Mechanically responsive, or "mechanomutable", polyelectrolyte tube arrays are fabricated and studied using atomic force microscopy-based nanoindentation and microstructurally specific finite element analysis simulations. Mechanical responsiveness is controlled through the coupling of pH-dependent "inherent" molecular-level material properties to anisotropic microscale geometry. A unique geometrically controlled transition is discovered that amplifies mechanical responsiveness due to a change in deformation mechanisms.