A Comprehensive Laboratory Design for Amphoteric Polyelectrolyte Synthesis and Hydrogel Functionalization toward the Development of Innovation Competence

Abstract

To address the predominance of verification-based exercises and the limited opportunities for inquiry-based training in polymer chemistry laboratory courses, this study developed a comprehensive instructional experiment that engages upper-division undergraduates in authentic scientific inquiry. The experiment spans the full sequence of “molecular design–controlled synthesis–structural characterization–property regulation–functional extension” and is conducted over three experimental cycles. In the first cycle, students prepared linear amphoteric polyacrylamide through aqueous free-radical copolymerization of acrylamide (AM), acrylic acid (AA), and either 2-(methacryloyloxy)ethyl trimethylammonium chloride (DMC) or 2-(acryloyloxy)ethyl trimethylammonium chloride (DAC). Using a “collaborative grouping with focused variables” strategy, different groups investigated the effects of reaction temperature, cationic monomer structure, reaction time, and initiator dosage on the apparent viscosity of the products. In the second cycle, hydrogels were prepared under the optimized conditions identified in the first cycle using poly(ethylene glycol) diacrylate (PEGDA) as the cross-linker, and the relationships among cross-linker content, network structure, and water uptake were examined. In the third cycle, three fluorescent dyes were incorporated to prepare luminescent hydrogels and extend the materials toward potential optical applications. Finally, the entire class integrated the shared data from all groups to construct a “synthesis condition–structure–property–function” relationship map and used laboratory reports to justify evidence-based conclusions. From an educational perspective, students shifted from following prescribed procedures to actively proposing hypotheses, controlling variables, and interpreting FT-IR and 1H NMR spectra, while gaining experience with synthesis, characterization, and property-testing methods commonly used in academic research and industrial development. Assessment using rubrics aligned with the three learning objectives yielded attainment values of 0.78–0.84, exceeding the benchmark of 0.70, indicating effective improvement in multivariable experimental design, data integration, scientific reasoning, and teamwork. The individual modules can be adjusted or simplified according to available class time, laboratory resources, and student preparation, making the experiment suitable for third-year and more advanced undergraduates and adaptable to polymer laboratory courses at different instructional levels.