Tzeng Ping, Stevens Bart, Devlaming Ian, Grunlan Jaime C
Langmuir. 2015 Jun 2;31(21):5919-27. doi: 10.1021/acs.langmuir.5b00717. Epub 2015 May 21.
Layer-by-layer assembly was used to create quadlayers (QLs) of chitosan (CH), poly(acrylic acid) (PAA), CH, and graphene oxide (GO). Electron microscopy confirmed GO coverage over the film and a highly ordered nanobrick wall structure. By varying pH deviation between CH and PAA, a thick and interdiffused polymer matrix was created because of the altered chain conformation. A 5 CH (pH 5.5)/PAA (pH 3)/CH (pH 5.5)/GO QL assembly (48 nm) exhibits very low oxygen permeability (3.9 × 10(-20) cm(3) cm cm(-2) Pa(-1) s(-1)) that matches SiOx barrier coatings. In an effort to maintain barrier performance under high humidity, GO was thermally reduced to increase hydrophobicity of the film. This reduction step increased H2/CO2 selectivity of a 5 QL film from 5 to 215, exceeding Robeson's upper bound limit. This unique water-based multilayer nanocoating is very promising for a variety of gas purification and packaging applications.
采用层层组装法制备了壳聚糖（CH）、聚丙烯酸（PAA）、CH和氧化石墨烯（GO）的四层结构（QLs）。电子显微镜证实了GO覆盖在薄膜上以及高度有序的纳米砖壁结构。通过改变CH和PAA之间的pH偏差，由于链构象的改变，形成了一个厚的且相互扩散的聚合物基质。一种5 CH（pH 5.5）/PAA（pH 3）/CH（pH 5.5）/GO QL组装体（48纳米）表现出非常低的氧气渗透率（3.9×10（-20）立方厘米·厘米·厘米（-2）帕斯卡（-1）秒（-1）），与氧化硅阻挡涂层相当。为了在高湿度下保持阻挡性能，对GO进行热还原以增加薄膜的疏水性。这一还原步骤将5 QL薄膜的H2/CO2选择性从5提高到215，超过了罗伯逊上限。这种独特的水基金属多层纳米涂层在各种气体净化和包装应用中非常有前景。
