Lefaux Christophe J, Kim Byoung-Suhk, Venkat Narayanan, Mather Patrick T
†Polymer Program, Institute of Materials Science and Chemical Engineering Department, University of Connecticut, Storrs, Connecticut 06269, United States.
‡Department of Organic Materials and Fiber Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 561-756, Republic of Korea.
ACS Appl Mater Interfaces. 2015 May 20;7(19):10365-73. doi: 10.1021/acsami.5b01371. Epub 2015 May 7.
Controlled growth of nanometer-scale multilayered coatings of negatively charged sulfonated poly(benzobisimidazole) (SPBI), complexed with positively charged poly(2-vinylpyridine) (P2VP) on quartz, and Nafion membrane as substrates has been explored. Both polymers, SPBI and P2VP, possess a net charge in methanol as a result of the dissolution of SPBI by complexation with triethylamine (TEA) and the protonation of P2VP with HCl, respectively, and thereby can form a multilayered molecular composite of alternating anionic SPBI and cationic P2VP via an electrostatic layer-by-layer (LbL) self-assembly. UV-vis absorption spectrophotometry was used to monitor the buildup and growth rate of such SPBI/P2VP multilayer films. Atomic force microscopy (AFM) was used to determine the roughness and thickness of the resulting SPBI/P2VP multilayers. As a result, it was found that a steady-state linear growth regime for the LbL self-assembled SPBI/P2VP multilayer films and coatings onto quartz and Nafion membranes was observed after completion of the first few deposition cycles, indicating the successful formation of the SPBI/P2VP multilayered assembly in methanol solutions. In addition, the SPBI/P2VP multilayer films in the perpendicular direction (flat view) demonstrated isotropic orientation distribution on the Nafion membrane, while the SPBI/P2VP multilayer films examined by X-ray scattering in the parallel direction (edge view) revealed anisotropic orientation, the combined observations indicating confinement of SPBI rods to the plane of the coating. We further found that the SPBI/P2VP multilayer coated Nafion possesses good thermal stability, as indicated by isothermal gravimetric analysis at 310 °C, and it was further observed that SPBI/P2VP multilayer coatings using the LbL self-assembly technique on Nafion membrane significantly increased the membrane stiffness, despite the small coating thickness employed.
人们探索了在石英和Nafion膜等基底上，使带负电荷的磺化聚（苯并双咪唑）（SPBI）与带正电荷的聚（2-乙烯基吡啶）（P2VP）络合，从而实现纳米级多层涂层的可控生长。两种聚合物，即SPBI和P2VP，在甲醇中分别由于SPBI与三乙胺（TEA）络合而溶解以及P2VP与HCl质子化而带有净电荷，进而能够通过静电逐层（LbL）自组装形成由交替的阴离子型SPBI和阳离子型P2VP组成的多层分子复合物。紫外可见吸收分光光度法用于监测此类SPBI/P2VP多层膜的堆积和生长速率。原子力显微镜（AFM）用于测定所得SPBI/P2VP多层膜的粗糙度和厚度。结果发现，在前几个沉积循环完成后，观察到LbL自组装的SPBI/P2VP多层膜和涂层在石英和Nafion膜上呈现稳态线性生长模式，这表明在甲醇溶液中成功形成了SPBI/P2VP多层组装体。此外，垂直方向（俯视图）的SPBI/P2VP多层膜在Nafion膜上表现出各向同性取向分布，而通过X射线散射在平行方向（侧视图）检测的SPBI/P2VP多层膜显示出各向异性取向，综合观察结果表明SPBI棒被限制在涂层平面内。我们进一步发现，经等温重量分析在310°C下表明，涂覆有SPBI/P2VP多层的Nafion具有良好的热稳定性，并且进一步观察到，尽管使用的涂层厚度较小，但在Nafion膜上采用LbL自组装技术的SPBI/P2VP多层涂层显著提高了膜的刚度。
