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Regulating the aqueous polymerization of acrylic acid (AA) is a major opportunity for future materials design, requiring the development of scalable, industry‐oriented procedures that afford modest molar mass and dispersity control without long reaction times and environmentally demanding conditions. To address these challenges, this report presents the rapid copolymerization of aqueous mixtures of AA and sodium acrylate using an inexpensive and scalable protocol based on alkyl iodides/sodium iodide as mediators in water.

The utilization of sodium iodide, potassium persulfate, and a thermal radical initiator enables facile access to PAA via the direct reverse iodine transfer polymerization of acrylic acid. This polymerization proceeds rapidly in aqueous media using inexpensive and commercially available reagents.

Core cross-linked star (CCS) polymers with radiating arms composed of high-order multiblock copolymers have been synthesized in a one-pot system via iterative copper-mediated radical polymerization. The employed "arm-first" technique ensures the multiblock sequence of the macroinitiator is carried through to the star structure with no arm defects. The versatility of this approach is demonstrated by the synthesis of three distinct star polymers with differing arm compositions, two with an alternating ABABAB block sequence and one with six different block units (i.e. ABCDEF). Owing to the star architecture, CCS polymers in which the arm composition consists of alternating hydrophilic-hydrophobic (ABABAB) segments undergo supramolecular self-assembly in selective solvents, whereas linear polymers with the same block sequence did not yield self-assembled structures, as evidenced by DLS analysis. The combination of microstructural and topological control in CCS polymers offers exciting possibilities for the development of tailor-made nanoparticles with spatially defined regions of functionality.

Macromolecular architecture is a key factor determining the materials properties of polymers. Exploration of novel structural arrangements has become a viable means to develop advanced functional nanomaterials. Recent developments in polymer chemistry have forged robust synthetic platforms for innovative polymeric materials with highly regulated structures, functionalities, and compositions. This review summarizes the latest synthetic strategies for well-defined polymer architectures through covalent chemistry, with the focus on four main types of well-defined macromolecular constructs.

The first example of core cross-linked star (CCS) polyrotaxane was prepared using the poly(ϵ-caprolactone) (PCL) CCS three-dimensional (3D) scaffold. The 3D CCS polymer was firstly prepared through the "arm-first" approach. Then, the "arms" of the resultant PCL CCS polymer were threaded with α-cyclodextrins (α-CDs). The threaded α-CDs were permanently locked by the "click" reaction of terminal alkyne functionalities of the star polymers with the azide-functionalized end caps to afford the CCS polyrotaxanes. All analytical results confirm the formation of the CCS polyrotaxanes and reveal their characteristics, including fluorescence under UV, a channel-type crystalline structure, a two-step thermal decomposition, and a unique core-shell structure in great contrast to the polymer precursors.