Acoustic Bubble Suppression by Constructing a Hydrophilic Coating on HDPE Surface.

Abstract

Ultrasonic bubbles on the solid surface of various sonochemical devices largely affect signal resolution due to the serious reflection/scattering of sound waves. The Laplace pressure of the cavitation bubble can be tuned by constructing an ultrathin hydrophilic layer, which leads to the solvation or pinching off of the bubbles from the surface. In this article, we successfully coated a polydopamine polymer layer on the high-density polyethylene (HDPE) surface. The formed hydrophilic layer with a contact angle of less than 45° almost completely eliminates the bubbles in both water and 32.5 vol % diesel exhaust fluid solutions upon sonication, which results in the operation of the piezoelectric sensor over 500 h, while the sensor with pure HDPE only ran for less than 2 h. Further, the coated sensors showed high stability under the temperatures of 60-80 °C. An improved mechanical property was confirmed via abrasion test, enabling long-term stability in harsh environments, including acidic urine and ultrasonic agitation. The acoustic bubble suppression via the hydrophilic polymer coating on HDPE surface displays broad applications, particularly with acoustic sensors, sonobuoys, and nondestructive surface detection in sonochemistry.