Ultrasonic controlling of degradation of polymer materials

BACKGROUND: Degradable polymer materials initiate the degradation process immediately after implantation. How to regulate the degradation of these materials is rarely reported at present. OBJECTIVE: To study the effect of ultrasonic wave on controlling the degradation of polymer materials. METHODS: The sample is made of ε-caprolactone/L-lactide copolymer, and its core was coated with low density polyethylene on the surface with the following four different methods. (1) The core surface was firstly covered with CaCl2 powder, and then coated with polyethylene. (2) The core was firstly coated with polyethylene and coarsened for 3 hours. (3) The core surface was firstly covered with CaCl2 powder, and then coated with polyethylene, and coarsened for 3 hours. (4) The core was directly coated with polyethylene. The four kinds of specimens obtained were embedded in pork for ultrasonic bombardment experiment in vitro. RESULTS AND CONCLUSION: In the specimens prepared with methods 1 and 4, the lyophobic layer could protect core materials before ultrasonic treatment, and no absorption peak was found at 631 nm. After ultrasonic treatment, the lyophobic layer was destroyed, toluidine blue dye was released, leading to change the color of immersion solution and increase the absorption peak at 631 nm. In the specimens prepared with methods 2 and 3, the lyophobic layer cannot exhibit the protection effects, the absorption peak was found at 631 nm. Under electron microscope, the appearance of the specimens in four groups was changed obviously. It is feasible to control the starting of the degradation by coating the degradable copolymer with LDPE and using ultrasonic as a trigger.