Polymer Characterization by NMR, GPC, and pH Titration

Polymer structure was characterized by nuclear magnetic resonance (NMR) spectroscopy via ¹H NMR in CDCl₃ (Bruker 500 MHz) and analyzed using TopSpin 3.5 software. Polymer molecular weight was characterized by gel permeation chromatography (GPC); polymers were dissolved in butylated hydroxytoluene–stabilized tetrahydrofuran with 5% DMSO and 1% piperidine, filtered through a 0.2-μm polytetrafluoroethylene filter, and characterized using GPC against linear polystyrene standards (Waters, Milford, MA). pH titrations were performed using a SevenEasy pH meter (Mettler Toledo) with 10 mg of polymer dissolved in 10 ml of 100 mM NaCl acidified with HCl, as previously described (15 (link)). Polymer was titrated from pH 3.0 to 11.0 using 100 mM NaOH added stepwise, and pH was recorded after each addition.