Mechanoresponsive Hard Elastic Materials Based on Semicrystalline Polymers: From Preparation to Applied Properties

This work offers an alternative strategy for the preparation of hard elastic (HE) materials via environmental intercrystallite crazing and subsequent spontaneous strain recovery. Structure and properties of HE materials are characterized: secondary loading in air is accompanied by the development of porosity (up to 40%) with pores below 20 nm; upon unloading, the as-opened porous structure is closed in the elastic manner (strain recovery up to 90%). Upon loading/unloading cycles, the HE samples behave as "living" mechanoresponsive materials with openable and closable mesopores. This strategy has proved to be universal for diverse semicrystalline polymers [high-density polyethylene, polypropylene, poly(tetrafluoroethylene)]. The phenomenon of the forced impregnation of polymer matrixes with target cargo upon cyclic loading offers benefits for the incorporation of diverse additives when the overall uptake can be increased by 500%. The mechanism behind this phenomenon is discussed. Practical benefits of HE polymers and related nanocomposites as applied materials (including antibacterial and photoactive materials) are highlighted.