Ultrasound healable shape memory dynamic polymers†
The concept of using ultrasound to trigger shape memory assisted healing of covalently cross-linked dynamic polymers is demonstrated. The well-designed dynamically crosslinked poly(ε-caprolactone)-based polyurethane bearing Diels–Alder bonds not only possesses high mechanical strength and toughness, but also exhibits shape memory assisted crack-closure and healing upon exposure to high-intensity focused ultrasound owing to breaking and reformation of dynamic bonds. The use of focused ultrasound allows the healing process to be activated remotely and to be controlled locally by depositing the acoustic energy only in the damaged region without detriment to the undamaged parts of the material. The healable polyurethane materials have potential applications such as long-term load-bearing engineering components and anti-fatigue medical devices.