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Materials that feature bistable elements, hysterons, exhibit memory effects. Often, these hysterons are difficult to observe or control directly. Here, we introduce a mechanical metamaterial in which slender elements, interacting with pushers, act as mechanical hysterons. We show how we can tune the hysteron properties and pathways under cyclic compression by the geometric design of these elements and how we can tune the pathways of a given sample by tilting one of the boundaries. Furthermore, we investigate the effect of the coupling of a global shear mode to the hysterons as an example of the interactions between hysteron and non-hysteron degrees of freedom. We hope our work will inspire further studies on designer matter with targeted pathways. [ABSTRACT FROM AUTHOR]

Novel phthalonitrile resins (BPAPNs) were prepared by blending phthalonitrile-terminated oligomeric polyaryl ether nitrile, 4,4′-(1,3-phenylenebis(oxy))diphthalonitrile (PN), and 4-amino-4-(3,4-dicyanophenoxy)phenyl. The curing behavior of the blends was studied by differential scanning calorimetry, Fourier-transform infrared spectroscopy, and rheology measurements. Additionally, quartz fiber-reinforced composites were prepared by hot-pressing process. Thermal stability and mechanical properties of cured phthalonitrile resins and composites were characterized and discussed. Compared with that of pristine PN, the impact strength of cured BPAPNs increased by 60%, while the thermal properties were not sharply compromised. Additionally, the maximum bending strength of BPAPNs composites reached 855 MPa, which was 56% higher than that of pristine PN. The current method shed light on the toughening of phthalonitrile resins, and the corresponding phthalonitrile resins could be used as the matrix for high-performance composites. [ABSTRACT FROM AUTHOR]