Solvent-Induced self-assembly in cardanol-based urethane methacrylate comb polymers

Abstract

We report side chain urethane-methacrylate comb polymers based on the renewable resource cardanol and its saturated analogue 3-pentadecyl phenol and their self-assembly into pores, spheres, vesicles, tubes, and so forth. The monomers were synthesized in one pot by coupling 1 equiv. of isophorone diisocyanate with 1 equiv. of cardanol/pentadecyl phenol followed by coupling with 1 equiv. of hydroxyethyl methacrylate. They were polymerized free radically using benzoyl peroxide as the initiator and were characterized by NMR and FTIR, and their molecular weights were determined by gel permeation chromatography. The unique polymer design had sites for self-organization via hydrogen bonding of the side chain urethane units, pi-pi stacking interactions of the aromatic units as well as interdigitation of the long C(15) alkyl side chains in the polymer. The morphologies of solvent cast polymer films were studied using microscopic techniques such as scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. The polymers exhibited three-dimensional honeycomb morphology in CHCl(3), whereas in tetrahydrofuran, they formed spheres. The direct cardanol-derived polymer PCIH showed a tendency for multiple morphologies such as spheres and tubes in tetrahydrofuran