Preparation and properties of fluorosilicone polyether polyurethane underwater acoustically transparent encapsulant

Fluorosilicone polyether polyurethane (FSPU) was successfully prepared from polytetramethylene glycol, hydroxyl fluorosilicone oil, toluene diisocyanate and chain extender 2,4-diamino-3,5-dimethylthiotoluene. The obtained material was characterized by Fourier transform infrared spectroscopy, dynamic mechanical analysis and scanning electron microscopy. And the water resistance, mechanical and acoustic performance of the materials were tested by video optical contact angle measuring instrument, electronic universal testing machine and sound field, respectively. The results showed that the glass transition temperature of FSPU was lowered and the cold resistance was improved with the addition of hydroxyl fluorosilicone oil. When the amount of hydroxyl fluorosilicone oil was 40 wt%, the water contact angle of FSPU increased to 113.6°, and the water absorption reached a minimum of 0.7%. Compared with polyurethane, the hydrophobic performance of FSPU was significantly improved. The insertion loss of FSPU-40 at 1000 kHz was only 220.60 dB/m, which was 68.7% lower than that of polyurethane. Above all, FSPU has excellent water resistance, cold resistance and acoustic performance, and is an ideal material for underwater acoustically transparent encapsulant.