Preparation of α,ω-telechelic hexyl acrylate polymers with ----OH, ----COOH, and ----NH₂ functional groups by RAFT

The design, synthesis, and use of two new, stable, functionalized chain transfer agents (CTA's) containing OH and amine end groups for the RAFT polymerization is reported: 2-hydroxyethoxy-carbonylphenylmethyl dithiobenzoate and 2-(2-(tert-butoxycarbonyl)ethylamino)-2-oxo-1-phenylethyl benzodithioate, respectively. The RAFT polymerization of n-hexyl acrylate (HA) using those CTA's, were compared to several other functionalized dithiobenzoate esters reported in the literature containing COOH and Ester groups. The performances of the dithiobenzoates were compared in terms of kinetics and molecular weight distribution control. Good control in polymerization of n-hexyl acrylate with a linear increase of Mn with conversion mantaining polydispersity indices (PDI) below 1.1 was obtained by use of the new functionalized CTA's developed and also by use of some other CTA's tested, to produce well-defined linear polymers with one specific chain-end functionality: ---OH, ---COOH or Amine. Using a postpolymerization reaction with functionalized azocompounds in a 5 to 1 ratio, α,ω-telechelic polymers, with ---OH or ---COOH as functional group at the second end were obtained. By using this synthetic strategy α,ω-homotelechelic and heterotelechelic polymers were readily prepared. The chemical availability of functional end-groups in the telechelics was demonstrated by reaction with methacrylic anhydride.