Synthesis and micellization of a novel diblock copolymer of poly(N-isopropylacrylamide)-b-SGLCP and its application in stability of 5CB droplets in aqueous medium

Abstract

A novel diblock copolymer of poly(N-isopropylacrylamide)-b-poly(4-cyanobiphenyl-4-oxyundecylacrylate) (PNIPAM-b-LCP) was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. PNIPAM-b-LCP was formed into the core–shell micelle in an aqueous solution, which consisted of the hydrophobic LCP block in the core and the hydrophilic PNIPAM block in the shell with a critical micelle concentration of 0.043 mg mL⁻¹. The hydrophobic 4-cyano-4′-pentylbiphenyl (5CB, nematic liquid crystal (LC)) was added into the PNIPAM-b-LCP aqueous solution to incorporate hydrophobic LC monomers in the micelle core. The size of the micelles increased as the concentration of the 5CB increased, indicating that the 5CB was successfully loaded in the core. The size of the PNIPAM-b-LCP micelle in water also showed a step-wise decrease at ∼33 °C as temperature increased (or vice versa) due to the lower critical solution temperature (LCST) behavior of the PNIPAM. The combination of the LC properties in the core and the thermo-responsive behaviors in the shell might open new applications in the fields of smart windows, nanoactuation, controlled release, photonics, etc.