From single-ring phthalocyanines to conductive composite fibers with a rigid-polymer matrix

Single ring phthalocyanine compounds (NiPc, SiPc(OH){dollar}sb2{dollar}) and rigid rod polymers are used as starting materials for the preparation of conductive composite fibers (doped NiPc or (SiPcO){dollar}sb{lcub}rm n{rcub}{dollar} dispersed inside a rigid rod matrix). A study of the material formation processes involved in the preparation of the fibers is presented. The solid state polymerization of SiPc(OH){dollar}sb2{dollar} is proposed to follow a 'chain polycondensation' scheme, and the observed chain lengths are interpreted as results of a relation between crystallographic lengths of the starting and the product lattices along the propagation reaction direction. Regarding the composite fiber structure, the formation of a pure rigid rod fiber is studied first and a model yielding a hierarchical structure is described. The inclusion of NiPc in the spinning solution leads, upon coagulation, to isolated NiPc domains, in arrangements that are predicted to correspond to body centered cells and exhibit various degrees of disorder (depending on solution composition and process parameters). The observed dependence of fiber conductivity on composition is explained in terms of tunneling and percolation processes. The structure formation and conductivity levels of doped (SiPcO){dollar}sb{lcub}rm n{rcub}{dollar}/rigid-rod composites are analyzed semi-quantitatively.