Force-Induced Melting Of A Single Polyethylene Oxide Chain From Single Crystal: Molecular Behavior And Influencing Factors

Force-induced melting plays a key role in defining the mechanical strength and toughness of semicrystalline polymer materials. To understand its molecular mechanism, the direct measurement and monitoring of force-induced melting process at the single-molecule level are necessary. Here, the force-induced melting of a single polyethylene oxide (PEO) chain from the single crystal has been investigated by using atomic force microscopy-based single-molecule force spectroscopy. Both the constant-speed and constant-force experiments show that PEO folds are unfolded predominantly one by one during the force-induced melting process. The mechanical stability of PEO fold is confirmed to increase significantly with the increasing interfacial tension of polymer solvent and the thickness of crystal. The results obtained here provide new concepts in tuning the nanomechanical properties of crystalline polymer materials.