Synthesis of hybrid silica nanoparticles grafted with thermoresponsive poly(ethylene glycol) methyl ether methacrylate via AGET-ATRP

Abstract

Thermosensitive SiO₂ nanoparticles were prepared with graft-on poly(ethylene glycol) methyl ether methacrylate (POEGMA, M_n ∼ 300 or 500 g mol⁻¹) via atom transfer radical polymerization with activators generated through electron transfer (AGET ATRP). CuBr₂/PMDETA and ascorbic acid (AA) were employed as the catalyst and reducing agent respectively in the fabrication process. The structure and surface composition of our hybrid materials were analyzed using Fourier Transform Infrared (FTIR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS) in detail. The results of Thermogravimetric Analysis (TGA) show that AGET-ATRP could provide a higher surface grafting density to get more pronounced thermosensitive properties. The morphology of our hybrid SiO₂ nanoparticles was characterized by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). measurements of turbidity, Dynamic Light Scattering (DLS), and phase transfer were conducted to investigate the thermal responses of the hybrid material. In addition, Pickering emulsions were prepared using such hybrid SiO₂-POEGMA as an emulsifier. Moreover, its fast de-emulsification above a lower critical solution temperature (LCST) may be exploited for the efficient separation and recycling of catalysts in future.