Prof. Tao XIE's Group

Solvent freezing is an important method to produce polymer foams with highly tunable pore structure. However, foams prepared from aqueous solution precursors commonly suffer from poor water resistance, whereas those organo-phase systems are not environmental-friendly. Here we present that using an emulsion lyophilization method can overcome such a contradiction and synthesize multi-functional polymer foams. Commercially available polyacrylate-based emulsions with various targeted glass transition temperatures (T_gs) were applied. Adipodihydrazide molecules contained in the water phase of the emulsions reacted with the acetyl groups on the polymers during the freeze-drying, forming elastic networks to maintain the pore structure. The foams can tolerant a 650% elongation without failure and are notch insensitive. The porosity of the foams can be tuned from approximately 45% to 90% via lyophilization of diluted emulsions. The facile blending of emulsions with different targeted T_g enabled foams with multi-shape memory capability. Moreover, the foams showed an excellent mechanical damping property, and the slow recovery nature enabled a clip application of clamping extremely weak objects.

Online reading: https://pubs.acs.org/doi/full/10.1021/acsami.9b11424