Poly(phenylene methylene) (PPM) is a thermally stable, hydrophobic, fluorescent hydrocarbon polymer. PPM has been proposed earlier to be useful as a coating material but this polymer was isolated in relevant molar masses only recently, and in large quantities. Accordingly, the preparation of coatings based on PPM and their behavior was explored in this study, with the example of the metal alloy AA2024 as a common substrate for corrosion tests. Coatings free of bubbles and cracks were obtained by hot pressing and application of the following steps: Coating on AA2024 with a layer of polybenzylsiloxane to improve the adhesion between PPM and the metal surface, the addition of polybenzylsiloxane to PPM in order to enhance the viscosity of the molten PPM, and the addition of benzyl butyl phthalate as a plasticizer. Electrochemical corrosion tests showed good protection of the metal surface towards a NaCl solution, thanks to a passive-like behavior in a wide potential window and a very low current density. Remarkably, the PPM coating also exhibited self-healing towards localized attacks, which inhibits the propagation of corrosion.

Poly(phenylene methylene)s (PPMs) with high molar masses were isolated by polymerization of benzyl chloride catalyzed with tungsten(II) compounds and subsequent fractionation. Four different tungsten(II) catalysts were successfully exploited for the polymerization, for which a strict temperature profile was developed. The PPMs possessed roughly a trimodal molar mass distribution. Simple fractionation by phase separation of 2-butanone solutions allowed to effectively segregate the products primarily into PPM of low molar mass (M_n = 1600 g mol⁻¹) and high molar mass (M_n = 167,900 g mol⁻¹); the latter can be obtained in large quantities up to 50 g. The evolution of the trimodal distribution and the monomer conversion was monitored by gel permeation chromatography (GPC) and ¹H NMR spectroscopy, respectively, over the course of the polymerization. The results revealed that polymerization proceeded via a chain-growth mechanism. This study illustrates a new approach to synthesize PPM with hitherto unknown high molar masses which opens the possibility to explore new applications, e.g., for temperature-resistant coatings, fluorescent coatings, barrier materials or optical materials.