Ring opening polymerization of 3-semifluoro- and 3-bromomethyloxetanes to poly(2,2-substituted-1,3-propylene oxide) telechelics for soft blocks in polyurethanes

The synthesis of hydroxy-terminated poly(2,2-substituted-1,3-propylene oxide) polyoxetane telechelics and co-telechelics bearing semifluorinated (-CH2OCH2(CF2)nCF3) and functional bromomethyl pendant groups is reported. Characterization utilized 1H NMR spectroscopy, temperature modulated DSC (MDCS), and gel permeation chromatography (GPC). Analysis of relative reactivity ratios for a 1:1 3FOx to BrOx feed indicates that in the early stages of reaction BrOx-BrOx dyad mole fraction is below the statistically predicted amount. However, a model suggests that the final telechelic dyad composition at complete reaction is not very different from a statistical copolymer. The co-telechelics have low Tgs (−33 to −39 °C) and molecular weight in a desirable range (Mw≈3-5 k). Telechelics were incorporated in polyurethanes (PUs) with isophorone diisocyanate (IPDI) and butanediol (BD) as the hard block. Characterization of polyurethane composition and bulk properties by 1H NMR, MDSC, and GPC is described. The new polyurethanes hold promise for a 'reaction on polymer' approach to polyurethanes with functional soft blocks.