Self-assembling patchy colloidal particles are promising candidates to create designer soft materials. To dress such systems with mechanical functionality, one can take inspiration from biological semiflexible filaments, whose mechanical behavior is central to the cell’s function.
We perform mechanical experiments on analogues of biological filaments, semiflexible “colloidal polymers” made from bonded dipatch colloidal particles, whose bonding strength and persistence length we can adjust in-situ. Using optical tweezers to probe their extreme mechanics under increasingly high compressions, we reveal a rich non-linear mechanical response involving buckling, viscoelastic creep, and ultimately fracture. By characterizing this response using elastic and viscoelastic models involving Euler buckling and stress relaxation, we relate the critical bending at fracture to the finite patch size of the colloids. Our results demonstrate the crucial role of finite patch size in the mechanics of self-assembled colloidal materials, and provide mechanical information essential to design functional colloidal architectures inspired by nature.