Synthesis of poly(phenylquinoxaline)s via self-polymerizable quinoxaline monomers

The development of three new self-polymerizable quinoxaline monomers was pursued in an attempt to increase the susceptibility of the monomers toward aromatic nucleophilic substitution reactions. The polymerizations were carried out in N-methyl-2-pyrrolidinone in the presence of potassium carbonate, to yield high molecular weight poly(phenylquinoxaline)s (PPQs). Replacement of the 1,4-phenylene group of the phenol in the isomeric monomer mixture of 2-(4-hydroxyphenyl)-3-phenyl-6-fluoroquinoxaline and 3-(4-hydroxyphenyl)-2-phenyl-6-fluoroquinoxaline with the 2,6-naphthylene, 4,4 ' -biphenylene, and 4,4 ' -oxydiphenylene groups resulted in more reactive monomers as evidenced by shorter polymerization times and lower polymerization temperatures needed to obtain PPQs with high intrinsic viscosities. Polymerizations of the 1,4-phenylene-, 2,6-naphthylene-, 4,4 ' -biphenylene-, and 4,4 ' -oxydiphenylene-containing monomers led to PPQs with intrinsic viscosities ranging from 1.4 to 2.5 dL/g and glass transition temperatures ranging from 221 to 287 degreesC. All of the PPQs exhibited high tensile properties, with tensile strengths of greater than or equal to 92 MPa, tensile moduli of greater than or equal to2.6 GPa, and elongations of greater than or equal to 88%.