Synthesis of adamantyl and benzoxazole substituted poly( m-phenylene)s via the nickel catalysed coupling of aryl chlorides

Abstract

Poly( m-phenylene)s (PMP) with 1-adamantyl and 5-methyl-2-benzoaxozole or 2-benzoaxazole substituents ortho and meta to the backbone were synthesized via the nickel(0) catalysed dehalogenative coupling of aryl dichlorides. Ortho substituted polymers, which can have head-to-head and head-to-tail linkages, displayed better solubility in common organic solvents. The benzoxazole-containing PMPs exhibited excellent thermal stability in air by dynamic t.g.a. (thermogravimetric analysis) with values of 5% weight loss of 530–600°C while the adamantyl-substituted polymer showed a much lower thermal stability (5% weight loss at 370°C). All benzoxazole-functionalized polymers exhibited relatively high glass transition temperatures of 221–250°C. No glass transition was observed for the adamantyl-substituted PMP before the onset of decomposition at 350°C. Polymer number average molecular weights ranged from only 2000–4500 relative to polystyrene standards, indicating the need for further development of polymerization conditions.