Phase transfer catalyzed polymerization of 4‐bromo‐2,6‐dimethylphenol in the presence of either 2,4,6‐trimethylphenol or 4‐tert‐butyl‐2,6‐dimethylphenol

Abstract

The synthesis of poly(2,6‐dimethyl‐1,4‐phenylene oxide) with one 2,6‐dimethylphenol chain end (PPO–OH) and with well‐defined molecular weight by phase transfer catalyzed polymerization of 4‐bromo‐2,6‐dimethylphenol (20) in the presence of either 2,4,6‐trimethylphenol (1) or 4‐t‐butyl‐2,6‐dimethylphenol (1′) as chain initiators is described. The range of controllable molecular weights and the mechanism of molecular weight control are discussed based on the differences between the reactivities of 20, 1, and 1′ and of the corresponding reactive species. The PPO–OH synthesized from 20/1′ has structural units derived from 1′ attached only at the chain end. PPO–OH synthesized from 20/1 contains structural units derived from 1 both internally and at the chain ends. Structural units derived from side reactions were identified by 1H‐NMR spectroscopy. A reaction mechanism is proposed to account for their formation.

Cobalt Mediated Radical Polymerization of 4-Bromo-2,6-Dimethyl Phenol and Its Copolymerization with Poly(dimethyl siloxane) in the Presence of Co(acac)2: DMF Catalyst

“…An important advantage of CMCRP is copolymerization reaction of various monomers such as vinyl acetate, styrene, poly(dimethyl siloxane) (PDMS), methyl methacrylate (MMA) and 4-bromo-2,6-dimethylphenol (BDMP). New architectural designs for controlled compositions of aromatic ethers is of a great need in the area of macromolecular design of membranes, foams, and drug delivery systems [3,4]. Poly(phenylene oxide) (PPO) was synthesized from 4-bromo-2,6-dimethylphenol (BDMP) in the presence of cobalt acetoacetonate (Co(acac) 2 ) catalyst with dimethyl formamaide (DMF) ligand.…”

“…BDMP reacted with PDMS in a novel controlled copolymerization reaction within a good yield. PPO itself composed of aromatic ether resembles a number of vital biomaterials and vitamins [1,4,5]. A variety of synthetic polymers has been reported from the random reactions at ortho and para positions of the aromatic nuclei in the basic conditions.…”

“…In addition, low reactivity of dihalo or trihalo dialkyl monomers have limited the oxidative coupling reactions of the halo dialkyl phenols [1][2][3]. Recently, reactivity of monomers has been important in a phase transfer radical polymerization, where reactivity of the monomer has been assisted by other alkyl phenols like trimethyl phenol [4][5][6][7]. Displacement of halogen atoms in BDMP has been extensively used by us and others to make a flame-retardant polyether with high glass transition temperature [1,2].…”

“…The presence of bromine in the aromatic ring was used to provide cobalt-mediated system to copolymerize this monomer with PDMS. Presence of the radical in this system increased reactivity of the monomer and allowed us to synthesis new copolymers with a number of monomers with new properties [4][5][6][7]. Some of the limitations that had restricted the direct application of PPO as such is its high glass transition temperature (T g = 220°C), poor melt flow and the susceptibility of its methyl group to thermal oxidation.…”

Chain-Growth Polycondensation: Living Polymerization Nature in Polycondensation and Approach to Condensation Polymer Architecture

“…The observation that the polymer end group was more reactive than monomer has been reported in the polycondensation of alkali 4-halothiophenoxide, 9 4-fluoro-4 0 -hydroxydiphenylsulphone, 10 4-fluoro-4 0 -hydroxybenzophenone, 11 4-halobenzenesulfinate, 12 2,6-dimethylphenol, 13,14 and 4-bromo-2,6-dimethylphenol. [15][16][17] However, condensation polymers with precisely controlled molecular weights and low polydispersities have not been obtained because of insolubility of polymers and of contamination of conventional step-growth polycondensation. The cationic polycondensation of phosphoranimines [18][19][20][21] and the polycondensation of dimethylsulfoxonium methylide initiated by trialkylboranes [22][23][24][25][26][27] yield well-defined polyphospahzenes and polymethylenes, respectively, but the structures of these propagating groups are different from the polymerizable groups of the monomers, and the monomers do not essentially react with each other.…”