Synthesis and characterization of mid- and end-chain functional telechelics by controlled polymerization methods and coupling processes

Well-defined polystyrene- (PSt) or poly(e-caprolactone) (PCL)-based polymers containing mid- or end-chain 2,5 or 3,5- dibromobenzene moieties were prepared by controlled polymerization methods, such as atom transfer radical polymerization (ATRP) or ring opening polymerization (ROP). 1,4-Dibromo-2- (bromomethyl)benzene, 1,3-dibromo-5-(bromomethyl)benzene, and 1,4-dibromo-2,5-di(bromomethyl)benzene were used as initiators in ATRP of styrene (St) in conjunction with CuBr/2,2'-bipyridine as catalyst. 2,5-Dibromo-l,4-(dihydroxymethyl)benzene initiated the ROP of e-caprolactone (CL) in the presence of stannous octoate (Sn(Oct)₂) catalyst. The reaction of these polymers with amino- or aldehyde-functionalized monoboronic acids, in Suzuki-type couplings, afforded the corresponding telechelics. Further functionalization with oxidable groups such as 2-pyrrolyl or 1-naphthyl was attained by condensation reactions of the amino or aldehyde groups with low molecular weight aldehydes or amines, respectively, with the formation of azomethine linkages. Preliminary attempts for the synthesis of fully conjugated poly(Schiff base) with polymeric segments as substituents, by oxidative polymerization of the macromonomers, are presented. All the starting, intermediate, or final polymers were structurally analyzed by spectral methods (¹H NMR, ¹³C NMR, and IR).