Dynamics of Pseudo Second-Order Phase Transition Behaviour inPolymer Melt Disclosed by Single Molecule Spectroscopy

摘要

Since the advent of single-molecule spectroscopy (SMS) based on fluorescence detectiona new era has been opened for exploring the molecular basis of various research subjects.Among them our interest is in disclosing polymer dynamics above its glass transitiontemperature Tg.Our SMS previously revealed the highly fluctuating collective motion ofpolymer chains distinctly activated above Tg,particularly between 40°C and 50°C;;it looks likea critical phenomenon in the second-order phase transition although glass transition is notrecognized as phase transition.Figs.1A-1C show the crucial observations of second-orderphase transition like phenomena given by the highly fluctuating fluorescence trajectories I (t)and cosine waveform of autocorrelation C(τ) of single viscosity-sensitive Cy3 moleculescovered with a poly (vinyl acetate) (PVAc,Tg=36.5 °C) at 41.9 °C.