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

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