Polymerization of aromatic nuclei. VIII. Molecular weight control in benzene polymerization

Abstract

The molecular weight of p‐polyphenyl prepared from benzene—aluminum chloride—cupric chloride, was affected by solvent, concentration, and temperature. Relative molecular weights were measured by polymer solubility in chloroform, and positions of the infrared para band and ultraviolet reflectance λmax. The order of effectiveness of the solvents in reducing molecular weight was: o‐C6H4Cl2 > 1,2,4‐C6H3Cl3 > SnCl4 ∼ CS2 > [C6H6]. Degradative oxidation revealed that o‐dichlorobenzene solvent was incorporated as an endgroup to only a minor extent. In general, the molecular weight of p‐polyphenyl decreased with increasing temperature and with decreasing concentration. The theoretical aspects are treated.

Dehydro coupling of aromatic nuclei by catalyst-oxidant systems: poly(p-phenylene)

“…Some is in the form of p-chlorophenyl end groups, according to oxidative degradation, and part is substituted along the chain as evidenced by IR and dechlorination experiments. 188 It is conceivable that chloride functions as the gegen ion for the radical cations present in ordinary PPP. The oligomer exists with a low concentration of radical cations, in stable form, associated with the chains.187 Uptake of bromine and peroxide supports the proposition that small quantities of cyclohexadiene or p-quinoid structures interrupt the normal repeating units, as a consequence of incomplete oxidative rearomatization during polymerization.…”

“…Relative molecular weights were measured by polymer solubility in chloroform, and positions of the infrared para band and ultraviolet reflectance X^. 188 The order of effectiveness of the solvents in reducing molecular weight was: o-C6H4C12 > 1,2,4-C6H3C13 > SnCl4 ~CS2 > [C6H6], In general, the molecular weight decreased with increasing temperature and with decreasing concentration.…”

The Effect of Reaction Time on the Chain Structure of Poly(p-phenylene) and a Study of Doping with FeCl3

“…Poly(p-phenylene) (PPP) has a stable structure that is not degraded when heated to 525°C [ll, and it has a relatively high electrical conductivity after doping 6] is widely used in the synthesis of PPP because of the easily available raw materials and simple operation; even PPP film can be prepared using special equipment [ 71. Nevertheless, research is still lacking on the relation between polymerization time and PPP structure, which seems to be of great significance.…”

Chemical synthesis of polyphenylene in an ionic liquid: the possibility of relative molecular mass regulation

“…It is known from the literature that there are at least three ways of estimating the relative molecular mass ( M , ) of PpP from I R spectroscopic data . [5][6][7] These are all based on the calculation of the ratio between the intensities of the bands characteristic for the protons of the terminal phenyl nuclei (760 and 690 cm-1) and the intensity of the 807 cm-1 band for 1,4-disubstituted phenyl rings. For our calculations a formula [see eqn.…”