Size-dependent behaviors of femtosecond laser-prototyped polymer micronanowires

A remarkable recent progress in two-photon photopolymerization is the achievement of fabrication resolution around tens of nanometers, establishing a femtosecond laser as a nanofabrication tool. However, how the superresolution has been made possible is still under arguement. We propose a concept of polymer network permeability to solvents, meaning a structure-loosened nanopolymer state that allows free penetration of small molecules to interpret the mechanism. Experimentally, we found proof showing existence of the state, including an unusually large volume shrinkage rate (>60%), shape-memory effect, a giant softness of nanospring, and the mechanical stability of rinsed two-photon written polymer nanowires.