Abstract

The phosphazene homo and copolymers combining the ? 5- phosphorus-dioxy-biaryl units [NP(O 2C 12H 8)] or {[NP(O 2C 20H 12)] n (O 2C 12H 82,2?-dioxy-1,1?-biphenyl, O 2C 20H 12 = R or R/S-2,2?-dioxy-1, 1?-binaphthyl) and the conventional units [NP(OC 6H 4CO 2Pr) 2] or [NP(OCH 2CF 3) 2], including the new series {[NP(O 2C 12H 8)] 1-x[NP(OCH 2CF 3) 2] x} n (x = 0-1), all prepared by alkali carbonate assisted sequential macromolecular substitution from [NPCl 2] n have been studied by DSC-assisted thermo mechanical analysis. The results showed that the thermal expansion coefficient changes in dilatation mode and the softening temperature in the compression mode are coincident with the glass transition temperatures (T g) as measured by DSC except for the random copolymers containing the ? 5- phosphorus-dioxy-biaryl units in the approximate interval 40-60% for which the softening temperatures were much higher. For the chiral polymers with [NP(O 2C 20H 12)] n units, the TMA differences between the isomers R, R/S and the atactic products formed by their thermal atropisomerisation near the T g suggest that the R/S product resulting in the macromolecular substitution from [NPCl 2] n and rac-binaphthol may have some degree of tacticity. © 2011 Elsevier Ltd. All rights reserved.