Direct Observation and Modeling of Transient Nucleation in Isothermal Thickening of Polymer Lamellar Crystal Monolayers

Direct observation and modeling of transient nucleation in isothermal thickening of polymer lamellar crystal monolayers was studied. A low molecular weight (LMW) poly(ethylene oxide) (PEO) fraction with both chain ends of -OH was used as a sample. The PEO monolayer were prepared on freshly cleaved mica surfaces by the simple static solution casting. The concentration of the PEO/methylene chloride solution was δ0.5 mg mL-1, and the as-cast samples were dried in vacuum for days. The samples were heated to 70δC for 5 min to ensure the complete melting, followed by quenching to 18δC or below. Isothermal thickening from integral-folding chain IF(1) to IF(0) of the samples was realized by annealing the IF(1) monolayers at elevated Ts. The numerical study indicates that the increase in the thickening nucleation rate with T is mainly caused by the reduction of surface energy.