以ZnO-g-PSS纳米线为模板的PEDOT/PSS纳米线/管的大规模制备研究

The aqueous dispersion of intrinsic conductive polymer complex, poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) has been widely used in capacitor, anti-static coatings, sensor, and etc, for its moderate band gap, low redox potential, and high optical transparency in its electrically conductive state. However, its conductivity decreases rapidly at the high temperature or high humidity which is related to the microphase separation between conductive PEDOT domain and hydrophilic PSS domain.In addition, it has been demonstrated that the conductivity of PEDOT nanowire and nanotube with high respect ratio is much higher than that of the nanoparticle of granular powder. However, the PEDOT nanowire and nanotube are mainly fabricated by electrochemical polymerization with template and physical approaches such as electrospinning. Though there are many existing technologies available but the large scale production of PEDOT nanowire and naotube with controlled morphologies and sizes is still a great challenge. Herein, we proposed a novel strategy to prepare the PEDOT/PSS naowire and tube with controlled size and morphology in large scale. The process is consisted in three steps. The first is to synthesize nanowire of ZnO (NWZnO) in large scale with tunable diameters and lengths by the reaction of commercial zinc powder with NaOH in aqueous solution of ammonium persulphate at ambient. The second is to introduce a covalently bonded PSS graft chain (NWZnO-g-PSS ) to the surface of NWZnO by a controlled free radical grafting polymerization (such as ATRP, RAFT, TEMPO) followed by a silane coupling process. The grafting density, the chain length of the grafting chains and the cross-linking structures could be tailor-made by the controlled grafting polymerization. Furthermore, the functional groups, including EDOT moiety pendant for covalently bonding the PEDOT chains and PSS chains, and the thermal curable groups for cross-linking in the film formation are also could be achieved. At the last, the chemical oxidative polymerization of EDOT is carried out with the as-synthesized NWZnO-g-PSS as templates with various architecture. It is possible that the size and morphologies of the PDOT/PSS could be mediated via the structure of NWZnO-g-PSS.

PEDOT/PSS微观相分离导致的电导率降低和对温湿度的敏感性，限制了其应用范围。大长径比的PEDOT纳米线/管比相应的纳米粒子有更高的电导率，但大规模制备仍是一个难题。基于集成创新的思路，设计了一种制备PEDOT/PSS纳米线/管的新方法。以氧化锌纳米线(NWZnO)为模板，在NWZnO表面利用硅烷偶联剂的化学修饰和可控接枝自由基聚合，制备NWZnO-g-PSS。然后通过EDOT的原位化学氧化聚合，得到PEDOT/PSS@NWZnO的纳米线/管。技术关键是通过调控PSS接枝链的结构，如接枝密度、接枝链长和共接枝，实现对EDOT/PSS层厚度和微观形貌的调控。特别是通过共接枝聚合，在PSS接枝链中引入交联结构和EDOT单元。在PEDOT与PSS掺杂剂之间形成共价键连接的互穿网络。通过对PEDOT与PSS的微观相分离的限制，实现提高电导率和降低电导率对温湿度敏感性的目的。

成功地制备了1D结构的ZnO@PEDOT，MnO2@PEDOT，埃洛石HNTs@PEDOT，BaTiO3@PEDOT纳米纤维(管)，以及BaTiO3@PEDOT纳米粒子。并研究了其导电性，电化学比容和作为介电填料的PVDF的性能。.通过在ZnO纳米纤维表面接枝PTFEMA-b-PSSNa和形成交联氧化硅的方法解决了ZnO纳米纤维(管)在EDOT聚合过程中的溶解问题。以表面接枝PTFEMA-b-PSSNa的ZnO纳米纤维为模板，壳层PEDOT的厚度随EDOT聚合的进行而逐渐增大。当EDOT/ZnO的质量比大于1:2时，ZnO纳米纤维模板溶解而得到PEDOT纳米管。ZnO@PEDOT的比电容在20 mV/s时高达101.3 F/g。.利用DPE封端的PSSNa的大分子链自由基链转移的方法实现了MnO2表面的接枝(SI-ATRP不适用)。当MnO2-g-PSSNa/EDOT的质量比≤1时，可以得到PEDOT纳米管。MnO2@PEDOT的比电容达到62.9 F/g( MnO2-g-PSSNa/EDOT = 1:1，纯MnO2为18.5 F/g)。充放电500次后，比电容的保持率为61.2%。.以BaTiO3为核(220-260 nm)，PEDOT为壳(厚20-60 nm)为介电填料，PVDF为基材的复合材料的介电常数高达22(填充量20 wt%)，比纯BaTiO3填充高2倍以上，而介电损耗仅为0.12。BaTiO3@PEDOT的比电容高达63.7 F/g，是纯BaTiO3 (1.95 F/g)的大约60倍。.BaTiO3纳米粒子表面接枝PMMA和PTFEMA填料可以显著地提高PVDF基复合材料的介电常数，当填充量为80%时(PMMA)，介电常数可以达到30 (100 kHz)，而PVDF的为6.2，同时保持了较低的介电损耗。基于硅烷水解生成交联的硅氧烷保护层技术，开发了高介电性能的改性BaTiO3纳米粒子涂料，在PET薄膜表面涂布3 μm(PET膜后的2%)的涂层，介电常数提高了26%。.研制了HNTs@PEDOT复合材料。初步实验结果显示，当HNTs含量为50%时，电导率可达到17.08 S/cm(粉末压片)，用TsOH进一步掺杂后，电导率可以达到37.4 S/cm。比ZnO@PEDOT，MnO2@PEDOT和BaTiO3@PEDOT纳米纤维的电导率提高一个数量级以上。