Abstract: pH-responsive amphiphilic block copolymer polystyrene-b-poly(2-vinylpyridine)(PS₁₀₁-b-P2VP₇₀) 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 PS₁₀₁-b-P2VP₇₀ micellar solution, the relationship between particle size and the electrochemical performance of PANI were investigated. The molecular weight distribution and structure of PS₁₀₁-b-P2VP₇₀ were determined by size exclusive chromatography(SEC) and nuclear magnetic resonance spectroscopy(¹H 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 PS₁₀₁-b-P2VP₇₀ 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.

Key words: Amphipilic block copolymer, Polystyrene-b-poly(2-vinylpyridine)(PS₁₀₁-b-P2VP₇₀), pH regulation, Polyaniline, Capacitance characteristics