Chemistry Department, DDU Gorakhpur University, 273009 India.
J Phys Chem B. 2010 Oct 14;114(40):12888-96. doi: 10.1021/jp105183q.
Fractal and dendrimer growth patterns of polypyrrole were obtained during electrochemical polymerization of pyrrole in systems (A) pyrrole-sodium dodecyl sulfate (NaDS)-water and (B) pyrrole-NaDS-cetyl trimethyl ammonium bromide (CTAB)-water. Different morphological transitions including compact → flower-like and fractal → dendrimer → fractal were observed depending on experimental conditions. Growth kinetics during electropolymerization of pyrrole was studied. Growth rate was found to be higher in system A than in B. Effect of [NaDS], [pyrrole], and field intensity on morphology and weight of polymer aggregates was also studied in both the systems. Different empirical equations were obeyed under different conditions. Electropolymerized aggregates were characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), electrical conductivity measurement, and reflectance spectroscopy. TEM studies revealed that the particle size decreased to ∼140-200 nm in the presence of CTAB. The decrease in particle size on addition of CTAB was also observed in XRD studies. Reflectance spectra of the polymer aggregates support the large π-conjugation in the dendrimer. During electropolymerization, oscillations in potential were monitored as a function of time. Results indicated that growth pattern and electric potential oscillations were interrelated. In the case of fractal growth, the amplitude of chaotic oscillation was higher than the amplitude of oscillation during the growth of dendrimer. Growth morphologies and electric potential oscillations have been explained on the basis of modified Diaz's mechanism.
聚吡咯的分形和树突状生长模式是在吡咯电化学聚合过程中获得的，聚合体系分别为（A）吡咯-十二烷基硫酸钠（NaDS）-水和（B）吡咯-NaDS-十六烷基三甲基溴化铵（CTAB）-水。根据实验条件的不同，观察到了不同的形态转变，包括致密→花状和分形→树突状→分形。研究了吡咯电聚合过程中的生长动力学。发现体系 A 中的生长速率高于体系 B。还研究了[NaDS]、[吡咯]和场强对两种体系中聚合物聚集体形态和重量的影响。在不同条件下遵循不同的经验方程。用电镜（TEM）、粉末 X 射线衍射（XRD）、电导率测量和反射光谱对电聚合聚集体进行了表征。TEM 研究表明，在 CTAB 的存在下，粒径减小到约 140-200nm。在添加 CTAB 时，XRD 研究也观察到粒径减小。聚合物聚集体的反射光谱支持树突的大 π 共轭。在电聚合过程中，监测了作为时间函数的电位振荡。结果表明，生长模式和电势振荡是相互关联的。在分形生长的情况下，混沌振荡的幅度高于树突生长期间的振荡幅度。基于 Diaz 改进的机制解释了生长形态和电势振荡。
