Hydrogen bonding driven self-assembly of side-chain amino acid and fatty acid appended poly(methacrylate)s: Gelation and application in oil spill recovery

We report an interesting class of fatty acid appended side-chain phenylalanine (Phe) containing poly(methacrylate) homopolymers that undergo self-assembly leading to gelation in selective organic hydrocarbons, due to association among the side-chain functionalities. Fatty acids of different n-alkyl chain lengths have been attached to the N-terminal of the Phe-based methacrylate and the corresponding homopolymers have been synthesized via reversible addition-fragmentation chain transfer polymerization. These homopolymers undergo gelation in selective organic hydrocarbons. The morphology of these organogels has been characterized by field emission scanning electron microscopy which revealed macroporous structure of the organogels. Viscoelastic properties of organogels and the thermoreversible gel-to-sol transition have been investigated by rheological measurements. Powder X-ray diffraction study has been performed to understand the effect of long n-alkyl chains on the gelation process. FTIR study reveals inter-/intra-chain hydrogen bonding which is the driving force of organogelation of the polymers in suitable solvents. In absence of hydrogen bonding interaction, hydrophobic association fails to direct the self-assembly process and no gelation is observed. An interesting feature of the homopolymeric gelators is that it can selectively congeal the diesel part from an oil-water biphasic mixture, which might be useful in oil spill treatment. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 511-521