Enhanced Dispersibility of Polytetrafluoroethylene (PTFE) via Ultrasonic‐Assisted Grafting Technique

Polytetrafluoroethylene (PTFE), renowned for its exceptional chemical and thermal stability, presents challenges in water‐based system dispersion due to its inherent hydrophobic nature. To address this, we developed a method for the construction of water‐dispersible PTFE nano‐powders via an ultrasonic‐assisted E‐beam radiation grafting technique. A maximum grafting yield of 25% was achieved at the monomer concentration of 20%. Analytical techniques, including Fourier‐transform infrared spectroscopy (FTIR) and x‐ray photoelectron spectroscopy (XPS), confirmed the successful grafting of acrylic acid onto the PTFE surface, while transmission electron microscopy (TEM) verified the formation of a poly(acrylic acid) layer on the PTFE nano‐powders. The resultant PTFE nano‐powders exhibited a low water contact angle (60.67°) and good dispersibility in water for over 10 days without aggregation. Density functional theory (DFT) calculations reveal that ultrasonic irradiation significantly reduces the energy barriers for free radical transfer along the PTFE chain, thus promoting the migration of free radicals to the nano‐powder surface and triggering polymerization with the vinyl monomer. Electron spin resonance (ESR) spectroscopy confirmed the DFT calculation results by showing a marked decrease in free radical concentration after ultrasonic treatment. These findings not only highlight the efficacy of ultrasound in altering the properties of temperature‐sensitive materials without affecting their physicochemical characteristics but also pave the way for a promising technique in the synthesis of water‐dispersible PTFE nano‐powders.