through transmission electron microscopy, atomic force microscopy and Raman imaging for CNF in the rubber matrix. The structural properties were determined using Raman spectra and X-ray diffraction. The rheological studies revealed a good interaction between filler and NR. The work presented comprehensively compares different types of nanocellulose as reinforcing filler in NR matrix, which will help the researchers select an ideal type for their specific application and, thus, the proper usage of renewable resources, leading to sustainability and a circular economy.

This is an editorial article. It has no abstract.

Epoxidized natural rubber (ENR) with varying levels of epoxide groups ranging from 10 to 50 mol% was prepared and dynamically phenolic vulcanized by blending it with poly(ether-block-amide) copolymer (PEBA). The results indicate that the thermoplastic vulcanizates (TPVs) of ENR/PEBA blends display a sea-island morphology and enhance a number of properties. Specifically, increasing the epoxide content and PEBA proportion enhances strength properties, including higher Young’s modulus (stiffness), toughness, tensile properties, and hardness, along with smaller vulcanized ENR domains dispersed in the PEBA matrix. Moreover, the decrease in tension set values indicates an improvement in the elastic properties. The attributed cause of this is the interaction between the polar groups present in the phenolic-cured ENR domains and the PEBA molecules. As a result, interfacial adhesion between the ENR domains and PEBA interfaces improved, contributing to the observed enhancements in the strength and elastic properties of the TPVs with smaller ENR domains. Furthermore, an increase in the epoxide content was found to be correlated with a decrease in tanδ and tension set, which further supported the observed improvements in strength and elasticity. Additionally, the ENR/PEBA blends showed a single glass transition temperature (T_g), while pure PEBA exhibited two T_gs. The presence of a single T_g in the ENR/PEBA blend is attributed to the overlapping of the T_g of the ENR and PEBA immiscible blend components.