Properties of dioxybiphenyl- and chiral dioxybinaphthylphosphazene copolymers with propyl-carboxylate-phenoxy units and the randomization of the substitution reactions of poly(dichlorophosphazene)

The reaction of [NPCl2](n) first with 2,2'-dihydroxybiphenyl and K2CO3 or (R)-(+)-2,2'-dihydroxy-1,1'-binaphthyl and CS2CO3, and subsequently with HO-C6H4-CO2Prn and Cs2CO3, gave the phosphazene copolymers {[NP(O2C12H8)](1-x)[NP(O-C6H4-CO2Prn)(2)](x)}(n) [x = 0.2 (1a), 0.35 (1b), 0.5 (1c), 0.7 (1d), and 0.85 (1e)] and the chiral analogues {[NP(O2C20H12)](1-x)[NP(O-C6H4-CO2Prn)(2)](x)}(n) [x = 0.2 (2a), 0.4 (2b), 0.45 (2c), 0.5 (2d), 0.55 (2e), 0.7 (2f), and 0.8(2g)]. The study of their properties as a function of the composition have revealed systematic changes in the electronic structure of the macromolecules, in the interplanar distances of their mesophases and in glass transition temperatures. The latter variation has demonstrated the strictly alternating nature of the copolymeric structures in the series 1 and 2. This is an experimental evidence supporting that the substitution of Cl in the [NPCl2](n) With the bifunctional reagents or 2,2'-dihydroxybiphenyl and (R)-(+)-2,2'-dihydroxy-1,1'-binaphthyl as promoted by alkali carbonates are essentially random for all values of x and that the chirality of the binaphthyls has no stereochemical effect.