Ring-opening polymerization and the synthesis of new inorganic polymers

The subject of this thesis is the utilization of ring-opening polymerization for the synthesis of new inorganic polymers. The research involves (1) the use of ring strain as a means to enhance the polymerizability of cyclic phosphazene compounds, (2) the development of electronically conductive poly(organophosphazenes), and (3) the discovery of a new class of inorganic polymers, the poly(thiophosphazenes).; A series of transannular ferrocenylcyclotriphosphazenes that do not possess phosphorus-halogen bonds were synthesized for studies of the relationship between molecular structure and polymerization behavior. The compounds were of general structure N{dollar}sb3{dollar}P{dollar}sb3{dollar}(R){dollar}sb4(eta{dollar}-C{dollar}sb5{dollar}H{dollar}sb4)sb2{dollar}Fe. Most of these strained, cyclic phosphazenes undergo ring-opening polymerization when heated at 250{dollar}spcirc{dollar}C in the presence of a small amount (1%) of (NPCl{dollar}sb2rbrack sb3,{dollar} which functions as a polymerization initiator. Certain species polymerize in the absence of any initiator and these transformations are the first examples of uncatalyzed ring-opening polymerization of cyclic phosphazenes that lack phosphorus-halogen bonds.; The synthesis and chemical oxidation of linear poly(organophosphazenes) that bear polymerizable, heterocyclic side groups is described. The polymers were prepared for use as precursors to electronically conductive materials. The polymers have the general structure (NP(OR){dollar}sb2rbracksb{lcub}rm n{rcub}{dollar} or (NP(NHR){dollar}sb2rbracksb{lcub}rm n{rcub},{dollar} where R is a pyrrole, thiophene or furan moiety. Chemical oxidation of the materials was carried out in solution using Fe(ClO{dollar}sb4)sb3{dollar} or FeCl{dollar}sb3.{dollar} The resultant dark, insoluble powders were found to be semi-conductive.; The cyclic thiophosphazene N{dollar}sb3{dollar}P{dollar}sb2{dollar}SCl{dollar}sb5{dollar} undergoes thermal ring-opening polymerization when heated at 90{dollar}spcirc{dollar}C. The resultant polymer, (N{dollar}sb3{dollar}P{dollar}sb2{dollar}SCl{dollar}sb5rbracksb{lcub}rm n,{rcub}{dollar} is a hydrolytically sensitive, yellow, elastomeric material. This polymer reacts with aryloxide nucleophiles to give poly((aryloxy)thiophosphazenes) of general structure (N{dollar}sb3{dollar}P{dollar}sb2{dollar}S(OAr){dollar}sb{lcub}rm x{rcub}{dollar}Cl{dollar}sb{lcub}rm y{rcub}rbrack {dollar} (X {dollar}>{dollar} Y). These materials were structurally characterized by using {dollar}sp1{dollar}H and {dollar}sp{lcub}31{rcub}{dollar}P NMR, elemental microanalysis and gel permeation chromatography. The glass transition temperatures of the polymers were measured by using differential scanning calorimetry and were found to be in a range from {dollar}-{dollar}40{dollar}spcirc{dollar}C to 79{dollar}spcirc{dollar}C. These T{dollar}sb{lcub}rm g{rcub}{dollar} values are compared to poly(carbophosphazene) and classical phosphazene analogues. Small-molecule model reactions of N{dollar}sb3{dollar}P{dollar}sb2{dollar}SCl{dollar}sb5{dollar} with NaOCH{dollar}sb2{dollar}CF{dollar}sb3{dollar} and NaOPh-Ph-o are also described.