Li Ben, Liu Wanpeng, Jiang Zhongyi, Dong Xiao, Wang Baoyi, Zhong Yurong
Key Laboratory for Green Chemical Technology, Ministry of Education of China School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China.
Langmuir. 2009 Jul 7;25(13):7368-74. doi: 10.1021/la900262p.
We demonstrate that dopamine is able to self-polymerize and adhere firmly onto the substrate, which can create a hierarchical structure comprising an ultrathin active layer and a porous support layer. Such an approach opens a novel way to fabricating highly efficient and stable composite materials including composite membranes. More specifically, in this study the composite membranes are fabricated by simply dipping microporous substrate in aqueous dopamine solution under mild conditions. Nanoindentation measurement reveals the tight adhesion of dopamine onto microporous substrate, which is ascribed to numerous pi-pi and hydrogen-bonding interactions. The chemical composition of the active layer is analyzed by XPS, which demonstrates the self-polymerization of dopamine. The water contact angle of the dopamine coated membranes is reduced remarkably compared with that of the uncoated counterpart. Stylus profiler measurements display that the poly(dopamine) thickness increases as the coating time increases. FESEM images of the membranes' cross section show that an active layer (<100 nm) is deposited on the porous polysulfone (PS) substrate. Positron annihilation spectroscopy (PAS) is introduced to probe the fractional free volume properties throughout the cross section of the composite membranes and reveal that after dopamine double-coating the active layer becomes thicker and more compact. Moreover, pH and concentration of the dopamine solution exert notable influence on the fractional free volume of the composite membranes. The as-prepared membranes are tentatively employed for pervaporative desulfurization and exhibits satisfying separation performance as well as durability. This facile, versatile, and efficient approach enables a promising prospect for the wide applications of such novel kinds of ultrathin composite materials.
我们证明多巴胺能够自聚合并牢固地附着在基底上，这可以形成一种包含超薄活性层和多孔支撑层的分级结构。这种方法为制造包括复合膜在内的高效稳定复合材料开辟了一条新途径。更具体地说，在本研究中，通过在温和条件下将微孔基底简单地浸入多巴胺水溶液中来制备复合膜。纳米压痕测量揭示了多巴胺与微孔基底之间的紧密粘附，这归因于大量的π-π和氢键相互作用。通过X射线光电子能谱（XPS）分析活性层的化学成分，结果表明多巴胺发生了自聚合。与未涂覆的对应物相比，涂覆多巴胺的膜的水接触角显著降低。触针轮廓仪测量显示，聚多巴胺的厚度随着涂覆时间的增加而增加。膜横截面的场发射扫描电子显微镜（FESEM）图像表明，在多孔聚砜（PS）基底上沉积了一层活性层（<100 nm）。引入正电子湮没光谱（PAS）来探测复合膜整个横截面的自由体积分数特性，结果表明经过多巴胺双涂覆后，活性层变得更厚且更致密。此外，多巴胺溶液的pH值和浓度对复合膜的自由体积分数有显著影响。所制备的膜初步用于渗透汽化脱硫，表现出令人满意的分离性能和耐久性。这种简便、通用且高效的方法为这类新型超薄复合材料的广泛应用带来了广阔前景。
