PMMA Nanocomposites Based on PMMA-Grafted α-Zirconium Phosphate Nanoplatelets

Covalently surface-grafting α‑zirconium phosphate nanoplatelets enables collagen fiber matrix with ultraviolet barrier, antibacterial, and flame-retardant properties

Manipulating the dispersibility and reactivity of two-dimensional nanomaterials in collagen fibers (CFs) matrix has aroused attention in the fabrication of multifunctional collagen-based nanocomposites. Here, α‑zirconium phosphate nanoplatelets (ZrP NPs) were surface-functionalized with gallic acid (GA) to afford ZrP-GA NPs for engineering CFs matrix. The influence of ZrP-GA NPs on the ultraviolet barrier, antibacterial, and flame-retardant properties of resultant CFs matrix were investigated. Microstructural analysis revealed that ZrP-GA NPs were dispersed and bound within the collagen fibrils and onto the collagen strands in the CFs matrix. The resultant CFs matrix also maintained typical D-periodic structures of collagen fibrils and native branching and interwoven structures of CFs networks with increased porosity and enhanced ultraviolet barrier properties. Inhibition zone testing presented excellent antibacterial activities of the CFs matrix owing to surface grafting of antibacterial GA. Thanks to enhanced dispersion and binding of ZrP NPs with the CFs matrix by surface-functionalization with GA, the resultant CFs matrix reduced the peak heat release rate and the total heat release by 42.9 % and 39.0 %, respectively, highlighting improved flame-retardant properties. We envision that two-dimensional nanomaterials possess great potential in developing reasonable collagen-based nanocomposites towards the manufacture of emergent multifunctional collagen fibers-based wearable electronics.

Preparation of Polyethylene/α-Zirconium Phosphate Nanocomposites via a Well-Controlled Polyethylene-Grafted Interface

It is a daunting task to prepare polyolefin nanocomposites that contain well-exfoliated nanoplatelets due to the nonpolar and high crystallinity nature of polyolefins. In this research, a robust approach was developed to prepare polyethylene (PE) nanocomposites by grafting maleated polyethylene (MPE) onto pre-exfoliated α-zirconium phosphate (ZrP) nanoplatelets via a simple amine-anhydride reaction to form ZrP-g-MPE. Several variables, including maleic anhydride (MA) content, MPE graft density, MPE molecular weight, and PE matrix crystallinity, were investigated to determine how they influence ZrP-g-MPE dispersion in PE. It was found that grafted PE has a different morphology and that the long PE brushes with medium graft density on ZrP can achieve sufficient chain entanglement and cocrystallization with PE matrix to stabilize and maintain ZrP-g-MPE dispersion after solution or melt mixing. This leads to enhanced Young's modulus, yield stress, and ductility. The structure-property relationship of PE/ZrP-g-MPE nanocomposites and usefulness of this study for the preparation of high-performance polyolefin nanocomposites are discussed.