Synthesis of Oligomers of 12-Acryloyloxydodecanoic Acid via Reversible Addition Fragmentation Transfer (RAFT) Polymerisation

Abstract

A long chain fatty acid carrying an acryloyl functionality, 12-acryloyloxydodecanoic acid (12-ADA), was preparedfrom 11-hydroxydodecanoic acid and acryloyl chloride and used as monomer in the synthesis of oligomers of 12-ADAvia the RAFT controlled polymerisation process. Reversible Addition Fragmentation Transfer (RAFT) reagents wereprepared and used to control the polymerisation process and produced an oligomeric product with few monomeric unitsinstead of a high molecular weight polymer of 12-ADA. The transfer reagents were prepared from Grignardintermediates from a reaction of dithioacids with free radical initiators 2,2-azobisisobutyronitrile (AIBN) and4,4-azobis(4-cyanopropanoic acid) (ACP). It was found that short-chain oligomers in the form of dimers and trimerscharacterized by Electrospray Mass Spectrometry, ESMS and Gel Permeation chromatography, GPC were the majorproducts obtained when RAFT reagents had been used in the controlled polymerisation. As a control, polymerisationwas carried out in the absence of RAFT reagents and high molecular-weight polymers were obtained. This confirmedthe effectiveness of the prepared RAFT reagents as polymerisation controllers and provided a way for the synthesis ofoligomers. Here, the preparation of oligomers of 12-ADA using AIBN-RAFT reagents is reported. The method isexpected to provide one way of preparing oligomers of controlled chain length/molecular mass which also carry acarboxylic acid functional group at one end.