Molecular Weight Dependence of Polymer Chain Mobility within Multilayer Films Li Xu Victor Selin Aliaksandr Zhuk John F. Ankner Svetlana A. Sukhishvili 10.1021/mz400413v.s001 https://acs.figshare.com/articles/journal_contribution/Molecular_Weight_Dependence_of_Polymer_Chain_Mobility_within_Multilayer_Films/2366758 Fluorescence recovery after photobleaching has been applied to determine, to our knowledge for the first time, the molecular weight (<i>M</i><sub>w</sub>) dependence of lateral diffusion of polymer chains within layer-by-layer (LbL) films. As shown by neutron reflectometry, polyelectrolyte multilayers containing polymethacrylic acid (PMAA, <i>M</i><sub>w</sub>/<i>M</i><sub>n</sub> < 1.05) of various molecular weights assembled from solutions of low ionic strengths at pH 4.5, where film growth was linear, showed similar diffusion of PMAA in the direction perpendicular to the film surface. At a salt concentration sufficient for unfreezing electrostatically bonded chains, layer intermixing remained almost unaffected (changes <1.0 nm), while the lateral diffusion coefficient (<i>D</i>) scaled with the PMAA molecular weight as <i>D ∼ M</i><sub>w</sub><sup>–1±0.05</sup>. 2013-10-15 00:00:00 layer intermixing Polymer Chain Mobility unfreezing electrostatically film growth polymethacrylic acid Multilayer FilmsFluorescence recovery neutron reflectometry film surface Molecular Weight Dependence diffusion coefficient salt concentration Mw polyelectrolyte multilayers PMAA polymer chains