This work reports the preparation of an adhesive primer derived from biobased caffeic acid (CA). CA is decarboxylated to form 4-vinylcatechol (4VC), which is Boc-protected and polymerised by RAFT solution polymerization to yield a range of molecular weight polymers. Polymer molecular weight and structure are analysed by NMR, GPC, DSC and TGA. After deprotection using trifluoroacetic acid (TFA) or heating the catecholic polymer was used as a primer to enhance adhesion between aluminium and a polyurethane coating through the use of dip-coating. Tensile tests indicate that the deprotected catecholic primer improved adhesion from 4.1 to >15 MPa, and effects of molecular weight variation and exposure to water were studied. Catecholic polymers are a major focus of research into biomimetic, sustainable adhesives. The report extends the previous work published by this work with the main innovations being the strategy of Boc protection and deprotection using heat, and the demonstration of the deprotected polymer as a primer. The application of bio-derived catecholic polymers synthesised from caffeic acid have potential industrial value. However, I would suggest that to be considered to be publishable in RSC sustainability a more thorough discussion is needed with regards to the strategy used, particularly around the Boc chemistry and deprotection chemistry/method itself. For example, whilst the authors mention the benefit of gaseous byproducts, boc chemistry, the use of TFA or high temperatures are inevitable drawbacks. Since this chemistry seems to be the main innovation of the paper, I would therefore say that these discussions are necessary in the context of this journal. If these discussions are added there is a sufficient evidence base to support the rest of the conclusions made and the work should be of interest to the readership of this journal. I would therefore recommend publication once this major point and the following queries are addressed.

1. Figure 1 The Mn (SEC) value in (D) is not consistent with the Mn value in (C) whilst the caption only indicates one synthetic condition. These data should be made consistent or the caption modified.
2. P7 data for the coating with deprotected primer and no primer are given. It would be beneficial to compare with the protected primer too, if the data is available at this time.
3. P8 L8 Error on the thickness extrapolation should be quoted.
   What is the effect of changing the primer thickness on the adhesive strength?
   Ellipsometry can measure thicknesses to sub-nm levels – why not use this to measure thickness directly?
4. P8 L5 What evidence is there of covalent bond formation occurring when primer is applied to urethane adhesive? (e.g. in-situ FTIR)

In addition the following minor comments should be addressed.

1. Abstract ‘higher strong adhesion’ should be rephrased.
2. Throughout manuscript – no units are given for molecular weight values. These should be added to all figures, tables and in the text.
3. P2 L8 ‘water resistanct’ should read ‘water resistant’.
4. P2 L10-11 ‘synthesized light-activated adhesive’ should read ‘synthesized a light-activated adhesive’.
5. P2 L15-16 ‘protecting the hydroxyl groups and followed by deprotection’ should read ‘protecting the hydroxyl groups followed by deprotection’.
6. P3 L2 ‘Catechol stability was evaluated at different temperature’ should read ‘Catechol stability was evaluated at different temperatures’.
7. P3 L18 More explanation needed about how molecular weight was calculated from NMR, as according to NMR supplied on P4 aromatic protons from the terminal RAFT agent and repeat unit overlap.
8. P4 Figure 1 Axis titles for graph B do not make sense, and it would be helpful to have an indication what the circles and triangles represent.
9. Figure 2 caption – should be updated to make it clear that the Mn data and graphs are from SEC analysis.
10. P5 & Figure 3 caption: the text often refers to ‘the polymer’, which is ambiguous. The specific polymer the authors are discussing should be made more clear.
11. P6 L3 ‘deprotection proceeded quantitatively within several hours’ – how many hours?
12. P6 References should be added to support the statement that ‘urethane adhesives are not effective for adhering to aluminium’.
13. P7 – describe how PU was applied briefly, or explicitly refer to the supporting information.
14. P7 L8 It would be preferable to measure the actual adhesion strength on an instrument which can give an accurate value.
15. P7 Figure 4 Tensile test loading rate, but not temperature, are mentioned in S5; this could be noted on the plot or mentioned in the text in main article.
16. P8 Table 1 If Stress values are measured as an average of multiple measurements, why is no value for error quoted for these values?
17. Table 1 – the authors mention the maximum stress measurable is 15MPa in the text but values of 16 MPa in this table.
18. Table 1 – how was the % cohesive failure determined?
19. P9 L1 ‘Practical’ adhesive design involving debonding by immersion in TFA for 2 days is dubious – would be better to refer to debonding by heat specifically if this was intended.
20. Supporting information – cam the authors clarify in the synthesis sections what is meant by ‘syringe technique’? This is not clear from the descriptions.
21. Figure S6 – state the gas used during TGA analysis in the caption for clarity.
22. Figure S10 – why was only SEC data included for this part of the study and not NMR?

The authors have performed an update of their manuscript based on the detailed sets of reviewer’s comments received. The response to reviewers mostly explains and justifies the decisions made when revising the manuscript, both in terms of the revisions made and defending other aspects of the work. These updates have improved the manuscript and added valuable further discussions and clarifications.
However, the main point of reviewer 1 that "a more thorough discussion is needed with regards to the strategy used, particularly around the Boc chemistry and deprotection chemistry/method itself" in relation to sustainability has not been addressed in the revisions made to a satisfactory extent. As such, I would judge that this aspect of the manuscript should be improved upon before it is accepted for publication.