A series of weakly basic random copolymers composed of 2-(dimethylamino)ethyl methacrylate (DMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) were synthesized to investigate the influence of charge on their solution behavior. The random comonomer distribution was confirmed via 1H NMR spectroscopy by calculating reactivity ratios and monitoring reaction kinetics. Their pH-responsive behavior was characterized by acid–base titration and zeta potential analysis, revealing a direct correlation between degree of protonation and copolymer charge density. Dynamic light scattering (DLS), transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS) studies revealed acid-induced changes in coil size and conformation, driven by intrachain electrostatic repulsion. Fitting SAXS data to a wormlike chain model combined with a polymer reference interaction site model (WLC-PRISM) enabled quantification of key parameters such as Kuhn length, interaction strength, and effective interaction distance to investigate the backbone flexibility and charge interactions. Higher degree of protonation led to more rigid, expanded coils, while salt screening reduced electrostatic interactions and coil dimensions. Concentration-dependent structural analysis highlighted interchain repulsion in the dilute regime, and structure factor scaling agreed with prior polyelectrolyte studies. Gel Permeation Chromatography – Multi-Angle Laser Light Scattering (GPC-MALLS) confirmed charge-induced coil swelling across a range of molecular weights. In summary, a WLC-based framework, when combined with PRISM-type interaction terms, provides a consistent and physically meaningful description of chain conformation for this class of weakly charged random copolymers within the explored pH, ionic strength, and concentration ranges.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)