Self‐Organization of Amphiphilic Copolymers into Nanoparticles: Study by 1H NMR Longitudinal Relaxation Time

Abstract

The aggregation and nanoparticle formation of a novel amphiphilic polymer 1 based on polyethylene glycol has been studied by 1H NMR longitudinal relaxation time (T 1). The T 1 of proton NMR, which may be associated with the mobility of molecular chains showed different trends when the amphiphilic polymer was dissolved in aqueous and organic solvents. It was observed that the T 1 relaxation time of protons on hydrophobic chains decreases with the increase in concentration in aqueous media and stabilizes above the critical micelle concentration (CMC). The stabilization of T 1 relaxation time of protons on hydrophobic chains in aqueous media occurs because of the aggregation of hydrophobic side chains in the core of nanospheres formed due to hydrophobic interactions. However, in organic solvent, the T 1 of protons on hydrophobic as well as hydrophilic chain of amphiphilic polymer did not show any evidence of particle formation. Thus, the restricted motion of the side‐chain protons may be indicative of nanoparticle formation in aqueous solution and non‐formation of such particles in organic solution.