Several acrylic hydrogels were prepared via ultrasonic polymerization of water soluble monomers and macromonomers. Ultrasound was used to create initiating radicals in viscous aqueous monomer solutions using the additives glycerol, sorbitol or glucose in an open system at 37 degrees C. The water soluble additives were essential for the hydrogel production, glycerol being the most effective. Hydrogels were prepared from the monomers 2-hydroxyethyl methacrylate, poly(ethylene glycol) dimethacrylate, dextran methacrylate, acrylic acid/ethylene glycol dimethacrylate and acrylamide/bis-acrylamide. For example a 5% w/w solution of dextran methacrylate formed a hydrogel in 6.5min in a 70% w/w solution of glycerol in water at 37 degrees C with 20kHz ultrasound, 56Wcm(-2). The ultrasonic polymerization method described here has a wide range of applications such a biomaterial synthesis where initiators are not desired.

In vitro oxidative stability of two siloxane poly(urethane urea)s synthesized using 4,4′‐methylenediphenyl diisocyanate (in SiPUU‐1) and Isophorone diisocyanate (in SiPUU‐2) linked soft segment was evaluated using 20% H2O2 and 0.1 mol/L CoCl2 solution at 37°C under 150% strain. Commercially available siloxane polyurethane (Elast‐Eon™ 2A) and polyether polyurethane (ChronoThane P™ 80A) were used as negative and positive controls, respectively. ChronoSil™ 80A was included as another commercially available polycarbonate polyurethane. Scanning electron microscopic (SEM) examinations, attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR) spectroscopy, and molecular weight reduction revealed the extensive degradation of ChronoThane P™ 80A after 90 days while SiPUU‐1, SiPUU‐2 and Elast‐Eon™ 2A showed no noticeable surface degradation. ChronoSil™ 80A showed degradation in both soft and hard segments. Tensile testing was carried out only on unstrained polyurethanes for 90 days. ChronoThane P™ 80A showed 35% loss in ultimate tensile strength and it was only 13–14% for SiPUU‐1 and Elast‐Eon™ 2A. However, the tensile strength of ChronoSil™ 80A was not significantly affected. The results of this study proved that SiPUU‐1 possess oxidative stability comparable with Elast‐Eon™ 2A. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2557–2565, 2019.

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