Preparation of near-infrared laser responsive hydrogels with enhanced laser marking performance

Abstract

Polystyrene modified bismuth oxide particles (PS@Bi₂O₃) were prepared and characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Using acrylamide (AM) as a monomer, and PS@Bi₂O₃ as laser sensitive additives, PAM/PS@Bi₂O₃ hydrogels were fabricated and treated by a 1064 nm near-infrared laser. The laser responsive properties of PAM/PS@Bi₂O₃ hydrogels were investigated at different current intensities and loading content of PS@Bi₂O₃ by visual observation, optical microscopy, and SEM, and the mechanism of laser response was analyzed by XRD and Raman spectroscopy. The results indicate that the PAM hydrogel with added PS@Bi₂O₃ particles showed excellent response to the laser, and high contrast and resolution text and pattern marks on the hydrogel surface can be obtained. The selection of suitable laser current intensity is key to the laser response of the PAM/PS@Bi₂O₃ composite hydrogel. Through analysis of XRD, Raman spectroscopy, and TGA data, the laser marking of the PAM/PS@Bi₂O₃ hydrogels originates from the generation of both bismuth metal and amorphous carbonized materials. After adding PS@Bi₂O₃ with a loading content from 1% to 3%, the mechanical properties of the hydrogels were improved, but the swelling properties were finally decreased.