Synthesis and phase behavior of a dual-responsive graft amphiphilic polymer via a green one-pot condensation approach

A novel dual-responsive (temperature and pH) graft amphiphilic polymer, denoted gPMF, was successfully synthesized via an environmentally friendly one-pot condensation polymerization. The polymer architecture features a hydrophobic poly(propylene glycol) diglycidyl ether (PPGDGE) backbone functionalized with hydrophilic Jeffamine FL-1000 side chains, with monoethanolamine (MEA) serving as a regulator for the hydrophilic-hydrophobic balance. Structural characterization via FTIR spectroscopy confirmed the successful nucleophilic addition and ring-opening reaction. Gel permeation chromatography (GPC) revealed number-average molecular weights (M _n) in the range of 1.1 × 10⁴ to 1.6 × 10⁴ g mol^-1. Dynamic light scattering (DLS) analysis showed that gPMF self-assembles into stable micelles with a hydrodynamic diameter of ∼20 nm, independent of the monomer feed ratio. The phase transition behavior was systematically investigated via turbidity measurements at 600 nm. The cloud point (T _t) decreased with increasing polymer concentration but increased with higher FL-1000 content or lower pH. Notably, the graft architecture exhibited a significantly faster phase transition rate compared to a linear analogue, attributed to enhanced local hydrophobic interactions and efficient chain relaxation. This work demonstrates that the phase transition temperature can be precisely tuned by adjusting composition and environmental stimuli, making gPMF a promising candidate for smart materials in controlled drug delivery and sensing applications.