Abstract
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 (Mn = 1600 g mol−1) and high molar mass (Mn = 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.
Highlights
Poly(phenylene methylene) (PPM) consists of phenylene rings bridged by a methylene unit (Figure 1a)
Without solvents and under a steady and controlled nitrogen flow to remove hydrogen chloride (HCl) which evolves during polymerization
The polymerization of benzyl chloride did not start until the temperature was elevated to 80 ◦ C
Summary
Poly(phenylene methylene) (PPM) consists of phenylene rings bridged by a methylene unit (Figure 1a). Essentially the same 13C NMR spectra were found for a number of poly(phenylene methylene)s synthesized under different conditions and with different catalysts, and for products with methylene)s synthesized under different conditions and with different catalysts, and for products different molar masses [33,34,35,36], suggesting that the substitution patterns but most likely with different molar masses [33,34,35,36], suggesting that the substitution patterns but most likely the polymerization mechanism was the same in those cases Such polymers were reported to be strictly the polymerization mechanism was the same in those cases.
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