This manuscript reports the synthesis of three alkoxyamine-based NMP² photoinitiators bearing benzophenone, naphthol, and anthracene chromophores. The authors systematically investigated the effects of chromophore substitution on UV-Vis absorption, photolysis kinetics, and polymerization control in nitroxide-mediated photopolymerization. The study offers a systematic comparison of three chromophores with increasing conjugation, filling a gap in structure–property relationships for NMP² initiators. Overall, the work is suitable for publication in Polymer Chemistry after minor revisions. The following points should be addressed before publication:
1. Quantitative kinetic analysis is lacking. The relationship between photolysis decay constants (kdecay) and polymerization rates or molecular weight control is only qualitatively described. It would strengthen the paper to include a correlation plot or table linking decay constants，polymerization rate (e.g., Rp), and final PDI for the three initiators.
2. Visible-light polymerization demonstration is incomplete. Although the anthracene-based initiator (4) shows absorption at 405 nm, all photopolymerization experiments were performed using a broadband 320–500 nm source. To convincingly claim visible-light responsiveness, a separate experiment using a 405 nm LED (or narrow-band filter) should be performed, at least for initiator 4, showing conversion and molecular weight evolution under purely visible light.
3. PDI values remain relatively high for some initiators. Initiator 2 and 4 give PDIs >2.0, which is higher than typical NMP systems (often <1.5). The authors should provide a more detailed discussion of possible reasons (e.g., chain transfer, uneven photolysis, oxygen inhibition, or inadequate mediation). Suggestions for improving PDI (e.g., lower initiator concentration, temperature control) would be welcome.
4. Minor inconsistencies in data presentation. In the text (page 22), it is stated that initiator 3 requires “almost 3500 s to reach the same level” while the half-life in Table 2 is 920 s. This is not contradictory but could confuse readers. Please clarify or rephrase to avoid misinterpretation.
5. Figure 5 caption and text should ensure consistent use of “half-life” vs “t₁/₂” and correct units.