Advances in atom transfer radical polymerization (ATRP) have enabled the precise design and preparation of nanostructured polymeric materials for a variety of biomedical applications. This paper briefly summarizes recent developments in the synthesis of bio-therapeutics for drug delivery based on linear and branched block copolymers and bioconjugates using ATRP, which have been tested in drug delivery systems (DDSs) over the past decade. An important trend is the rapid development of a number of smart DDSs that can release bioactive materials in response to certain external stimuli, either physical (e.g., light, ultrasound, or temperature) or chemical factors (e.g., changes in pH values and/or environmental redox potential). The use of ATRPs in the synthesis of polymeric bioconjugates containing drugs, proteins, and nucleic acids, as well as systems applied in combination therapies, has also received considerable attention.

Block copolymers utilizing oligomeric poly(pentylene‐co‐hexylene carbonate)diol modified with 2,4‐diisocyanatotoluene and further with 2‐bromo‐N‐(3‐hydroxypropyl)‐2‐methylpropanamide were synthesized and utilized as Activators ReGenerated by Electron Transfer Atom Transfer Radical Polymerization macroinitiators to obtain a first generation of multifunctional recycling additives with poly(glycidyl methacrylate‐co‐butyl methacrylate‐co‐methyl methacrylate) side chains, which could act as chain extenders. Then, chosen additive was reacted with a radical scavenger, 3,5‐ditertbutyl‐4‐hydroxybenzoic acid (DHBA), to obtain a second generation of reactive additives. Those copolymers had different numbers of epoxy groups per polymer chain, and different number of epoxides opened with DHBA, hence showed a range of properties, and were utilized as reactive modifiers for polylactide (PLA) extrusion melting. The first‐generation modifiers caused an increase in PLA's blends relative melt viscosity, stabilized material properties, and enhanced impact strength, while the second‐generation modifiers with more than 8 % of epoxide ring opened showed worse properties. However, they managed to suppress the UV degradation of PLA blend plates.

We report a thermal hydrogen atom transfer (HAT) depolymerization strategy for the efficient chemical recycling of unmodified commercial poly(methyl methacrylate) (PMMA). A reaction engineering approach combining controlled radical concentration with continuous monomer removal enables efficient depolymerization under practical conditions without light, chlorinated solvents, or high dilution. A semibatch protocol employing multiple small additions of cumene hydroperoxide (CHP) and continuous removal of methyl methacrylate (MMA) suppressed radical side reactions and shifted the equilibrium toward monomer formation. At a repeating-unit concentration of 1.83 M and a total CHP loading of 3 mol %, depolymerization reached 90% with only 2% monomer consumption. The method remained effective at 3.00 M, scaled to 20 g of polymer (79% depolymerization, 4.5 mol % CHP loading), and was effective for commercial Plexiglas containing stabilizing additives. Recovered MMA was successfully repolymerized, demonstrating its circularity. These results establish radical concentration control and continuous monomer removal as the key design principles for hydroperoxide-assisted thermal HAT depolymerization.