Editing Poly(p-phenylene) (section)

{{DISPLAYTITLE:Poly(''p''-phenylene)}}
[[Image:Poly(p-phenylene)-repeat-2D-skeletal.svg|thumb|right|200px|The structure of the repeating unit of PPP]]
[[File:Poly(para-phenylene)-based-on-xtal-3D-view-2-sf.png|thumb|right|200px|[[Space-filling model]] of a short section of PPP]]
'''Poly(''p''-phenylene)''' ('''PPP''') is made of repeating ''p''-[[phenylene]] units, which act as the precursor to a [[conductive polymer|conducting polymer]] of the [[rigid-rod polymer]] family. The synthesis of PPP has proven challenging, but has been accomplished through excess polycondensation with the Suzuki coupling method.<ref>{{cite journal
|first1=Marcus 
|last1=Remmers
|first2=Beate 
|last2=Müller
|first3=Kai 
|last3=Martin
|first4=Hans-Joachim 
|last4=Räder
|title=Poly(p-phenylene)s. Synthesis, Optical Properties, and Quantitative Analysis with HPLC and MALDI−TOF Mass Spectrometry
|journal=Macromolecules
|volume=32
|issue=4
|pages=1073–1079
|doi=10.1021/ma981260s
|date=1999}}</ref><ref>{{ cite journal | title = A New Solution to an Old Problem: Synthesis of Unsubstituted Poly(para-phenylene) | first1 = Ali | last1 = Abdulkarim | first2 = Felix | last2 = Hinkel | first3 = Daniel | last3 = Jänsch | first4 = Jan | last4 = Freudenberg | first5 = Florian E. | last5 = Golling | first6 = Klaus | last6 = Müllen | authorlink6 = Klaus Müllen | journal = [[Journal of the American Chemical Society|J. Am. Chem. Soc.]] | year = 2016 | volume = 138 | issue = 50 | pages = 16208–16211 | doi = 10.1021/jacs.6b10254 }}</ref>

Early efforts typically produced black, insoluble powders that were difficult to characterize. For example, a 1962 paper reports "The solid glowed red-hot in a Bunsen flame, with no evidence of flame formation, and disappeared only slowly."<ref>{{cite journal|last1=Kovacic|first1=Peter|last2=Kyriakis|first2=Alexander|title=Polymerization of benzene to p-polyphenyl|journal=Tetrahedron Letters|date=1962|volume=3|issue=11|pages=467–469|doi=10.1016/S0040-4039(00)70494-1}}</ref> (J. Polym. Sci. (1960), 47, 45) Initially, the chemical and thermal stability of the material drove interest in its synthesis. It was used in rocket nozzles and some fabrics requiring high thermal stability.

[[Oxidation]] or the use of [[dopant]]s is used to convert the non-conductive form to a [[semiconductor]].