Controlled orthogonal reactions in neat polymerizations

Polymerization reactions in neat conditions have had a long history since the beginning of synthetic polymers. The absence of a solvent is attractive for many applications, but also poses challenges in carrying out multiple polymerization reactions simultaneously or sequentially. In this Minireview, we focus on recent development of controlled orthogonal reactions used in neat systems. We first overview the available functional groups, as well as their synthesis from neat polymerization reactions, categorized by the involved atoms such as carbon only, carbon & oxygen, carbon & nitrogen, and carbon & sulfur. We then summarize literature reports, mostly from the past three years, that utilized orthogonal reactions to synthesize polymers with novel chemical structures for emerging applications including 3D printing, multimaterials, optical materials, and photo-responsive materials. Last, we discuss future directions for this exciting field that will unlock opportunities for unprecedented chemical structures, microstructures, material processing techniques, and material properties. Consequently, we hope this Minireview guides the design of orthogonal reactions in neat polymerizations for the synthesis of next-generation structural and functional polymer materials.