Aromatic polymers obtained by precipitation polycondensation: 4. Synthesis of poly(ether ketone ketone)s☆
Abstract High molecular weight aromatic poly(ether ketone ketone)s were synthesized by the Friedel-Crafts polyacylation condensation of iso- and terephthaloyl chlorides with diphenyl ether, 1,4- and 1,3-bis(4-phenoxybenzoyl)benzenes. Depending on the monomers used for polycondensation, polyketones of regular structure with different iso-/tereisomer repeating unit ratio ( 100 0 , 50 50 , 0 100 ) in the main chain were obtained. Polymers of each repeating isomer unit were prepared in two different ways. All the polymer syntheses were performed as precipitation polycondensations and the resulting polymers were obtained in particle form. The influence of reaction conditions and preparation route on the polymer properties were examined. The monomer concentration and monomer stoichiometric ratio were found to affect the polymer viscosity. The size and shape of the polyketone particles obtained were also found to be governed by reaction conditions and preparation route.
Aromatic homopolymers obtained by precipitation polycondensation: 1. Synthesis of naphthalene-containing polyketones
Abstract High molecular weight film-forming semicrystalline aromatic polyketones with a regular structure were obtained by precipitation electrophilic Friedel-Crafts polycondensation of 2,6-naphthalenedicarboxylic acid chloride with diphenyl ether, 1,4-bis( p -phenoxy) benzophenone and 1,4-bis( p -phenoxybenzoyl) benzene. Using 1 H and 13 C n.m.r. spectroscopy, the polyketones obtained were shown to be linear with para -substituted arylene fragments in the main chain. These polymers are soluble in strong protic acids and in common organic solvents, such as dichloroacetic acid and CHCl 3 /CF 3 CO 2 H mixtures. Depending on the chemical structure, these ‘as-made’ polyketones were found to show multiple melting behaviour on heating.
Structure, crystallization and morphology of poly (aryl ether ketone ketone)
Abstract The structure, crystallization and morphology of poly (aryl ether ketone ketone)s (PEKKs) prepared from diphenyl ether (DPE), terephthalic acid (T) and isophthalic acid (I) and having different T/I ratios have been investigated. As prepared, these copolymers can be thought of as consisting of ‘phthalate diads’ containing -DPE-T-DPE-T-(TT) and/or -DPE-T-DPE-I-(TI). Melt-crystallized PEKKs (all T/I ratios) form a structure similar to that observed in other poly(aryl ether ketone)s (form 1; a = 0.769 nm, b = 0.606 nm and fibre axis c = 1.016 nm). However, depending on composition, both TT and TI crystals were observed. All PEKK materials grow in the form of spherulites having negative birefringence. The incorporation of isophthaloyl moieties is observed to increase the chain flexibility and decrease the rate of crystallization. The equilibrium melting temperatures of various PEKKs were estimated using the Hoffman-Weeks approach, and showed a linear correlation with the meta isomer content. In contrast to other poly(aryl ether ketone)s, a form 2 crystalline modification ( a = 0.393 nm, b = 0.575 nm and c = 1.016 nm) can be induced either by exposure to solvents or by cold crystallization. The two crystalline modifications differ from each other in the placement of the chains and, consequently, the interchain interactions.