Xu Li, Selin Victor, Zhuk Aliaksandr, Ankner John F, Sukhishvili Svetlana A
Department of Chemistry, Chemical Biology and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States.
Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
ACS Macro Lett. 2013 Oct 15;2(10):865-868. doi: 10.1021/mz400413v. Epub 2013 Sep 16.
Fluorescence recovery after photobleaching has been applied to determine, to our knowledge for the first time, the molecular weight () dependence of lateral diffusion of polymer chains within layer-by-layer (LbL) films. As shown by neutron reflectometry, polyelectrolyte multilayers containing polymethacrylic acid (PMAA, / < 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 () scaled with the PMAA molecular weight as .
据我们所知，光漂白后荧光恢复首次被用于确定逐层（LbL）薄膜中聚合物链横向扩散对分子量（）的依赖性。如中子反射法所示，在pH 4.5的低离子强度溶液中组装的含有不同分子量聚甲基丙烯酸（PMAA，/ < 1.05）的聚电解质多层膜，其膜生长呈线性，PMAA在垂直于膜表面的方向上表现出相似的扩散。在足以解冻静电结合链的盐浓度下，层间混合几乎不受影响（变化<1.0 nm），而横向扩散系数（）与PMAA分子量的关系为 。
