Undergraduate Laboratory Experiment Examining Free-Radical and Copper(0)-Mediated Polymerization and Postpolymerization Modification

A three-part undergraduate laboratory experiment enabling third-year undergraduates to compare and contrast core aspects of free radical polymerization with Cu(0)-mediated polymerization is reported. The latter is a common reversible deactivation radical polymerization (RDRP) method. In addition, postpolymerization modification was introduced to students. The first part of this experiment involves the polymerization of tert-butyl acrylate (tBA) by free radical polymerization using a peroxide initiator and characterization of the resulting polymer. The second part involves polymerization of the same monomer via Cu(0)-mediated RDRP. These two protocols provided the opportunity for students to compare the properties of the polymeric products obtained from both reactions. Furthermore, students could experimentally observe how different reaction mechanisms influence the dispersity of polymer molar mass distribution. This serves to complement, extend, and test theoretical concepts introduced in the classroom. The final part of this experiment involves postpolymerization modification of poly(tBA) via ester deprotection to produce poly(acrylic acid). This enables students to appreciate the reactivity, modification, and resulting change in property of polymeric substrates (e.g., hydrophilicity) and how this can be monitored. In the written component of this laboratory experiment, students are required to discuss the debate that exists in the scientific literature regarding the prevailing mechanistic proposals for single-electron transfer-living radical polymerization (SET-LRP) and atom-transfer radical polymerization (ATRP) for this process. This serves as an advanced learning experience for students as part of their undergraduate laboratory program and reinforces the evolving nature of science. This experiment was developed through a cross-institutional collaboration between two Australian universities.