NEW POLYMER SYNTHESES .88. THERMOSETTING CHOLESTERIN OLIGOCARBONATES WITH PROPARGYL ENDGROUPS

Thermosetting cholesteric oligocarbonates were prepared by polycondens ation of mesogenic diphenols such as 4,4'-dihydroxybiphenyl (DHB) or h ydroquinone 4-hydroxybenzoate (HQHB; system. name: 4-hydroxyphenyl 4-h ydroxybenzoate) with methylhydroquinone and isosorbide. Trichloromethy l chloroformate served as condensing agent and propargyl alcohol (syst em. name of propargyl: 2-propynyl), 4-propargyloxybenzoyl chloride or 6-propargyloxy-2-naphthoyl chloride served as chain stoppers. Most oli gocarbonates form a cholesteric phase over a broad temperature range. Depending on the mole fraction of isosorbide these oligocarbonates for m Grandjean textures when sheared in the molten state.