Fu, Yi Lau, Yiu-Ting R. Weng, Lu-Tao Ng, Kai-Mo Chan, Chi-Ming Evidence of Enhanced Mobility at the Free Surface of Supported Polymer Films by in Situ Variable-Temperature Time-of-Flight-Secondary Ion Mass Spectrometry Time-of-flight secondary ion mass spectrometry (TOF-SIMS) spectra of polystyrene (PS) films supported on silicon wafers were obtained at temperatures ranging from room temperature to 100 °C. Principal component analysis (PCA) of the TOF-SIMS data revealed a transition temperature (<i>T</i><sub>T</sub>) at which the surface structure of PS was rearranged. The <i>T</i><sub>T</sub> of a 120-nm thick PS (weight-average molecular weight of 3 000 g/mol) thin film was determined to be about 36 °C, which is approximately 30 °C lower than the bulk glass transition temperature (<i>T</i><sub>g</sub>) of that PS. Similar <i>T</i><sub>T</sub>s were observed on PSs with different molecular weights. As the <i>T</i><sub>T</sub> is strongly related to the <i>T</i><sub>g</sub> and dependent on the molecular weight, it is believed that the <i>T</i><sub>T</sub> determined by TOF-SIMS is related to the surface glass transition temperature (<i>T</i><sub>g</sub><sup>S</sup>) measured by other techniques. This suggests that TOF-SIMS combined with PCA can be used to determine the <i>T</i><sub>g</sub><sup>S</sup> of polymer films. Furthermore, the detailed PCA analyses indicate that the phenyl groups of PS tended to move away from the surface at temperatures above <i>T</i><sub>T</sub>. This conclusion was further confirmed by contact angle and XPS measurements. contact angle;PCA analyses;room temperature;XPS measurements;ion mass spectrometry;Polymer Films;3 000;Principal component analysis;Similar TTs;Enhanced Mobility;bulk glass transition temperature;Free Surface;transition temperature;polymer films;silicon wafers;phenyl groups;surface structure;surface glass transition temperature 2013-11-19
    https://acs.figshare.com/articles/journal_contribution/Evidence_of_Enhanced_Mobility_at_the_Free_Surface_of_Supported_Polymer_Films_by_in_Situ_Variable_Temperature_Time_of_Flight_Secondary_Ion_Mass_Spectrometry/2351554
10.1021/ac401335j.s001