The synthesis, processing, and engineering of halogen-free, low heat release, fire-resistant materials present important challenges in polymer materials chemistry. One approach to this problem involves the use of polymers that char upon decomposition, reducing the evolution of flammable gas and acting as an insulating layer. Demonstrated here is the synthesis of novel char-forming polyarylates prepared by interfacial polycondensation of 4,4′-bishydroxydeoxybenzoin (BHDB) and isophthaloyl chloride. A variety of copolyarylates containing BHDB, bisphenol A (BPA), and isophthaloyl chloride were prepared and shown to exhibit superior fire resistance to many polymers in the low flammability category. A char yield of 42% and heat release capacity of 62 J/(g K) were measured for the BHDB-containing polyarylate, while polyarylates containing both BHDB and BPA combined desirable fire-resistant properties with appreciable polymer solubility and processability.

The bicyclo[2.2.1]heptene and bicyclo[2.2.1]heptadiene ring systems are versatile in their polymerization behavior in that they can form polymers with very different microstructures depending upon the initiator employed. Ring-opening metathesis polymerization (ROMP) initiators yield structures with an unsaturated backbone. 1 Olefin insertion initiators yield the 2,3-addition polymer (or more correctly the 5,6-addition for the substituted monomers discussed herein), 2 and 2,6-addition polymerizations (via intramolecular cyclizations) are produced when cationic 3 initiators are used. Radical-initiated polymerizations of norbornadiene results in a copolymer possessing both 2,3-and 2,6-addition units. 4 However, selective 2,6-addition is observed in radical polymerizations of a monoester substituted norbornadiene, presumably due to resonance stabilization of the propagating radical. 5 These structures are illustrated in Scheme 1 for norbornadiene.The innate appeal of these rich structural motifs and the widely different properties observed for the isomeric polymers (vide infra) has prompted us to study both the homo-and copolymerization of 2,3-disubstituted norbornadiene derivatives. Although norbornadiene itself has been successfully homo-and copolymerized via insertion mechanisms using cationic palladium(II) complexes, 1c,6 these initiators proved ineffective in the polymerization of electron-deficient derivatives 7 such as diethyl bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate (1). However, by choosing initiators that compensate for this electron perturbation, living polymerizations of these monomers can be obtained. 8 Polymerizations of 1 required the use of more electron rich neutral palladium(II) complexes such as bis(µ-halo)bis(exo-6-methoxy-2-norbornene-endo-σ,2π)dipalladium (halo ) chloride, Ia; bromide, Ib). 9 Likewise, living copolymerizations of 1 with carbon monoxide could also be accomplished using the monophosphine (or pyridine) adduct, bromo-(endo-6-phenyl-2-norbornene-endo-5σ,2π)(triphenylphosphine)palladium (II). 8b,10 Not surprisingly, the structures of both poly-1 and poly(1-co-CO) are exclusively composed of 5,6-insertion units, and no 2,6-additions can be detected.Obtaining the 2,6-addition isomer of poly-1 proved far more elusive. Attempts to cationically polymerize 1 failed to produce any polymer, undoubtedly due to the electron deficient nature of the olefin. We recently discovered, however, that 1 will undergo radical polymerization to exclusively give the 2,6-addition structure. Furthermore, these monomers are amenable to controlled polymerizations using living radical techniques. 11 These findings and the use of 1 to thermally stabilize polymers derived from atom transfer radical polymerization (ATRP) 12-14 methods are reported herein.When tracking down some occasional inconsistencies in the polymerization behavior of 1 with I, we found that this monomer would undergo spontaneous polymerization (albeit slowly) at subambient temperatures. Tandem size exclusion chromatography-light scatter...

Introduction. Polyaniline, prepared by chemical or electrochemical oxidation of aniline, possesses in part a polyaromatic quinone imine structure. Its remarkable electrical, electrooptical, and tensile properties have drawn

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