The synthesis of a series of new high-barrier poly(hydroxy amide ethers) is described. The polymers are formed by the reactions of aromatic diglycidyl ethers, OCH2CHCH2OArOCH2CHCH2O, with N,N'-bis(3-hydroxyphenyl)adipamide, HOC6H4NHCO(CH2)(4)CONHC6H4OH, at 140-160 degrees C in propylene glycol monophenyl ether solvent using ethyltriphenylphosphonium acetate as initiator. Poly(hydroxy amide ethers) of general structure [-CH2CH(OH)CH2OArOCH2CH(OH)CH2OC6H4NH(CH2)(4)CONHC6H4O-](n) are readily prepared in high molecular weight. The mainly amorphous thermoplastics have glass transition temperatures (T-g) of 78-146 degrees C and oxygen transmission rates (O2TR) that range from 0.2 to 1.8 cc.mil/(100 in.(2).atm.day) (barrier units or BU) at 23 degrees C and 45-90% relative humidity. It was determined that barrier properties improve (i.e., O2TR decreases) as the aromatic core unit, Ar, becomes less bulky or more polar. For example, the poly(hydroxy amide ether) in which Ar is the aromatic unit based on 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane has an O2TR of 1.8 BU, while the poly(hydroxy amide ethers) in which Ar is based on the more compact 2,6-dihydroxynaphthylene or more polar 1,1-bis(4-hydroxyphenyl)acetamide units have lower O2TR of 0.2 BU. In one instance, an amorphous poly(hydroxy amide ether) was induced to crystallize, yielding a semicrystalline polymer with significantly lower O2TR. The derivative in which Ar is the 4,4'-biphenylene unit (O2TR = 0.3 BU, T-g = 110 degrees C) was annealed at 160 degrees C to yield a crystalline material with significant improvement in oxygen barrier (O2TR = 0.06 BU, T-g = 117 degrees C, T-m = 195 degrees C). Other effects that polymer structure has on O2TR and T-g are discussed.
