以PS-b-P2VP为模板剂诱导调控聚苯胺形貌、尺寸及电化学性能

Morphology and Size Regulation of Polyaniline Induced by PS-b-P2VP as Template and Its Electrochemical Characters

采用可逆加成-断裂链转移自由基聚合(RAFT)法合成了具有pH响应性的两亲嵌段共聚物聚苯乙烯-b-聚(2-乙烯基吡啶)(PS 101-b-P2VP 70),并以其胶束为“模板”,通过氧化聚合制备聚苯胺(PANI).通过调节PS 101-b-P2VP 70胶束溶液的pH值,探究PANI颗粒形貌的可控调节及颗粒尺寸与PANI电化学性能之间的关系.利用凝胶渗透色谱(SEC)和核磁共振氢谱(^1 H NMR)确定了PS 101-b-P2VP 70的分子量分布及结构;利用傅里叶变换红外光谱(FTIR)、透射电子显微镜(TEM)、粒度测试、循环伏安(CV)、计时电位(Chronopotentio-metry)及交流阻抗谱(EIS)对PANI结构、形貌和电化学性能进行了表征.结果表明“模板”法合成的PANI形貌尺寸得到了很好的控制,在pH≤4时其尺寸随pH值的增加而减小;当pH=5时,模板剂中P2VP段疏水性的明显增大导致其胶束颗粒聚集为尺寸较大的聚集体,并使其诱导的PANI颗粒平均粒径显著增大;当pH=4时PANI颗粒在溶液中的平均粒径为141 nm,呈“串状”形貌且分散性最好.PANI具有快速充放电能力和良好的赝电容特性,随颗粒尺寸减小样品电化学性能增强.pH=4时样品电化学活性最好,循环伏安曲线面积最大,放电比容量最高,在电流密度为1 A/g时,其放电比容量可达1411.88 F/g,且该样品阻抗值最小.

pH-responsive amphiphilic block copolymer polystyrene-b-poly(2-vinylpyridine)(PS 101 -b-P2VP 70 ) was synthesized by reversible addition-fragmentation chain transfer radical polymerization(RAFT). The micellar solution of block copolymer was used as a template to prepare polyaniline(PANI) micro-nano particles. The controllable adjustment of particle morphology and size of PANI realized by pH regulation of the PS 101 -b-P2VP 70 micellar solution, the relationship between particle size and the electrochemical performance of PANI were investigated. The molecular weight distribution and structure of PS 101 -b-P2VP 70 were determined by size exclusive chromatography(SEC) and nuclear magnetic resonance spectroscopy( ^1 H NMR). Fourier infrared spectroscopy(FTIR), transmission electron microscopy(TEM), cyclic voltammetry(CV), chronopotentiometry, and electrochemical impedance spectroscopy(EIS) were used to test the structure, morphology and electrochemical properties of PANI. The results showed that the morphology andsize of PANI was well controlled, and its size decreases with increasing pH value at pH≤4. At pH=5, the significant increase in the hydrophobicity of the P2VP segment in the templating agent resulted in the deposition of the micelle particles into larger-sized aggregates, and the average particle size of the PANI particles induced by the PS 101 -b-P2VP 70 micelles was also significantly increased. When pH=4, the average particle size of PANI particles in solution tested by particle size measurement is 141 nm, which is “string-like” and has the best dispersion. PANI has fast charge and discharge capability and good pseudo-capacitance characteristics, and the electrochemical performance of each sample increases as the particle size decreases. At pH=4, the electrochemical activity of the sample is the best, the peak area of CV curve is the largest, and the discharge specific capacity is the highest. When the current density is 1 A/g, the specific discharge capacity can reach 1411.88 F/g and this sample has the smallest impedance value.