Technical and Macromolecular Chemistry, University of Paderborn , 33098 Paderborn, Germany.
Institute for Plastics Processing (IKV), RWTH Aachen University , 52074 Aachen, Germany.
ACS Appl Mater Interfaces. 2018 Feb 28;10(8):7422-7434. doi: 10.1021/acsami.7b14916. Epub 2018 Feb 19.
A study on the plasma-enhanced atomic layer deposition of amorphous inorganic oxides SiO and AlO on polypropylene (PP) was carried out with respect to growth taking place at the interface of the polymer substrate and the thin film employing in situ quartz-crystal microbalance (QCM) experiments. A model layer of spin-coated PP (scPP) was deposited on QCM crystals prior to depositions to allow a transfer of findings from QCM studies to industrially applied PP foil. The influence of precursor choice (trimethylaluminum (TMA) vs [3-(dimethylamino)propyl]-dimethyl aluminum (DMAD)) and of plasma pretreatment on the monitored QCM response was investigated. Furthermore, dyads of SiO/AlO, using different Al precursors for the AlO thin-film deposition, were investigated regarding their barrier performance. Although the growth of SiO and AlO from TMA on scPP is significantly hindered if no oxygen plasma pretreatment is applied to the scPP prior to depositions, the DMAD process was found to yield comparable AlO growth directly on scPP similar to that found on a bare QCM crystal. From this, the interface formed between the AlO and the PP substrate is suggested to be different for the two precursors TMA and DMAD due to different growth modes. Furthermore, the residual stress of the thin films influences the barrier properties of SiO/AlO dyads. Dyads composed of 5 nm AlO (DMAD) + 5 nm SiO exhibit an oxygen transmission rate (OTR) of 57.4 cm m day, which correlates with a barrier improvement factor of 24 against 5 when AlO from TMA is applied.
采用原位石英晶体微天平（QCM）实验，对在聚合物基底和薄膜界面处生长的非晶无机氧化物 SiO 和 AlO 的等离子体增强原子层沉积进行了研究。在进行沉积之前，在 QCM 晶体上沉积了一层旋涂的聚丙烯（scPP）模型层，以将 QCM 研究的结果转移到工业应用的聚丙烯箔上。研究了前驱体选择（三甲基铝（TMA）与[3-（二甲基氨基）丙基]-二甲基铝（DMAD））和等离子体预处理对监测到的 QCM 响应的影响。此外，还研究了不同 Al 前驱体用于 AlO 薄膜沉积的 SiO/AlO 偶联物的阻隔性能。尽管在沉积前不对 scPP 进行氧气等离子体预处理，TMA 生长 SiO 和 AlO 在 scPP 上的生长会受到显著抑制，但发现 DMAD 工艺在直接在 scPP 上沉积时，可得到与裸 QCM 晶体上类似的 AlO 生长。由此可以看出，由于不同的生长模式，TMA 和 DMAD 两种前驱体与 PP 基底之间形成的界面是不同的。此外，薄膜的残余应力会影响 SiO/AlO 偶联物的阻隔性能。由 5nm AlO（DMAD）+5nm SiO 组成的偶联物的氧气透过率（OTR）为 57.4cm³m²day，这与当使用 TMA 时，OTR 为 57.4cm³m²day 相比，阻隔性能提高了 24 倍。
