Tuning the surface functionality of polyamide films via termination reaction in molecular layer-by-layer deposition
Tuning the surface functionality of polyamide films via termination reaction in molecular layer-by-layer deposition
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DOI：
10.1016/j.memsci.2022.120855
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发表时间：
2022-08-27
影响因子：
9.5
通讯作者：
Liu, Xitong
中科院分区：
文献类型：
--
作者：
Stafford, Christopher M.;Guan, Xun;Liu, Xitong
高度交联的基于聚酰胺的膜的分子逐层（mLbL）沉积提供了灵活性和对膜性质如选择性膜层的厚度、粗糙度和化学性质的控制。特别感兴趣的是非破坏性地定制膜的表面化学以用于特定目的的能力，例如增强亲水性或使膜污染最小化。在这里，我们表明，mLbL膜的表面化学可以通过终止反应来调整，使表面富含-COOH，-NH 2，-聚乙二醇（-PEG），或-氟化基团。我们用X射线光电子能谱（XPS）和原子力显微镜（AFM）系统地表征所得表面，以验证成功的改性，并确保分别保持低表面粗糙度。然后，我们使用pH值依赖的接触角和羧基修饰的胶体探针原子力显微镜测量的表面润湿性和粘附性的改性表面。测量的粘附力遵循-NH 2>> -氟化> -COOH近似于-PEG的排序，其中-COOH和-PEG分别由于电荷相互作用和水合状态而排斥。结合由mLbL沉积提供的低表面粗糙度，通过终止反应的表面功能化，如这里所示，将使研究人员能够从表面粗糙度到聚酰胺基膜的整体性能和结垢的表面化学贡献中解脱出来，用于水净化和先进的化学分离。
Molecular layer-by-layer (mLbL) deposition of highly crosslinked polyamide-based membranes affords flexibility and control over membrane properties such as thickness, roughness, and chemistry of the selective membrane layer. Of particular interest is the ability to non-destructively tailor the surface chemistry of the membrane for a particular purpose, such as enhancing hydrophilicity or minimizing membrane fouling. Here, we show that the surface chemistry of the mLbL membrane can be tuned via termination reactions to render the surface rich in -COOH, -NH2, -polyethylene glycol (-PEG), or -fluorinated groups. We systematically characterize the resulting surfaces with X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) to validate successful modification and to ensure the low surface roughness is maintained, respectively. We then use pH-dependent contact angle and carboxylate-modified colloidal probe AFM to measure the surface wettability and adhesion of the modified surfaces. The measured adhesion force follows the ranking -NH2 >> -fluorinated > -COOH approximate to -PEG, where the -COOH and -PEG are repulsive due to charge interactions and hydration state, respectively. Combined with the low surface roughness afforded by mLbL deposition, surface functionalization through termination reactions as shown here will allow researchers to disentangle contributions of surface chemistry from surface roughness to the overall performance and fouling of polyamide-based membranes for water purification and advanced chemical separations.