Polyfurans have never been established as useful conjugated polymers, as previously they were considered to be inherently unstable and poorly conductive. Here, we show the preparation of stable and conducting polyfuran films by electropolymerization of a series of oligofurans of different chain lengths substituted with alkyl groups. The polyfuran films show good conductivity in the order of 1 S cm–1, good environmental and electrochemical stabilities, very smooth morphologies (roughness 1–5 nm), long effective conjugation lengths, well-defined spectroelectrochemistry and electro-optical switching (in the Vis-NIR region), and have optical band-gaps in the range of 2.2–2.3 eV. A low oxidation potential needed for polymerization of oligofurans (compared to furan) is a key factor in achievement of improved properties of polyfurans reported in this work. DFT calculations and experiments show that polyfurans are much more rigid than polythiophenes, and alkyl substitution does not disturb backbone planarity and conjugation. The obtained properties of polyfuran films are similar or superior to the properties of electrochemically prepared poly(oligothiophene)s under similar conditions.
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机译：聚呋喃从未被确立为有用的共轭聚合物，因为以前它们被认为具有固有的不稳定性和不良的导电性。在这里，我们展示了通过一系列烷基取代的不同链长的低聚呋喃的电聚合制备稳定且导电的聚呋喃薄膜的方法。聚呋喃薄膜显示出良好的电导率（约1 S cm -1 ），良好的环境和电化学稳定性，非常平滑的形貌（粗糙度为1-5 nm），有效的共轭长度长，光谱电化学和化学性质明确。光电开关（在Vis-NIR区域内），并且光学带隙在2.2–2.3 eV的范围内。寡聚呋喃（与呋喃相比）聚合所需的低氧化电位是实现这项工作中报道的聚呋喃性能改善的关键因素。 DFT计算和实验表明，聚呋喃比聚噻吩具有更高的刚性，并且烷基取代不会干扰主链的平面度和结合。在相似条件下，所获得的聚呋喃薄膜的性能与电化学制备的聚（低聚噻吩）的性能相似或更好。
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