Preparation of AB-type diblock copolymers containing poly-(2,6-dimethyl-1,4-phenylene oxide) and methyl methacrylate or styrene blocks

Abstract

High molecular weight poly-(2,6-dimethyl-1,4-phenylene oxide) (PPO) is obtained from 2,6-dimethylphenol (DMP) by oxidative coupling polymerization. The polymerization is accomplished by passing oxygen through a solution of DMP, a catalytic amount of copper(I) salt, and amine in an organic solvent. High molecular weight PPO is a useful material for engineering thermoplastic applications because of its outstanding physical and chemical properties. However, the use of neat poly-PPO is insignificant as a commercial product because of its high melt viscosity. The commercially available products are generally blends of PPO with high-impact polystyrene. Recently, low molecular weight PPO has attracted considerable interest as starting materials for the preparation of block copolymers, graft copolymers, macromonomers, and star-type polymers of well-defined architectures. Low molecular weight PPO with a narrow molecular weight distribution can be prepared by the precipitation polymerization of DMP in the solvent/nonsolvent mixture under the action of Cu(I) Cl/amine-catalyst and oxygen or by the redistribution of PPO with functional phenols. Tingerthal et al. carried out the synthesis of an ABA-type triblock copolymer containing PPO (A) and polysulfone (B) blocks. Servens et al. studied the preparation of a diblock copolymer with PPO and 1,4polyisoprene segments. More recently, VanAert et al. prepared diblock copolymers by the reaction of phenolterminated polystyrene with PPO. The controlled/“living” radical polymerization such as copper-catalyst-mediated atom transfer radical polymerizations (ATRP) has been utilized for the synthesis of well-defined polymers with narrow molecular weight distributions. ATRP involves the activation and deactivation of a propagating chain end as a result of the reversible atom transfer reaction between a metal salt and alkyl halides. A wide variety of monomers such as styrenes, acrylates, and acrylonitrile have been used for ATRP. To the best of our knowledge, this is the first report on the synthesis and characterization of AB-type block copolymers with well-defined PPO and methyl methacrylate (MMA) blocks. Also, a sample of block copolymer containing PPO and styrene (St) segments was achieved. The PPO oligomers with activated halogen end groups were used as macroinitiators for ATRP.