Hagen David A, Foster Brendan, Stevens Bart, Grunlan Jaime C
Department of Mechanical Engineering, Texas A&M University, College Station, Texas 77843, United States.
ACS Macro Lett. 2014 Jul 15;3(7):663-666. doi: 10.1021/mz500276r. Epub 2014 Jun 19.
In an effort to reduce deposition time and number of layers needed to achieve high gas barrier, multilayer films were deposited using 1 s exposures for the first four bilayers (BLs) and 1 min for subsequent dips. Thin-film assemblies of polyethylenimine (PEI) and poly(acrylic acid) (PAA) were deposited onto poly(ethylene terephthalate) [PET] using the layer-by-layer deposition process. Varying the exposure time of PET to polyelectrolyte solutions (i.e., dip time) significantly alters the growth rate of the multilayer thin films. The PEI/PAA system grows linearly with 1 s dip times and exponentially with longer times. Eight bilayers (650 nm) were required to achieve an undetectable oxygen transmission rate (<0.005 cm/(m·day)) using 1 min deposition steps, but this barrier was obtained with only 6 BLs (552 nm) using 1s deposition of the initial layers, reducing total deposition time by 73%. This "shift-time" concept makes layer-by-layer assembly much faster and more commercially feasible.
为了减少沉积时间和实现高气阻隔性所需的层数,在前四个双层(BL)中使用1秒曝光时间沉积多层膜,后续浸渍则使用1分钟曝光时间。通过逐层沉积工艺将聚乙烯亚胺(PEI)和聚丙烯酸(PAA)的薄膜组件沉积到聚对苯二甲酸乙二酯[PET]上。改变PET在聚电解质溶液中的曝光时间(即浸渍时间)会显著改变多层薄膜的生长速率。PEI/PAA体系在1秒浸渍时间下呈线性生长,在较长时间下呈指数生长。使用1分钟沉积步骤时,需要八个双层(650纳米)才能实现不可检测的氧气透过率(<0.005厘米/(米·天)),但通过对初始层使用1秒沉积,仅用6个双层(552纳米)就获得了这种阻隔性,总沉积时间减少了73%。这种“移位时间”概念使逐层组装更快且在商业上更可行。