An Initial Study into the Use of 400 kHz Ultrasound for Vinylbenzyl Chloride Copolymer Incorporation into Low-Density Polyethylene Film

Abstract The sonolysis of water using 400 kHz ultrasound can lead to the formation of reactive OH· radicals. This study investigates whether these radicals can break the chemical bonds in a polymer film substrate and allow for copolymer incorporation. This would be an alternative to the high-energy, electron-beam radiation grafting of copolymers. LDPE films were submerged into air-exposed ultrapure water and subjected to 400 kHz ultrasound. They were then heated in an aqueous dispersion of a model monomer (vinylbenzyl chloride, VBC) at 60 °C for 24 h. Spectroscopy indicated that poly(VBC) chains were successfully incorporated into the LDPE (without using additional oxidizing agents) with the 1612 cm–1 poly(VBC) Raman band increasing in area by ca. 900% (vs. control experiment with no ultrasound), and that poly(VBC) was still present after 5 weeks of toluene washing at 70 °C. Ultrasound techniques can therefore graft comonomers onto inert polymer substrates.