Controlled synthesis of uniform hollow polypyrrole microcapsules by a cosolvent approach

Abstract

A simple and effective synthetic approach is demonstrated for the formation of uniform hollow polypyrrole (PPy) microcapsules. This process entails the preparation of homogeneous polystyrene@polypyrrole (PS@PPy; core@shell) microspheres, followed by chemical extraction of the PS cores. By proper dispersion of monodispersive PS microspheres and pyrrole molecules in a water/ethanol cosolvent to minimize the diffusion of pyrrole molecules to the PS microspheres, we are able to prepare uniform PS@PPy microspheres with significantly reduced size variation, deformation, and aggregation. The PS microspheres, in diameter of 490 nm, carry negative surface charges, and after the deposition of PPy, reveal a transition from positive to negative surface charges with increasing pH values. The hollow PPy microcapsules, in diameter of 527 nm and shell thickness of 20 nm, are fabricated after selective removal of PS cores from the PS@PPy microspheres in tetrahydrofuran. Analysis tools including Fourier transform infrared spectroscopy, thermogravimetric analyzer, and zeta potential, as well as scanning and transmission electron microscopes are employed for material characterization.

Fabrication of Polypyrrole Hollow Nanospheres by Hard-Template Method for Supercapacitor Electrode Material

“…Figure 2e,f display the thermal degradation profiles of PS, PPy, and the core-shell PS@PPy particles. As shown in Figure 2e, the initial decomposition temperature of PS was approximately 270 • C [27]. However, the core-shell PS@PPy sample exhibited an onset point of decomposition at 340 • C. This finding provides evidence that the PPy shell shields the PS cores, thereby enhancing the decomposition temperature.…”

“…To overcome this limitation, the PS cores were removed using organic solvents to create hollow PPy nanospheres. Different organic solvents, such as cyclohexane (CHX), tetrahydrofuran (THF), chloroform (CHCl 3 ), toluene (TOL), acetone (AC), and N,N-dimethylformamide (DMF) have been reported for PS core dissolution [20][21][22][23][24][25][26][27]. However, the dissolution process and the corresponding structure of the PPy shell, as well as its impact on the electrochemical properties, have not been extensively studied.…”

MOF-derived Cu/N–C Composite Based Electrochemical Sensor for Simultaneous Detection of Catechol and Hydroquinone

“…26 At the same time, the N-H stretching vibration peak at 3500-3550 cm −1 appears in the infrared spectra of PS@PPy and PS@PPy-Cu-MOF-5, while the peak in MOF-5 can't be found, indicating that PS@PPy was successfully loaded on the surface of Cu-MOF-5, and it was consistent with the results in the SEM image. 27 The elemental composition and valence state of the Cu/N-C composite were studied by XPS, and the results are shown in Figs. S1 and 3d 31,32 The peak of pyrrole-N at 400.2 eV can be found in the high-resolution XPS spectrum of N 1s.…”

Synthesis of IrO2 decorated core–shell PS@PPyNH2 microspheres for bio-interface application

“…The difference in diameter between the PS and PS@PPyNH 2 microspheres was 46 nm, indicating a surface overcoat of PPyNH 2 with a thickness of 23 nm. We note that in our previous work on synthesizing uniform PS@PPy microspheres from a water/ethanol mixture, we determined an ethanol volume of 7% to be the optimal ratio for producing uniform PS@PPy microspheres [47].…”

“…Following the removal of excess water, a powdery mixture of a dark green color (PS@PPyNH 2 microspheres) was collected. For reference purposes, we also synthesized uniform PS@PPy microspheres for IrO 2 deposition [47]. This control sample was used to distinguish the effect of functionalized PPy for anchoring IrO 2 nanoparticles.…”