Synthesis of telechelic methacrylate oligomers with carboxyl ends through radical polymerization-chemical modification

A new method used to obtain α,ω-carboxyl terminated oligo(butyl methacrylate) (di-CTBMA) is introduced in this paper, which combines a conventional solution free-radical polymerization and a chemical modification, i.e. saponification. Here, a ω-carboxyl terminated oligo(butyl methacrylate) (CTBMA) is firstly synthesized by a solution polymerization in tetrahydrofuran, where 4,4′-azobis(4-cyanovaleric acid) is used as radical initiator, and thioglycolic acid as chain transfer agent. Then, CTBMA is transferred into di-CTBMA via saponifying CTBMA in an organic solvent/H₂O/KOH solution. The influence of important reaction parameters, such as the type of organic solvent and reaction time are studied by acid-base titration and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis. It is experimentally shown that a saponified CTBMA with a functionality of about two, i.e. di-CTBMA could be obtained under a certain experimental condition.